Clinicians › Shoulder
Shoulder Instability
Traumatic unidirectional and atraumatic multidirectional instability — pathomechanics, structural failure patterns, and clinical differentiation for treatment planning.
For patients: a plain-language version of this topic is available. See the patient guide.
Overview¶
Shoulder instability management relies on precise evaluation of bone loss to determine surgical indications and predict outcomes [17]. The MOON Shoulder Instability Study has enrolled the largest cohort of patients undergoing shoulder stabilization to date [1]. Current consensus aims to improve diagnosis and treatment through universal agreement on outcome measurement tools and tailored treatment based on pathology, patient age, activity demands, and surgeon skills [15]. Proper assessment of glenoid bone loss is critical, as the indications for an isolated soft-tissue procedure in anterior shoulder instability are now narrower; the ideal candidate presents with minimal glenoid bone loss (13.5%) [53]. In the interim, surgical soft-tissue stabilization might be more aggressively indicated in cases of primary shoulder dislocation, whereas recurrent instability with bone loss should be referred to experienced high-volume specialists [79].
Non-operative management carries significant long-term risks, with nearly 40% of patients treated non-operatively for posterior shoulder instability eventually requiring surgery [6]. At long-term follow-up of 17 years, a high rate of poor outcomes was observed following nonoperative management of anterior shoulder instability [7]. Conversely, the 1-year outcomes in a prospective study suggest superiority of operative over non-operative treatment for posterior shoulder instability [9]. Most patients younger than 40 years with shoulder instability who were initially treated nonoperatively for 6 months were definitively treated without surgery [13]. Surgical options include free bone block procedures, which are considered safe and clinically effective for the management of anterior shoulder instability with glenoid bone loss [37]. Long-term data suggest that the benefits of the Latarjet procedure are durable, and the procedure should be considered as a viable and reliable treatment option for anterior glenohumeral instability [74].
Outcome reporting remains a challenge due to substantial variability, with 28 different outcome tools used in high-impact anterior shoulder instability literature, making it difficult to compare outcomes between studies [76]. Despite the wide array of available PROMs for assessing shoulder instability surgery outcomes, the availability of clinically significant outcome thresholds such as MCID and PASS remains relatively limited [233]. The French version of the Western Ontario Shoulder Instability Index (WOSI-Fr) is recommended for following up patients with shoulder instability [57]. RCTs reporting on shoulder instability surgery are well performed but poorly reported [56]. More than a third of continuous outcomes in anterior shoulder instability trials had a continuous fragility index less than the reported loss to follow-up [10]. This highlights the need for a consensus on definition of recurrence across shoulder instability studies [8]. A systematic review supports the need for standardized outcome reporting after arthroscopic anterior shoulder instability surgery in adolescents [235].
Anatomy & Pathophysiology¶
Osseous Anatomy¶
The glenoid cavity is a shallow, convex socket shaped like an inverted pear, approximately one-third the size of the humeral head [88]. The subchondral bone of the glenoid is relatively flat, with the articular concavity augmented by cartilage and a circumferential labrum [92]. The glenoid articular surface and labrum combine to create a socket that is approximately 9 mm deep in the superoinferior direction and 5 mm deep in the anteroposterior direction [100]. The glenoid labrum increases the depth of the socket by 50% around the humeral head, increasing the glenoid surface to 75% of the humeral head vertically and 57% horizontally [100]. The glenoid diameter ranges from 18-30 mm (superior anteroposterior) to 21-35 mm (inferior anteroposterior) and 30-48 mm (superoinferior height) [99]. Glenoid inclination averages 4.2 degrees, with a range of –7 to 20 degrees [99]. Glenoid version averages 1.5 degrees retroversion, with a range of 10.5-9.5 degrees anteversion [99]. The glenoid surface area ranges from 4-6 mm, and glenoid cartilage thickness is 2.16 mm [99]. The glenoid radius of curvature ranges from 22-28 mm, which is 2 to 3 mm larger than that of the humeral head [99].
The humeral head is spherical with a diameter of 37 to 57 mm [88]. The articular surface of the humeral head is essentially spherical, with an arc of approximately 160 degrees covered by articular cartilage [99]. The radius of curvature of the humeral head is approximately 25 mm and is slightly larger in men than in women [99]. Humeral head radius of curvature ranges from 23-28 mm, smaller in women than men [99]. Humeral head surface area ranges from 11-19 mm, and humeral head cartilage thickness is 1.44 mm [99]. The most superior portion of the articular surface of the humeral head averages 8 mm above the greater tuberosity [88]. The superior margin of the humeral head articular surface is normally superior to the top of the greater tuberosity by 8 to 10 mm [99]. The head height is approximately 5.6 cm above the superior border of the pectoralis major tendon [103].
Humeral version averages 29.8 degrees, with a range of 10 to 55 degrees [88]. Humeral head retroversion ranges from 0-55 degrees, dependent on measurement method and highly variable among individuals [99]. The humeral head is retroverted 30 degrees relative to the transepicondylar axis of the humerus [103]. The humeral head is inclined approximately 130 degrees with respect to the humeral shaft [88]. Humeral head inclination ranges from 30-55 degrees [99]. The average neck-shaft angle is 45 degrees (±5 degrees), with a range of 30 to 50 degrees [99]. Head-shaft angle ranges from 30-55 degrees [99]. The humeral head averages 19° of retroversion and 41° of inclination (neck-shaft angle) [92]. Medial (coronal) humeral offset ranges from 4-14 mm, and posterior (transverse) humeral offset ranges from –2 to 10 mm [99]. The distance from the lateral base of the coracoid process to the lateral margin of the greater tuberosity is called the lateral humeral offset [99].
The glenoid averages 5° of retroversion in relation to the axis of the scapular body [92]. The glenoid is retroverted approximately 5 degrees relative to the scapular body [103]. The scapula is anteverted on the chest wall approximately 30 degrees relative to the body [103]. The scapula spans the second through seventh ribs and serves as an attachment for 17 muscles [103]. The anatomic neck of the proximal humerus is located at the junction of the articular surface and the tuberosities [88]. The anatomic neck is directly below the humeral head and serves as an attachment for the shoulder capsule [103]. The surgical neck represents an indistinct region (metadiaphyseal junction) below the tuberosities but above the humeral shaft [88]. The surgical neck is more distal and more often involved in fractures [103].
The greater tuberosity serves as the attachment site for the supraspinatus, infraspinatus, and teres minor tendons of the rotator cuff [88]. The lesser tuberosity serves as the attachment site for the subscapularis tendon [88]. The bicipital groove lies between the greater and lesser tuberosities and serves as a pathway for the long head of the biceps [88]. The distal aspect of the bicipital groove is internally rotated with respect to the proximal portion [88]. The coracoid process has attachments to the coracoacromial ligament, coracoclavicular ligaments (conoid and trapezoid), conjoined tendon (coracobrachialis and short head of biceps), and pectoralis minor [103]. The coracobrachialis muscle and the short head of the biceps tendon originate from the coracoid process [92]. The pectoralis minor muscle inserts onto the medial coracoid process [92].
The acromion has three ossification centers: the metacromion (base), the mesoacromion (middle), and the preacromion (tip) [92]. Failure of fusion of the acromial ossification centers results in os acromiale [92]. The acromion, coracoacromial ligament, and coracoid process form the coracoacromial arch, a rigid bony-ligamentous structure that imparts stability to the shoulder girdle [88]. The clavicle is the first bone to ossify (fifth week of gestation) and is the only long bone to ossify by intramembranous ossification [92]. The medial (sternal) epiphysis of the clavicle is the last ossification center to fuse, at age 20 to 25 years [92]. The primary blood supply of the clavicle is periosteal, with no nutrient artery present [92].
The proximal humerus has three centers of ossification: the humeral head (4 to 6 months), the greater tuberosity (1 to 3 years), and the lesser tuberosity (3 to 5 years) [92]. The proximal humeral ossification centers fuse to the shaft at age 17 to 20 years [92]. The formation of the humerus begins with the appearance of the cartilage anlage, which is present by the fifth week of gestation [96]. The primary ossification center for the humerus appears at about the sixth week [96]. By the time of birth, the entire humeral diaphysis is completely ossified [96]. The proximal humerus is primarily cartilaginous at birth, with ossification centers detectable by ultrasonography as early as the 38th week of gestation [96]. The ossification center for the humeral head is usually present at birth [96]. The greater tuberosity ossification center appears by 1 to 3 years of age [96]. The lesser tuberosity ossification center appears by 5 years of age [96]. The proximal humeral ossification centers fuse by 5 to 7 years of age to form the humeral head [96]. The proximal humeral physis closes by 14 to 17 years of age in girls and by 16 to 18 years in boys [96]. Humeral retroversion averages 65 degrees in infants and young children and gradually decreases, approaching adult values by 11 years of age [96]. Eighty percent of subsequent humeral growth comes from the proximal humeral physis, accounting for approximately 40% of the growth of the entire upper extremity [96]. Less than 75% of humeral growth occurs before 2 years of age, and more than 85% occurs by 8 years of age [96].
The scapula in humans is suspended by muscles alone and has shifted caudally from the cervical position in lower animals [97]. The scapular index is extremely high in pronograde animals with a long, narrow scapula, while the scapula is broader in humans and other primates [97]. Broadening of the infraspinatus fossa has resulted in a change in the vector of muscle pull from the axillary border of the scapula to the glenoid fossa [97]. This adaptation allows the infraspinatus and teres minor muscles to be more effective in their roles as depressors and external rotators of the humeral head [97]. The supraspinatus fossa and muscle have changed little in size or shape over time [97]. The acromion has enlarged over time, reflecting the increasing role of the deltoid muscle in shoulder function [97]. The broader attachment of the deltoid on the acromion and its more distal insertion on the humerus have increased its mechanical advantage in shoulder motion [97]. The coracoid process has undergone an increase in size over time [97]. With the shoulder in 90 degrees of abduction, the coracoid extension over the glenohumeral joint can mechanically limit anterior translation of the humerus relative to the glenoid [97]. In one shoulder tested after sectioning the capsule, it would not dislocate anteriorly in full abduction until the coracoid process was removed [97].
Ligamentous & Soft Tissue Anatomy¶
The superior shoulder suspensory complex (SSSC) provides a stable connection between the scapula and the axial skeleton [92]. The SSSC is composed of the glenoid, coracoid process, coracoclavicular ligaments, distal clavicle, AC joint, and acromion [92]. The superior strut of the SSSC comprises the middle clavicle [92]. The inferior strut of the SSSC comprises the lateral scapular border/spine of the scapula [92]. The sternoclavicular (SC) joint is the only true diarthrodial articulation between the upper appendicular and axial skeletons [92]. The posterior SC joint capsule and ligaments are the primary stabilizers to anterior and posterior translation of the medial clavicle [92]. The posterior sternoclavicular ligament is the strongest and primary restraint to anteroposterior instability of the SC joint [103]. The SC joint rotates 30 degrees with shoulder motion [103].
The acromioclavicular (AC) joint is a small diarthrodial joint with an interposed fibrocartilaginous disk [92]. The scapula has only one true diarthrodial articulation, the acromioclavicular (AC) joint [92]. The superior and posterior AC ligaments are the primary stabilizers to anterior and posterior (horizontal) translation of the clavicle [92]. The AC ligaments prevent anteroposterior displacement of the clavicle [103]. The posterior and superior AC ligaments are considered the strongest [103]. The coracoclavicular ligaments (conoid: medial; trapezoid: lateral) are the primary stabilizers to superior (vertical) translation of the distal clavicle [92]. The coracoclavicular ligaments prevent superior displacement of the distal clavicle [103]. The trapezoid ligament is located approximately 25 mm from the AC joint [103]. The conoid ligament is located approximately 45 mm from the AC joint and is stronger than the trapezoid ligament [103].
The coracoacromial ligament contributes to anterosuperior stability in rotator cuff deficiency [103]. The coracoacromial ligament should be preserved with irreparable cuff tears to prevent anterosuperior escape [103]. The acromial branch of the thoracoacromial artery runs on the medial aspect of the coracoacromial ligament [103]. The coracoacromial ligament is the arthroscopic landmark for a complete release of the rotator interval for adhesive capsulitis [103]. The transverse humeral ligament is an important stabilizer of the biceps tendon [103].
The superior transverse scapular ligament arises from the medial base of the coracoid overlying the suprascapular notch [92]. The spinoglenoid ligament overlies the suprascapular nerve at the spinoglenoid notch [92].
Vascular & Neural Anatomy¶
The proximal humerus receives its blood supply from the anterior and posterior humeral circumflex branches from the third division of the axillary artery [88]. The anterior humeral circumflex artery provides vascular inflow to the humeral head by way of its terminal anterolateral branch known as the artery of Laing (also known as the arcuate artery) [88]. The anterolateral ascending branch of the anterior humeral circumflex artery provides the primary blood supply to the humeral head [92]. The terminal intraosseous portion of the anterior humeral circumflex artery enters at the proximal aspect of the intertubercular groove as the arcuate artery [92]. The posterior humeral circumflex artery travels with the axillary nerve, enters the quadrilateral space posteriorly, and anastomoses with a branch of the anterior circumflex to supply the posterior cuff [88]. The anterior and posterior humeral circumflex arteries provide a rich blood supply to the proximal humerus [96]. 64% of the humeral head blood supply arises from the posterior humeral circumflex artery [96].
The suprascapular artery runs superior to the superior transverse scapular ligament, and the nerve runs deep to the ligament [92]. The suprascapular artery passes superior to the superior transverse scapular ligament and the suprascapular nerve passes inferior to the ligament through the notch [103]. Entrapment of the suprascapular nerve at the superior transverse scapular ligament causes denervation of both the supraspinatus and infraspinatus [92]. Both the artery and nerve pass inferior to the inferior transverse scapular ligament at the spinoglenoid notch [103]. Entrapment, traction, or compression of the suprascapular nerve at the spinoglenoid notch causes denervation of the infraspinatus [92].
The brachial plexus is prone to injury when the proximal humerus is injured in fractures or dislocations, or during traction [96]. The axillary nerve circles the humeral neck just inferior to the glenohumeral joint as it courses posteriorly [96].
Muscular Anatomy¶
The subscapularis originates from the anterior scapula and inserts anteriorly onto the lesser tuberosity [96]. The greater tuberosity provides attachment superiorly and posteriorly for the supraspinatus, infraspinatus, and teres minor [96]. The deltoid forward flexes and abducts the shoulder and courses from the clavicle and acromion superiorly, coalescing into a common tendinous insertion onto the lateral upper third of the humeral shaft [96]. The pectoralis major powers adduction and internal rotation due to its tendinous insertion anteriorly onto the lateral wall of the bicipital groove [96]. The pectoralis major forms the roof of the distal continuation of the bicipital tunnel, which is a closed space that extends proximally to the glenohumeral joint [96].
Kinematics & Joint Mechanics¶
Normal shoulder motion is approximately two-thirds glenohumeral and one-third scapulothoracic [92]. The capsule of the glenohumeral joint extends from the glenoid rim, progressing laterally toward the surgical neck of the humerus and blending with the tendons of the rotator cuff musculature [96]. The posteromedial metaphysis, a portion of the physis, and the epiphysis are intracapsular [96]. A large part of the proximal humeral physis is extracapsular, making it susceptible to traumatic injury [96]. The proximal humeral physis is irregularly shaped, with its apex located on the posteromedial portion of the proximal humerus [96]. The periosteum is thicker and stronger in the posteromedial portion of the proximal humerus compared to the anterolateral portion [96].
Classification¶
Historical and General Classifications¶
Since the 1980s, 18 classifications have been developed to define sub-groups of shoulder instability, but none have demonstrated strong measurement properties [2]. In 1979, Rockwood distinguished shoulder instabilities based on the presence or absence of trauma [2]. The Thomas and Matsen classification introduced the AMBRI acronym for atraumatic multidirectional instability, which is often bilateral and requires rehabilitation and inferior capsular shift [2]. This same classification introduced the TUBS acronym for traumatic unidirectional instability with a Bankart lesion, which often requires surgery [2]. The Stanmore classification, introduced in 2004, encompasses Polar type I (true TUBS), Polar type II (true AMBRI), and Polar type III (atraumatic with functional origin) [2]. It also includes presentations of instability that combine multiple categories [2]. The Lewis et al. classification system is all-inclusive and recognizes that more than one pathology can occur in an individual shoulder [4]. The Trauma-instability-voluntarism classification is useful for comparing pathogenesis and treatment results in patients with glenohumeral instability [202]. The 2010 classification system categorizes instability based on frequency, aetiology, direction, and severity [114]. Discrepancies in the definition and classification of multidirectional instability can make diagnosis and treatment selection challenging [196]. Shoulder instability cannot reliably be classified using the ICD-9 coding system [137].
FEDS Classification¶
The FEDS system has content validity and is highly reliable for classifying glenohumeral instability [215]. The frequency and etiology components of the FEDS classification may be helpful in identifying patients with a higher likelihood of undergoing surgical treatment [44, 45, 46]. Patient demographic characteristics in a study on Western Ontario Shoulder Instability Index administration were classified according to the Frequency, Etiology, Direction, and Severity classification system [294].
Gerber Classification¶
The Gerber classification distinguishes multidirectional instability from multidirectional hyperlaxity, considering hyperlaxity an individual constitution rather than a primary disease [52]. It includes chronic locked dislocation, unidirectional instability without hyperlaxity, unidirectional instability with hyperlaxity, multidirectional instability without hyperlaxity, multidirectional instability with multidirectional hyperlaxity, and uni- or multidirectional voluntary instability [52]. Class A static instabilities are defined by the absence of classic symptoms of instability yet the humeral head is displaced and fixed superior, anterior, or posterior relative to its normal position on the glenoid fossa [52]. The diagnosis of Class A static instabilities is radiological, not clinical [52]. These static instabilities may remain asymptomatic for a long period and can co-exist with dynamic instabilities, requiring a decision as to which instability has priority in treatment [52].
Class A1 Static Superior Subluxation: This condition is present if the normal distance between the undersurface of the acromion and the most cranial aspect of the humeral head on an AP radiograph is decreased [52]. Seven millimetres is currently the value used to define static superior subluxation [52]. The cause of cranial migration seems to be insufficiency of the infraspinatus in the presence of a supraspinatus tear [52]. Loss of the acromiohumeral distance to less than 7 mm is associated with loss of strength of abduction and external rotation [52]. Static superior subluxation carries a poor prognosis for repair of the rotator cuff tear and is considered a predictor of an irreparable tear [52]. Superior static subluxation is essentially irreversible by conventional repair techniques [52].
Class A2 Static Anterior Subluxation: This is a fixed anterior position of the humeral head on the glenoid fossa, often manifesting as moderate to severe shoulder pain and loss of anterior elevation [52]. It is usually detected on CT scans or MRI scans taken with the arm in neutral rotation [52]. Static anterior subluxation usually is not associated with recurrent anterior shoulder instability [52]. To develop a static anterior subluxation without any previous operation, a combination of a subscapularis tear, a supraspinatus tear, and fatty degeneration of the infraspinatus muscle seems necessary [52]. Static anterior subluxation has been irreversible with soft tissue procedures [52].
Class A3 Static Posterior Subluxation: This is a fixed posterior position of the humeral head on the glenoid fossa on CT or MRI scans with the arm in neutral rotation [52]. It is most frequently but not always associated with congenital dysplasia of the glenoid or with degenerative glenohumeral joint disease [52]. Static posterior subluxation may be associated with glenoid deformations such as those classified by Walch and co-workers [52]. Static posterior subluxations are generally found to be irreversible [52].
Class A4 Inferior Subluxation: This is characterized by straight inferior translation of the humerus relative to the glenoid fossa [52]. Inferior subluxation after trauma and surgery, if not associated with permanent nerve injury, usually resolves within 6 weeks but always resolves within 2 years [52]. Inferior subluxation caused by infection tends to result in joint surface destruction and only successful treatment of infection results in resolution of the inferior subluxation [52].
Posterior Shoulder Instability (ABC Classification)¶
The ABC classification distinguishes three groups of posterior glenohumeral instability with two different subtypes based on the pathomechanical type of instability and the current standard of treatment [173]. It distinguishes three groups based on the nature of pathology (first-time, dynamic, or static) and two different subtypes based on the pathomechanical causes [58]. The classification aims to facilitate diagnosis and assist the treatment decision-making process for posterior shoulder instability [58]. An international expert Delphi consensus statement recommends that posterior shoulder instability be classified by the ABC classification [77].
Other Specific Classifications and Systems¶
Walch Classification: Used to classify glenoid deformities in primary glenohumeral osteoarthritis [303]. Snyder Classification: A reliable system for identifying SLAP lesions among experienced shoulder surgeons [214]. Glenoid Bone Loss Classification: A proposed classification system is a helpful guide to the degree of glenoid bone loss when embarking on revision shoulder arthroplasty [213]. Glenoid Morphology Clusters: The formation of clusters based on glenoid morphology indicates that patterns exist in the types of glenoid defects, highlighting a need to further investigate a three-dimensional classification system [222]. Chronologic Classification: A chronologic classification based on dynamic pathophysiologic reasoning was formulated to explain the time-dependent, recurrence-dependent worsening of labral and ligamentous pathology in posttraumatic anterior shoulder instability [86]. Gilbert Grading: Categorizes impairment of shoulder abduction in obstetric brachial plexus palsy into four grades based on the range of abduction [281].
Clinical Presentation¶
Definitions and Classification¶
Shoulder instability is defined as a condition wherein the patient experiences symptoms of some shoulder problem, distinguishing it from asymptomatic laxity [69]. Non-traumatic shoulder instability (NTSI) is defined as abnormal movement or position of the shoulder leading to pain, subluxation, or dislocation and functional discomfort without a significant history of injury [2]. The AMBRI acronym describes atraumatic multidirectional instability, bilateral involvement, and a treatment approach often requiring rehabilitation and inferior capsular shift [2]. The TUBS acronym describes traumatic unidirectional instability with a Bankart lesion, often requiring surgery [2].
The Stanmore classification encompasses three categories: Polar type I (traumatic structural), Polar type II (atraumatic structural), and Polar type III (atraumatic with functional origin due to muscle patterning disorders or habitual non-structural) [2]. This classification recognizes that more than one pathology can occur in an individual shoulder [4]. The Bayley et al. classification system is anchored by three polar groups: traumatic structural, atraumatic structural, and habitual nonstructural (muscle patterning) [78]. In this system, traumatic structural instability is characterized by significant trauma, often a Bankart defect, usually unilateral presentation, and no abnormal muscle patterning [78]. Atraumatic structural instability is characterized by no trauma, structural damage to articular surfaces, capsular dysfunction, no abnormal muscle patterning, and is not uncommonly bilateral [78]. Habitual nonstructural instability is characterized by no trauma, no structural damage to articular surfaces, capsular dysfunction, abnormal muscle patterning, and is often bilateral [78]. Patients with shoulder instability may present with dual pathology that overlaps between the three polar groups of the Stanmore/Bayley classification [78].
Multidirectional instability (MDI) is characterized by inferior laxity in addition to anterior and/or posterior laxity [11]. True multidirectional instability, where translations are symptomatic in all directions, is uncommon [51]. MDI can have a traumatic or atraumatic etiology, or a combination of both [51]. Patients with MDI may exhibit symptomatic instability in the presence of positive anterior and posterior apprehension, a pathologic sulcus sign with no history of trauma, and no history of dislocation requiring reduction [51]. MDI is characterized by generalized ligamentous laxity as well as abnormal shoulder and scapular kinematics [51]. The contralateral shoulder in patients with MDI may exhibit similar characteristics but may or may not be symptomatic [51]. Capsular laxity is the essential lesion in MDI [51]. Increased capsular volume and cross-sectional area are nonspecific findings common to many patients with capsular laxity and recurrent instability [51]. Injury to the rotator interval is an important component of anterior capsular injury in general [51]. Shallow glenoid morphology has been identified as a contributing factor in some cases of MDI [51]. Voluntary dislocators with natural laxity and untreated skeletal dyskinesia can become involuntary dislocators with labral tears or capsular pathology [51].
Posterior glenohumeral instability accounts for 2% to 5% of all glenohumeral instability [25]. Up to 50% of traumatic posterior shoulder dislocations are undiagnosed upon presentation to hospital emergency departments [25]. Recurrent posterior shoulder instability is an uncommon condition often unrecognized, leading to incorrect diagnoses and delays [31]. The presentation of posterior instability is typically more subtle than anterior instability [68]. The incidence rate of posterior instability is 4 per 1,000 person-years [68]. In most cases of posterior instability, no acute traumatic event occurs, and patients complain primarily of vague posterior shoulder pain [68]. A unique presentation of posterior instability is the locked posterior dislocation, which most commonly occurs with violent trauma or a seizure [68]. Fixed posterior dislocations are often associated with a large reverse Hill-Sachs lesion that requires surgical intervention [68]. Traumatic posterior glenohumeral dislocation or recurrent instability can cause posterior labral tearing or disruption of the posterior IGHL [25]. A compression fracture of the anterosuperior portion of the humeral head (a reverse Hill-Sachs) may be present in posterior instability [25]. Posterior glenoid bone loss may be present in cases of recurrent posterior instability [25]. The PHAGL lesion is challenging to diagnose clinically and can be the cause of posterior instability or a component of the spectrum of shoulder instability [131]. HAGL lesions are a rare and underdiagnosed cause of anterior shoulder instability that can lead to recurrent dislocations if unaddressed [141]. GAGL lesions are an uncommon cause of anterior shoulder instability and require a high level of suspicion [143]. Minor shoulder instability is an intra-articular pathology presenting with extra-articular subacromial impingement symptoms [134]. Microinstability is diagnostically challenging and can be diagnosed in young patients with ambiguous shoulder pain during motion, without instability [138]. Pain can serve as a clinical indicator of larger labral pathology in patients presenting with shoulder instability [112].
History Taking¶
The history should define the mechanism of injury, including the position of the arm, the amount of force applied, and the point of force application [166]. Injury with the arm in extension, abduction, and external rotation favors anterior dislocation [166]. Electoshock, seizures, or a fall on the flexed and adducted arm are commonly associated with posterior dislocation [166]. For recurrent instability, the history defines the initial injury, the position or action that results in instability, how long the shoulder stays out, whether radiographs are available with the shoulder out of joint, and what means have been necessary to reduce the shoulder [166]. The history solicits evidence of neurologic or rotator cuff problems after previous episodes of shoulder instability [166]. Previous treatment of recurrent instability and its effectiveness should be documented in the history [166]. Note should be made of age at first dislocation, increasing ease of dislocation, frequency of recurrence, duration of symptoms, and patient's ability to reduce the dislocation himself or herself [162]. A thorough history and physical examination most often diagnose the degree, direction, frequency, and etiology of shoulder instability [12]. A thorough history and physical examination should allow the examiner to understand the etiology, direction, degree, and frequency of a patient’s shoulder instability [156]. The history takes account of the degree of trauma required to cause the first dislocation and whether the displacement was complete and requiring formal reduction or incomplete and spontaneously reducing [78].
Most patients with atraumatic instability are younger than 30 years [243]. Atraumatic instability typically causes discomfort and dysfunction in ordinary activities of daily living because it occurs in midrange positions of the shoulder [243]. Patients with atraumatic instability commonly have the greatest difficulty sleeping, lifting overhead, and throwing [243]. The onset of atraumatic instability is usually insidious but can occur after a minor injury or period of disuse [243]. An initial traumatic dislocation often requires assistance in reduction rather than reducing spontaneously as is usually the case in atraumatic instability [243]. Radiographs from previous emergency department visits may be available to show the shoulder in its dislocated position for traumatic instability [243]. Axillary or other neuropathy may have accompanied the glenohumeral dislocation in traumatic instability [243]. Traumatic instability can occur without a complete dislocation, manifesting as apprehension or subluxation when the arm is placed near the position of injury [243]. Patients with traumatic instability have no history of the need for reduction and have no radiographs with the shoulder in the dislocated position when only subluxation occurs [243]. A shoulder with traumatic instability is characteristically comfortable when troublesome positions are avoided [243]. Apprehension or fear of instability can prevent the patient from returning to work or sports [243]. Recurrent subluxation or dislocation can occur when the shoulder is unexpectedly forced into the abducted, externally rotated position or during sleep [243]. Patients may have a history of increasing ease of dislocation as remaining stabilizing factors are progressively compromised [243].
Symptoms elicited with the arm in adduction and internal rotation may suggest posterior instability [238]. Symptoms reproduced by holding objects with the arms at the sides often indicate inferior instability [238]. In throwers, pain during cocking is often a result of instability or internal impingement with a type II SLAP lesion [238]. In throwers, pain during follow-through arises from rotator cuff or posterior capsular problems [238]. In swimmers, instability is often the principal culprit, exacerbating symptoms of impingement [238]. The association of symptoms with paresthesia down the arm is nearly always related to shoulder instability [69]. True symptomatic multidirectional instability is typically symptomatic in midrange positions before the ligament tension reaches the end of its range [69]. Pain is the more common symptom with a shoulder instability based on ligamentous laxity (AMBRI) [69]. Apprehension is more common with unidirectional traumatic instability (TUBS) [69]. The classic patient with traumatic instability is a male athlete who sustained an identifiable traumatic event during the course of a violent activity [69]. The classic patient with multidirectional shoulder instability is the young, asthenic female ballet dancer, swimmer, or volleyball player with nondescript shoulder pain that also involves the scapula and provokes paresthesia down the arm, occurring in the absence of a defined traumatic event [69]. Isolated symptomatic posterior shoulder instability is most often associated with a very specific event or process [69]. Posterior shoulder dislocations are rarely associated with traumatic events that include falls [69]. Posterior shoulder instability is seen most often in the scenario of electric shocks and epilepsy [69]. A history of trauma with the arm locked in internal rotation is characteristic of posterior instability [25]. Volitional dislocation of the shoulder must be ruled out in the history for posterior instability [25]. Symptoms of MDI include pain, weakness, ipsilateral paresthesias, popping or clicking of the shoulder, instability of the shoulder during sleep, difficulty with throwing, and pain when carrying heavy objects [11]. Differential diagnoses for MDI include unidirectional shoulder instability, cervical disease, brachial plexitis, and thoracic outlet syndrome [11]. Rotator cuff tendinitis in an individual younger than 20 years should raise concern for MDI [11]. Patients do not always recognize anterior shoulder instability, and initial physical examination may be limited in the acute setting [111]. A thorough clinical exam is the most important factor when determining indication for shoulder instability surgery [20]. Detailed and specific information about prognosis is critical in the management of a first-time anterior dislocation [36]. The diagnosis of a stiff shoulder depends on awareness of the problem, with history and physical examination being paramount [5].
Physical Examination¶
An acutely dislocated shoulder is usually very painful, and muscles are in spasm in an attempt to stabilize the joint [166]. The humeral head may be palpable anteriorly in an anterior dislocation [166]. The posterior and lateral aspect of the shoulder shows a hollow beneath the acromion in an anterior dislocation [166]. The arm is held in slight abduction in an anterior dislocation [166]. Passive and active motions are limited by pain in an anterior dislocation [166]. Assessment of the neurovascular status of the upper extremity and charting of the findings before reduction is an essential part of the physical examination of an anteriorly dislocated shoulder [166].
Recognition of a posterior dislocation may be impaired by the lack of a striking deformity and by the fact that the shoulder is held in the traditional sling position of adduction and internal rotation [166]. Limited external rotation of the shoulder, often to less than 0 degrees, is a classic feature of posterior dislocation [166]. Limited elevation of the arm, often to less than 90 degrees, is a classic feature of posterior dislocation [166]. Posterior prominence and rounding of the shoulder in comparison to the normal side is a classic feature of posterior dislocation [166]. Flattening of the anterior aspect of the shoulder is a classic feature of posterior dislocation [166]. Prominence of the coracoid process on the dislocated side is a classic feature of posterior dislocation [166]. Asymmetry of the shoulder contours can often best be visualized by viewing the shoulders from above while standing behind the patient [166]. Motion is limited in posterior dislocation because the head of the humerus is fixed on the posterior glenoid rim by muscle forces or impaled on the glenoid rim [166]. Patients with old, unreduced posterior dislocations of the shoulder can have 30 to 40 degrees of glenohumeral abduction and some humeral rotation as a result of enlargement of the groove [166]. Atrophy of muscles about the shoulder in long-standing disuse accentuates the flattening of the anterior portion of the shoulder, the prominence of the coracoid, and the fullness of the posterior portion [166]. In the interval before diagnosis, a posterior dislocation may be misdiagnosed as a frozen shoulder [166]. An acute posterior dislocation will present with a prominent posterior shoulder and anterior coracoid and a limited ability to externally rotate the shoulder [25]. Posterior instability can lead to compensatory scapular winging [25].
The apprehension-relocation test (Fowler test) is the most sensitive test for anterior instability [162]. In the apprehension-relocation test, the arm is placed into abduction and external rotation, and the patient experiences a sense of instability that is relieved by a posterior force applied by the examiner [162]. The load-and-shift test can be used to classify degrees of instability on the basis of distance of humeral head translation [162]. In the load-and-shift test, 1+ corresponds to 0 to 1 cm of translation to before the glenoid rim [162]. In the load-and-shift test, 2+ corresponds to 1 to 2 cm of translation to the glenoid rim [162]. In the load-and-shift test, 3+ corresponds to greater than 2 cm translation or over the glenoid rim [162]. An evaluation of generalized laxity should be performed during physical examination [162]. Assess for generalized ligamentous laxity using Beighton criteria in MDI [11]. A positive sulcus sign assesses the competency of the rotator interval in MDI [11]. Specialized tests to assess posterior stability include the posterior stress test and jerk test [25]. The posterior stress test is positive if palpable crepitus or subluxation is present when a posterior force is applied through the humerus [25]. Pain elicited during the posterior stress test is less specific for posterior shoulder instability [25]. The jerk test involves applying a posterior force along the axis of the humerus with the arm in forward flexion and internal rotation, causing the humeral head to subluxate posteriorly [25]. In the jerk test, a clunk is felt as the humerus reduces into the glenoid cavity when the arm is brought into extension [25].
The diagnosis of anterior shoulder instability can be very easy when the patient presents with an appropriate history of trauma [69]. A more challenging problem occurs in patients with a sense of slipping and looseness in their shoulder without a history of macrotrauma [69]. Subtle instability patterns are often associated with a nondescript level of discomfort and diffuse pain around the shoulder girdle [69]. The discomfort in subtle instability is poorly localized and may be more scapular in location [69]. The sense of instability might occur with the arm only in certain positions or may be present regardless of arm placement or position [69]. Patients with multidirectional instability might have symptoms that are so incapacitating that they tend to avoid extremes of glenohumeral motion [69]. It is critical to allow the patient to demonstrate his or
Investigations¶
Clinical Evaluation: A thorough clinical examination is the most important factor when determining the indication for shoulder instability surgery [20]. Diagnostic practices vary significantly, with high variety in the use of diagnostic tools [14] and substantial variability in what is considered important in radiological reports for anterior instability, regardless of imaging modality [21]. Recurrent posterior shoulder instability is an uncommon condition that is often unrecognized, leading to incorrect diagnoses and delays [31]. If the problem is not apparent on history, physical examination, and plain radiographs, or if the patient does not appear to be an excellent surgical candidate, nonoperative management is likely recommended [42].
Plain radiography: Conventional radiography remains the initial imaging study for evaluating patients with persistent shoulder pain and instability [206]. Standardized plain films are almost always sufficient to garner the information needed for shoulder evaluation [32]. The purpose of shoulder imaging is to help establish the diagnosis, determine the severity of the pathoanatomy, assist in surgical planning, and enable the surgeon to illustrate the condition of the shoulder to the patient [32]. The first key radiographic view is the anteroposterior (AP) view in the plane of the scapula, taken so that the x-ray beam passes through the glenohumeral joint [32]. This view shows the superoinferior position of the humeral head relative to the glenoid, presence of osteophytes, narrowing of the joint space, degree of medial displacement of the humerus, quality of bone, presence of loose bodies, and humeral head collapse or deformity [32]. The second key radiographic view is the axillary view taken with the arm in the functional position of elevation in the plane of the scapula [32]. The axillary view demonstrates glenohumeral relationships in the functional position of elevation, referred to as the "truth view" [32]. The standardized axillary view enables the measurement of posterior subluxation or "functional decentering" that is not evident in images taken with the arm at the side [32]. The degree of posterior subluxation can be measured by the position of the center of the humeral head in relation to the plane of the scapula, the position of the center of the humeral head in relation to the glenoid face, or the point of contact of the humeral articular surface on the glenoid articular surface [32].
Specific views are indicated for particular pathologies: the Stryker notch view is indicated to evaluate Hill-Sachs lesions after dislocation [161]; the West Point view is indicated for anterior glenoid bone loss [161]; and the apical oblique view is indicated to evaluate for glenoid rim fracture in instability [161]. Focal cortical bone loss at the inferior aspect of the glenoid is a radiographic sign of anterior shoulder instability of traumatic origin [285]. Radiographic analysis of the Hill-Sachs lesion with a constant, reproducible technique can play a role in the diagnosis of anterior shoulder instability and patient selection for therapeutic intervention [307]. Radiography can be used for screening patients for significant glenoid bone loss [309]. However, CT and MRI (2D or 3D) accurately measure glenoid bone loss in anterior shoulder instability, but radiographs do not [270]. In patients with suspected posterior glenohumeral instability, imaging of the affected shoulder can show abnormalities of the bone, labrum, and joint capsule [301]. Radiographic progression of glenohumeral arthritis occurred in 14% of patients with posterior shoulder instability [313].
CT: CT imaging is frequently used to evaluate fractures of the shoulder, to assess for bony lesions in recurrent instability cases, or for preoperative templating for shoulder arthritis [154]. CT with three-dimensional reconstructions is the advanced imaging study of choice for determining the extent of glenoid bone loss in the setting of shoulder instability [161]. Despite the advantages of MRI in the detection of soft tissue damages in recurrent anterior shoulder instability, CT imaging proved to be more important for glenoid defects [264]. CT scans may offer a few degrees of increased precision in the measurement of glenoid version, but this precision does not necessarily improve the quality of the surgery or the clinical outcome [32]. Advanced imaging modalities are essential for identifying associated lesions, and bony reconstruction procedures should be considered for patients with significant glenoid bone loss or recurrent instability after soft tissue reconstruction [254].
MRI: MRI is the modality of choice for evaluating the rotator cuff, biceps, and subacromial/subdeltoid bursa [154]. T1-weighted MRI can reveal Hill-Sachs lesions and is often used with magnetic resonance (MR) arthrograms to provide a more detailed picture of the joint surfaces [154]. T2-weighted MRI provides better visualization of full thickness rotator cuff tears [154]. Magnetic resonance arthrography (MRA) is considered the benchmark for evaluation of labral tears and is rarely indicated for evaluation of rotator cuff pathology [154]. MRA has been firmly established as the imaging modality of choice for demonstrating specific soft tissue abnormalities associated with glenohumeral instability [206]. MRA is regarded as the gold-standard imaging modality for shoulder instability [241]. MRA is identified as the main tool in diagnosing shoulder instability injuries [279]. MRI provides an accurate diagnosis of anterior glenohumeral subluxation and dislocation, allowing for expeditious and appropriate management of occult anterior glenohumeral instability [38]. Identification of critical radiographic variables on magnetic resonance arthrography assists in the accurate diagnosis and management of clinically significant posterior shoulder instability [35]. MRA was an accurate method to assess accompanying lesions in first-time and recurrent anterior dislocation of the shoulder [259]. Capsular injury is commonly seen in magnetic resonance imaging of patients with anterior shoulder instability [248]. MRI provided an accurate, non-invasive method of imaging the glenohumeral joint that was superior to CT arthrography in diagnosing labral, glenoid rim, and humeral head abnormalities commonly associated with glenohumeral instability [318]. MRA has a high sensitivity when used to identify associated injuries in shoulder dislocation, although arthroscopy identified an additional injury in 8 patients (13%) [293].
Routine MRI has similar diagnostic value to MR arthrogram for measuring labral tear extent up to approximately 2 weeks postacute shoulder dislocation, after which it significantly loses accuracy and precision [312]. Patients who undergo MRI greater than 6 months from the time of primary shoulder dislocation demonstrate a greater incidence and severity of intra-articular pathology including SLAP tears, posterior labral tears, and anterior glenoid cartilage damage [302]. Static MRI does not appear helpful for diagnosing shoulder instability, however CINE MRI can reproducibly confirm the diagnosis [228]. Patients with multidirectional instability demonstrated quantifiable dynamic instability on cine MRI with significantly greater humeral head deviation and faster deviation velocity than healthy controls [316]. The superior-capsular elongation and its diagnostic criteria of measurements by MR arthrography could serve as references for diagnosing atraumatic posteroinferior shoulder instability [310]. ZTE MRI demonstrated high reproducibility for the evaluation of glenoid bone defect in shoulders with anterior instability [314]. MRI is a valid imaging tool to diagnose and measure osseous lesions of the shoulder in adolescents [317]. A useful MRI measurement, the increased glenoid index, may help identify patients at risk for primary or recurrent anterior glenohumeral instability events and may help with guiding treatment and prevention [263]. In the future, CT is expected to be superseded by MRI in anterior shoulder instability [300]. Even without posterior instability complaints or findings, posterior labral tears should be considered in patients with posterior shoulder pain during daily activities or sports, even when MRI or MRA findings are ambiguous [305].
Ultrasonography: Ultrasonography is a low-cost alternative to MRI and arthrography for evaluating both skeletal and soft-tissue structures of the shoulder [154]. Ultrasonography can provide immediate, real-time visualization of the rotator cuff, biceps tendon, and calcific deposits [154]. Ultrasonography can be used to measure the subacromial space and detect atrophy of rotator cuff muscles [154]. Ultrasonography can evaluate impingement in various positions and motions due to real-time imaging [154]. Ultrasonography is highly operator dependent and is not as useful for evaluating labral tears or rotator cuff tears that are very small or larger than 3 cm [154].
Other Considerations: 3D MRI is a validated and reliable alternative to 3D CT for preoperative evaluation of static glenohumeral bone loss and dynamic morphological variables in shoulder instability [298, 299]. The Multicenter Orthopaedic Outcomes Network (MOON) Shoulder Instability group focuses on patients undergoing surgical treatment for shoulder instability [3]. Early MOON Shoulder Instability studies have described baseline demographics, modifying factors, and limited early outcomes in these patients [3].
Treatment¶
Non-Operative Management¶
Nonsurgical management is the primary strategy for atraumatic shoulder instability, with 80% of patients expected to respond to non-operative measures [260]. For multidirectional instability (MDI), extensive physical therapy focusing on rotator cuff strengthening, scapular kinematics, and proprioceptive training is required for 6 to 9 months before surgical consideration [11]. Approximately 20% of MDI patients fail nonsurgical management [11]. Nonsurgical treatment for posterior instability involves immobilization in neutral rotation with the elbow in adduction for 1 to 2 weeks, followed by therapy [25]. For anterior instability, nonsurgical management typically includes a brief period of sling immobilization (3 to 7 days) followed by structured rehabilitation involving cryotherapy, restoration of full range of motion, periscapular and rotator cuff strengthening, and sport-specific drills [28]. NHL team physicians strongly favor nonoperative management in-season for initial posterior instability events [230]. Recent studies continue to demonstrate a role for nonoperative treatment in the successful long-term management of anterior glenohumeral instability [219]. However, primary non-operative management is a prominent risk factor for recurrence in young and adolescent athletes [129], with recurrence rates as high as 86.7% in high-risk patients treated nonoperatively after their first incident of instability [246]. Nonoperative treatment of shoulder instability carries substantial societal costs [210]. The cornerstone of treatment for instability remains immobilization followed by rehabilitation, though the optimal nonoperative treatment of a shoulder dislocation is still unknown and deserves further study [12]. Athletes may return to play after a shoulder dislocation or after stabilization surgery when strength and mobility have normalized [12].
Operative Management¶
Indications: Surgery is contraindicated for voluntary dislocators and patients who have not attempted physical therapy for MDI [11]. Surgery is also contraindicated for voluntary posterior dislocators due to an extremely high failure rate [68]. Surgical treatment of primary, traumatic, anterior shoulder instability results in reduced rates of recurrence compared with nonsurgical treatment at 10-year follow-up [43]. Early operative stabilization of Bankart lesions in young patients offers a significant reduction in the risk of recurrent instability compared to non-operative management [265]. Early arthroscopic stabilization by anterior capsule-labrum reinsertion after initial anterior shoulder dislocation is associated with a low 10-year recurrence rate of 35% compared to non-operative management [255]. Surgical shoulder stabilization in an athlete after a first episode of posterior instability is not indicated in all patients [242]. The success of treating anterior glenohumeral instability relies on multiple factors, including glenoid bone loss [155].
Surgical Approach / Technique: Arthroscopic anterior capsulolabral repair has become the most common surgical technique in North America, accounting for more than 90% of surgical cases for anterior shoulder instability [28]. An isolated arthroscopic soft-tissue stabilization is best suited for patients with little to no glenoid bone loss, minimal humeral bone loss, and good capsular and labral tissue quality [28]. The indications for an isolated soft-tissue procedure in anterior shoulder instability are now narrower, with the ideal candidate presenting with minimal glenoid bone loss (13.5%) [53]. A large 2017 cohort study showed subjective instability in 62% and revision surgery in 32% of patients undergoing arthroscopic Bankart repair after multiple episodes of instability, rates that were fourfold higher than in first-time dislocators [28]. The open Bankart procedure typically involves a pants-over-vest capsular shift in addition to labral repair, making it not biomechanically equivalent to the arthroscopic Bankart procedure [28]. A meta-analysis of 22 studies found no difference in rates of recurrent instability or patient-reported outcomes between open and arthroscopic anterior stabilization techniques [28]. If the definition of recurrent instability is extended beyond frank dislocations to include apprehension and subluxations, open repairs outperform arthroscopic repairs [28]. Failure rates in all available studies are lower with open repairs than arthroscopic repairs in contact athletes [28]. In a randomized clinical trial comparing open versus arthroscopic Bankart repair, an increased rate of recurrence was noted after arthroscopic repair (23% versus 11% in open repair) [160]. The highest rate of recurrence in the comparison of open versus arthroscopic Bankart repair was noted in males younger than 25 years with Hill-Sachs lesions [160]. A systematic review of more recent meta-analyses demonstrated no difference in recurrence between open and arthroscopic anterior stabilization techniques [160]. Arthroscopic stabilization for recurrent anterior shoulder instability can be performed safely, with clinical outcomes comparable to those after traditional open stabilization [172]. Successful results were obtained in patients younger than 40 years with both primary and recurrent anterior instability after arthroscopic treatment [171]. A humeral avulsion of the glenohumeral ligaments (HAGL) typically warrants an open repair with anchors back to the humeral neck [28]. The Latarjet procedure is a safe and effective procedure for patients with shoulder instability [159]. Current evidence supports the safety and efficacy of both the Latarjet and free bone block (FBB) procedures for anterior shoulder stabilization in the presence of glenoid bone loss [200]. The proposed dynamic anterior stabilization procedure using buttons demonstrated effectiveness and safety, being a viable option for treating anterior shoulder instability with glenoid bone loss of less than 20% [201]. Long head of biceps tendon transfer is indicated for shoulder instability in high-impact athletes, together with a capsule-labrum reconstruction, and for poor tissue quality of the labrum in patients with multiple long-term dislocations [250]. Successful treatment of anterior instability of the shoulder requires a balance between restoring joint stability and minimizing loss of glenohumeral motion [177].
For posterior instability, the benchmark treatment when nonsurgical treatment is unsuccessful is an anchor-based arthroscopic capsulolabral repair [68]. Primary arthroscopic treatment of posterior shoulder instability is associated with favorable outcomes and high return to sport and work rates [170]. Arthroscopic stabilization of posterior shoulder instability resulted in good outcomes with high patient satisfaction and low rates of recurrent instability, revisions, and residual pain [195]. Arthroscopic treatment of posterior shoulder instability is an effective means to improve symptoms associated with recurrent posterior subluxation of the shoulder [187]. Treatment of posterior shoulder instability by capsulolabral reconstruction leads to good clinical outcomes; however, the recurrence rate is high [151]. The iliac posterior shoulder bone-block is effective in managing instances of involuntary posterior shoulder instability, showing satisfactory results in terms of non-recurrence, pain relief, and function recovery [272]. The presence of a posterior glenoid fracture (bony Bankart lesion) did not represent a contraindication to arthroscopic shoulder stabilization [249]. Beyond 20% posterior bone loss, an isolated labral repair cannot restore adequate shoulder stability [68].
For multidirectional instability, arthroscopic pancapsular plication ± rotator interval closure is a surgical technique, with anterior or posterior labral repair indicated if labral pathology is encountered [11]. To avoid asymmetric tightening in MDI surgery, capsulorrhaphy should address the inferior redundancy in a balanced fashion [11]. Open anterior-inferior capsular shift is a surgical technique for MDI [11]. The results demonstrate the efficacy and durability of the inferior capsular shift procedure for the treatment of shoulders with multidirectional instability [124]. Results in a series demonstrate the efficacy and durability of a modified capsular shift procedure for the treatment of atraumatic anterior-inferior shoulder instability [189]. Adolescent multidirectional shoulder instability refractory to non-surgical management appears to have long-term outcomes after surgical intervention that are comparable to adolescent patients with unidirectional instability [182].
Outcomes and Complications: Recurrent instability rates for posterior stabilization are low (8%), and 90% of patients return to sport [68]. In throwers, only 58% were able to return to sport at the same level after posterior stabilization [68]. Revision surgery is only required in 6% of patients with posterior instability, and the outcomes are far inferior to those of index surgery, with only 15% returning to sport at their preoperative level [68]. Recurrence of MDI is reported at 7% for both open and arthroscopic techniques [11]. Axillary nerve injury, stiffness (rare), and subscapularis insufficiency (after open procedure) are complications of MDI surgery [11]. To assess the effectiveness of an arthroscopic stabilization procedure for anterior shoulder instability using the Rowe score, a difference of at least 9.7 in the score is clinically relevant [140]. Stabilization of the dominant shoulder resulted in residual surgery-related functional impairments on both sides, whereas stabilization of the nondominant shoulder resulted in impairments primarily noted in the nondominant, operative shoulder [266]. Regardless of treatment, professional hockey players experience a high rate of return to play with acceptable performance outcomes following in-game shoulder instability events [194].
Other Considerations: There was no evidence regarding the effectiveness of surgical management for post-traumatic chronic shoulder instability [239]. There is insufficient evidence from randomised trials comparing arthroscopic with open surgery for treating anterior shoulder instability [262]. The WOSI-Fr is recommended for following up patients with shoulder instability [57]. This paper reviews the nonoperative treatment and the postoperative management of patients with various classifications of shoulder instability [50]. The Delphi method is a structured communication technique used to allow a panel of experts to achieve a consensus in a systematic manner, resulting in an international consensus statement on shoulder instability covering diagnosis, nonoperative management, surgical options, rehabilitation, and clinical follow-up [19]. The MOON Shoulder Group is made up of 16 fellowship-trained orthopaedic surgeons and research personnel from nine academic and private practice sites in the United States [3]. MOON Shoulder Instability is an offshoot of MOON Shoulder, focusing on patients undergoing surgical treatment for shoulder instability [3]. Early studies have described baseline demographics, modifying factors, and limited early outcomes in MOON Shoulder Instability patients [3]. The authors propose a classification system for shoulder instability which challenges previous systems by being all inclusive and recognises that more than one pathology can occur in an individual shoulder [4]. Non-traumatic shoulder instability (NTSI) is defined as abnormal movement or position of the shoulder, leading to pain, subluxation or even dislocation and functional discomfort without a significant history of injury [2]. Since the 1980s, 18 classifications have been developed in an attempt to define the sub-groups of instability, but none of them have demonstrated strong measurement properties [2]. The Thomas and Matsen classification introduced the AMBRI (atraumatic multidirectional instability) versus TUBS (traumatic unidirectional instability.
Rehabilitation and Post-Operative Care¶
Postoperative rehabilitation protocols for shoulder instability typically include a period of immobilization in a sling for 3 -4 weeks [277]. Pendulums exercises are begun immediately after shoulder instability surgery, along with active assisted range of motion exercises for external rotation (0 -30°) and forward flexion (0 -90°) [277]. From weeks six to twelve after shoulder instability surgery, active and active assisted motion is emphasized to re-establish full range of motion [277]. Strengthening is begun once full, painless, range of motion has been restored after shoulder instability surgery [277]. Sports specific exercises are started around 16 -20 weeks post-surgery for shoulder instability [277]. Patients may return to contact sports at 20 and 24 weeks following Latarjet and arthroscopic stabilization respectively [277]. In open procedures where the subscapularis is incised, active internal rotation and passive external rotation is avoided while the subscapularis heals [277].
For posterior instability, the shoulder should be placed in a rigid immobilizer with the arm abducted to 30° in neutral rotation [25]. After a short period of immobilization for posterior instability, ROM exercises may begin, and strengthening should begin at 12 weeks [25]. Patients may return to heavy labor or contact sports 6 months after posterior instability surgery [25]. The pooled published rate of return to any sport and to preinjury level of sport after posterior instability surgery is 91% and 67%, respectively [25].
For anterior instability, the shoulder was placed in a sling for 3 weeks, while allowing nonresisted activities of daily living without elevation of the shoulder [258]. Patients immediately began physiotherapy after anterior instability surgery, which continuously increased in intensity over the next 9 weeks [258]. Return to contact in training was allowed after 12 weeks following anterior instability surgery [258]. Return to full contact and competition usually follows within the next 3 months after anterior instability surgery, depending on progress of physiotherapy [258]. Follow-up evaluations for anterior shoulder instability surgery were performed at 3 and 6 weeks after surgery before discontinuing the sling [252]. Subsequently, patients were examined at 3, 6, 12, 24, and 36 months after anterior shoulder instability surgery [252]. The last evaluation for anterior shoulder instability surgery was performed by an orthopaedic surgeon who was not involved in the surgical procedure or rehabilitation management [252]. Shoulder function was assessed at the last follow-up with the Oxford Shoulder Score (OSS) [252].
The rehabilitation protocol for SLAP tears involved placing the shoulder in a sling for 3 weeks, allowing non-resisted activities of daily living without elevation [245]. Patients immediately began physiotherapy after SLAP tear repair, which continuously increased in intensity over the next nine weeks [245]. Return to contact in training was allowed after twelve weeks following SLAP tear repair [245]. Return to full contact and competition usually followed within the next three months after SLAP tear repair, depending on progress of physiotherapy [245].
The arm was placed in a sling for comfort for a few days after radiofrequency capsular shrinkage for voluntary shoulder instability [261]. Motion was allowed after radiofrequency capsular shrinkage, avoiding extremes in all directions for the first 6 weeks [261]. Proprioceptive physiotherapy was initiated within the first week after radiofrequency capsular shrinkage [261].
Postoperative protocols are in widespread use across the UK with 93.5% of participants reporting their use [253]. Three quarters (75%) of UK participants have a single protocol that is used by all surgeons and physiotherapists for shoulder stabilization [253]. In most cases (72.1%), UK postoperative protocols were jointly written between surgical and physiotherapy teams [253]. Immobilisation of the shoulder following arthroscopic stabilisation was reported as routine by 79.9% of UK respondents [253]. A cross body sling was the most common position of immobilisation (63.4%) in UK practice [253]. The duration of immobilisation reported in UK practice varied, ranging from less than 48 hours to up to 6 weeks [253]. Over half (53.6%) of UK protocols allowed for patients to commence passive movement either immediately or as soon as they felt able [253].
Complications¶
Recurrence and Failure of Stabilization¶
Recurrent instability remains a significant concern following primary stabilization. In a US epidemiologic population of patients under 40 years old, the rate of recurrent anterior shoulder instability was roughly one-third after initial physician consultation [269]. Following primary arthroscopic anterior capsulolabral repair, recurrence rates reached 30% at midterm follow-up [24]. With a follow-up of 97%, about one third of stabilized shoulders experienced at least one redislocation after 8 to 10 years [54]. Some risk of recurrent instability is part of the natural history of anterior shoulder dislocation [49]. A history of multiple instability episodes prior to presentation was the greatest predictor of recurrent instability and failure of nonoperative treatment and progression to surgery [73]. Failure of primary shoulder stabilization procedures is often related to uncorrected anatomic pathology [18]. Recurrent instability requiring capsular reconstruction seems to be more prevalent in patients with a previous history of shoulder dislocation [251].
Preoperative risk factors for recurrent anterior glenohumeral instability following a primary Latarjet procedure included history of bilateral shoulder instability and atraumatic mechanism of dislocation [267]. The open Latarjet procedure is a safe and reliable technique for recurrent anterior shoulder instability [70, 71]. Female patients undergoing the Latarjet procedure for recurrent shoulder instability showed similar 90-day complication and 2-year secondary surgery rates to a matched cohort of male patients [220]. The 1-year outcomes in a prospective study suggest superiority of operative over non-operative treatment for posterior instability [9]. The short-term outcome in a small series of arthroscopic revision surgery in shoulder instability is challenging and encouraging [29].
Arthropathy and Joint Degeneration¶
The incidence of shoulder arthropathy in patients with shoulder instability is difficult to measure [75]. The natural history of the first time shoulder dislocations is bound up with arthropathy [65]. In a series of 63 patients with first-time traumatic dislocations evaluated arthroscopically within 10 days, osteochondral lesions of the humeral head were noted in 34 patients and chondral lesions were noted in an additional 23 [75]. In a series of 24 patients with first-time anterior shoulder dislocation assessed arthroscopically 1 to 3 days after injury, osteochondral lesions were found in six shoulders and chondral lesions in the remaining 18 [75]. Of 88 patients with acute instability (within 90 days of index injury to surgery), 24% had grade I or higher chondral lesions and 12% had Grade III or IV chondral damage [75].
Suture anchors that are misplaced can give rise to secondary degenerative joint disease or "anchor arthropathy" [22]. The degree of arthropathy 33 to 35 years after the Bristow-Latarjet repair seems to follow the natural history of shoulder dislocation with respect to arthropathic joint degeneration [83]. Shoulder arthroplasty may improve functional outcomes for patients experiencing instability arthropathy with a history of stabilization surgery [240]. At mid-term follow-up, patients with a history of anterior shoulder instability undergoing total shoulder arthroplasty can expect continued improvement in function compared with preoperative values [64].
Surgical and Procedural Complications¶
The Latarjet procedure for anterior shoulder instability results in an overall complication rate of 16.1% and a reoperation rate of 2.6% [211]. Serious complications at short-term follow-up after the Latarjet procedure appear rare [211]. Complications associated with arthroscopic shoulder stabilization are relatively common [292]. Excluding recurrence, complications associated with arthroscopic shoulder stabilization are rarely disabling [292]. Current statistics undoubtedly underestimate the true incidence of complications associated with arthroscopic shoulder stabilization [292]. Many complications, including neurovascular injuries and articular damage, are preventable and can be minimized through familiarity with anatomy, proper surgical technique and instrumentation, and clinical experience [292]. Use of intra-articular infusion of local antibiotics via a pain pump after arthroscopic instability repairs results in a risk of glenohumeral chondrolysis [22].
Recurrence of multidirectional instability (MDI) is 7% for both open and arthroscopic techniques [11]. Axillary nerve injury is a complication of multidirectional instability surgery [11]. Stiffness is a rare complication of multidirectional instability surgery [11]. Subscapularis insufficiency is a complication after open procedures for multidirectional instability [11]. Failure to recognize the posterior instability element in combined anterior and posterior instability will lead to potential failure of repair, recurrent instability, and patient dissatisfaction after surgery [27]. The routine use of bone transfers for glenohumeral instability in the absence of major glenoid bone loss is not advisable because of the increased risk of arthritis, screw-related problems, damage to the subscapularis, and difficulty in revision [22]. Nerve injuries from interscalene blocks can be permanent [22].
Other Considerations¶
Instability is the second leading cause of complications associated with shoulder arthroplasty, with a reported prevalence of 4% and accounting for 30% of all complications [282]. In a meta-analysis of 11 series of total shoulder arthroplasties that included 838 patients, the incidence of postoperative dislocation was 1.2% over a follow-up period of 20 to 54 months [282]. Approximately 80% of instability complications after total shoulder arthroplasty involve anterior or superior instability [282]. Anterior instability after total shoulder arthroplasty is most commonly associated with subscapularis failure, glenoid component malposition, or anterior deltoid dysfunction [282]. Posterior instability after total shoulder arthroplasty has been attributed most often to malposition of the components [282]. Inferior instability after shoulder arthroplasty is related to the loss of normal humeral height and is most common after hemiarthroplasty for proximal humeral fractures [282].
The overall complication rate after total shoulder arthroplasty is estimated to be approximately 15% [288]. Complications after total shoulder arthroplasty tend to occur late in the postoperative course, with component loosening reported at approximately 8 years, infection at 12 years, and periprosthetic fractures at 6 years [288]. The most common complications after reverse total shoulder arthroplasty are scapular notching, hematoma formation, glenoid dissociation such as baseplate failure or aseptic loosening, glenohumeral dislocation, acromial and scapular spine fractures, infection, loosening or dissociation of the humeral component, and nerve injury [288]. A torn subscapularis tendon is likely to be underreported and will not correlate with the postoperative physical examination [282]. One report suggested that lesser tuberosity osteotomy (LTO) failure may be an underreported complication [282]. Patients with a history of shoulder instability or replacement are at risk for shoulder dislocation during common elbow and hand procedures [237].
Recovery¶
Rehabilitation protocol: The cornerstone of treatment for shoulder instability remains immobilization followed by rehabilitation [12]. Adequate nonsurgical treatment typically involves a brief period of sling immobilization (3 to 7 days), followed by a course of structured rehabilitation focusing on cryotherapy, restoration of full range of motion, periscapular and rotator cuff strengthening to improve dynamic stabilizers, and finally stabilization and sport-specific drills [28]. For multidirectional instability (MDI), which often manifests as bilateral shoulder subluxations in a susceptible patient, treatment involves an extended course of physical therapy [12].
Other Considerations: The optimal nonoperative treatment of a shoulder dislocation is still unknown and deserves further study [12]. Nonsurgical management for anterior shoulder instability is typically considered in preadolescents, older patients (older than 30 years), and/or those with low activity demands, as well as in-season athletes [28]. Young age, male sex, and hyperlaxity are clear risk factors for failure of conservative treatment for anterior shoulder instability [28]. Multiple episodes of instability have been linked to increased attritional glenoid bone loss [28], increased procedural complexity such as remplissage or coracoid transfer [28], increased severity of glenoid chondral defects [28], compromised outcomes at the time of surgical shoulder stabilization [28], and higher rates of glenohumeral osteoarthritis [28]. Seventy percent of patients younger than 22 years had recurrent instability, with 50% requiring surgical stabilization [28]. Regardless of age, glenohumeral posttraumatic arthritis developed in two-thirds of patients by the end of the 25-year period [28].
Early arthroscopic stabilization can decrease recurrence rates and improve functional outcomes in young (>25 years old), high-risk patients with first-time anterior dislocations and an associated Bankart lesion [12]. In the absence of severe capsular laxity or bony deficiency, arthroscopic stabilization is considered a first-line therapy in recurrent anterior and posterior instability of traumatic origin [12]. Participation in a contact sport is not a contraindication to arthroscopic stabilization [12]. Arthroscopic surgery using modern suture-anchor techniques and shoulder-specific instrumentation have yielded results comparable to those of open surgery [12]. Open surgery has a slightly lower recurrence rate at the cost of some loss of external rotation compared to arthroscopic surgery [12]. Open surgery should be strongly considered in cases of severe capsular laxity or deficiency, glenoid or humeral bone loss, avulsion of the capsule from the humeral side, documented connective tissue disorders, and for revision stabilizations [12]. Arthroscopic and open capsular shifts have been successful in restoring stability and decreasing pain [12]. Thermal capsulorrhaphy has recently shown a high complication rate [12]. The results of arthroscopic treatment are less predictable in patients with greater than 2+ instability in two or more directions, patients with 3+ (locking) unidirectional patterns without evidence of capsular injury, and those with atraumatic posterior instability [12]. An open capsular shift may provide a more predictable outcome than arthroscopic treatment in patients with greater than 2+ instability in two or more directions, patients with 3+ (locking) unidirectional patterns without evidence of capsular injury, and those with atraumatic posterior instability [12].
Risk factors for failure of operative stabilization include age younger than 20 years, competitive overhead or contact athlete, shoulder capsular attenuation (due to a genetic collagen disorder and/or poor quality capsulolabral tissue), a Hill-Sachs lesion present on the anteroposterior (AP) radiograph in external rotation, and loss of the anteroinferior glenoid contour on the AP radiograph [63]. These risk factors have been used to develop the instability severity index score (ISIS), which identifies patients for whom open stabilization may be more effective [63]. When the interval of time between the dislocation and reduction approaches 5 hours or more, stabilization techniques that address bone loss such as the Latarjet reconstruction should be considered [63]. The number of formal reductions required for anterior dislocation has been shown to directly correlate with failure following arthroscopic repair [63]. Patients with demonstrable bone loss from the glenoid or humeral head that warrants bone augmentation or transfer (e.g., Latarjet procedure, Bristow procedure, free allograft or autograft), patients with capsular injury, and those who require a revision stabilization through an open approach may still benefit from a diagnostic arthroscopy prior to open surgery to document all pathology [63]. Although capsular avulsions of the glenohumeral ligaments have been successfully repaired arthroscopically, many arthroscopic shoulder surgeons still consider HAGL lesions as a relative contraindication to an all-arthroscopic stabilization [63]. Detailed and specific information about prognosis is critical in the management of a first-time anterior shoulder dislocation [36]. Further research is needed to assess the implications of morphological changes following single versus recurrent traumatic posterior shoulder dislocation events on surgical outcomes and long-term shoulder stability [62].
This study demonstrates a long-term benefit in overall shoulder stability and functional outcome in high-risk patients who have undergone ABR for first-time anterior dislocation [61]. The 1-year outcomes in this prospective study suggest superiority of operative over non-operative treatment for posterior shoulder instability [9]. These results emphasize the importance of performing long-term follow-up studies after surgical reconstruction for unidirectional, posttraumatic, anterior shoulder instability [60]. The degree of arthropathy 33 to 35 years after the B-L repair seems to follow the natural history of shoulder dislocation with respect to arthropathic joint degeneration [83]. Arthroscopic repair for posterior shoulder instability yields favorable mid-term outcomes, with significant improvements in functional scores and a low recurrence rate at a mean follow-up of 10.6 years [224]. The combination of arthroscopic remplissage and classic Bankart repair for recurrent anterior shoulder instability with engaging Hill–Sachs lesions has long-term outcomes in terms of the recurrence rate and does not significantly influence the range of motion of the shoulder [226]. In a series of open shoulder anterior capsular reconstruction for instability from severe capsular deficiency, 9 shoulders (45%) remained completely stable at 3.8 years [319]. The number of episodes of dislocation before surgery and the delayed surgical intervention did not increase the recurrent anterior shoulder instability rates postoperatively [321]. In a cohort of young patients undergoing arthroscopic surgery for posterior shoulder instability, there was no significant difference in reoperation rate and recurrence of symptoms between athletes who underwent objective return to sport testing and those who were released to sport on a time-based protocol [322]. None of the patients has had instability after an average follow-up of 26 months following repair of humeral and glenoid detachment of the anterior inferior glenohumeral ligament [324]. At 3-year follow-up, the shoulders were stable and revealed no recurrent instability in a case of luxatio erecta of bilateral shoulders [47]. Short-term outcomes for pre-shaped allograft for glenoid reconstruction in anterior shoulder instability are reassuring, but more research is needed to study long-term graft union, graft resorption, glenohumeral arthritis, and patient outcomes including recurrent shoulder instability [55].
Key Evidence¶
- [L4] The MOON Shoulder Instability Study has enrolled the largest cohort of patients undergoing shoulder stabilization to date. [1] (10.1177/0363546518755752)
- [L5] [2] (10.1177/17585732251320070)
- [L5] The authors propose a classification system, which challenges previous systems by being all inclusive and recognises that more than one pathology can occur in an individual shoulder. [4] (10.1016/j.cuor.2004.04.002)
- [L3] Long-term follow-up demonstrates that nearly 40% of patients treated non-operatively for posterior shoulder instability eventually require surgery. [6] (10.1177/2325967118s00098)
- [L4] At long-term follow-up of 17 years, a high rate of poor outcomes was observed following nonoperative management of anterior shoulder instability. [7] (10.1016/j.jse.2021.07.016)
- [L4] This highlights the need for a consensus on definition of recurrence across shoulder instability studies. [8] (10.1016/j.asmr.2021.02.002)
- [L3] The 1-year outcomes in this prospective study suggest superiority of operative over non-operative treatment for posterior shoulder instability. [9] (10.1016/j.otsr.2017.08.004)
- [L2] More than a third of continuous outcomes in anterior shoulder instability trials had a continuous fragility index less than the reported loss to follow-up. [10] (10.1177/03635465231202522)
- [L3] Most patients younger than 40 years with shoulder instability who were initially treated nonoperatively for 6 months were definitively treated without surgery. [13] (10.1016/j.arthro.2021.03.047)
- [L4] Many different diagnostic examinations for assessing shoulder instability are used and a high variety is seen in the use of diagnostic tools. [14] (10.1007/s00402-016-2443-7)
- [L5] The consensus statement aims to improve diagnosis and treatment of shoulder instability through universal agreement on outcome measurement tools and tailored treatment based on pathology, patient age, activity demands, and surgeon skills. [15] (10.1016/j.arthro.2009.06.022)
- [L5] Proper evaluation of bone loss best determines shoulder instability surgical indications and outcomes. [17] (10.1016/j.arthro.2021.01.004)
- [L5] Failure of primary shoulder stabilization procedures is often related to uncorrected anatomic pathology, and the instability severity index score permits precise identification of patients at risk. [18] (10.1016/j.arthro.2010.11.057)
- [L5] The Delphi method is a structured communication technique used to allow a panel of experts to achieve a consensus in a systematic manner, resulting in an international consensus statement on shoulder instability covering diagnosis, nonoperative management, surgical options, rehabilitation, and clinical follow-up. [19] (10.1016/j.arthro.2021.11.052)
- [L3] A thorough clinical exam is the most important factor when determining indication for shoulder instability surgery. [20] (10.1016/j.xrrt.2026.100675)
- [L5] Substantial variability was observed in the scoring of important elements in the radiological report for the evaluation of anterior shoulder instability, regardless of modality. [21] (10.1016/j.jseint.2024.03.012)
- [L3] At midterm follow-up, recurrent shoulder instability following primary arthroscopic anterior capsulolabral repair was 30% in this series. [24] (10.1016/j.arthro.2019.11.109)
- [L1] The early and midterm results of arthroscopic stabilization of the shoulder for posterior instability are promising. [26] (10.1016/j.arthro.2014.11.009)
- [L4] The short-term outcome in this small series of arthroscopic revision surgery in shoulder instability is challenging and encouraging. [29] (10.1016/s1058-2746(96)80315-6)
- [L5] Recurrent posterior shoulder instability is an uncommon condition often unrecognized, leading to incorrect diagnoses and delays. [31] (10.5435/00124635-200608000-00004)
- [L3] Identification of these critical radiographic variables on magnetic resonance arthrography assists in the accurate diagnosis and management of clinically significant posterior shoulder instability. [35] (10.1177/0363546516660076)
- [L2] Detailed and specific information about prognosis is critical in the management of a first-time anterior shoulder dislocation. [36] (10.1016/j.jse.2010.10.037)
- [L4] They are considered safe and clinically effective for the management of anterior shoulder instability with glenoid bone loss. [37] (10.5435/jaaos-d-22-00837)
- [L4] MRI provides an accurate diagnosis of these disorders, thus allowing the expeditious, and appropriate management of occult anterior glenohumeral instability. [38] (10.1016/s1058-2746(96)80175-3)
- [L1] Surgical treatment of primary, traumatic, anterior shoulder instability results in reduced rates of recurrence compared with nonsurgical treatment at 10-year follow-up. [43] (10.1016/j.arthro.2006.11.026)
- [L2] The FEDS classification, particularly the frequency and etiology of the patient's shoulder instability, may be helpful in identifying patients with a higher likelihood of undergoing surgical treatment. [44] (10.1177/2325967115607434)
- [L2] The FEDS classification, particularly the frequency and etiology of the patient's shoulder instability, may be helpful in identifying patients with a higher likelihood of undergoing surgical treatment. [45] (10.1016/j.jse.2016.07.053)
- [L2] The FEDS classification, particularly the frequency and etiology of the patient's shoulder instability, may be helpful in identifying patients with a higher likelihood of undergoing surgical treatment. [46] (10.1016/j.jse.2016.07.054)
- [L5] At 3-year follow-up, the shoulders were stable and revealed no recurrent instability. [47] (10.1067/mse.2001.115987)
- [L4] The thresholds defined in this study can provide a guideline for interpreting patient outcomes following arthroscopic stabilization for posterior shoulder instability, allowing for earlier detection of recurrent posterior instability. [48] (10.1016/j.jseint.2025.08.006)
- [L4] Some risk of recurrent instability is part of the natural history of anterior shoulder dislocation. [49] (10.1016/j.jor.2015.01.030)
- [L5] This paper reviews the nonoperative treatment and the postoperative management of patients with various classifications of shoulder instability. [50] (10.2519/jospt.2002.32.10.497)
- [Paper] The indications for an isolated soft-tissue procedure in anterior shoulder instability are now narrower; the ideal candidate presents with minimal glenoid bone loss (13.5%). [53] (10.2106/jbjs.rvw.26.00033)
- [L4] With a follow-up of 97%, about one third of the stabilized shoulders experienced at least one redislocation after 8 to 10 years. [54] (10.1177/0363546511415657)
- [Paper] Short-term outcomes are reassuring, but more research is needed to study long-term graft union, graft resorption, glenohumeral arthritis, and patient outcomes including recurrent shoulder instability. [55] (10.1016/j.eats.2017.10.007)
- [L2] RCTs reporting on shoulder instability surgery are well performed but poorly reported. [56] (10.1177/1758573218754370)
- [L2] We recommend using it in following up patients with shoulder instability. [57] (10.1016/j.otsr.2016.10.024)
- [L5] [58] (10.1530/eor-24-0025)
- [L4] These results emphasize the importance of performing long-term follow-up studies after surgical reconstruction for unidirectional, posttraumatic, anterior shoulder instability. [60] (10.1177/03635465020300060401)
- [L1] This study demonstrates a long-term benefit in overall shoulder stability and functional outcome in high-risk patients who have undergone ABR for first-time anterior dislocation. [61] (10.2106/jbjs.19.00858)
- [L4] Further research is needed to assess the implications of these morphological changes on surgical outcomes and long-term shoulder stability. [62] (10.1177/2325967126s00514)
- [L3] At mid-term follow-up, patients with a history of anterior shoulder instability undergoing total shoulder arthroplasty can expect continued improvement in function compared with preoperative values. [64] (10.1016/j.jse.2023.07.005)
- [Abstract] The natural history of the first time shoulder dislocations is bound up with arthropathy. [65] (10.1016/j.jse.2007.02.100)
- [L3] This long-term follow-up study demonstrated that the open Latarjet procedure is a safe and reliable technique for recurrent anterior shoulder instability. [70] (10.1016/j.jse.2021.03.097)
- [L3] This long-term follow-up study demonstrated that the open Latarjet procedure is a safe and reliable technique for recurrent anterior shoulder instability. [71] (10.1007/s00402-020-03426-2)
- [L3] A history of multiple instability episodes prior to presentation was the greatest predictor of recurrent instability and failure of nonoperative treatment and progression to surgery. [73] (10.1016/j.asmr.2023.03.014)
- [L4] The long-term data suggest that these benefits are durable, and the Latarjet procedure should be considered as a viable and reliable treatment option for anterior glenohumeral instability. [74] (10.1016/j.jseint.2025.04.033)
- [L4] [75] (10.1016/j.csm.2004.08.010)
- [L4] There is substantial variability in outcome reporting for high-impact anterior shoulder instability literature with 28 different outcome tools used, making it difficult to compare outcomes between studies. [76] (10.1016/j.arthro.2016.07.027)
- [L5] [77] (10.1016/j.arthro.2024.04.035)
- [L5] In the interim, surgical soft-tissue stabilization might be more aggressively indicated in cases of primary shoulder dislocation, whereas recurrent instability with bone loss should be referred to experienced high-volume specialists. [79] (10.1016/j.arthro.2016.06.032)
- [L4] The degree of arthropathy 33 to 35 years after the B-L repair seems to follow the natural history of shoulder dislocation with respect to arthropathic joint degeneration. [83] (10.1016/j.jse.2014.09.021)
- [L3] [86] (10.1016/s1058-2746(99)90058-7)
- [L3] Patients do not always recognize anterior shoulder instability, and initial physical examination may be limited in the acute setting. [111] (10.1177/23259671251414851)
- [L4] Pain can serve as a clinical indicator of larger labral pathology in patients presenting with shoulder instability. [112] (10.1177/17585732251316476)
- [L5] The system categorizes instability based on frequency, aetiology, direction, and severity. [114] (10.1136/bjsm.2009.071183)
- [L2] Primary non-operative management is a prominent risk factor for recurrence of shoulder instability. [129] (10.1136/bjsports-2016-096895)
- [L4] The PHAGL lesion is challenging to diagnose clinically and can be the cause of posterior instability or a component of the spectrum of shoulder instability. [131] (10.1016/j.arthro.2007.02.006)
- [L3] Minor shoulder instability is an intra-articular pathology presenting with extra-articular subacromial impingement symptoms. [134] (10.1007/s00167-011-1552-7)
- [L1] Shoulder instability cannot reliably be classified using the ICD-9 coding system. [137] (10.1016/j.jse.2008.10.005)
- [L3] Microinstability is diagnostically challenging and can be diagnosed in young patients with ambiguous shoulder pain during motion, without instability. [138] (10.1007/s00167-022-06941-4)
- [L4] To assess the effectiveness of an arthroscopic stabilization procedure for anterior shoulder instability using the Rowe score, a difference of at least 9.7 in the score is clinically relevant. [140] (10.1016/j.jse.2017.10.032)
- [Paper] HAGL lesions are a rare and underdiagnosed cause of anterior shoulder instability that can lead to recurrent dislocations if unaddressed. [141] (10.1016/j.eats.2020.10.053)
- [Paper] GAGL lesions are an uncommon cause of anterior shoulder instability and require a high level of suspicion. [143] (10.1016/j.eats.2019.06.001)
- [Paper] Treatment of posterior shoulder instability by capsulolabral reconstruction leads to good clinical outcomes; however the recurrence rate is high. [151] (10.1016/j.otsr.2017.08.002)
- [L5] The success of treating anterior glenohumeral instability relies on multiple factors, including glenoid bone loss. [155] (10.1016/j.arthro.2021.09.002)
- [L1] The Latarjet is a safe and effective procedure for patients with shoulder instability. [159] (10.1177/1758573220945318)
- [L1] Primary arthroscopic treatment of posterior shoulder instability is associated with favorable outcomes and high return to sport and work rates. [170] (10.1016/j.asmr.2024.101032)
- [L3] Successful results were obtained in patients younger than 40 years with both primary and recurrent anterior shoulder instability after arthroscopic treatment. [171] (10.1016/j.jse.2023.05.029)
- [L1] Arthroscopic stabilization for recurrent anterior shoulder instability can be performed safely; the clinical outcomes are comparable to those after traditional open stabilization. [172] (10.1177/0363546506288239)
- [L5] The ABC classification distinguishes three groups of posterior glenohumeral instability with two different subtypes based on the pathomechanical type of instability and the current standard of treatment. [173] (10.1007/s11678-017-0404-6)
- [L5] Successful treatment of anterior instability of the shoulder requires a balance between restoring joint stability and minimizing loss of glenohumeral motion. [177] (10.1177/03635465030310011001)
- [L4] Adolescent multidirectional shoulder instability refractory to non-surgical management appears to have long-term outcomes after surgical intervention that are comparable to adolescent patients with unidirectional instability. [182] (10.1177/2325967121s00021)
- [L4] Arthroscopic treatment of posterior shoulder instability is an effective means to improve symptoms associated with recurrent posterior subluxation of the shoulder. [187] (10.1177/0363546505278301)
- [L4] Results in this series demonstrate the efficacy and durability of a modified capsular shift procedure for the treatment of atraumatic anterior-inferior shoulder instability. [189] (10.1177/0363546504272685)
- [L3] Regardless of treatment, professional hockey players experience a high rate of return to play with acceptable performance outcomes following in-game shoulder instability events. [194] (10.1177/2325967120s00383)
- [L4] Arthroscopic stabilization of posterior shoulder instability resulted in good outcomes with high patient satisfaction and low rates of recurrent instability, revisions, and residual pain. [195] (10.1016/j.jse.2024.04.006)
- [L5] There are discrepancies in the definition and classification of multidirectional instability, which can make diagnosis and treatment selection challenging. [196] (10.1016/j.jht.2017.03.005)
- [L4] Current evidence supports the safety and efficacy of both the Latarjet and FBB procedures for anterior shoulder stabilization in the presence of glenoid bone loss. [200] (10.1177/0363546520925833)
- [L4] The proposed procedure demonstrated effectiveness and safety, being a viable option for treating anterior shoulder instability with glenoid bone loss of less than 20% and especially beneficial for athletes. [201] (10.1016/j.jseint.2024.06.016)
- [L4] This classification is very useful to compare pathogenesis and results of treatment in patients with glenohumeral instability. [202] (10.1016/s1058-2746(05)80051-5)
- [L5] Conventional radiography remains the initial imaging study for evaluating patients with persistent shoulder pain and instability, while magnetic resonance arthrography has been firmly established as the imaging modality of choice for demonstrating specific soft tissue abnormalities associated with glenohumeral instability. [206] (10.1177/03635465000280032501)
- [L3] Nonoperative treatment of shoulder instability has substantial societal costs. [210] (10.1177/1758573218773543)
- [L4] The Latarjet procedure for anterior shoulder instability results in an overall complication rate of 16.1% and a reoperation rate of 2.6%, though serious complications at short-term follow-up appear rare. [211] (10.1177/03635465211042314)
- [L4] The proposed classification system is a helpful guide to the degree of glenoid bone loss when embarking on revision shoulder arthroplasty. [213] (10.1302/0301-620x.98b3.36664)
- [L3] For experienced shoulder surgeons, the Snyder classification is a reliable system for identifying SLAP lesions. [214] (10.1177/0363546510392332)
- [L2] The FEDS system has content validity and is highly reliable for classifying glenohumeral instability. [215] (10.1016/j.jse.2010.10.027)
- [L4] Recent studies continue to demonstrate a role for nonoperative treatment in the successful long-term management of anterior glenohumeral instability. [219] (10.1007/s12178-017-9432-5)
- [L3] Female patients undergoing the Latarjet procedure for recurrent shoulder instability showed similar 90-day complication and 2-year secondary surgery rates to a matched cohort of male patients. [220] (10.1016/j.arthro.2024.02.043)
- [L4] The formation of clusters based on glenoid morphology indicates that patterns exist in the types of glenoid defects, highlighting a need to further investigate a three-dimensional classification system and potentially new standardized revision implant component designs. [222] (10.1016/j.jse.2026.04.002)
- [L5] Arthroscopic repair for posterior shoulder instability yields favorable mid-term outcomes, with significant improvements in functional scores and a low recurrence rate at a mean follow-up of 10.6 years. [224] (10.1016/j.arthro.2025.07.040)
- [L4] This combination has long-term outcomes in terms of the recurrence rate and does not significantly influence the range of motion of the shoulder. [226] (10.1007/s00167-018-5261-3)
- [Paper] Static MRI does not appear helpful, however CINE MRI can reproducibly confirm the diagnosis of shoulder instability. [228] (10.1016/s1058-2746(96)80178-9)
- [L4] NHL team physicians strongly favor nonoperative management in-season for initial posterior instability events of the shoulder. [230] (10.1177/23259671261440208)
- [L4] Arthroscopic management of a failed instability repair provides similar success to open reconstruction if one selects proper indications. [231] (10.1097/00132589-200212000-00008)
- [L1] Despite the wide array of available PROMs for assessing shoulder instability surgery outcomes, the availability of clinically significant outcome thresholds such as MCID and PASS remains relatively limited. [233] (10.1016/j.arthro.2024.07.039)
- [L1] This study supports the need for standardized outcome reporting after arthroscopic anterior shoulder instability surgery in adolescents. [235] (10.1016/j.arthro.2017.10.041)
- [L4] Arthroscopic capsulolabral repair for posterior shoulder instability was a durable treatment option that improved long-term shoulder pain and function and facilitated return to sport in the majority of patients at a mean follow-up of 15.4 years, although a notable proportion of patients met various criteria for failure. [236] (10.1177/03635465231162271)
- [Case_report] Patients with a history of shoulder instability or replacement are at risk for shoulder dislocation during common elbow and hand procedures. [237] (10.1016/j.jse.2020.04.012)
- [L1] There was no evidence regarding the effectiveness of surgical management for post-traumatic chronic shoulder instability. [239] (10.1136/bjsports-2017-098539)
- [L4] Shoulder arthroplasty may improve functional outcomes for patients experiencing instability arthropathy with a history of stabilization surgery. [240] (10.1016/j.xrrt.2023.01.003)
- [L5] Magnetic resonance arthrography is regarded as the gold-standard imaging modality for shoulder instability. [241] (10.1016/j.mric.2019.12.005)
- [L3] Surgical shoulder stabilization in an athlete after a first episode of instability is not indicated in all patients. [242] (10.1016/j.arthro.2017.04.088)
- [L3] [245] (10.1007/s00167-020-06388-5)
- [L4] The recurrence of anterior shoulder instability can be as high as 86.7% in high-risk patients who are treated nonoperatively after their first incident of instability. [246] (10.5435/jaaosglobal-d-19-00168)
- [L1] Capsular injury is commonly seen in magnetic resonance imaging of patients with anterior shoulder instability. [248] (10.1016/j.xrrt.2024.08.004)
- [L4] By contrast, the presence of a posterior glenoid fracture (bony Bankart lesion) did not represent a contraindication to arthroscopic shoulder stabilization. [249] (10.1177/03635465251403499)
- [L5] Its main indications are for shoulder instability in high-impact athletes, together with a capsule-labrum reconstruction, and poor tissue quality of the labrum in patients with multiple long-term dislocations. [250] (10.1097/bte.0000000000000153)
- [L4] Recurrent instability requiring capsular reconstruction seems to be more prevalent in patients with a previous history of shoulder dislocation. [251] (10.1016/j.jse.2009.07.062)
- [L3] [252] (10.1177/2325967119853507)
- [L4] [253] (10.1177/17585732231154889)
- [Paper] Advanced imaging modalities are essential for identifying associated lesions, and bony reconstruction procedures should be considered for patients with significant glenoid bone loss or recurrent instability after soft tissue reconstruction. [254] (10.1016/j.csm.2014.06.006)
- [L2] Early arthroscopic stabilization by anterior capsule-labrum reinsertion after initial anterior shoulder dislocation is associated with a low 10-year recurrence rate of 35% compared to non-operative management. [255] (10.1016/j.otsr.2015.09.029)
- [L4] [258] (10.1016/j.jse.2019.12.012)
- [L3] Magnetic resonance arthrography was an accurate method to assess accompanying lesions in first-time and recurrent anterior dislocation of the shoulder. [259] (10.1177/0363546510371607)
- [L5] [260] (10.1177/1758573218815002)
- [L4] [261] (10.1016/j.jse.2005.11.011)
- [L1] There is insufficient evidence from randomised trials comparing arthroscopic with open surgery for treating anterior shoulder instability. [262] (10.1002/14651858.cd005077.pub2)
- [L3] This useful MRI measurement may help identify patients at risk for primary or recurrent anterior glenohumeral instability events and may therefore help with guiding treatment and prevention. [263] (10.1177/2325967120986139)
- [L3] Despite the advantages of MRI in the detection of soft tissue damages in recurrent anterior shoulder instability CT imaging proved to be more important for glenoid defects. [264] (10.1007/s00402-012-1656-7)
- [L1] Early operative stabilization of Bankart lesions in young patients offers a significant reduction in the risk of recurrent instability compared to non-operative management. [265] (10.1111/j.1758-5740.2010.00083.x)
- [L3] Stabilization of the dominant shoulder resulted in residual surgery-related functional impairments on both sides, whereas stabilization of the nondominant shoulder resulted in impairments primarily noted in the nondominant, operative shoulder. [266] (10.1177/03635465231156181)
- [L3] Preoperative risk factors included history of bilateral shoulder instability and atraumatic mechanism of dislocation. [267] (10.1177/2325967120s00378)
- [L3] In a US epidemiologic population of patients <40 years old, the rate of recurrent anterior shoulder instability was roughly one-third after initial physician consultation. [269] (10.1177/0363546519886861)
- [L4] CT and MRI (2D or 3D) accurately measure glenoid bone loss in anterior shoulder instability, but radiographs do not. [270] (10.2214/ajr.18.20504)
- [L4] The iliac posterior shoulder bone-block is effective in managing instances of involuntary posterior shoulder instability, showing satisfactory results in terms of non-recurrence, pain relief, and function recovery. [272] (10.1016/j.otsr.2008.09.008)
- [L4] [277] (10.1007/s12178-011-9092-9)
- [L5] MR-arthrography is identified as the main tool in diagnosing shoulder instability injuries. [279] (10.21037/qims.2017.08.05)
- [L4] [281] (10.1054/jhsb.1999.0282)
- [L4] These findings suggest that this radiographic change should be regarded as a new sign of anterior shoulder instability of traumatic origin. [285] (10.1016/1058-2746(92)90092-h)
- [L5] [292] (10.1016/s0278-5919(05)70183-6)
- [L4] Magnetic resonance angiography has a high sensitivity when used to identify associated injuries in shoulder dislocation, although in 8 patients (13 %) arthroscopy identified an additional injury. [293] (10.1007/s00256-014-2080-6)
- [L3] [294] (10.1097/corr.0000000000002320)
- [L2] Overall, 3D MRI is a validated and reliable alternative to 3D CT for preoperative evaluation of static glenohumeral bone loss and dynamic morphological variables in shoulder instability, allowing clinicians to choose the modality that best fits their practice. [298] (10.1177/23259671251343325)
- [L3] Overall, 3D MRI is a validated and reliable alternative to 3D CT for preoperative evaluation of static glenohumeral bone loss and dynamic morphological variables in shoulder instability, allowing clinicians to choose the modality that best fits their practice. [299] (10.1177/2325967125s00129)
- [L4] In the future, we expect CT to be superseded by MRI in anterior shoulder instability. [300] (10.1016/j.jseint.2025.101440)
- [L5] In patients with suspected posterior glenohumeral instability, imaging of the affected shoulder can show abnormalities of the bone, labrum, and joint capsule. [301] (10.2214/ajr.07.3849)
- [L3] Patients who undergo MRI greater than 6 months from the time of primary shoulder dislocation demonstrate a greater incidence and severity of intra‐articular pathology including SLAP tears, posterior labral tears and anterior glenoid cartilage damage. [302] (10.1177/2325967117s00360)
- [L4] [303] (10.1016/j.jse.2017.01.027)
- [L5] Even without posterior instability complaints or findings, in patients with posterior shoulder pain during daily activities or sports, posterior labral tears should be considered even when MRI or MRA findings are ambiguous. [305] (10.1016/j.arthro.2023.07.004)
- [L4] The radiographic analysis of the Hill-Sachs lesion with a constant, reproducible technique can play a role in the diagnosis of anterior shoulder instability and patient selection for therapeutic intervention. [307] (10.1067/mse.2000.106920)
- [L4] Radiography can be used for screening patients for significant glenoid bone loss. [309] (10.1186/s12891-015-0607-1)
- [L3] The superior-capsular elongation as well as its diagnostic criteria of measurements by MR arthrography revealed in the present study could serve as references for diagnosing atraumatic posteroinferior shoulder instability and offer insight into the spectrum of imaging findings corresponding to the pathologies encountered at clinical presentation. [310] (10.3109/02841850903524421)
- [L3] Routine MRI has similar diagnostic value to MR arthrogram for measuring labral tear extent up to approximately 2 weeks postacute shoulder dislocation, after which it significantly loses accuracy and precision. [312] (10.1177/2325967124s00075)
- [L3] Radiographic progression of glenohumeral arthritis occurred in 14% of patients with posterior shoulder instability. [313] (10.1177/2325967118s00154)
- [L3] ZTE MRI demonstrated high reproducibility for the evaluation of glenoid bone defect in shoulders with anterior instability. [314] (10.1016/j.jseint.2024.03.003)
- [L4] Patients with multidirectional instability demonstrated quantifiable dynamic instability on cine MRI with significantly greater humeral head deviation and faster deviation velocity than healthy controls. [316] (10.1016/j.jseint.2025.101419)
- [L4] Additionally, MRI is a valid imaging tool to diagnose and measure osseous lesions of the shoulder. [317] (10.1007/s00247-018-4318-2)
- [L3] MRI provided an accurate, non-invasive method of imaging the glenohumeral joint that was superior to CTA in diagnosing labral, gienoid rim, and humeral head abnormalities, commonly associated with glenohumeral instability. [318] (10.1016/s1058-2746(96)80388-0)
- [L4] In our series 9 shoulders (45%) remained completely stable at 3.8 years. [319] (10.1016/j.arthro.2011.07.002)
- [L4] The number of episodes of dislocation before surgery and the delayed surgical intervention did not increase the recurrent anterior shoulder instability rates postoperatively. [321] (10.1016/j.jseint.2022.12.003)
- [L3] In our cohort of young patients undergoing arthroscopic surgery for posterior shoulder instability, we detected no significant difference in reoperation rate and recurrence of symptoms between athletes who underwent objective return to sport testing and those who were released to sport on a time-based protocol. [322] (10.1177/2325967121s00549)
- [L4] None of the patients has had instability after an average follow-up of 26 months. [324] (10.1016/s1058-2746(97)90064-1)
See Also¶
- Latarjet Procedure
- Fractures
- Rotator Cuff
- Os Acromiale
- Shoulder Arthroplasty
- Thoracic Outlet Syndrome
- Frozen Shoulder
- Shoulder Arthritis
- Total shoulder arthroplasty
References¶
[1] Descriptive Epidemiology of the MOON Shoulder Instability Cohort. The American Journal of Sports Medicine. 2018. DOI: 10.1177/0363546518755752
[2] Assessment and diagnosis of non-traumatic shoulder instability: A scoping review. Shoulder & Elbow. 2025. DOI: 10.1177/17585732251320070
[3] Orthopaedic Knowledge Update Sports Medicine 6. Research Studies and Registries in Sports Medicine > Multicenter and Registry-Based Research in Sports Medicine > Shoulder Research.
[4] (ii) The classification of shoulder instability: new light through old windows!. Current Orthopaedics. 2004. DOI: 10.1016/j.cuor.2004.04.002
[5] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > SUMMARY.
[6] Non-operative Management of Posterior Shoulder Instability: An Assessment of Survival and Predictors for Conversion to Surgery at 1 to 13 Years After Diagnosis. Orthopaedic Journal of Sports Medicine. 2018. DOI: 10.1177/2325967118s00098
[7] Nonoperative management of anterior shoulder instability can result in high rates of recurrent instability and pain at long-term follow-up. Journal of Shoulder and Elbow Surgery. 2022. DOI: 10.1016/j.jse.2021.07.016
[8] High Variability of the Definition of Recurrent Glenohumeral Instability: An Analysis of the Current Literature by a Systematic Review. Arthroscopy, Sports Medicine, and Rehabilitation. 2021. DOI: 10.1016/j.asmr.2021.02.002
[9] Posterior shoulder instability: Prospective non-randomised comparison of operative and non-operative treatment in 51 patients. Orthopaedics & Traumatology: Surgery & Research. 2017. DOI: 10.1016/j.otsr.2017.08.004
[10] The Continuous Fragility Index of Statistically Significant Findings in Randomized Controlled Trials That Compare Interventions for Anterior Shoulder Instability. The American Journal of Sports Medicine. 2024. DOI: 10.1177/03635465231202522
[11] Aaos Comprehensive Orthopaedic Review 3. The Unstable Shoulder > V. Multidirectional Instability.
[12] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > CONCLUSIONS.
[13] Multiple Instability Events at Initial Presentation Are the Major Predictor of Failure of Nonoperative Treatment for Anterior Shoulder Instability. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2021. DOI: 10.1016/j.arthro.2021.03.047
[14] International survey and surgeon’s preferences in diagnostic work-up towards treatment of anterior shoulder instability. Archives of Orthopaedic and Trauma Surgery. 2016. DOI: 10.1007/s00402-016-2443-7
[15] Consensus Statement on Shoulder Instability. Arthroscopy. 2009. DOI: 10.1016/j.arthro.2009.06.022
[17] Proper Evaluation of Bone Loss Determines Shoulder Instability Indications and Outcomes. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2021. DOI: 10.1016/j.arthro.2021.01.004
[18] Failure of Operative Treatment for Glenohumeral Instability: Etiology and Management. Arthroscopy. 2011. DOI: 10.1016/j.arthro.2010.11.057
[19] Comprehensive Review of Shoulder Instability Includes Diagnosis, Nonoperative Management, Bankart, Latarjet, Remplissage, Glenoid Bone‐Grafting, Revision Surgery, Rehabilitation and Return to Play, and Clinical Follow‐Up. Arthroscopy. 2022. DOI: 10.1016/j.arthro.2021.11.052
[20] No difference in outcomes for posterior shoulder instability surgery in patients with a normal vs. pathological radiologist reported magnetic resonance arthrogram study. JSES Reviews, Reports, and Techniques. 2026. DOI: 10.1016/j.xrrt.2026.100675
[21] Substantial variability in what is considered important in the radiological report for anterior shoulder instability: a Delphi study with Dutch musculoskeletal radiologists and orthopedic surgeons. JSES International. 2024. DOI: 10.1016/j.jseint.2024.03.012
[22] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > Instability.
[24] Predicting Failure After Primary Arthroscopic Bankart Repair: Analysis of a Statistical Model Using Anatomic Risk Factors. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2020. DOI: 10.1016/j.arthro.2019.11.109
[25] Aaos Comprehensive Orthopaedic Review 3. The Unstable Shoulder > IV. Posterior Instability.
[26] Arthroscopic Treatment of Posterior Shoulder Instability: A Systematic Review. Arthroscopy. 2014. DOI: 10.1016/j.arthro.2014.11.009
[27] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > Operative Management of Posterior Instability.
[28] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Shoulder Instability, Rotator Cuff Disorders, Muscular Ruptures, Adhesive Capsulitis, Calcific Tendinitis > Shoulder Instability > Anterior Instability.
[29] Arthroscopic revision surgery in shoulder instability. Journal of Shoulder and Elbow Surgery. 1996. DOI: 10.1016/s1058-2746(96)80315-6
[31] Recurrent Posterior Shoulder Instability. Journal of the American Academy of Orthopaedic Surgeons. 2006. DOI: 10.5435/00124635-200608000-00004
[32] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > Radiographic Evaluation.
[35] Critical Findings on Magnetic Resonance Arthrograms in Posterior Shoulder Instability Compared With an Age-Matched Controlled Cohort. The American Journal of Sports Medicine. 2016. DOI: 10.1177/0363546516660076
[36] A predictive model of shoulder instability after a first-time anterior shoulder dislocation. Journal of Shoulder and Elbow Surgery. 2011. DOI: 10.1016/j.jse.2010.10.037
[37] Free Bone Block Procedures for Glenoid Reconstruction in Anterior Shoulder Instability. Journal of the American Academy of Orthopaedic Surgeons. 2023. DOI: 10.5435/jaaos-d-22-00837
[38] MRI findings in anterior glenohumeral subluxation and dislocation. Journal of Shoulder and Elbow Surgery. 1996. DOI: 10.1016/s1058-2746(96)80175-3
[42] Rockwood And Matsen S The Shoulder. Developmental Anatomy of the Shoulder and Anatomy of the Glenohumeral Joint > SENIOR EDITOR COMMENTARY.
[43] Shoulder Instability: Surgical Versus Nonsurgical Treatment. Arthroscopy. 2007. DOI: 10.1016/j.arthro.2006.11.026
[44] Predictors for Surgery in Shoulder Instability. Orthopaedic Journal of Sports Medicine. 2015. DOI: 10.1177/2325967115607434
[45] Clinical and radiographic outcomes of distal tibia allograft reconstruction for glenoid bone defects in recurrent anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 2016. DOI: 10.1016/j.jse.2016.07.053
[46] Predictors for surgery in shoulder instability: a retrospective cohort study using the FEDS system. Journal of Shoulder and Elbow Surgery. 2016. DOI: 10.1016/j.jse.2016.07.054
[47] Luxatio erecta of bilateral shoulders. Journal of Shoulder and Elbow Surgery. 2001. DOI: 10.1067/mse.2001.115987
[48] Defining clinical significance following primary stabilization of posterior shoulder instability. JSES International. 2025. DOI: 10.1016/j.jseint.2025.08.006
[49] The management of secondary frozen shoulder after anterior shoulder dislocation – The results of manipulation under anaesthesia and injection. Journal of Orthopaedics. 2016. DOI: 10.1016/j.jor.2015.01.030
[50] Shoulder Instability: Management and Rehabilitation. Journal of Orthopaedic & Sports Physical Therapy. 2002. DOI: 10.2519/jospt.2002.32.10.497
[51] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > Multidirectional Instability.
[52] Classifications And Scores Of The Shoulder. 7.9 Classification of shoulder instability according to Gerber et al. [44, 45, 118]*.
[53] Current Approaches to Arthroscopic Management of Anterior Shoulder Instability. JBJS Reviews. 2026. DOI: 10.2106/jbjs.rvw.26.00033
[54] Long-term Results After Arthroscopic Shoulder Stabilization Using Suture Anchors. The American Journal of Sports Medicine. 2011. DOI: 10.1177/0363546511415657
[55] Pre‐shaped Allograft for Glenoid Reconstruction in Anterior Shoulder Instability. Arthroscopy Techniques. 2018. DOI: 10.1016/j.eats.2017.10.007
[56] An assessment of quality of randomized controlled trials in shoulder instability surgery using a modification of the clear CLEAR-NPT score. Shoulder & Elbow. 2018. DOI: 10.1177/1758573218754370
[57] Translation and validation of the French version of the Western Ontario Shoulder Instability Index (WOSI): WOSI-Fr. Orthopaedics & Traumatology: Surgery & Research. 2017. DOI: 10.1016/j.otsr.2016.10.024
[58] Diagnosis and treatment of posterior shoulder instability based on the ABC classification. EFORT Open Reviews. 2024. DOI: 10.1530/eor-24-0025
[60] Revisiting the Open Bankart Experience. The American Journal of Sports Medicine. 2002. DOI: 10.1177/03635465020300060401
[61] Primary Arthroscopic Stabilization for a First-Time Anterior Dislocation of the Shoulder. Journal of Bone and Joint Surgery. 2019. DOI: 10.2106/jbjs.19.00858
[62] Poster 218. Morphological Characteristics Following Single versus Recurrent Traumatic Posterior Shoulder Dislocation Events in a High-Risk Population. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00514
[63] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > Arthroscopic Versus Open Anterior Stabilization.
[64] Outcomes of total shoulder arthroplasty in patients with prior anterior shoulder instability: minimum 5-year follow-up. Journal of Shoulder and Elbow Surgery. 2024. DOI: 10.1016/j.jse.2023.07.005
[65] Long-Term Prognosis Of First Time Anterior Shoulder Dislocation In The Young: 229 Shoulders Prospectively Followed For 25 Years. Journal of Shoulder and Elbow Surgery. 2007. DOI: 10.1016/j.jse.2007.02.100
[68] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Shoulder Instability, Rotator Cuff Disorders, Muscular Ruptures, Adhesive Capsulitis, Calcific Tendinitis > Shoulder Instability > Posterior Instability.
[69] Rockwood And Matsen S The Shoulder. Developmental Anatomy of the Shoulder and Anatomy of the Glenohumeral Joint > Instability.
[70] Latarjet Procedure for Anterior Shoulder Instability: A 24-Year Follow Up Study. Journal of Shoulder and Elbow Surgery. 2021. DOI: 10.1016/j.jse.2021.03.097
[71] Latarjet procedure for anterior shoulder instability: a 24-year follow-up study. Archives of Orthopaedic and Trauma Surgery. 2020. DOI: 10.1007/s00402-020-03426-2
[73] Patients Aged >50 Years With Anterior Shoulder Instability Have a Decreased Risk of Recurrent Dislocation After Operative Treatment Compared With Non‐Operative Treatment. Arthroscopy, Sports Medicine, and Rehabilitation. 2023. DOI: 10.1016/j.asmr.2023.03.014
[74] Long-term outcomes of the Latarjet procedure in a North American population. JSES International. 2025. DOI: 10.1016/j.jseint.2025.04.033
[75] Osteoarthritis Following Shoulder Instability. Clinics in Sports Medicine. 2005. DOI: 10.1016/j.csm.2004.08.010
[76] Variability in Outcome Reporting for Operatively Managed Anterior Glenohumeral Instability: A Systematic Review. Arthroscopy. 2016. DOI: 10.1016/j.arthro.2016.07.027
[77] Posterior Shoulder Instability, Part I—Diagnosis, Nonoperative Management, and Labral Repair for Posterior Shoulder Instability—An International Expert Delphi Consensus Statement. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2024.04.035
[78] Classifications And Scores Of The Shoulder. 7.10 Classification of shoulder instability according to Bayley et al. [5, 6]*.
[79] Editorial Commentary: Glenoid Bone Reconstruction for Recurrent Shoulder Instability—Risk or Benefit?. Arthroscopy. 2016. DOI: 10.1016/j.arthro.2016.06.032
[83] Risk of arthropathy after the Bristow-Latarjet repair: a radiologic and clinical thirty-three to thirty-five years of follow-up of thirty-one shoulders. Journal of Shoulder and Elbow Surgery. 2015. DOI: 10.1016/j.jse.2014.09.021
[86] Evolution of lesions of the labrum-ligament complex in posttraumatic anterior shoulder instability: A prospective study. Journal of Shoulder and Elbow Surgery. 1999. DOI: 10.1016/s1058-2746(99)90058-7
[88] Rockwood And Matsen S The Shoulder. Shoulder and Elbow Specialty Clinic Workers’ Survey > ANATOMY.
[90] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 2Musculoskeletal Trauma Surgery > SHOULDER AND ARM INJURIES.
[92] Aaos Comprehensive Orthopaedic Review 3. Anatomy of the Shoulder, Arm, and Elbow > I. Shoulder.
[96] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > FRACTURES OF THE PROXIMAL HUMERUS.
[97] Rockwood And Matsen S The Shoulder. Developmental Anatomy of the Shoulder and Anatomy of the Glenohumeral Joint > Development of Individual Regions.
[99] Campbell S Operative Orthopaedics 4 Volume Set. RECONSTRUCTIVE PROCEDURES OF THE SHOULDER AND ELBOW IN ADULTS > ANATOMY AND BIOMECHANICS.
[100] Campbell S Operative Orthopaedics 4 Volume Set. ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION WITH BONE-PATELLAR TENDON-BONE GRAFT > SHOULDER INJURIES > ANATOMY AND BIOMECHANICS.
[103] Miller S Review Of Orthopaedics. Genetics of musculoskeletal conditions and abnormalities are summarized in Table 1.27 > UPPER EXTREMITY > SHOULDER.
[111] Unperceived First-Time Anterior Shoulder Subluxation: The Role of MRI in Detection and Characterization of Pathoanatomy. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671251414851
[112] Traumatic 270° and 360° labral tears of shoulder – Injury patterns, surgical technique, and mid-term outcomes. Shoulder & Elbow. 2025. DOI: 10.1177/17585732251316476
[114] A new classification system for shoulder instability. British Journal of Sports Medicine. 2010. DOI: 10.1136/bjsm.2009.071183
[124] Early Rehabilitation After a Modified Inferior Capsular Shift Procedure for Multidirectional Instability of the Shoulder. 1998.
[129] Recurrence and return to play after shoulder instability events in young and adolescent athletes: a systematic review and meta-analysis. British Journal of Sports Medicine. 2016. DOI: 10.1136/bjsports-2016-096895
[131] Posterior Humeral Avulsion of the Glenohumeral Ligament: A Clinical Review of 9 Cases. Arthroscopy. 2007. DOI: 10.1016/j.arthro.2007.02.006
[134] Minor or occult shoulder instability: an intra‐articular pathology presenting with extra‐articular subacromial impingement symptoms. Knee Surgery, Sports Traumatology, Arthroscopy. 2011. DOI: 10.1007/s00167-011-1552-7
[137] Intraobserver and interobserver agreement of International Classification of Diseases, Ninth Revision codes in classifying shoulder instability. Journal of Shoulder and Elbow Surgery. 2009. DOI: 10.1016/j.jse.2008.10.005
[138] Microinstability characterised by small and easily overlooked anterior labral or Hill–Sachs lesions can be managed with arthroscopic anterior labral repair. Knee Surgery, Sports Traumatology, Arthroscopy. 2022. DOI: 10.1007/s00167-022-06941-4
[140] Minimal clinically important differences in Rowe and Western Ontario Shoulder Instability Index scores after arthroscopic repair of anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 2018. DOI: 10.1016/j.jse.2017.10.032
[141] Arthroscopic Repair of Humeral Avulsion of the Glenohumeral Ligament for Anterior Shoulder Instability. Arthroscopy Techniques. 2021. DOI: 10.1016/j.eats.2020.10.053
[143] Understanding the Glenoid Avulsion of the Glenohumeral Ligaments as a Cause of Shoulder Instability: Surgical and Postsurgical Management. Arthroscopy Techniques. 2019. DOI: 10.1016/j.eats.2019.06.001
[151] Outcomes of capsulolabral reconstruction for posterior shoulder instability. Orthopaedics & Traumatology: Surgery & Research. 2017. DOI: 10.1016/j.otsr.2017.08.002
[154] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Shoulder Anatomy and Biomechanics, Clinical Evaluation, Imaging > Clinical Evaluation > Imaging.
[155] Editorial Commentary: Recurrent Anterior Shoulder Instability With Glenoid Bone Loss Requires Restoring the Bone. Arthroscopy. 2022. DOI: 10.1016/j.arthro.2021.09.002
[156] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > DIAGNOSIS AND DIAGNOSTIC ARTHROSCOPY IN SHOULDER INSTABILITY.
[159] Outcomes of the Latarjet procedure with minimum 5- and 10-year follow-up: A systematic review. Shoulder & Elbow. 2020. DOI: 10.1177/1758573220945318
[160] Orthopaedic Knowledge Update Sports Medicine 6. Shoulder Instability > Anterior Instability > Management.
[161] Aaos Comprehensive Orthopaedic Review 3. Imaging of the Shoulder and Elbow > I. Shoulder.
[162] Miller S Review Of Orthopaedics. SHOULDER INSTABILITY > History and physical examination.
[166] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > Clinical Findings.
[170] Arthroscopic Repair for Posterior Shoulder Instability Is Associated With Favorable Outcomes and High Return to Sport or Work: A Systematic Review and Meta‐Analysis. Arthroscopy, Sports Medicine, and Rehabilitation. 2024. DOI: 10.1016/j.asmr.2024.101032
[171] Lesion prevalence and patient outcome comparison between primary and recurrent anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 2023. DOI: 10.1016/j.jse.2023.05.029
[172] Arthroscopic versus Open Shoulder Stabilization for Recurrent Anterior Instability. The American Journal of Sports Medicine. 2006. DOI: 10.1177/0363546506288239
[173] ABC classification of posterior shoulder instability. Obere Extremität. 2017. DOI: 10.1007/s11678-017-0404-6
[177] Open Repairs for the Treatment of Anterior Shoulder Instability. The American Journal of Sports Medicine. 2003. DOI: 10.1177/03635465030310011001
[182] MEAN 6 YEAR CLINICAL OUTCOMES, SURVIVORSHIP, AND RETURN TO SPORTS AFTER ARTHROSCOPIC CAPSULAR REPAIR WITH SUTURE ANCHORS FOR ADOLESCENT MULTIDIRECTIONAL SHOULDER INSTABILITY. Orthopaedic Journal of Sports Medicine. 2021. DOI: 10.1177/2325967121s00021
[187] Arthroscopic Treatment of Posterior Shoulder Instability. The American Journal of Sports Medicine. 2005. DOI: 10.1177/0363546505278301
[189] A Modified Capsular Shift for Atraumatic Anterior-Inferior Shoulder Instability. The American Journal of Sports Medicine. 2005. DOI: 10.1177/0363546504272685
[194] Shoulder Instability, Performance and Return to Play in National Hockey League Athletes. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967120s00383
[195] Outcomes of arthroscopic stabilization for posterior shoulder instability: a systematic review. Journal of Shoulder and Elbow Surgery. 2024. DOI: 10.1016/j.jse.2024.04.006
[196] Multidirectional instability of the glenohumeral joint: Etiology, classification, assessment, and management. Journal of Hand Therapy. 2017. DOI: 10.1016/j.jht.2017.03.005
[200] Outcomes of the Latarjet Procedure Versus Free Bone Block Procedures for Anterior Shoulder Instability: A Systematic Review and Meta-analysis. The American Journal of Sports Medicine. 2020. DOI: 10.1177/0363546520925833
[201] Dynamic anterior stabilization of the shoulder using buttons. JSES International. 2024. DOI: 10.1016/j.jseint.2024.06.016
[202] Trauma-instability-voluntarism classification for glenohumeral instability. Journal of Shoulder and Elbow Surgery. 1995. DOI: 10.1016/s1058-2746(05)80051-5
[206] Imaging Techniques for the Evaluation of Glenohumeral Instability. The American Journal of Sports Medicine. 2000. DOI: 10.1177/03635465000280032501
[210] Direct and indirect costs associated with nonoperative treatment for shoulder instability: an observational study in 132 patients. Shoulder & Elbow. 2018. DOI: 10.1177/1758573218773543
[211] Complications Related to Latarjet Shoulder Stabilization: A Systematic Review. The American Journal of Sports Medicine. 2021. DOI: 10.1177/03635465211042314
[213] A new classification of glenoid bone loss to help plan the implantation of a glenoid component before revision arthroplasty of the shoulder. The Bone & Joint Journal. 2016. DOI: 10.1302/0301-620x.98b3.36664
[214] Reproducibility and Reliability of the Snyder Classification of Superior Labral Anterior Posterior Lesions Among Shoulder Surgeons. The American Journal of Sports Medicine. 2011. DOI: 10.1177/0363546510392332
[215] Development and reliability testing of the frequency, etiology, direction, and severity (FEDS) system for classifying glenohumeral instability. Journal of Shoulder and Elbow Surgery. 2011. DOI: 10.1016/j.jse.2010.10.027
[219] The Epidemiology and Natural History of Anterior Shoulder Instability. Current Reviews in Musculoskeletal Medicine. 2017. DOI: 10.1007/s12178-017-9432-5
[220] Female Patients Undergoing Latarjet Surgery Show Similar 2‐Year Secondary Surgery Rates but Greater Risk of Emergency Department Visits Compared With a Matched Cohort of Male Patients. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2024.02.043
[222] Three-Dimensional Characterization of Glenoid Defects in Failed Shoulder Arthroplasties. Journal of Shoulder and Elbow Surgery. 2026. DOI: 10.1016/j.jse.2026.04.002
[224] Posterior Labral Repair With Capsular Plication Shows Enduring Mid-Term Outcomes and Return to Sports With Low Recurrence Rates. Arthroscopy: The Journal of Arthroscopic & Related Surgery. 2025. DOI: 10.1016/j.arthro.2025.07.040
[226] Long‐term outcome of arthroscopic remplissage in addition to the classic Bankart repair for the management of recurrent anterior shoulder instability with engaging Hill–Sachs lesions. Knee Surgery, Sports Traumatology, Arthroscopy. 2018. DOI: 10.1007/s00167-018-5261-3
[228] Diagnosis of shoulder instability via cine MRI. Journal of Shoulder and Elbow Surgery. 1996. DOI: 10.1016/s1058-2746(96)80178-9
[230] Treatment of Posterior Shoulder Instability in National Hockey League Players: A Survey of NHL Team Physicians. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671261440208
[231] Arthroscopic Revision Bankart Repair for Failed Anterior Shoulder Instability. Techniques in Shoulder and Elbow Surgery. 2002. DOI: 10.1097/00132589-200212000-00008
[233] High Variability in Standardized Outcome Thresholds of Clinically Important Changes in Shoulder Instability Surgery: A Systematic Review. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2024.07.039
[235] Variability of Outcome Reporting Following Arthroscopic Bankart Repair in Adolescent Athletes: A Systematic Review. Arthroscopy. 2018. DOI: 10.1016/j.arthro.2017.10.041
[236] Minimum 10-Year Clinical Outcomes After Arthroscopic Capsulolabral Repair for Isolated Posterior Shoulder Instability. The American Journal of Sports Medicine. 2023. DOI: 10.1177/03635465231162271
[237] Intraoperative anterior shoulder dislocation during ulnar nerve transposition: a case report. Journal of Shoulder and Elbow Surgery. 2020. DOI: 10.1016/j.jse.2020.04.012
[238] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > EVALUATION OF THE OVERHEAD ATHLETE.
[239] Treatment after traumatic shoulder dislocation: a systematic review with a network meta-analysis. British Journal of Sports Medicine. 2018. DOI: 10.1136/bjsports-2017-098539
[240] Shoulder arthroplasty in the setting of previous stabilization surgery: a systematic review of matched case control studies at minimum 2 years follow-up. JSES Reviews, Reports, and Techniques. 2023. DOI: 10.1016/j.xrrt.2023.01.003
[241] Posterior Shoulder Instability. Magnetic Resonance Imaging Clinics of North America. 2020. DOI: 10.1016/j.mric.2019.12.005
[242] Posterior Shoulder Instability in Athletes: An Analysis of the MOON Shoulder Stabilization Cohort. Arthroscopy. 2017. DOI: 10.1016/j.arthro.2017.04.088
[243] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > RECURRENT DISLOCATION > History.
[245] Type V superior labral anterior–posterior tears results in lower rates of return to play. Knee Surgery, Sports Traumatology, Arthroscopy. 2021. DOI: 10.1007/s00167-020-06388-5
[246] An Algorithmic Approach to the Management of Shoulder Instability. JAAOS: Global Research and Reviews. 2019. DOI: 10.5435/jaaosglobal-d-19-00168
[248] Glenohumeral capsular injury rate in patients with glenohumeral instability: a systematic review and meta-analysis. JSES Reviews, Reports, and Techniques. 2024. DOI: 10.1016/j.xrrt.2024.08.004
[249] Arthroscopic Posterior Bankart Repair: Risk Factors for Recurrence of Instability. The American Journal of Sports Medicine. 2026. DOI: 10.1177/03635465251403499
[250] Long Head of Biceps Tendon Transfer for Anterior Shoulder Instability. Techniques in Shoulder & Elbow Surgery. 2018. DOI: 10.1097/bte.0000000000000153
[251] Results of treatment of luxatio erecta (inferior shoulder dislocation). Journal of Shoulder and Elbow Surgery. 2010. DOI: 10.1016/j.jse.2009.07.062
[252] Multiple Subscapularis Tendon Sign: A New Risk Factor for Recurrence After Arthroscopic Anterior Shoulder Instability Surgery. Orthopaedic Journal of Sports Medicine. 2019. DOI: 10.1177/2325967119853507
[253] Rehabilitation following shoulder arthroscopic stabilisation surgery: A survey of UK practice. Shoulder & Elbow. 2023. DOI: 10.1177/17585732231154889
[254] Shoulder Instability in the Military. Clinics in Sports Medicine. 2014. DOI: 10.1016/j.csm.2014.06.006
[255] Ten-year follow-up of acute arthroscopic Bankart repair for initial anterior shoulder dislocation in young patients. Orthopaedics & Traumatology: Surgery & Research. 2015. DOI: 10.1016/j.otsr.2015.09.029
[258] Outcomes following arthroscopic Bankart repair in female patients. Journal of Shoulder and Elbow Surgery. 2020. DOI: 10.1016/j.jse.2019.12.012
[259] Prevalence Comparison of Accompanying Lesions between Primary and Recurrent Anterior Dislocation in the Shoulder. The American Journal of Sports Medicine. 2010. DOI: 10.1177/0363546510371607
[260] BESS/BOA patient care pathways: Atraumatic shoulder instability. Shoulder & Elbow. 2018. DOI: 10.1177/1758573218815002
[261] Radiofrequency capsular shrinkage for voluntary shoulder instability. Journal of Shoulder and Elbow Surgery. 2007. DOI: 10.1016/j.jse.2005.11.011
[262] Surgical interventions for anterior shoulder instability in adults. Cochrane Database of Systematic Reviews. 2009. DOI: 10.1002/14651858.cd005077.pub2
[263] Increased Glenoid Index as a Risk Factor for Pediatric and Adolescent Anterior Glenohumeral Dislocation: An MRI-Based, Case-Control Study. Orthopaedic Journal of Sports Medicine. 2021. DOI: 10.1177/2325967120986139
[264] The importance of CT for the pre-operative surgical planning in recurrent anterior shoulder instability. Archives of Orthopaedic and Trauma Surgery. 2012. DOI: 10.1007/s00402-012-1656-7
[265] The Management of Acute Traumatic Primary Anterior Shoulder Dislocation in Young Adults. Shoulder & Elbow. 2010. DOI: 10.1111/j.1758-5740.2010.00083.x
[266] Functional Deficits After Open Latarjet Procedure and Dominance of the Operated Shoulder: An Analysis of 133 Patients. The American Journal of Sports Medicine. 2023. DOI: 10.1177/03635465231156181
[267] Risk Factors for Recurrent Anterior Glenohumeral Instability Following a Primary Latarjet Procedure: A Prospective Analysis of 358 Patients. Orthopaedic Journal of Sports Medicine. 2020. DOI: 10.1177/2325967120s00378
[269] An Age-Based Approach to Anterior Shoulder Instability in Patients Under 40 Years Old: Analysis of a US Population. The American Journal of Sports Medicine. 2019. DOI: 10.1177/0363546519886861
[270] Imaging Quantification of Glenoid Bone Loss in Patients With Glenohumeral Instability: A Systematic Review. American Journal of Roentgenology. 2019. DOI: 10.2214/ajr.18.20504
[272] Iliac bone-block autograft for posterior shoulder instability. Orthopaedics & Traumatology: Surgery & Research. 2009. DOI: 10.1016/j.otsr.2008.09.008
[277] Anterior shoulder instability: a review of pathoanatomy, diagnosis and treatment. Current Reviews in Musculoskeletal Medicine. 2011. DOI: 10.1007/s12178-011-9092-9
[279] Imaging of shoulder instability. Quantitative Imaging in Medicine and Surgery. 2017. DOI: 10.21037/qims.2017.08.05
[281] Classification of Impairment of Shoulder Abduction in Obstetric Brachial Plexus Palsy and its Clinical Significance. Journal of Hand Surgery. 2000. DOI: 10.1054/jhsb.1999.0282
[282] Campbell S Operative Orthopaedics 4 Volume Set. RECONSTRUCTIVE PROCEDURES OF THE SHOULDER AND ELBOW IN ADULTS > INSTABILITY.
[285] Focal cortical bone loss at the inferior aspect of the glenoid: A new radiographic sign of anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 1992. DOI: 10.1016/1058-2746(92)90092-h
[288] Campbell S Operative Orthopaedics 4 Volume Set. RECONSTRUCTIVE PROCEDURES OF THE SHOULDER AND ELBOW IN ADULTS > COMPLICATIONS OF SHOULDER ARTHROPLASTY.
[292] ARTHROSCOPIC SHOULDER INSTABILITY SURGERY. Clinics in Sports Medicine. 1999. DOI: 10.1016/s0278-5919(05)70183-6
[293] A comparison of magnetic resonance arthrography and arthroscopic findings in the assessment of anterior shoulder dislocations. Skeletal Radiology. 2014. DOI: 10.1007/s00256-014-2080-6
[294] Phone Administration of the Western Ontario Shoulder Instability Index Is More Reliable Than Administration via Email. Clinical Orthopaedics & Related Research. 2022. DOI: 10.1097/corr.0000000000002320
[298] Comparative Analysis of 3D MRI and CT in Assessing Static Bone Loss and Dynamic Bipolar Interaction in Glenohumeral Instability. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/23259671251343325
[299] Poster 16: Comparative Analysis of 3D MRI and CT in Assessing Static Bone Loss and Dynamic Bipolar Interaction in Glenohumeral Instability. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/2325967125s00129
[300] MRI augmented with novel artificial intelligence system is superior to CT in shoulder instability. JSES International. 2026. DOI: 10.1016/j.jseint.2025.101440
[301] Imaging Signs of Posterior Glenohumeral Instability. American Journal of Roentgenology. 2009. DOI: 10.2214/ajr.07.3849
[302] Acute Versus Delayed MRI Imaging and Associated Pathology in Traumatic Shoulder Dislocations. Orthopaedic Journal of Sports Medicine. 2017. DOI: 10.1177/2325967117s00360
[303] Interest in the glenoid hull method for analyzing humeral subluxation in primary glenohumeral osteoarthritis. Journal of Shoulder and Elbow Surgery. 2017. DOI: 10.1016/j.jse.2017.01.027
[305] Editorial Commentary: Patients May Have Posterior Glenoid Labral Tears in the Absence of Instability or Magnetic Resonance Imaging Findings. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2023.07.004
[307] Radiographic evaluation of the Hill-Sachs lesion in patients with recurrent anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 2000. DOI: 10.1067/mse.2000.106920
[309] Imaging methods for quantifying glenoid and Hill-Sachs bone loss in traumatic instability of the shoulder: a scoping review. BMC Musculoskeletal Disorders. 2015. DOI: 10.1186/s12891-015-0607-1
[310] Superior-capsular elongation and its significance in atraumatic posteroinferior multidirectional shoulder instability in magnetic resonance arthrography. Acta Radiologica. 2010. DOI: 10.3109/02841850903524421
[312] Poster 105: MRI Demonstrates Similar Diagnostic Value to MR Arthrogram for Determining Labral Tear Extent up to 2 Weeks Following Shoulder Dislocation. Orthopaedic Journal of Sports Medicine. 2024. DOI: 10.1177/2325967124s00075
[313] Does Labral Reconstruction Prevent Osteoarthritis After Posterior Shoulder Instability: A Population-Based Study. Orthopaedic Journal of Sports Medicine. 2018. DOI: 10.1177/2325967118s00154
[314] Evaluation of glenoid morphology and bony Bankart lesion in shoulders with traumatic anterior instability using zero echo time magnetic resonance imaging. JSES International. 2024. DOI: 10.1016/j.jseint.2024.03.003
[316] Humeral head deviation and velocity in multidirectional instability of the glenohumeral joint: a cine magnetic resonance imaging study. JSES International. 2026. DOI: 10.1016/j.jseint.2025.101419
[317] Magnetic resonance imaging predictors of shoulder instability in adolescents. Pediatric Radiology. 2018. DOI: 10.1007/s00247-018-4318-2
[318] Diagnostic imaging of glenohumeral instability: Mri VS. CT arthrography. Journal of Shoulder and Elbow Surgery. 1996. DOI: 10.1016/s1058-2746(96)80388-0
[319] Two‐Year Outcomes of Open Shoulder Anterior Capsular Reconstruction for Instability From Severe Capsular Deficiency. Arthroscopy. 2011. DOI: 10.1016/j.arthro.2011.07.002
[321] Quality of life following an open Latarjet-Bristow procedure in a general population with recurrent anterior shoulder instability. JSES International. 2023. DOI: 10.1016/j.jseint.2022.12.003
[322] Paper 11: Return to Sport Testing vs Time-Based Clearance in Posterior Shoulder Instability. Orthopaedic Journal of Sports Medicine. 2022. DOI: 10.1177/2325967121s00549
[324] Humeral and glenoid detachment of the anterior inferior glenohumeral ligament: A cause of anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 1997. DOI: 10.1016/s1058-2746(97)90064-1