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Soft Tissue Structures

Anatomy and pathology of the glenohumeral capsule, subacromial bursa, and rotator interval, focusing on their roles in joint stability and pain generation.

124 citationsUpdated Oct 2026

Overview¶

Soft tissue integrity is fundamental to restoring anatomic attachments and preventing chronic instability in global elbow instability [1]. In isolated anteromedial radial head dislocation, open reduction of interposed tissues can result in a good functional outcome, at least in the short term [2]. For shoulder pathology, the purpose of reviewing current literature concerning anatomy and stability is to improve clinical diagnosis and surgical treatment [26]. While most studies on physical tests for shoulder impingements and local lesions were set in secondary or tertiary care using reference standards such as arthroscopic surgery, MRI, or ultrasonography [7], surgical intervention for shoulder impingement resulted in a small statistically significant but clinically unimportant improvement in long-term functional outcomes [22].

In rotator cuff pathology, while retear is common, patients may still experience pain and functional improvement, though intact repairs generally lead to better long-term outcomes [39]. Current evidence is insufficient to clearly define the relationship between structural integrity of repaired rotator cuffs and long-term clinical outcome [19]. The biomechanical consequence of biceps adhesions may limit range of motion and clinical outcomes in situations where the biceps is at risk for scarring [8]. Regarding anterior shoulder instability, long-term outcomes beyond five years and high-quality comparative or randomized trials are needed to define durability, refine indications, and position long head of the biceps-based dynamic anterior stabilization within the broader algorithm for management [23]. SLAP repairs are generally favored in younger, active patients, whereas treating the biceps is preferred in lower-demand patients aged >30 years [60].

Revision total shoulder arthroplasty is technically challenging with inferior results compared to primary arthroplasty, particularly when soft-tissue problems are the indication [6]. Although anatomic restoration of the shoulder can be accomplished using subscapularis-sparing total shoulder arthroplasty, retained osteophytes and significant mismatch of the humeral head diameter raise concerns regarding long-term outcomes [43]. Clinical outcomes of reverse total shoulder arthroplasty at a minimum follow-up of 1 year were similar in the high- and lower-risk groups for iatrogenic suprascapular neuropathy by screw violation [40]. Periscapular tendon transfers provide a novel means of addressing difficult-to-treat and complex shoulder girdle pathologies, although many treatment techniques remain in their infancy and further follow-up is necessary before universal adoption [10]. Bankart augmentation with a split subscapularis tendon flap is a novel technique for managing severe capsulolabral deficiency that is less invasive than open approaches but technically difficult, with further studies needed to confirm consistent success [65].

Anatomy & Pathophysiology¶

Bony Anatomy¶

The proximal humerus comprises four main parts: the humeral head, greater tuberosity, lesser tuberosity, and humeral shaft [74]. The articular head is spherical with a diameter of 37 to 57 mm [74] and a radius of curvature of approximately 25 mm, which is slightly larger in men than in women [86]. The articular surface is essentially spherical, with an arc of approximately 160 degrees covered by articular cartilage [86]. The most superior portion of the articular surface averages 8 mm above the greater tuberosity [74], or 8 to 10 mm above the top of the greater tuberosity [86]. The head height is approximately 5.6 cm above the superior border of the pectoralis major tendon [88]. Humeral version averages 29.8 degrees, with a range of 10 to 55 degrees [74], though proximal humeral retroversion is highly variable, ranging from 0 to 55 degrees depending on the measurement method [86]. The humeral head is retroverted 30 degrees relative to the transepicondylar axis of the humerus [88] and averages 19° of retroversion [77]. The humeral head is inclined approximately 130 degrees with respect to the humeral shaft [74], or averages 41° of inclination (neck-shaft angle) [77]. The average neck-shaft angle is 45 degrees, with a range of 30 to 50 degrees [86], while arthritic shoulders have a flatter neck-shaft angle close to 50 degrees [86]. The humeral head inclination ranges from 30-55 degrees [86].

The bicipital groove lies between the greater and lesser tuberosities and serves as a pathway for the long head of the biceps [74]. The distal aspect of the bicipital groove is internally rotated with respect to the proximal portion [74]. The anatomic neck is located at the junction of the articular surface and the tuberosities [74], directly below the humeral head, and serves as an attachment for the shoulder capsule [88]. The surgical neck represents an indistinct region below the tuberosities but above the humeral shaft [74]; it is more distal than the anatomic neck and is more often involved in fractures [88]. The greater tuberosity serves as the attachment site for the supraspinatus, infraspinatus, and teres minor tendons [74]. The lesser tuberosity serves as the attachment site for the subscapularis tendon [74]. The transverse humeral ligament is an important stabilizer of the biceps tendon [88].

The glenoid is a convex structure of shallow depth shaped like an inverted pear [74]. The subchondral bone of the glenoid is relatively flat, with the articular concavity augmented by cartilage and a circumferential labrum [77]. The glenoid labrum provides concavity and up to 50% of marginal glenoid socket depth [77]. The glenoid articular surface radius of curvature is 2 to 3 mm larger than that of the humeral head [86], ranging from 22-28 mm [86]. The humeral head radius of curvature ranges from 23-28 mm [86]. The glenoid diameter ranges from 18-30 mm superior anteroposteriorly and 21-35 mm inferior anteroposteriorly [86]. The glenoid superoinferior height ranges from 30-48 mm [86]. The glenoid inclination averages 4.2 degrees, with a range of –7 to 20 degrees [86]. The glenoid version averages 5° of retroversion in relation to the axis of the scapular body [77], or approximately 5 degrees relative to the scapular body [88]. The normal position of the glenoid surface in relation to the axis of the scapular body ranges from 2 degrees of anteversion to 7 degrees of retroversion [86]. The glenoid version averages 1.5 degrees retroversion, with a range of 10.5-9.5 degrees anteversion [86]. The glenoid surface area ranges from 4-6 mm [86], while the humeral head surface area ranges from 11-19 mm [86]. The glenoid cartilage thickness is 2.16 mm [86], and the humeral head cartilage thickness is 1.44 mm [86].

The distance from the lateral base of the coracoid process to the lateral margin of the greater tuberosity is called the lateral humeral offset [86]. A significant decrease in lateral humeral offset reduces the lever arms for the deltoid and supraspinatus muscles, weakening abduction [86]. A significant increase in lateral humeral offset causes excessive tension on soft tissues, resulting in loss of motion and likely accelerating polyethylene wear [86]. Humeral articular malposition of more than 4 mm leads to increased subacromial contact [86]. An offset of 8 mm in any direction significantly decreases passive range of motion [86]. The medial humeral offset ranges from 4-14 mm [86], and the posterior humeral offset ranges from –2 to 10 mm [86].

The acromion, coracoacromial ligament, and coracoid process form the coracoacromial arch [74]. The rotator cuff, subacromial bursa, and subdeltoid bursa pass underneath the coracoacromial arch [74]. The scapula is attached to the axial skeleton by the acromioclavicular and sternoclavicular joints [76]. The scapula is separated from the chest wall by thin gliding fibro-fatty tissue, allowing smooth excursion over the chest wall [76]. The scapula spans the second through seventh ribs and serves as an attachment for 17 muscles [88]. The scapula is anteverted on the chest wall approximately 30 degrees relative to the body [88]. The glenoid is connected with the flat body of the scapula by the scapular neck [76]. The coracoid process curves forwards from the superior surface of the scapular neck [76]. The acromion is a flattened bony process that curves forwards from the scapular spine [76]. The highest concentration of bony mass in the scapula is found in the glenoid, the scapular neck, and the lateral border of the scapular body [76]. Two bony pillars transmit compressive forces from the glenoid fossa: the lateral pillar and the spinal pillar [76]. The weakest bone in the scapula is located primarily in the central part of the biomechanical body, specifically in the infraspinous fossa [76]. The weakest area of the circumference of the biomechanical body of the scapula is the spinomedial angle [76].

The clavicle is the first bone to ossify at the fifth week of gestation and is the only long bone to ossify by intramembranous ossification [77]. The medial epiphysis of the clavicle is the last ossification center to fuse, occurring at age 20 to 25 years [77]. The primary blood supply to the clavicle is periosteal, with no nutrient artery present [77]. The scapula has only one true diarthrodial articulation, the acromioclavicular joint [77]. Normal shoulder motion is approximately two-thirds glenohumeral and one-third scapulothoracic [77]. The acromion has three ossification centers: the metacromion, mesoacromion, and preacromion [77]. Failure of fusion of the acromial ossification centers results in os acromiale [77]. Os acromiale is incomplete fusion of secondary ossification centers, most commonly between the mesoacromion and meta-acromion [88]. The coracoid process serves as an attachment for the coracoacromial ligament, coracoclavicular ligaments, conjoined tendon, and pectoralis minor [88].

The sternoclavicular joint is the only true diarthrodial articulation between the upper appendicular and axial skeletons [77]. The posterior sternoclavicular joint capsule and ligaments are the primary stabilizers to anterior and posterior translation of the medial clavicle [77]. The acromioclavicular joint is a small diarthrodial joint with an interposed fibrocartilaginous disk [77]. The superior and posterior acromioclavicular ligaments are the primary stabilizers to anterior and posterior translation of the clavicle [77]. The coracoclavicular ligaments are the primary stabilizers to superior translation of the distal clavicle [77].

The formation of the humerus begins with the appearance of the cartilage anlage by the fifth week of gestation [81]. The primary ossification center for the humerus appears at about the sixth week [81]. The proximal humerus has three centers of ossification: the humeral head, greater tuberosity, and lesser tuberosity [77]. The ossification center for the humeral head is usually present at birth [81]. The greater tuberosity ossification center appears by 1 to 3 years of age [81]. The lesser tuberosity ossification center appears by 5 years of age [81]. The proximal humeral ossification centers fuse by 5 to 7 years of age to form the humeral head [81]. The proximal humeral physis closes by 14 to 17 years of age in girls and by 16 to 18 years in boys [81]. Humeral retroversion averages 65 degrees in infants and young children, gradually decreasing to adult values by 11 years of age [81]. Eighty percent of subsequent humeral growth comes from the proximal humeral physis [81]. The proximal humeral physis accounts for approximately 40% of the growth of the entire upper extremity [81]. Less than 75% of proximal humeral growth occurs before 2 years of age [81]. More than 85% of proximal humeral growth occurs by 8 years of age [81].

The scapula has shifted caudally from the cervical position in lower animals, freeing the shoulder from the head and neck [84]. The scapular index is extremely high in pronograde animals with a long, narrow scapula [84]. The scapula is broader in humans and other primates, with the most pronounced differences observed in the infraspinatus fossa [84]. Broadening of the infraspinatus fossa has changed the vector of muscle pull from the axillary border of the scapula to the glenoid fossa [84]. 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 [84]. The acromion has enlarged over time, reflecting the increasing role of the deltoid muscle in shoulder function [84]. 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 [84]. The coracoid process has undergone an increase in size over time [84]. 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 [84].

Soft Tissue Structures¶

The function of ligaments is to restrict joint motion and stabilize joints [12]. Ligaments are composed of densely packed type I collagen, proteoglycans, elastin, and water [12]. Type I collagen makes up about 70% of the dry weight of ligaments [12]. Ligaments are shorter and wider than tendons [12]. Ligaments have a lower percentage of collagen and a higher percentage of proteoglycans and water compared to tendons [12]. The collagen fibers in ligaments are less organized than in tendons [12]. The main cell type in ligaments is the fibroblast, which appears rounder than tendon fibroblasts [12]. Ligaments have relatively low vascularity and cellularity [12]. Ligaments exhibit viscoelastic behavior similar to that of tendons [12]. Ligament injuries are generally classified into three grades: I (mild sprain), II (moderate sprain/partial tear), and III (complete ligament tear) [12]. An additional type of ligament injury is avulsion of the ligament from its bony insertion [12].

The rotator cuff is a sheet of conjoined tendons closely applied over the shoulder capsule and inserting mainly into the greater tuberosity of the humerus [82]. The subscapularis inserts into the lesser tuberosity [82]. The rotator cuff consists of the subscapularis in front, supraspinatus above, and infraspinatus and teres minor behind [82]. The rotator cuff stabilizes the head of the humerus by pulling it firmly into the glenoid whenever the deltoid lifts the arm forwards or sideways [82]. The coracoacromial arch is formed by the acromion process posterosuperiorly, the coracoid process anteriorly, and the coracoacromial ligament joining them [82]. The subacromial bursa separates the rotator cuff tendons from the coracoacromial arch, allowing them to glide [82]. The superior boundary of the subacromial space is formed by the acromion and the coracoacromial ligament [27]. The anterior acromion and superior boundary of the subacromial space have to move superiorly for the humeral head to elevate during arm elevation [27]. The anterior acromion has been identified as the site at which compression on the bursal side of the rotator cuff tendon occurs if it does not move superiorly [27]. The inferior subacromial space is defined by the humeral head, superior glenohumeral joint, and the coracohumeral ligament [27]. Only 25% to 30% of the surface of the head of humerus is in contact with the glenoid at one time [27].

The rotator interval is defined medially by the base of the coracoid, superiorly by the supraspinatus tendon, and inferiorly by the subscapularis tendon [77]. The rotator interval contains the coracohumeral ligament, the superior glenohumeral ligament, and the intra-articular portion of the long head of the biceps tendon [77]. Laxity of the rotator interval results in inferior laxity, known as the sulcus sign [77]. Contracture of the rotator interval is seen with adhesive capsulitis [77]. The coracohumeral ligament restricts external rotation in adduction and is a static restraint to inferior and posterior translation in adduction and external rotation [77]. The superior glenohumeral ligament is a primary static restraint against anterior translation with the arm at the side [77]. With the coracohumeral ligament, the superior glenohumeral ligament forms a pulley that provides restraint against medial subluxation of the long head of the biceps tendon [77]. The middle glenohumeral ligament is a primary static restraint against anterior translation with the arm in external rotation and 45° of abduction [77]. The anterior band of the inferior glenohumeral ligament is a primary static restraint against anterior-inferior dislocation of the glenohumeral joint in 90° of abduction and external rotation [77]. The posterior band of the inferior glenohumeral ligament is a primary static restraint against posterior-inferior translation in internal rotation and adduction [77].

The suprascapular artery passes superior to the superior transverse scapular ligament, while the suprascapular nerve passes inferior to it [88]. Both the suprascapular artery and nerve pass inferior to the inferior transverse scapular ligament at the spinoglenoid notch [88]. The anterolateral ascending branch of the anterior humeral circumflex artery provides the primary blood supply to the humeral head [77]. The terminal intraosseous portion of the anterior humeral circumflex artery enters at the proximal aspect of the intertubercular groove as the arcuate artery [77].

Classification¶

Ligaments and Tendons¶

Ligament fibroblasts appear rounder than tendon fibroblasts [12]. The subscapularis tendon is composed of two distinct fibrous layers, just like the supraspinatus tendon, but arranged differently [152]. The coracohumeral ligament is composed of irregular and sparse fibers containing relatively rich type III collagen, suggesting flexibility [160]. Based on its histologic features, the coracohumeral ligament is more capsular than ligamentous [163].

Injury Grading and Staging¶

Ligament injuries are generally classified into three grades: I, II, and III [12]. Grade I corresponds to a mild sprain [12]. Grade II corresponds to a moderate sprain or partial tear [12]. Grade III corresponds to a complete ligament tear [12]. Avulsion of the ligament from its bony insertion is an additional type of ligament injury distinct from grades I–III [12].

Enneking Staging System: This system classifies primary bone tumours according to whether they are high or low grade, whether metastases are present, and whether the tumour has grown out of its original compartment or remains confined to a compartment [104]. A compartment is defined as an enclosed tissue space, such as a bone, a joint space, or a muscle group confined by its fascial envelope [104].

TNM Staging System: For soft-tissue sarcomas, this system dichotomizes size to small (<5 cm) or large (>5 cm) [104]. For bone sarcomas, it dichotomizes size to small (<8 cm) or large (>8 cm) [104].

Anatomical Variations and Zones¶

The bicipital tunnel is a closed space with three anatomically and histologically distinct zones, where zones 1 and 2 differ from zone 3 [146]. A classification of 12 variations of the intra-articular portion of the long head of the biceps tendon has been proposed [158]. The most common type of subscapularis muscle variation is the muscle with three bellies, in line with Larson's model of the division of the subscapularis muscle into three parts [66]. DePalma types 1 and 3 are the most commonly encountered anatomic variants in the rotator interval region [165]. Fibrous bands are a common finding in the quadrilateral space in cadavers, suggesting they are a normal finding rather than a pathological cause [17].

Imaging and Diagnostic Classification¶

Sugaya Classification: This system grades rotator cuff tendon healing on MRI, with grade I indicating sufficient thickness with homogenously low intensity and grade V indicating the presence of a major discontinuity [172]. Grades I to III are classed as healed, while types IV and V are classed as either an iterative tear or a failed healing response [35].

Riley Classification: This system grades tendinopathy, with Grade III and Grade IV representing specific histological findings in rotator cuff responses [144].

Hamada-Fukuda Classification: This system is used to grade rotator cuff tears based on radiologic factors including subacromial space and glenohumeral arthritis [35].

Samilson-Prieto: Grades I to IV are used to assess the presence of glenohumeral arthritis on radiographs [35].

Boileau et al. Grading System: Using computed tomography arthrography, this system classifies structural integrity of repaired tendons as 'intact,' 'incomplete leakage,' or 'complete leakage' [148]. Healing is defined when the integrity is both intact at the insertion and in the tendon [148]. Incomplete healing is defined when the integrity is incomplete leakage either at the insertion or in the tendon [148]. Retears are defined if complete leakage is present at the insertion [148]. New tears are defined if complete leakage is present in the tendon [148].

Clinical Presentation¶

Shoulder Impingement Syndrome¶

Shoulder impingement syndrome is the most commonly diagnosed shoulder disorder [27], characterized as a clinical syndrome where diagnosis relies on a collection of signs and symptoms [115]. The aetiology is multifactorial, resulting from an interplay of intrinsic and extrinsic factors [115]. The most common and consistent presenting symptom is shoulder pain, with weakness of the shoulder and arm as a common secondary complaint [122]. Patients typically present with rotator cuff tendinopathy [27]. However, shoulder pain can also indicate joint instability, cervical radiculopathy, calcific tendinitis, adhesive capsulitis, degenerative joint disease, acromioclavicular osteoarthrosis, or nerve compression [115]. Consequently, the use of "shoulder impingement syndrome" as a diagnostic label has been debated due to its application across a spectrum of other shoulder and cervical conditions [115].

Diagnosis often relies upon a combination of physical examinations and further investigations [115]. The impingement sign is insufficient for diagnosis due to poor accuracy, the requirement for a clinical specialist to rule out rotator cuff tears, and the lack of conclusive evidence favoring any single test to detect rotator cuff disorders accurately [125]. In patients with shoulder impingement syndrome, forward elevation and external rotation were more reduced in the hypothermic group than in the hyperthermic and normal groups [125]. The range of forward elevation had a positive linear correlation with the lateral axillary thermographic region of interest in the hypothermic group [125]. The range of external rotation had a positive linear correlation with the anterior and posterior lateral thermographic regions of interest in the hypothermic group [125]. Extensive intraarticular contact observed in all subjects suggests that internal impingement mechanisms may play a role in the Neer and Hawkins sign positions [63].

Atypical etiologies include sternoclavicular joint arthritis, an unrecognized cause of shoulder impingement [57]. The 'shrug test' is recommended as part of routine shoulder examination to recognize sternoclavicular joint arthritis early [57]. A subacromial lipoma can cause shoulder impingement syndrome [49]. MRI is useful to determine the precise etiology and inform surgical treatment for subacromial lipoma causing shoulder impingement syndrome [49]. Soft tissue tumours can cause coracoid impingement syndrome [62]. Anterior shoulder impingement includes newly described entities that require a comprehensive classification to address conflicting theories and improve understanding of etiologic factors, diagnosis, and treatment [30]. Anterior shoulder pain can be caused by the persistence of a septum between the long head biceps tendon and intra-articular supraspinatus [33]. Recognizing this persistent septum may help arthroscopic surgeons decide the best therapeutic options depending on each patient's symptoms [33].

Rotator Cuff Pathology¶

Subjective mechanical symptoms in the affected shoulder are a common complaint in patients with suspected rotator cuff pathology [47]. Pathologic conditions located in the supraspinatus tendon are very common and related to age and not to clinical status [14]. Diagnosis of long head biceps tendon and subscapularis pathology in association with shoulder rotator cuff pathology can be challenging due to limitations in MRI and arthroscopic visualization [61]. Surgeons should maintain a high level of suspicion and utilize specific techniques to prevent missing long head biceps tendon and subscapularis pathology in association with shoulder rotator cuff pathology [61]. Calcific tendinitis of the rotator cuff can be associated with intraosseous loculation and bone erosion [53]. Recognition of atypical presentations of calcific tendinitis with bone erosion may prevent unnecessary biopsy and overtreatment [53].

Instability and Dislocation¶

Global elbow instability requires recognition of complex soft tissue injuries to restore anatomic attachments and prevent chronic instability [1]. Irreducible isolated anteromedial radial head dislocation can be caused by ruptured anterior capsule and annular ligament interposition [2]. Open reduction of interposed tissues in irreducible isolated anteromedial radial head dislocation can result in a good functional outcome, at least in the short term [2]. Understanding of the detailed anatomy and anatomical variations of the glenohumeral joint is essential for surgeons to understand pathology, make correct diagnoses of instability, and select proper treatment options [55]. Arthroscopic anatomy, variants, and pathologic findings are reviewed to improve clinical diagnosis and surgical treatment of shoulder instability [26].

Scapular and Periscapular Pathology¶

Scapular muscle detachment appears to be a clinically identifiable syndrome with a homogeneous set of history and physical findings [9]. Contracture of the deltoid muscle presents with pain, skin dimpling, palpable fibrous bands, and winging of the scapula [31]. Nuchal fibromas of the shoulder may involve deep skeletal muscle and fascia and can be difficult to resect [29]. Nonoperative treatment is quite effective for bursitis secondary to overuse; however, structural lesions causing painful crepitus are more resistant to such measures and often need to be surgically excised [50].

Tumors and Masses¶

A soft-tissue sarcoma in the deltoid muscle can present as a slowly growing mass with limited range of motion and strength deficits [48]. Myxoinflammatoric fibroblastic sarcoma is a rare low-grade sarcoma usually localised superficially in the subcutaneous layer, with approximately 100 cases published worldwide [32]. Epithelioid sarcoma is rare and does not always present as a typical sarcoma [52].

Ligaments and General Soft Tissue¶

Ligament injuries are generally classified into three grades: I (mild sprain), II (moderate sprain/partial tear), and III (complete ligament tear), with an additional type being avulsion from the bony insertion [12].

Investigations¶

Plain radiography: Standardized plain films are almost always sufficient to establish the diagnosis, determine pathoanatomic severity, assist in surgical planning, and illustrate the condition to the patient [45]. The primary 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 [45]. At least two views are required: an anteroposterior view in the plane of the glenoid and an axillary projection with the arm in abduction [91]. The first key view is the anteroposterior view in the plane of the scapula, taken so that the x-ray beam passes through the glenohumeral joint [45]. This view demonstrates the superoinferior position of the humeral head relative to the glenoid, the presence of osteophytes on the humeral head and glenoid, narrowing of the joint space, and the degree of medial displacement of the humerus in relation to the lateral acromial line [45]. The second key view is the axillary view taken with the arm in the functional position of elevation in the plane of the scapula [45]. Referred to as the “truth view,” it demonstrates glenohumeral relationships in the functional position of elevation [45]. This standardized axillary view enables measurement of posterior subluxation or “functional decentering” that is not evident in images taken with the arm at the side [45]. The degree of posterior subluxation can be measured as 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 [45]. The point of contact reflects the degree of centering of the net humeral joint reaction force on the glenoid [45]. Malcentering of the joint reaction force leads to posterior instability, posterior glenoid wear, and “rocking horse” loosening of prosthetic glenoid components [45].

For proximal humerus fractures, the recommended series is the Neer trauma series, consisting of an AP view, a lateral view in the scapular plane, and a Velpeau modified axillary view [94]. The lateral radiograph in the scapular plane is the tangential Y-view of the scapula [94]. The combination of these three views allows evaluation of the shoulder joint in three separate perpendicular planes [94]. The axillary view is important for evaluating the glenoid articular surface and the relationship of the humeral head anteriorly and posteriorly [94]. On occasion, CT scanning may be necessary for detailing bony anatomy in proximal humerus fractures [94]. Ultrasound, MRI, arthrogram, or arthroscopy may be valuable in making the diagnosis of rotator cuff injuries in the acute setting of proximal humerus fractures [94].

Normal radiographic measurements include an acromiohumeral distance of 7 to 14 mm and a coracoclavicular distance of 1.1 to 1.3 cm [101]. The width of the glenohumeral joint space should be symmetric superiorly and inferiorly [101]. Neer classified acromial morphology as type I (flat), type II (curved), and type III (hooked) [101]. Type III acromial morphology has been shown to have a correlation with the presence of rotator cuff disease, although no direct causal relationship has been demonstrated [101]. The classification of acromial morphology has shown relatively poor interobserver reliability [101]. A study demonstrates a significant association between oblique acromioclavicular joint morphology and patients requiring acromioclavicular joint excision for pain [21]. The radiograph of the 30° caudal tilt view is easy to obtain and always reveals the exact architecture of a bony spur of the anterior acromion [176]. The presentation of a resonant 'balloon-like' swelling is associated with gas in deeper structures, and plain radiography shows loculated air pockets increasing on serial films [167].

CT: Computed tomography (CT) is helpful for planning fracture surgery and shoulder joint replacement [91]. 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 [99]. 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 [101]. 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 [45]. CT scans have the disadvantage of being taken with the arm in the adducted position, unlike the axillary truth view [45]. Radiographic methods including 3-D CT and MRI as well as the intraoperative findings of the labrum cannot be considered an accurate and reliable basis for the diagnosis and treatment of subspine impingement in patients with femoroacetabular impingement [175].

MRI: Magnetic resonance imaging (MRI) is the modality of choice for evaluating the rotator cuff, biceps, and subacromial/subdeltoid bursa [99]. Traditional MRI is utilized for evaluation of soft tissues, which can be performed with high contrast and spatial resolution [97]. The acquired multi-planar imaging of MRI allows for the detailed evaluation of the glenoid, labrum, joint capsule, and rotator cuff in different planes [97]. MRI is useful to identify osteonecrosis of the humeral head, or a bone tumour [91]. MRI can identify labral tears and rotator cuff tears, although the accuracy for these is enhanced by combining the scan with arthrography [91]. T1-weighted MRI can reveal Hill-Sachs lesions and is often used with magnetic resonance arthrograms to provide a more detailed picture of the joint surfaces [99]. T2-weighted MRI provides better visualization of full thickness rotator cuff tears [99]. Magnetic resonance (MR) accuracy in identifying labral and rotator cuff tears in the literature ranges from 70% to 100% [97]. MRI is very useful to determine the precise etiology and inform surgical treatment for subacromial lipoma causing shoulder impingement syndrome [49]. Surgeons should maintain a high level of suspicion and utilize specific techniques to prevent missing pathology of the long head biceps tendon and subscapularis [61]. Magnetic resonance imaging indicates that the donor site after autologous osteochondral mosaicplasty for cartilaginous lesions of the elbow joint is resurfaced with fibrous tissue [151]. Multi-photon imaging revealed a clear three-dimensional structure of the human muscle in rotator cuff tears with or without fatty infiltration [184]. The H-loop technique resulted in a lower MRI signal-to-noise ratio compared to other suture constructs for upper one-third subscapularis tendon tear healing [192]. The IBR enabled a robust healing response evident through MRI and biopsy evaluation, demonstrating superior tendon quality and healing for full-thickness rotator cuff tears [70].

MR Arthrography: Magnetic resonance arthrography (MRA) refers to MRI of a joint that has been injected with an intra-articular contrast agent such as diluted gadolinium or saline solution [97]. The contrast material for MRA is injected prior to MRI by fluoroscopic or ultrasound guidance under strict aseptic technique [97]. By distending the joint capsule, the cartilage, ligaments, and labrum are outlined with contrast, increasing the sensitivity for detecting tears and other lesions [97]. In the acute dislocation setting, a joint effusion with distension of the joint may outline structures similarly, making the arthrogram unnecessary [97]. MRA has proven utility by increasing both sensitivity and specificity in detecting injuries to the capsulolabral–ligamentous complex as compared to traditional MRI [97]. A meta-analysis of 6 studies including 4,667 shoulders found greater diagnostic test accuracy for MRA over MRI in the detection of glenoid labral lesions [97]. MRA sensitivity was 88% and specificity was 93% for the detection of glenoid labral lesions, compared to MRI sensitivity of 76% and specificity of 87% [97]. Abduction and external rotation (ABER) of the arm is an alternative position utilized to increase the sensitivity and specificity for detecting anteroinferior labroligamentous injury [97]. Limited range of motion or pain may prohibit patients from performing the ABER provocative maneuver [97]. Schreinemachers et al. found that full routine MRI or MRA examination had similar accuracy as the ABER sequence in evaluating the anteroinferior labral–ligamentous complex [97]. Tian et al. found that the sensitivity of MRA with the ABER position for detecting anteroinferior labral lesions was significantly higher than that of the MRA in neutral position [97]. The ABER position was more effective in identifying Perthes lesions [97]. MRAs can demonstrate a patulous capsule on the coronal, sagittal, and axial imaging in patients with multidirectional instability [97]. MRAs can be helpful in evaluating lesions of the rotator interval and other associated findings that may affect the eventual surgical plan [97]. The presence of glenoid dysplasia, increased capsular cross-sectional area, and increased glenoid retroversion have all been found to be associated with increased posterior labral tears and symptomatic instability [97]. Glenoid retroversion was significantly increased in patients with symptomatic posterior labral tears, but there was no significant association between instability and increased humeral head subluxation [97]. The diagnosis of multidirectional instability is a clinical one, and the need for expensive and/or invasive imaging should be weighed against the information that will be gained from these studies [97]. MR arthrography is considered the benchmark for evaluation for labral tears and rarely is indicated for evaluation of rotator cuff pathology [99]. When MRI or MR arthrography is contraindicated, such as in patients with pacemakers or vascular clips, CT arthrography is indicated [99]. Arthrography involves injection of contrast agent in conjunction with either an MRI or CT scan, enhancing imaging of the joint to enable better identification of normal structures and pathology involving the joint surfaces [99].

Ultrasonography: Ultrasonography is a simple and accurate test for identifying rotator cuff tears and calcific tendinitis [91]. It is a low-cost alternative to MRI and arthrography for evaluating both skeletal and soft-tissue structures of the shoulder [99]. Ultrasonography can provide immediate, real-time visualization of the rotator cuff, biceps tendon, and calcific deposits [99]. It can be used to measure the subacromial space and detect atrophy of rotator cuff muscles [99]. As a result of providing images in real-time, ultrasonography can evaluate impingement in various positions and motions [99]. Ultrasonography can be useful in guiding injections or barbotage, such as aspirating calcific deposits in the rotator cuff [91]. Dynamic sonography allows direct visualization of the relationships between the acromion, humeral head, and intervening soft tissues during active shoulder motion [11]. Dynamic sonography can provide useful information regarding potential intrinsic and extrinsic causes of shoulder impingement syndrome [11]. The most commonly performed joint examination using ultrasonography is the shoulder examination [89]. Accuracy of rotator cuff ultrasonography depends on the skill of the scanner operator and an awareness of pitfalls that are encountered [89]. Ultrasonography can pick up on partial tears that may need treatment but have normal physical examination findings due to the ability to move the tendon with direct visualization [89]. The sensitivity of ultrasonography for the detection of full-thickness rotator cuff tears is 98% [101]. The specificity of ultrasonography for the detection of full-thickness rotator cuff tears is 80% [101]. The positive predictive value of ultrasonography for the detection of full-thickness rotator cuff tears is 90% [101]. The negative predictive value of ultrasonography for the detection of full-thickness rotator cuff tears is 95% [101]. The accuracy of ultrasonography for the detection of full-thickness rotator cuff tears is 94% [101]. 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 [99].

Arthroscopy: Arthroscopy is useful for diagnosing and treating subacromial impingement, intra-articular lesions, detachment of the glenoid labrum and rotator cuff tears [91]. The arthroscopic approach offers a unique advantage in diagnosing and treating occult intra-articular pathology [180]. Recognizing anterior shoulder pain due to persistence of a septum between long head biceps tendon and intra-articular supraspinatus may help arthroscopic surgeons decide the best therapeutic options depending on each patient's symptoms [33]. Open reduction of interposed tissues can result in a good functional outcome, at least in the short term, for irreducible isolated anteromedial radial head dislocation due to ruptured anterior capsule and annular ligament interposition [2]. The authors highlight the importance of recognizing complex soft tissue injuries to restore anatomic attachments and prevent chronic instability in global elbow instability [1].

Other Considerations: Neither the critical shoulder angle nor the acromial index influenced the functional outcomes of massive posterosuperior tears after repair [182].

Treatment¶

Non-Operative¶

Conservative management is the primary initial strategy for several soft-tissue pathologies. Conservative treatment is highly efficient in Stage I and Stage II shoulder impingement diseases [153] and is the first and main line of treatment for subcoracoid impingement [145]. For posterior capsular contracture, initial management should be nonsurgical, emphasizing range-of-motion stretching [133]. Nonoperative treatment is quite effective for bursitis secondary to overuse [50], and conservative measures should be pursued first when offering surgery to patients with shoulder impingement syndrome after a whiplash-type injury [142]. Nonsurgical treatment may be a viable option for spinoglenoid ganglion cysts in the absence of suprascapular nerve involvement or superior labrum anterior and posterior-related physical findings [59]. Complete decongestive therapy can be initiated before surgical intervention to optimize volume reduction and soft-tissue quality in patients with lymphedema [58]. However, conservative treatment was useless for idiopathic extension contracture of the little metacarpophalangeal joint [56]. A randomized controlled trial found no statistical difference in CC-index between brace and sling groups for conservative treatment of Rockwood type III acromioclavicular joint separation [138].

Operative¶

Indications: Operative intervention is indicated when conservative measures fail or specific structural lesions are present. Structural lesions causing painful crepitus in scapulothoracic bursitis are more resistant to nonoperative measures and often need to be surgically excised [50]. Subacromial decompression is considered a good choice for shoulder impingement if there is evidence of mechanical impingement with pain not responding to nonsurgical measures [150]. The authors recommend manipulation under anaesthetic in post-traumatic stiffness cases where conservative methods have failed [155]. For full-thickness rotator cuff tears, operative treatment resulted in greater improvement in Constant scores and significantly decreased pain scores compared to nonoperative management [139]. The study demonstrates a significant association between oblique acromioclavicular joint morphology and patients requiring acromioclavicular joint excision for pain [21].

Surgical Approach / Technique: Open reduction of interposed tissues for irreducible isolated anteromedial radial head dislocation can result in a good functional outcome, at least in the short term [2]. Bursectomy followed by mild coracoplasty is a safe and effective method for subcoracoid impingement when conservative treatment fails [145]. The authors advocate removal of the clavicular hook implant as soon as bony union and/or ligamentous healing is achieved to prevent subacromial shoulder impingement and rotator cuff lesion [68]. Recognizing a septum between the long head biceps tendon and intra-articular supraspinatus may help arthroscopic surgeons decide the best therapeutic options depending on each patient's symptoms [33]. Scapular muscle detachment appears to be a clinically identifiable syndrome with a homogeneous set of history and physical findings, for which surgical treatment has been described [9]. The authors present a novel technique for managing severe capsulolabral deficiency by Bankart augmentation with a split subscapularis tendon flap, noting that while less invasive than open approaches, it is technically difficult and further studies are needed to confirm consistent success [65]. Total resection and reconstruction of collateral ligaments in severe elbow stiffness induced by heterotopic ossification involves postoperative monitoring with a long-arm hinged brace, ROM exercises, and indomethacin therapy initiated on the first day [135].

Implant Selection: The combined suture bridge with Mason-Allen construct demonstrated substantially better structural healing and clinical outcomes at 2 years compared to suture bridge alone for rotator cuff repair, particularly in large and massive tears [36]. Repair of large rotator cuff tears structurally reinforced with xenograft ECM resulted in improved functional outcomes scores and strength [41]. An isolated bioinductive repair enabled a robust healing response evident through MRI and biopsy evaluation, demonstrating superior tendon quality and healing compared to sutured repair for full-thickness rotator cuff tears [70]. Medialization repair for postero superior retracted cuff tears provides less tension to the tendon, which leads to a more effective healing process and improves clinical outcome postoperatively [71]. Improved histology was correlated with improved final construct strength at the 12-week time point when using an interposition bioresorbable scaffold with a vented anchor for primary rotator cuff repair in sheep [42].

Pain Management: A prophylactic dose of 75 mg/day indomethacin administered for eight weeks postoperatively is used to prevent heterototic ossification following elbow ligament reconstruction [135].

Other Considerations: Clinical results for arthroscopic surgery of rotator cuff retear showed improvements in scores and decreased pain, especially in patients treated with a new repair [166]. Histologic evaluation revealed robust tissue healing and maturation after thermal treatment by the laser-assisted capsular shift procedure for glenohumeral instability [72]. The postoperative protocol for rotator interval capsuloligamentous plication typically involves placing patients into a sling for 4 to 6 weeks [134]. Patients undergoing rotator interval capsuloligamentous plication are advised to avoid more than 30 degrees of external rotation for the first 5 to 6 weeks to protect the plication [134]. Following sling removal after rotator interval capsuloligamentous plication, active and active-assisted exercises and terminal range of motion stretching are begun with a goal of full activity at 6 months [134]. The biomechanical and clinical evidence for routine plication of the rotator interval is inconclusive [134]. Current arthroscopic rotator interval cadaveric studies suggest that the most significant changes associated with rotator interval capsulolabral plication are decreased anterior translation and decreased external rotation [134]. A prospective clinical trial regarding the utility of rotator interval procedures in arthroscopic shoulder stabilization procedures is needed to better identify the potential clinical benefits and cost-effectiveness of these procedures [134]. In situations where the biceps is at risk for scarring, the biomechanical consequence of biceps adhesions may limit range of motion and clinical outcomes [8]. The patient's recovery from intermuscular shoulder lipoma excision was uneventful, with active forward elevation and abduction improving to 150 and 110 degrees respectively after 6 months of physical therapy [137].

Distinguishing soft-tissue and bone tumors is a key starting point to the treatment of a patient with a musculoskeletal tumor [100]. It is important to understand when various imaging techniques would be most helpful in the treatment of musculoskeletal tumors [100]. Understanding the key principles for performing a safe and effective musculoskeletal biopsy is paramount to care of patients with musculoskeletal tumors [100]. Functional testing in orthopaedic oncology is gaining importance in the care and follow-up of patients with musculoskeletal tumors [100]. A skin model allows simple wound closure to be practised safely on a medium which attempts to simulate the properties of soft tissue [3]. Langer's Lines diagrams are only guidelines for wound closure, as there are many contributors to the camouflaging of scars, including wrinkle and contour lines [18]. The authors recommend the 'shrug test' as part of routine shoulder examination to recognize sternoclavicular joint arthritis early, as it is an unrecognized cause of shoulder impingement [57].

Most studies evaluating physical tests for shoulder impingements were set in secondary or tertiary care and used reference standards such as arthroscopic surgery, MRI, or ultrasonography [7]. Current evidences are insufficient to clearly define the relationship between structural integrity of repaired rotator cuffs and long-term clinical outcome [19]. Despite good healing rates, not all patients with healed rotator cuffs experience good outcomes [37]. Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders [161]. The evidence for abnormal movement patterns in patient populations with shoulder pain is substantial, but the cross-sectional nature of the evidence cannot prove causation versus association [5]. The movement alterations identified in shoulder pain populations are not always consistent in direction, are often small in magnitude, and rely on different coordinate systems and measurement methods [5]. There are assumptions about how angular motion or position changes will impact rotator cuff proximity to potential impinging structures [5]. Capsular mobility impairments, either hypomobility or hypermobility, have been reported to contribute to subacromial impingement [67]. Increased laxity of the glenohumeral capsule may limit the ability of the capsule to restrain the accessory motions of the humeral head during active movements, thereby causing impingement [67]. Abnormal scapula motion that occurs during active movements is referred to as scapular dyskinesis and can predispose the patient to shoulder impingement [67]. Postural deviations such as scoliosis or rounded shoulder posture can influence both thoracic and cervical spine orientation and both resting and dynamic scapula position [67]. The lack of reporting of outcomes in the literature prevents drawing definitive conclusions regarding the most effective treatment strategies for paediatric patients with non-traumatic shoulder labrum tears [54]. The majority of included studies in the review of paediatric non-traumatic shoulder labrum tears were either case series or case reports, which limits the generalisability of findings because the sample size was small and may be biased to report more interesting surgical cases [54]. The studies included in the review of paediatric non-traumatic shoulder labrum tears were heterogeneous in nature, which prevented performing a robust meta-analysis [54]. There exists a paucity of high-level evidence investigating the management of non-traumatic shoulder labrum tears in the paediatric population [54]. Understanding the current evidence and appropriate indications of emerging technologies is of critical importance for their utilization in orthopaedic trauma [69].

Complications¶

Instability and Dislocation¶

Failure to recognize complex soft tissue injuries can lead to chronic instability [1]. Rupture of the anterior capsule and annular ligament can cause an irreducible isolated anteromedial radial head dislocation [2]. Open reduction of interposed tissues in cases of radial head dislocation can result in a good functional outcome, at least in the short term [2]. Spontaneous detachment of the deltoid origin can occur with chronic massive rotator cuff tears and can be responsible for an acute onset of shoulder weakness [147].

Iatrogenic Injury and Surgical Complications¶

Screw violation during reverse total shoulder arthroplasty poses a risk of iatrogenic suprascapular neuropathy [40]. Clinical outcomes of reverse total shoulder arthroplasty at a minimum follow-up of 1 year were similar in high-risk and lower-risk groups for screw penetration [40]. Retained osteophytes and significant mismatch of the humeral head diameter raise concerns regarding long-term outcomes in subscapularis-sparing total shoulder arthroplasty [43].

Tissue Degeneration and Healing Failures¶

Biceps adhesions may limit range of motion and clinical outcomes in situations where the biceps is at risk for scarring [8]. Remodeling following chronic tendon tear leads to a degenerative replacement of muscle with connective tissue rather than an active infiltrative process [73]. Age is associated with fatty infiltration or atrophy of rotator cuff muscles, increasing incidence of rotator cuff tearing, diminished capacity for healing of torn tendons, and higher failure rates for attempted repairs [64]. While retear is common in rotator cuff repairs, patients may still experience pain and functional improvement, though intact repairs generally lead to better long-term outcomes [39]. The combined suture bridge with Mason-Allen construct demonstrated substantially better structural healing and clinical outcomes at 2 years compared to suture bridge alone, particularly in large and massive tears [36]. Outcomes for the combined suture bridge with Mason-Allen construct were similar to suture bridge alone at 6 months [36].

Pathological Findings and Variations¶

A significant association exists between oblique acromioclavicular joint morphology and patients requiring acromioclavicular joint excision for pain [21]. Three congenital variations of the long head of the biceps tendon have been reported, but literature reviews have been unable to link these uncommon lesions to a common pathoanatomic presentation or suggest a universally accepted treatment algorithm [34]. The most common type of subscapularis muscle variation is the muscle with three bellies [66].

Specific Clinical Syndromes and Outcomes¶

Dynamic sonography allows direct visualization of the relationships between the acromion, humeral head, and intervening soft tissues during active shoulder motion and can provide useful information regarding potential intrinsic and extrinsic causes of shoulder impingement syndrome [11]. In patients with lymphedema, conservative therapies are available for those who require conservative orthopaedic therapy, have chronic conditions, or have injuries where intervention is less time-dependent [58]. Even patients with minimal volume differential in lymphedema may note notable clinical symptoms of heaviness or fibrosis, limited or diminished range of motion, or recurrent infections or cellulitis [58]. The procedure for deltoid contracture resolved pain, skin dimpling, palpable fibrous bands, and winging of the scapula, with no infections or neuromuscular complications [31]. Early surgical treatment seems to be a relevant factor allowing good shoulder function after arthroscopic repair of isolated subscapularis tears [15]. Despite major primary complications and high incidence of radiographic signs of degenerative changes after 8.8 years, mainly good clinical results were achieved with Judet's bipolar prosthesis for radial head arthroplasty [168]. Muscle flaps have dramatically changed the management of shoulder defects, particularly those resulting from irradiation, exposed bone, and chronic infection, by allowing single-stage reconstruction and bringing healthy tissue from a remote area [170].

Recovery¶

Ligament and Tendon Healing: Ligament injuries are classified into three grades: grade I corresponds to a mild sprain, grade II to a moderate sprain or partial tear, and grade III to a complete ligament tear [12]. The acromioclavicular ligament demonstrates an early and dynamic healing response following acute traumatic rupture [191]. Histological findings indicate that surgical treatment of acute acromioclavicular joint dislocations should be performed as early as possible, within a timeframe of 1 week after trauma, to exploit the utmost biological healing potential [191]. In the glenohumeral joint, histologic evaluation following laser-assisted capsular shift revealed robust tissue healing and maturation after thermal treatment [72]. At the hard-soft tissue interface, a zone exhibiting a gradient in mineral relative to collagen is detected as early as postnatal day 7 [38]. The development of this graded mineralized interface is linked to endochondral bone formation near the tendon insertion [38]. In a sheep model using an interposition bioresorbable scaffold, improved histology correlated with improved final construct strength at the 12-week time point [42]. Use of a biphasic interpositional allograft resulted in a histological profile essentially equivalent to that of a standard rotator cuff repair at 3-, 6-, and 12-week postoperative timepoints in an ovine model [185].

Muscle and Soft Tissue Remodeling: Histologic evaluation indicated that the extracellular matrix likely caused degenerative changes in the long head of the biceps tendon in the presence of rotator cuff tears [187].

Clinical Outcomes and Functional Recovery: Open reduction of interposed tissues can result in a good functional outcome, at least in the short term, for irreducible isolated anteromedial radial head dislocation [2]. While retear is common, patients may still experience pain and functional improvement, though intact repairs generally lead to better long-term outcomes [39]. Current evidence is insufficient to clearly define the relationship between structural integrity of repaired cuffs and long-term clinical outcome [19]. At long-term follow-up, arthroscopic rotator cuff repair with the double-row technique showed no significant difference in clinical outcome compared with single-row repair in small to medium tears [178]. The procedure for deltoid muscle contracture resolved pain, skin dimpling, palpable fibrous bands, and winging of the scapula, with no infections or neuromuscular complications [31]. No recurrence was observed at follow-up 1 to 8 years after surgery for subscapular elastofibroma [183].

Key Evidence¶

[Case_report] The authors highlight the importance of recognizing complex soft tissue injuries to restore anatomic attachments and prevent chronic instability. [1] (10.1016/j.xrrt.2022.08.005)
[Case_report] Open reduction of interposed tissues can result in a good functional outcome, at least in the short term. [2] (10.1177/17585732211039459)
[Paper] It allows simple wound closure to be practised safely on a medium which attempts to simulate the properties of soft tissue. [3] (10.1016/0020-1383(95)93506-d)
[L5] [5] (10.1007/s11517-013-1074-1)
[L5] Revision total shoulder arthroplasty is technically challenging with inferior results compared to primary arthroplasty, particularly when soft-tissue problems are the indication. [6] (10.5435/jaaos-21-01-23)
[L1] Most studies were set in secondary or tertiary care and used reference standards such as arthroscopic surgery, MRI, or ultrasonography. [7] (10.1002/14651858.cd007427.pub2)
[L5] In situations where the biceps is at risk for scarring, the biomechanical consequence of biceps adhesions may limit ROM and clinical outcomes. [8] (10.1016/j.jse.2012.07.003)
[L4] Scapular muscle detachment appears to be a clinically identifiable syndrome with a homogeneous set of history and physical findings. [9] (10.1016/j.jse.2013.05.008)
[L5] Although many treatment techniques remain in their infancy and further follow-up is necessary before universal adoption, they provide a novel means of addressing difficult-to-treat and complex shoulder girdle pathologies. [10] (10.1016/j.jhsa.2015.06.123)
[L4] Dynamic sonography allows direct visualization of the relationships between the acromion, humeral head, and intervening soft tissues during active shoulder motion and can provide useful information regarding potential intrinsic and extrinsic causes of shoulder impingement syndrome. [11] (10.2214/ajr.05.0528)
[L5] It allows for rapid healing, minimal scarring, and improved cosmesis. [13] (10.1097/bth.0b013e3181c848ea)
[L4] Pathologic conditions located in the supraspinatus tendon are very common and related to age and not to clinical status. [14] (10.1016/s1058-2746(99)90090-3)
[L4] Early surgical treatment seems to be a relevant factor allowing good shoulder function. [15] (10.1177/0363546516676261)
[L5] Fibrous bands are a common finding in the quadrilateral space in cadavers, suggesting they are a normal finding rather than a pathological cause. [17] (10.1016/j.jse.2007.05.013)
[L5] These diagrams are only guidelines; there are many contributors to the camouflaging of scars, including wrinkle and contour lines. [18] (10.1097/00006534-199907000-00033)
[L4] Current evidences are insufficient to clearly define the relationship between structural integrity of repaired cuffs and long-term clinical outcome. [19] (10.1007/s00167-014-3234-8)
[L3] Establishment of normative values may enable surgeons to explain the lack of progress after surgical joint release, determine progress with hand therapy, and choose the optimal timing of surgical intervention once soft-tissue equilibrium is achieved. [20] (10.1016/j.jhsg.2025.100748)
[L3] The study demonstrates a significant association between oblique AC joint morphology and patients requiring AC joint excision for pain. [21] (10.1177/1758573214525762)
[L1] Surgical intervention resulted in a small statistically significant but clinically unimportant improvement in long-term functional outcomes. [22] (10.9778/cmajo.20180179)
[L4] Long-term outcomes beyond five years and high-quality comparative or randomized trials are needed to define durability, refine indications, and position LHB-based DAS within the broader algorithm for anterior shoulder instability management. [23] (10.5397/cise.2025.00752)
[L5] The purpose of this article is to review the current literature concerning shoulder anatomy/pathology related to shoulder stability/instability to improve clinical diagnosis and surgical treatment of our patients. [26] (10.1016/j.arthro.2011.05.017)
[Paper] [27] (10.1016/j.clinbiomech.2015.06.001)
[L4] The findings demonstrate that nuchal fibromas, typically superficial lesions, may involve deep skeletal muscle and fascia and can be difficult to resect. [29] (10.2106/00004623-199811000-00017)
[L4] The article proposes a comprehensive classification of all individualized impingements occurring around the anterior aspect of the shoulder, including newly described entities, to address conflicting theories and improve understanding of their etiologic factors, diagnosis, and treatment. [30] (10.1007/s00264-017-3515-1)
[L3] The procedure resolved pain, skin dimpling, palpable fibrous bands, and winging of the scapula, with no infections or neuromuscular complications. [31] (10.2106/00004623-199802000-00010)
[L5] MIFS is a rare low-grade sarcoma usually localised superficially in the subcutaneous layer, with approximately 100 cases published worldwide. [32] (10.1016/j.jhsb.2007.01.008)
[L4] Recognizing this entity may help arthroscopic surgeons decide the best therapeutic options depending on each patient's symptoms. [33] (10.1016/j.jse.2011.10.019)
[L4] The authors present three patients with congenital variations of the long head of the biceps tendon, noting that literature reviews have been unable to link these uncommon lesions to a common pathoanatomic presentation or suggest a universally accepted treatment algorithm. [34] (10.1016/j.jse.2006.10.020)
[L3] [35] (10.1016/j.jse.2017.03.037)
[L5] The combined suture bridge with Mason-Allen construct demonstrated substantially better structural healing and clinical outcomes at 2 years compared to suture bridge alone, particularly in large and massive tears, though outcomes were similar at 6 months. [36] (10.1016/j.arthro.2023.10.038)
[L3] Despite good healing rates, not all patients with healed rotator cuffs experience good outcomes. [37] (10.1016/j.jse.2021.03.112)
[L5] A zone exhibiting a gradient in mineral relative to collagen was detected at the leading edge of the hard-soft tissue interface as early as postnatal day 7, and development of the graded mineralized interface is linked to endochondral bone formation near the tendon insertion. [38] (10.1371/journal.pone.0048630)
[L5] It highlights that while retear is common, patients may still experience pain and functional improvement, though intact repairs generally lead to better long-term outcomes. [39] (10.1016/j.csm.2017.12.013)
[L3] However, the clinical outcomes of RTSA at a minimum follow-up of 1 year were similar in the high- and lower-risk groups. [40] (10.1016/j.jse.2021.10.024)
[L4] Repair of large rotator cuff tears structurally reinforced with xenograft ECM resulted in improved functional outcomes scores and strength. [41] (10.1016/j.jse.2016.02.029)
[L5] Improved histology was correlated with improved final construct strength at the 12-week time point. [42] (10.1016/j.jse.2019.05.024)
[L2] Although anatomic restoration of the shoulder can be accomplished using subscapularis-sparing TSA, retained osteophytes and significant mismatch of the HHD raise concerns regarding long-term outcomes. [43] (10.1016/j.jse.2015.03.009)
[L2] Subjective mechanical symptoms in the affected shoulder are a common complaint in patients with suspected rotator cuff pathology. [47] (10.1016/j.jse.2024.02.024)
[Case_report] [48] (10.1016/j.jse.2006.04.004)
[L5] MRI is very useful to determine the precise etiology and inform surgical treatment. [49] (10.3233/bmr-140222)
[L5] Nonoperative treatment is quite effective for bursitis secondary to overuse; however, structural lesions causing painful crepitus are more resistant to such measures and often need to be surgically excised. [50] (10.1097/bte.0b013e31802c9f31)
[L4] Epithelioid sarcoma (ES) is not only rare, but does not always present as a typical sarcoma. [52] (10.1177/1558944716660555gx)
[L5] Recognition of atypical presentations of calcific tendinitis with bone erosion may prevent unnecessary biopsy and overtreatment. [53] (10.1016/j.jse.2009.02.009)
[L4] [54] (10.1136/jisakos-2016-000122)
[L5] Understanding of the detailed anatomy and anatomical variations of the glenohumeral joint is essential for surgeons to understand pathology, make correct diagnoses of instability, and select proper treatment options. [55] (10.1007/s00167-015-3892-1)
[L4] Conservative treatment was useless for this entity. [56] (10.1016/j.jhsa.2012.08.041)
[L4] The authors recommend the 'shrug test' as part of routine shoulder examination to recognize this pathology early. [57] (10.1111/j.1758-5740.2010.00060.x)
[L5] [58] (10.5435/jaaos-d-21-01136)
[L4] Nonsurgical treatment may be a viable option in the absence of suprascapular nerve involvement or superior labrum anterior and posterior-related physical findings. [59] (10.1016/j.jse.2023.11.025)
[L5] SLAP repairs are generally favored in younger, active patients, whereas treating the biceps is preferred in lower-demand patients aged >30 years. [60] (10.1016/j.jse.2024.09.040)
[L5] Diagnosis of long head biceps tendon and subscapularis pathology in association with shoulder rotator cuff pathology can be challenging due to limitations in MRI and arthroscopic visualization; surgeons should maintain a high level of suspicion and utilize specific techniques to prevent missing pathology. [61] (10.1016/j.arthro.2017.09.005)
[L4] Arthroscopic surgery allowed for complete resection of the lesions in patients with coracoid impingement caused by soft tissue tumours. [62] (10.1007/s00167-014-3048-8)
[L4] Extensive intraarticular contact observed in all subjects suggests that internal impingement mechanisms may play a role in these signs. [63] (10.1016/j.jse.2005.04.007)
[L5] [64] (10.2106/jbjs.16.00817)
[L4] The authors present a novel technique for managing severe capsulolabral deficiency by Bankart augmentation with a split subscapularis tendon flap, noting that while less invasive than open approaches, it is technically difficult and further studies are needed to confirm consistent success. [65] (10.1016/j.arthro.2011.02.032)
[L5] The most common type was the subscapularis muscle with three bellies, in line with Larson's model of the division of the subscapularis muscle into three parts. [66] (10.1155/2021/7450000)
[L5] [67] (10.2147/oajsm.s36646)
[L3] The authors advocate removal of the implant as soon as bony union and/or ligamentous healing is achieved. [68] (10.1186/1749-799X-9-6)
[L1] The IBR enabled a robust healing response evident through MRI and biopsy evaluation, demonstrating superior tendon quality and healing. [70] (10.1016/j.jse.2024.03.043)
[L4] The study aimed to evaluate functional and radiological outcomes, noting that medialization provides less tension to the tendon which leads to a more effective healing process and improves clinical outcome postoperatively. [71] (10.1016/j.jse.2021.03.122)
[L4] The study revealed histologic evidence of robust tissue healing and maturation after thermal treatment by the laser-assisted capsular shift procedure, although mechanical and biochemical characterization of the tissue was not evaluated. [72] (10.1177/03635465990270020801)
[L4] Remodeling following chronic tendon tear leads to a degenerative replacement of muscle with connective tissue rather than an active infiltrative process. [73] (10.1016/j.jse.2016.07.070)
[L2] [115] (10.1177/1758573216663201)
[L4] The most common and consistent presenting symptom is shoulder pain, with weakness of the shoulder and arm as a common secondary complaint. [122] (10.1016/s1058-2746(95)80145-6)
[L3] [125] (10.1016/j.jse.2006.11.010)
[L5] Initial management of posterior capsular contracture should be nonsurgical, emphasizing range-of-motion stretching. [133] (10.5435/00124635-200605000-00002)
[L5] [134] (10.1177/2325967115621494)
[L4] [135] (10.1016/j.jseint.2025.101418)
[Case_report] [137] (10.1016/j.jseint.2020.10.006)
[L2] [138] (10.1016/j.jseint.2023.02.017)
[L1] Operative treatment resulted in greater improvement in Constant scores and significantly decreased pain scores compared to nonoperative management. [139] (10.1016/j.jse.2017.09.032)
[L3] Caution should be used when offering surgery to these patients, and conservative measures should be pursued first. [142] (10.1111/j.1758-5740.2012.00199.x)
[L3] [144] (10.1111/j.1758-5740.2012.00178.x)
[Paper] The first and main line of treatment is usually conservative, but when it fails, bursectomy followed by mild coracoplasty is a safe and effective method. [145] (10.1530/eor-2025-0239)
[L5] The bicipital tunnel is a closed space with 3 anatomically and histologically distinct zones, where zones 1 and 2 differ from zone 3. [146] (10.1016/j.jse.2014.09.026)
[L4] Spontaneous detachment of the deltoid origin can occur with chronic massive rotator cuff tears and can be responsible for an acute onset of shoulder weakness. [147] (10.1016/s1058-2746(98)90029-5)
[L3] [148] (10.1007/s00167-011-1520-2)
[L5] The panel agreed that subacromial decompression is a good choice for shoulder impingement if there is evidence of mechanical impingement with pain not responding to nonsurgical measures. [150] (10.1016/j.arthro.2021.09.031)
[L4] However, magnetic resonance imaging indicates that the donor site is resurfaced with fibrous tissue. [151] (10.1177/0363546507306465)
[L5] The subscapularis tendon is composed of 2 distinct fibrous layers, just like the supraspinatus tendon, but arranged differently. [152] (10.1016/j.jse.2018.11.045)
[L3] Conservative treatment is highly efficient in Stage I and Stage II diseases. [153] (10.1016/s1058-2746(96)80283-7)
[L3] The authors recommend MUA in post-traumatic stiffness cases where conservative methods have failed. [155] (10.1177/1758573217693974)
[L4] The authors propose a classification of 12 variations of the intra-articular portion of the long head of the biceps tendon and suggest that these congenital conditions may acquire pathologic significance due to partial detachment from the mesothelial or synovial fusion with the inferior surface of the capsule. [158] (10.1016/j.jse.2009.03.006)
[L5] The ligament is composed of irregular and sparse fibers containing relatively rich type III collagen, suggesting flexibility. [160] (10.1016/j.jse.2014.02.009)
[L5] Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders. [161] (10.1016/j.jse.2009.12.006)
[L5] The coracohumeral ligament is more capsular than ligamentous based on its histologic features. [163] (10.1016/j.jse.2008.07.012)
[L4] While DePalma types 1 and 3 are most commonly encountered, other anatomic variants are frequent and should be considered when assessing and manipulating structures in region of the rotator interval and anterior shoulder. [165] (10.1016/j.jse.2012.08.024)
[L4] Clinical results showed improvements in scores and decreased pain, especially in patients treated with a new repair. [166] (10.1016/j.jse.2021.03.121)
[L5] The presentation of a resonant 'balloon-like' swelling is associated with gas in deeper structures, and plain radiography shows loculated air pockets increasing on serial films. [167] (10.1016/s1058-2746(97)90073-2)
[L4] Despite major primary complications and high incidence of radiographic signs of degenerative changes after 8.8 years, mainly good clinical results were achieved with Judet's bipolar prosthesis. [168] (10.1016/j.jse.2010.05.022)
[L4] These flaps have dramatically changed the management of shoulder defects, particularly those resulting from irradiation, exposed bone, and chronic infection, by allowing single-stage reconstruction and bringing healthy tissue from a remote area. [170] (10.1016/s0363-5023(80)80182-1)
[L1] [172] (10.3390/jcm12020581)
[L4] Radiographic methods including 3-D CT and MRI as well as the intraoperative findings of the labrum cannot be considered an accurate and reliable basis for the diagnosis and treatment of SSI in FAI patients. [175] (10.1186/s12891-022-06045-7)
[L4] The radiograph of the 30° caudal tilt view is easy to obtain and always reveals the exact architecture of a bony spur of the anterior acromion. [176] (10.1016/s1058-2746(09)80066-9)
[L2] At long-term follow-up, arthroscopic rotator cuff repair with the double-row technique showed no significant difference in clinical outcome compared with single-row repair in small to medium tears. [178] (10.1016/j.jse.2009.11.053)
[L4] Based on the results of this series, the authors no longer use nor recommend this technique. [179] (10.1016/j.jse.2009.06.005)
[L1] The arthroscopic approach offers a unique advantage in diagnosing and treating occult intra-articular pathology. [180] (10.1016/j.jse.2006.10.006)
[L5] This mechanical advantage must be weighed against surgical efficiency, with consideration given to factors such as tissue quality. [181] (10.1016/j.arthro.2010.02.035)
[L3] Neither of these radiographic parameters influenced the functional outcomes of massive posterosuperior tears after repair. [182] (10.1016/j.jisako.2024.07.008)
[L4] No recurrence was observed at follow-up 1 to 8 years after surgery. [183] (10.1016/s1058-2746(05)80008-4)
[L4] Multi-photon imaging revealed a clear three-dimensional structure of the human muscle. [184] (10.1016/j.jse.2018.05.005)
[L5] Use of the biphasic interpositional allograft resulted in a histological profile that was essentially equivalent to that of a standard RCR at 3-, 6-, and 12-week postoperative timepoints. [185] (10.1016/j.arthro.2023.03.018)
[L5] Histologic evaluation indicated that the extracellular matrix likely caused these degenerative changes. [187] (10.1186/s12891-023-06338-5)
[L4] Our histological findings suggest that surgical treatment of acute ACJ dislocations should be performed as early as possible within a timeframe of 1 week after trauma to exploit the utmost biological healing potential. [191] (10.1186/s12891-020-03614-6)
[L5] The H-loop technique resulted in more mature histological structures and a lower MRI signal-to-noise ratio. [192] (10.1177/03635465261415821)

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Soft Tissue Structures

Overview¶

Anatomy & Pathophysiology¶

Bony Anatomy¶

Soft Tissue Structures¶

Classification¶

Ligaments and Tendons¶

Injury Grading and Staging¶

Anatomical Variations and Zones¶

Imaging and Diagnostic Classification¶

Clinical Presentation¶

Shoulder Impingement Syndrome¶

Rotator Cuff Pathology¶

Instability and Dislocation¶

Scapular and Periscapular Pathology¶

Tumors and Masses¶

Ligaments and General Soft Tissue¶

Investigations¶

Treatment¶

Non-Operative¶

Operative¶

Complications¶

Instability and Dislocation¶

Iatrogenic Injury and Surgical Complications¶

Tissue Degeneration and Healing Failures¶

Pathological Findings and Variations¶

Specific Clinical Syndromes and Outcomes¶

Recovery¶

Key Evidence¶

See Also¶

References¶