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Rotator Cuff & Muscles

Rotator cuff muscle pathology, focusing on the prognostic impact of edema, fatty infiltration, and atrophy on surgical outcomes and repairability.

130 citationsUpdated Oct 2026

Overview¶

Rotator cuff pathology encompasses a spectrum of injuries where treatment has evolved from conservative management to advanced surgical techniques, including arthroscopic repair, muscle transfers, and reversed arthroplasty [29]. Arthroscopic rotator cuff repair is an effective and safe option that provides successful clinical results durable with time [13]. Patients who underwent repair of a massive posterosuperior rotator cuff tear maintained considerable improvements in clinical and radiographic outcomes at 10 years [2], and repair of a large or massive tear can have a satisfactory long-term outcome [7]. In patients 70 years of age or older with symptomatic full-thickness tears, arthroscopic repair outcomes are comparable with those in patients younger than 70 with at least 1-year follow-up [9].

Structural healing does not guarantee functional success; despite good healing rates, not all patients with healed rotator cuffs experience good outcomes [26]. Muscle atrophy and fatty infiltration, particularly of the infraspinatus, play a significant role in determining functional outcome after cuff repair [15], and supraspinatus muscle shortening negatively impacts shoulder function [14]. Recovery of fatty infiltration and muscle atrophy would rarely occur with current rotator cuff repairs [27]. While these factors influence repair outcomes, there was no influence of rotator cuff fatty infiltration and muscle atrophy on the functional outcome after total shoulder arthroplasty [18].

For irreparable massive tears, arthroscopic-assisted latissimus dorsi tendon transfer provides satisfactory functional outcomes [19], though female patients with poor shoulder function and generalized muscle weakness prior to surgery have a greater likelihood of a poor clinical result [20]. Deltoid transfer produces acceptable clinical and radiological results [28], and rotator cuff reconstruction with a dermal allograft demonstrated favorable structural healing rates and improved range of motion compared to maximal repair in the short term [3]. Deltoid complications combined with rotator cuff pathology represent a rare but devastating complication with no well-described surgical option [5]. Current evidence for treatment options for massive rotator cuff tears is based on low levels of evidence, highlighting the need for better, well-designed studies comparing outcomes [25].

Anatomy & Pathophysiology¶

Anatomy¶

The rotator cuff comprises four muscles: subscapularis, supraspinatus, infraspinatus, and teres minor [30]. The subscapularis arises from the anterior aspect of the scapula and attaches to the lesser tuberosity [94]. The supraspinatus arises from the fossa superior to the scapular spine and attaches to the superior aspect of the greater tuberosity [94]. The infraspinatus arises from the fossa below the scapular spine and attaches to the posterolateral aspect of the greater tuberosity [94]. The teres minor arises from the lower lateral aspect of the scapula and attaches to the lower portion of the greater tuberosity [94].

Innervation follows distinct neural pathways: * Supraspinatus: Innervated by the suprascapular nerve after it passes through the suprascapular notch [94]. * Infraspinatus: Innervated by the suprascapular nerve after it passes through the spinoglenoid notch [94]. * Teres minor: Innervated by a branch of the axillary nerve [94]. * Subscapularis: Innervated by the upper and lower subscapular nerves [94].

The rotator cuff tendons blend with the subjacent capsule as they attach to the humeral tuberosities [94]. The supraspinatus footprint measures 13 mm in width medially-laterally and 20 mm anteroposteriorly [47]. The infraspinatus footprint measures 14 mm wide and 20 mm superoinferiorly [47]. There is significant overlap and interdigitation of the supraspinatus and infraspinatus tendons near the footprint [94]. The infraspinatus insertion occupies the preponderance of the footprint on the greater tuberosity [94].

Histologically, the rotator cuff tendons possess five distinct layers [94]. The most superficial layer consists of coracohumeral ligament fibers [94]. The fifth and deepest layer is the continued sheet of collagen fibrils composing the superior joint capsule [94]. The long head of the biceps tendon attaches to the supraglenoid tubercle and runs between the subscapularis and supraspinatus [94]. The coracohumeral ligament and transverse humeral ligament keep the biceps tendon aligned in the bicipital groove [94].

The rotator cable is a thick bundle of fibers running perpendicular to the supraspinatus tendon fibers, connecting the supraspinatus and infraspinatus tendons [47]. It is divided into three segments: * Anterior segment: Forms the lateral part of the rotator interval [95]. * Middle portion: Lies under the supraspinatus tendon [95]. * Posterior part: Covered by the infraspinatus tendon and ends at the insertion region between the infraspinatus and teres minor tendons [95].

A hypovascular critical zone exists on the articular side of the rotator cuff close to the insertion on the greater tuberosity [47]. The coracoacromial arch is formed by the acromion process, coracoid process, and coracoacromial ligament [30]. The subacromial bursa separates the rotator cuff tendons from the coracoacromial arch [30].

Biomechanics & Function¶

The rotator cuff muscles stabilize the humeral head by pulling it into the glenoid when the deltoid lifts the arm [30]. The supraspinatus and deltoid muscles are equally responsible for producing torque about the shoulder joint in functional planes of motion [101]. The supraspinatus has a greater mechanical advantage than other tested muscles in the neutral arm position [108]. A larger contribution of force from the supraspinatus is required near the beginning of glenohumeral abduction, while the middle deltoid is more important near the end [105].

During high-velocity shoulder motions, the infraspinatus and teres minor are less involved than the subscapularis [1]. The subscapularis and pectoralis major are substantial actuators for shoulder internal rotation [123]. The supraspinatus and middle deltoid are active in both internal and external rotations [130]. The rotator cuff provides substantial anterior dynamic stability to the glenohumeral joint in both mid-range and end-range of motion [129]. Additionally, the rotator cuff actively stabilizes the humeral head against superior ascent [147].

In massive rotator cuff tears, the pectoralis major and latissimus dorsi muscles improve glenohumeral kinematics and reduce acromiohumeral pressures [56]. The pectoralis major muscle is not necessary for normal shoulder function but is required for athletics or strenuous activity [75]. Shoulder muscle volume has a clear relationship with the torques produced in all three rotational degrees of freedom [97]. Elevation moment arms are larger in the coronal plane than in the scapular or sagittal planes, making muscles more efficient in the coronal plane [111]. Human throwing capabilities result from derived anatomical features that enable elastic energy storage and release at the shoulder [104].

Pathophysiology & Natural History¶

Rotator cuff disease is a continuum progressing from impingement to partial tear, full-thickness tear, massive tear, and rotator cuff tear arthropathy [138]. The prevalence of full-thickness rotator cuff tears is approximately 25% in patients over 60 years of age and 50% in patients over 80 years of age [6]. The prevalence of rotator cuff tears ranges from 13% in patients in their fifties to 50% in patients aged 80 years or older [37]. If a patient has a symptomatic full-thickness rotator cuff tear in one shoulder, they have a 50% chance of an asymptomatic full-thickness rotator cuff tear in the contralateral shoulder [6]. Partial-thickness rotator cuff tears have an overall prevalence of 20%, increasing to 26% in patients older than 60 years [21]. As many as 53% of partial-thickness rotator cuff tears will progress in tear size [21]. Small full-thickness rotator cuff tears and painful partial-thickness tears become 25% to 50% larger within 3 to 4 years [47].

Intrinsic degeneration involves age-related changes in collagen, proteoglycan, water content, and vascularity, usually involving the supraspinatus and infraspinatus starting on the articular side [47]. Extrinsic impingement on the coracoacromial arch causes tears that usually start on the bursal side of the tendon [47]. Acute traumatic rotator cuff tears typically occur after a fall and/or dislocation in patients under 40 years of age [47].

Risk factors for rotator cuff tear development include male sex, manual labor, and history of trauma [37]. Risk factors for rotator cuff disease include age, smoking, female sex, family history, diabetes, and high cholesterol [47]. Genetic variations and single-nucleotide polymorphisms are associated with full-thickness rotator cuff tears [22]. The critical shoulder angle greater than 38° and acromial index greater than 0.7 are associated with higher retear rates after arthroscopic rotator cuff repair [12]. The critical shoulder angle is a static measure that does not change over time but is higher in patients with rotator cuff tears [12].

Fatty infiltration and muscle atrophy are associated with poorer functional outcomes and increased risk for retear following rotator cuff repair [87]. Muscle shortening negatively impacts shoulder function in torn rotator cuffs [14]. Microscopic muscle atrophy negatively correlates with the movement of abduction, leading to functional impairment [82]. Shoulder pain does not show a relationship with microscopic changes in the supraspinatus tendon and muscle [82]. MR imaging-derived rotator cuff muscle proton density fat fraction is associated with isometric strength independent of muscle atrophy and tendon rupture [40]. Myosteatosis and skeletal muscle atrophy correlate with increasing tear sizes of full-thickness rotator cuff tears, but fibrosis does not [189]. Delayed rotator cuff repair results in persistent muscle atrophy and fatty infiltration [17]. Fibroadipogenic progenitor cell response peaks prior to progressive fatty infiltration after rotator cuff tendon tear [172]. Rotator cuff muscle stem cells present reduced myogenic and increased adipogenic differentiation capacity compared to muscle stem cells from other body regions [87].

Cuff tear arthropathy is the final stage of the shoulder impingement syndrome spectrum, affecting patients with long-term insufficient massive rotator cuff tears [32]. Cuff tear arthropathy affects women at a 3:1 female to male ratio, more commonly in patients over 70 years old and on the dominant shoulder [32]. The integrity of the inferior subscapularis insertion is the single most important predictor for preserved shoulder function despite global tear extension [133].

Subjective mechanical symptoms are a common complaint in patients with suspected rotator cuff pathology [4]. Symptoms of pain do not correlate with rotator cuff tear severity in patients with symptomatic atraumatic full-thickness rotator cuff tears [22]. Shoulder strength deficits measured via isokinetic testing are weakly correlated with shoulder function in patients with rotator cuff tears [74]. The supraspinatus tendon is most often initially involved in subacromial bursitis and rotator cuff tendinosis [33].

Calcific tendinitis most commonly affects the critical zone of relative hypovascularity of the supraspinatus tendon [141]. Calcific tendinitis is characterized by a cyclical progression of reactive calcium hydroxyapatite crystal intratendinous deposition followed by spontaneous resorption and healing [141]. The precalcific stage of calcific tendinitis consists of predominantly fibrocartilaginous metaplasia within less vascular areas of the tendon [117]. The formative phase of the calcific stage involves matrix vesicles uniting to form calcium hydroxyapatite deposits separated by fibrocollagenous tissue [117]. The resorption phase of calcific tendinitis involves an inflammatory response and is generally the most painful phase [117]. Tendinitis has never been demonstrated in any human tendon; the pathology of extrasynovial tendons is one of tendinosis or intrinsic degeneration without inflammatory cells [190]. Subacromial changes are secondary to primary rotator cuff degenerative changes rather than the cause [190].

Classification¶

Tear Extent and Topography¶

Patte: This classification assesses tear extent, topography in the sagittal and frontal planes, muscle trophic quality, and the state of the long head of the biceps [51]. Segment 1 corresponds to a subscapularis tear; Segment 2 to a coracohumeral ligament tear; Segment 3 to an isolated supraspinatus tear; Segment 4 to a tear of the entire supraspinatus and one-half of the infraspinatus; Segment 5 to a tear of the supraspinatus and infraspinatus; and Segment 6 to a tear of the subscapularis, supraspinatus, and infraspinatus [51]. Isolated subscapularis tears (Segment 1) are seldom exclusively involved in degenerative tears and are generally due to traumatic avulsions often associated with a medial dislocation of the long head of the biceps [51]. Isolated coracohumeral ligament tears (Segment 2) are traumatic in nature and do not contribute to the pathology of the cuff [51]. Segments 4 and 5 merit special attention given the inherent difficulties of repair [51]. Secondary osteoarthritis was most common among patients with total-cuff tears (Segment 6) [51]. Anteriorly situated defects are more painful, whereas posterior lesions interfere more with function [51].

Medial Retraction (Patte): Medial retraction is assessed by the position of the torn end of the supraspinatus relative to the glenohumeral joint [90]. Stage 1 indicates that the proximal stump shows little retraction [90]. Stage 2 indicates that the proximal stump lies at the level of the humeral head [90]. Stage 3 indicates that the proximal stump lies at the level of the glenoid [90].

Massive Tear Definitions: Cofield and colleagues defined a massive rotator cuff tear as a tear of 5 cm or more [89]. Burkhart defined a massive tear as one that is at least 5 cm long with no superior coverage, referred to by Rockwood as a “bald head” [89]. Gerber and colleagues defined a tear as massive if it involved the detachment of at least 2 entire tendons [89]. Warner and colleagues supported the use of Gerber’s definition as more functional than one based on a simple measurement of tear length [89]. A massive rotator cuff tear is not necessarily irreparable, and an irreparable tear is not always massive [89].

Partial-Thickness Tear Classification¶

Ellman: This classification categorizes partial-thickness tears based on location and depth noted at arthroscopy [21]. Tears are classified as articular-sided (A), bursal-sided (B), or intratendinous (C) [21]. Grade 1 involves 3 mm or less of tendon [21]. Grade 2 involves 3 to 6 mm of tendon [21]. Grade 3 involves more than 6 mm of tendon [21]. Grade 3 tears represent tears of more than 50% of tendon width [21]. MRI evaluation classifies partial-thickness tears as low grade or high grade depending on whether they involve less than or more than 50% of the tendon width [21].

Ellman (Depth and Full-Thickness): The normal rotator cuff is considered to be 10–12-mm thick [146]. Grade 1 partial tears are less than 3-mm deep and involve definite disruption of tendinous fibres [146]. Grade 2 lesions are 3–6-mm deep and extend well into the substance of the cuff but do not exceed one-half of the thickness of the tendon [146]. Grade 3 lesions are more than 6 mm in depth and represent significant disruptions of more than one-half the substance of the cuff [146]. The area of defect is estimated by multiplying the length of the base of the tear by the distance of maximum retraction [146]. Full-thickness tears are designated by grades: Grade 1 is small (<2 cm), Grade 2 is large (2–4 cm), and Grade 3 is massive (>5 cm) [146]. A fourth grade includes cuff arthropathy, defined as a massive tear with articular irregularity, collapse of the humeral head, chronic synovitis, and capsular laxity [146].

Muscle Degeneration and Atrophy Classification¶

Goutallier: This classification grades rotator cuff muscle fatty infiltration as grade 0 (normal), grade 1 (some fatty streaks), grade 2 (less fat than muscle), grade 3 (equal amounts of muscle and fat), and grade 4 (more fat than muscle) [6]. Grades 3 and 4 indicate a long-term chronic rotator cuff tear with a higher potential for failure when surgery is undertaken and are likely deemed irreparable [6]. The classification was originally based on axial CT imaging [169] and has been modified by Fuchs et al. for MRI evaluation [6]. Fatty infiltration appears as early as 6 weeks after surgical detachment, starts near the musculotendinous junction, and progresses medially over time [8]. Medium fatty infiltration (stage 2) of the infraspinatus appears on average 2 and a half years after the onset of symptoms [86]. Severe fatty infiltration (stages 3 and 4) of the infraspinatus appears on average 4 years after symptom onset [86]. The modified 5-stage CT classification is a useful method for the evaluation of experimentally induced rabbit supraspinatus and infraspinatus fatty degeneration [188].

Other Considerations: The occupation ratio is determined by dividing the cross-sectional area of the rotator cuff muscle belly by that of the supraspinatus fossa to standardize muscle area according to individual body size [41]. Otsu's thresholding method offers a reliable, objective, and efficient approach for quantifying fatty change in rotator cuff muscles, outperforming the Goutallier classification in terms of inter-rater reliability [186].

Post-Repair Integrity Classification¶

Sugaya: This classification evaluates repair integrity to five categories based on MR imaging [52]. Type I indicates a repaired cuff with sufficient thickness and homogeneously low intensity on each image [52]. Type II indicates sufficient thickness associated with a partial high-intensity area [52]. Type III indicates insufficient thickness without discontinuity [52]. Type IV indicates the presence of a minor discontinuity in more than one slice of each image, suggesting a small tear [52]. Type V indicates the presence of a major discontinuity on each image, suggesting a medium or large tear [52]. Twenty-six different criteria described by multiple classification systems have been identified for the magnetic resonance assessment of rotator cuff after repair [46].

Clinical Presentation¶

History and Symptoms¶

Patients with symptomatic full-thickness rotator cuff tears typically report anterolateral shoulder pain radiating to the subdeltoid region, often exacerbated by overhead activity and lifting objects with an outstretched arm [6]. Frequent night pain and sleep disturbance are common complaints [6]. In chronic rotator cuff disease, patients often describe an insidious onset of lateral or anterior shoulder pain associated with overhead activities, alongside night pain [112]. A clear history of trauma resulting in acute pain and weakness strongly suggests an acute rotator cuff tear [112]. A family or personal history of rotator cuff disease increases the likelihood of diagnosis [112]. The combination of age over 65 years, night pain, and weakness has 95% specificity for rotator cuff tears [47].

Patients with cuff tear arthropathy present with chronic shoulder pain, night pain, weakness, and stiffness [32]. Those with subacromial bursitis and rotator cuff tendinosis present with mild or moderate pain during overhead shoulder motion and occasional night pain [33]. Pain in subacromial bursitis is present with overhead activity but usually absent or mild with the arm at the side [33]. Symptoms in rotator cuff tears may wax and wane periodically while physiological decline occurs over time [37]. Pain does not correlate with rotator cuff tear severity in a cross-sectional study of 393 patients with symptomatic atraumatic full-thickness tears [22]. Similarly, pain and duration of symptoms are not associated with tear severity according to the Multicenter Orthopaedic Outcomes Network Shoulder Group [39]. Shoulder strength deficits measured via isokinetic testing and shoulder function were weakly correlated in patients with rotator cuff tears overall [74].

Physical Examination Findings¶

Inspection of the shoulder in the upright position at rest and in motion may reveal rotator cuff muscle atrophy, signs of dysfunction, and anterosuperior escape [124]. Inspection for muscular atrophy of the deltoid and supraspinatus and infraspinatus fossa identifies chronic rotator cuff tears [47]. In long-standing cases of partial or complete rupture, wasting of the supraspinatus and infraspinatus is usually present [125]. Inspection in cuff tear arthropathy reveals supraspinatus and infraspinatus atrophy, anterior prominence of the humeral head with arm elevation (anterosuperior escape), and subcutaneous effusion [32].

Palpation of the greater tuberosity, acromioclavicular joint, bicipital groove, and coracoid process is part of the physical examination for rotator cuff tears [47]. Cervical spine palpation, range of motion, and the Spurling test are used to rule out cervical spine pathologies as a cause of shoulder pain [47]. There is often tenderness of the acromioclavicular joint in long-standing cases of partial or complete rotator cuff rupture [125].

Active range of shoulder motion may be limited by pain in subacromial bursitis and rotator cuff tendinosis, where no atrophy is present and manual muscle testing demonstrates mild weakness [33]. When the internally rotated shoulder is moved into forward flexion, the patient experiences discomfort, known as the Neer impingement sign [33]. Pain resolves and there is a dramatic increase in strength and range of motion with the Neer impingement test after subacromial injection of lidocaine [33]. On testing the biceps in long-standing rotator cuff tears, there may be an old tear of the long head of the biceps tendon [125].

In cuff tear arthropathy, subacromial/glenohumeral crepitus with movement is observed [32]. Very limited range of motion for elevation, external, and internal rotation is observed [32]. Pseudoparalysis in cuff tear arthropathy is defined as less than 60 degrees of elevation, lack of active external rotation, and incompetent subscapularis [32]. Chronic long head of biceps rupture is usually present [32]. The external rotation lag sign and hornblower sign indicate teres minor insufficiency [32]. The hornblower sign is defined as the inability to keep external rotation when the shoulder is 90 degrees flexed and 90 degrees abducted [32].

Special Tests and Diagnostic Accuracy¶

No one test for rotator cuff disease has reliably high diagnostic value, and a combination of tests increases diagnosis specificity [124]. None of the special tests for shoulder examination are absolutely diagnostic for any one pathologic entity, and many are poorly specific or unreliable if not performed precisely [53]. The Jobe or empty can test isolates the supraspinatus with resistance testing of the arm at 90 degrees of abduction, 30 degrees of flexion in the scapular plane, and thumb pointed down [124]. External rotation strength tests the infraspinatus with the arm in adduction and the elbow at 90 degrees of flexion [124]. The lift-off and belly press tests assess the subscapularis [124]. The external rotation lag sign and hornblower's sign both assess for massive failure of the infraspinatus and teres minor [124]. The drop arm test examines failure of the superior rotator cuff [124].

The empty can test has a sensitivity of 71.7% and a specificity of 64.6% for full-thickness supraspinatus tears [112]. The lift-off and belly-press tests have high specificity but low sensitivity for full-thickness subscapularis tears [112]. Patients with an external rotation lag sign at the side likely have a large posterosuperior tear involving the infraspinatus [112]. A positive hornblower sign suggests a massive posterosuperior cuff tear that prohibits the active positioning of the hand in space [112].

The painful arc test has a sensitivity of 71% (95% CI 60-83) and specificity of 81% (95% CI 68-93) for rotator cuff disease [112]. The cross-body adduction test has a sensitivity of 75% (95% CI 64-85) and specificity of 61% (95% CI 46-76) for rotator cuff disease [112]. The Hawkins test has a sensitivity of 76% (95% CI 56-89) and specificity of 48% (95% CI 23-74) for rotator cuff disease [112]. The Neer test has a sensitivity of 64-68% and specificity of 30-61% for rotator cuff disease [112]. The Yocum test has a sensitivity of 79% (95% CI 61-97) and specificity of 40% (95% CI 10-70) for rotator cuff disease [112]. The passive abduction test has a sensitivity of 74% (95% CI 54-93) and specificity of 10% (95% CI 0-29) for rotator cuff disease [112].

The external rotation lag test has a sensitivity of 47% (95% CI 21-71) and specificity of 94% (95% CI 85-100) for full-thickness rotator cuff tears [112]. The internal rotation lag test has a sensitivity of 97% (95% CI 88-100) and specificity of 83% (95% CI 70-96) for full-thickness rotator cuff tears [112]. The drop arm test has a sensitivity of 24% (95% CI 13-34) and specificity of 93% (95% CI 85-100) for rotator cuff disease [112]. The dropping sign has a sensitivity of 73% (95% CI 51-95) and specificity of 77% (95% CI 62-92) for full-thickness rotator cuff tears [112]. The Gerber (lift-off) test has a sensitivity of 34-68% and specificity of 50-77% for rotator cuff disease [112]. The external rotation resistance test has a sensitivity of 63% (95% CI 49-77) and specificity of 75% (95% CI 69-82) for rotator cuff disease [112]. The full can test has a sensitivity of 75% (95% CI 64-85) and specificity of 68% (95% CI 54-83) for rotator cuff disease [112]. The Patte test has a sensitivity of 58% (95% CI 36-80) and specificity of 60% (95% CI 30-90) for rotator cuff disease [112]. The empty can (Jobe) test has a sensitivity of 71% (95% CI 49-86) and specificity of 49% (95% CI 42-56) for rotator cuff disease [112]. The resisted abduction test has a sensitivity of 58% (95% CI 36-80) and specificity of 20% (95% CI 0-45) for rotator cuff disease [112]. Hawkins and Neer tests both positive have a sensitivity of 78% (95% CI 66-90) and specificity of 50% (95% CI 22-78) for rotator cuff disease [112].

Clinical tests including the O'Brien, Yergason, Speed, and direct palpation tests have limited specificity for long head of the biceps tendon pathology [142]. 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 [35]. Subscapularis tendon tears can be missed because of the poor sensitivity of clinical examination findings and advanced imaging [55].

Imaging and Diagnostic Studies¶

MRI is obtained in the evaluation of a potential rotator cuff tear if the patient has no contraindications [6]. MRI allows the surgeon to characterize the location, size, and amount of retraction of the rotator cuff tear, as well as the degree of atrophy and fatty infiltration of the rotator cuff musculature [6]. MRI is indicated in younger, active patients with acute rotator cuff tears and in patients with chronic rotator cuff tears in whom a trial of nonoperative treatment has failed [6]. MRI is the benchmark for diagnosing rotator cuff tears with 94% sensitivity and 93% specificity [47]. T2-weighted images best visualize rotator cuff tears [47]. T1 sagittal oblique cuts reveal muscle/tendon retraction and muscle atrophy to determine chronicity, reparability, and outcome of surgical rotator cuff repairs [47]. Intra-articular contrast-enhanced magnetic resonance arthrography is best for detecting partial-thickness rotator cuff tears with 95% sensitivity and 95% specificity [47].

Ultrasonography has good accuracy with 92% sensitivity and 93% specificity for rotator cuff tears [47]. Ultrasonography is more accurate for full-thickness rotator cuff tears, comparable to MRI [12]. Ultrasonography approaches the sensitivity and specificity of MRI for detecting the presence of a full-thickness rotator cuff tear with an experienced practitioner [112]. MRI accurately assesses muscle, bone, and cartilage, which has advantages for surgical planning [112]. MRI, but not radiography, can be used to help discriminate between traumatic and nontraumatic rotator cuff lesions [38].

Radiographs are used to rule out glenohumeral and acromioclavicular arthritis in the evaluation of rotator cuff tears [47]. The true AP view is used to evaluate the acromiohumeral interval, the critical shoulder angle, and acromion index [47]. Greater tuberosity excrescences on AP views in external and internal rotation are pathognomonic for cuff disease [47]. The supraspinatus outlet view is used to evaluate acromial morphology according to Bigliani classification [47]. The axillary view is used to assess glenohumeral joint morphology and joint space and rule out dislocations [47]. CT arthrography is useful in postoperative assessment, retear evaluation in patients with retained metallic anchors causing artifact on MRI, and when MRI is contraindicated [47].

Magnetic resonance imaging is useful for the evaluation of patients who have pain and loss of function after a repair of the rotator cuff, particularly for identifying full-thickness tears, intact cuffs, ruptures of the biceps tendon, and detachments of the origin of the deltoid muscle [66]. MRI is less effective than other modalities for partial-thickness tears in the evaluation of failed rotator cuff repairs [66].

Radiographs in cuff tear arthropathy show acetabularization of the acromion and femoralization of the humeral head [32]. Radiographs in cuff tear arthropathy show eccentric superior glenoid wear [32]. Radiographs in cuff tear arthropathy show absence of typical peripheral osteophytes around the humeral head as seen on osteoarthritis [32]. Radiographs in cuff tear arthropathy show osteopenia and subarticular sclerosis (snowcap sign) [32]. Radiographs in cuff tear arthropathy show loss of the coracoacromial arch, indicating anterosuperior escape [32]. MRI or CT scan is not routinely necessary for cuff tear arthropathy if radiographs show anterosuperior escape [32]. MRI or CT scan establishes the extent of rotator cuff tear, retraction, and fatty infiltration in cuff tear arthropathy [32]. CT is helpful to quantify glenoid bone stock when reverse shoulder replacement is considered in cases of advanced arthropathy [32].

The goal of diagnostic imaging is threefold: determine the presence, size, and orientation of the rotator cuff tear; evaluate the healing capacity of the tendon; and assess associated pathology such as long head biceps tendinitis, acromioclavicular joint pathology, and arthrosis [112]. Ultrasonography is relatively inexpensive, allowing for dynamic testing, guided injections, and immediate feedback [112]. Ultrasonography is operator dependent and has limited assessment of chondral lesions [47]. Ultrasonography has poor sensitivity to diagnose partial-thickness rotator cuff tears [47].

Pathologic conditions located in the supraspinatus tendon are very common and related to age and not to clinical status [34]. The radiographic morphology of the greater tuberosity is associated with muscle degeneration in patients with symptomatic rotator cuff tears [41]. Fatty infiltration of the rotator cuff muscles is closely related to patient age, the extent of the tendon rupture, and the time to onset [23]. Fatty infiltration of the rotator cuff worsens over the course of 1 year in the unrepaired rotator cuff [8]. Fatty infiltration and atrophy of the rotator cuff do not improve after rotator cuff repair and correlate with poor functional outcome [15]. Chronic rotator cuff tendon tears and suprascapular neuropathy are both associated with fatty infiltration and muscle atrophy of the rotator cuff muscles, but the pattern of fatty infiltration is markedly different in the two situations [65]. MR imaging-derived rotator cuff muscle proton density fat-fraction is associated with isometric strength independent of muscle atrophy and tendon rupture in shoulders with early and advanced degenerative changes [40]. Quantitative evaluation of the rotator cuff muscles is not well established, although muscular condition predicts the prognosis of the patients [11]. Supraspinatus muscle shortening negatively impacts shoulder function [14].

Investigations¶

Plain radiography: Radiographs may demonstrate classic changes within the acromion or coracoacromial ligament, including spurring and calcification, in addition to cystic changes within the greater tuberosity [57]. With chronic rotator cuff disease, superior migration of the humeral head with extensive degenerative change may be present [57]. The tangent sign is defined as failure of the supraspinatus muscle belly to cross a line from the superior border of the coracoid to the superior border of the scapular spine [57]. This sign correlates with muscle atrophy and fatty infiltration of the supraspinatus, and patients with its presence are more likely to have an irreparable rotator cuff tear [57]. A positive tangent sign predicts the repairability of rotator cuff tears [12]. Irreparable tears are more likely to occur when the acromiohumeral distance appears shorter than 7 mm on AP radiograph [57].

MRI: MRI and MRA are both sensitive and specific for full-thickness rotator cuff tears, with MRI sensitivity of 92.1% and specificity of 92.9%, and MRA sensitivity of 95.4% and specificity of 98.9% [114]. MRI sensitivity for partial-thickness rotator cuff tears is 63.6% with a specificity of 91.7%, while MRA sensitivity is 85.9% with a specificity of 96.0% [114]. MRA is more sensitive for the detection of partial-thickness, particularly articular-sided tears, which can be filled with contrast when the cuff relaxes with the arm in ABER position [114]. Articular-side thickening of the supraspinatus and infraspinatus on images obtained in the neutral position suggests the presence of a partial-thickness articular-side rotator cuff tear [114]. The rotator cable can be reliably identified with the shoulder in ABER position, even in the absence of a rotator cuff tear [114].

The description of a full-thickness rotator cuff tear on MRI should include the tendon(s) involved, the location within the tendon (footprint, critical zone, or myotendinous junction), the AP dimension measured on the sagittal view, and the extent of retraction measured on the coronal sequence for supraspinatus and infraspinatus and on the axial sequence for the subscapularis [114]. The description of a partial-thickness rotator cuff tear on MRI should include the tendon(s) involved, the location within the tendon, the percentage of tendon thickness affected (greater or less than 50%), and the side of the tendon that is torn [114]. MRI findings of tendon retraction to or beyond the glenoid, increased inferior glenohumeral distance, and a positive tangent sign are associated with irreparability of large and massive rotator cuff tears [177].

MRI is key for evaluating fatty infiltration of the rotator cuff, although the Goutallier classification was originally based on CT [57]. Fatty infiltration of the rotator cuff appears as early as 6 weeks after surgical detachment, starts near the musculotendinous junction, and progresses medially over time, worsening over the course of 1 year in the unrepaired rotator cuff [8]. Supraspinatus muscle atrophy appreciated on MRI is independently associated with patient age, tendon retraction, and atrophy of the supraspinatus myofibers at the histologic level [191]. Increased infraspinatus fatty infiltration was correlated with the severity of an infraspinatus tear, but substantial fatty infiltration was also seen in the absence of a tear and correlated with worsening severity of a concomitant supraspinatus tear and atrophy [196]. The occupation ratio of the supraspinatus may change after rotator cuff repair without volumetric improvement [90].

Magnetic resonance imaging is useful for evaluating patients with pain and loss of function after rotator cuff repair, particularly for identifying full-thickness tears, intact cuffs, ruptures of the biceps tendon, and detachments of the origin of the deltoid muscle, though it is less effective for partial-thickness tears [66]. Clinicians have been missing a significant number of rotator cuff tears by not routinely ordering MRI on patients with spontaneous proximal biceps tendon ruptures [76].

CT: Deep learning-based image segmentation provides a rapid, tireless and reliable automatic quantification of rotator cuff muscle atrophy, fatty infiltration, and overall muscle degeneration in patients undergoing preoperative CT planning prior to anatomic or reverse shoulder arthroplasty, with a higher reliability and similar accuracy compared with human observers [197].

Other Considerations: Ultrasound elastography, particularly shear wave elastography, is a promising tool for evaluating mechanical properties of musculoskeletal tissue in the shoulder, showing potential for detecting and monitoring pathologic processes such as fatty degeneration and tendon tears [73]. Artificial intelligence advancements using in-domain transfer learning, feature fusion, and machine learning classifiers allow for the effective automated classification of fatty infiltration of rotator cuff muscles on MRI [78]. Artificial intelligence advancements allow for the effective automated measurement of the fatty infiltration of rotator cuff muscles using shoulder MRI images [185].

Patients with painful shoulders, irrespective of having type 2 diabetes mellitus, seem to have abnormal shoulder muscles [36]. Microscopic muscle atrophy appeared to negatively correlate with the movement of abduction leading to functional impairment, while shoulder pain did not show any relationship with microscopic changes [82].

The overall prevalence of full-thickness rotator cuff tears is approximately 25% in patients over 60 years of age and increases to 50% in patients over 80 years of age [6]. The overall prevalence of asymptomatic partial-thickness rotator cuff tears is 20%, which increased to 26% in patients older than 60 years [21]. As many as 53% of partial-thickness rotator cuff tears will progress in tear size, and a portion of these will progress to full-thickness rotator cuff tears [21]. Tear progression of symptomatic full-thickness and partial-thickness rotator cuff tears correlates with presenting tear size [22]. Regardless of treatment, symptoms improved over the first year after treatment for full-thickness rotator cuff tears but then plateaued, representing a regression to the mean [12]. There is evidence for an inherited predisposition contributing to the risk for rotator cuff disease [12]. Two correlated single nucleotide polymorphisms are associated with full-thickness rotator cuff tears, lending evidence to a genetic component to rotator cuff disease [22].

Measures of rotator cuff tear size showed stronger associations with re-tear six months post-surgery than measures of tissue quality and concomitant shoulder pathology [16]. Patients who had repair of a massive posterosuperior rotator cuff tear maintained considerable improvements in clinical and radiographic outcomes at 10 years [2]. The clinical and structural outcomes of arthroscopic rotator cuff repair in patients 70 or older with symptomatic full-thickness rotator cuff tear are comparable with those in patients younger than 70 with at least 1-year follow-up [9]. There was no influence of the rotator cuff fatty infiltration and muscle atrophy on the functional outcome after total shoulder arthroplasty [18]. The degree of fatty infiltration, muscle atrophy and tendinopathy of the rotator cuff muscle on preoperative magnetic resonance imaging scanning is not associated with functional outcome score or functional movement at medium-term follow-up following total shoulder replacement [44]. Patient-reported outcomes and pain are not correlated with rotator cuff healing on ultrasonography or MRI, but postoperative strength is better in individuals with healed rotator cuffs versus those with defects after repair [59]. Patients with a critical shoulder angle greater than 38° and an acromial index greater than 0.7 had higher retear rates but similar functional rates compared to control patients [12]. The critical shoulder angle was higher in the patient group with rotator cuff tears but was a static measure that did not change over time [12]. Critical shoulder angle and acromial index do not influence 24-month functional outcome after arthroscopic rotator cuff repair [12].

Treatment¶

Non-Operative¶

Conservative management of rotator cuff pathology typically consists of 6 to 12 weeks of rest and activity modification, symptom management often with NSAIDs, and physical therapy [113]. The physical therapy program focuses on passive and active range of motion plus strengthening of scapular stabilizing muscles and the rotator cuff itself [113]. For partial-thickness tears, first-line treatment includes activity modification with avoidance of overhead sports or pain-provoking activities, a short course of NSAIDs, and directed home exercises or physical therapy [127]. In throwers with a PASTA lesion, focused stretching addressing a tight anterior capsule can lead to significant short- and long-term improvement [127].

Subacromial corticosteroid injections may be used for pain but require caution due to effects on tissue quality and infection risk associated with rotator cuff repair [113]. Current recommendations include avoiding steroid injection within 6 months prior to rotator cuff repair to decrease failure rates [57]. Bursal injection can be accomplished through anterior, lateral, or posterior routes, with anterior and lateral access points possibly demonstrating increased accuracy [113]. Some patients receive benefit from subacromial corticosteroid injections, particularly those with bursal-sided tears [127].

Nonoperative treatment is indicated for noncompliant patients, elderly patients (>65 years), patients with medical contraindications to surgery or rotator cuff arthropathy, and athletes with combined instability and cuff tearing resulting from articular-side partial-thickness failure [57]. Asymptomatic full-thickness tears should be treated nonoperatively [57]. In a study of 452 patients with asymptomatic full-thickness tears initially treated nonsurgically, 75% did not require surgery at 2-year follow-up [113]. Nonoperative treatment leads to a successful outcome in 60% of patients with symptomatic full-thickness rotator cuff tears [6]. However, the risk of tear progression with nonoperative treatment is approximately 50% at 2 years [6]. Risk factors for conservative management failure of partial-thickness tears include bursal-sided tears, tears in the dominant upper extremity, and tears involving greater than 50% of the tendon thickness [113]. The majority of patients who failed physical therapy in the MOON shoulder group study did so in the first 12 weeks [113]. Patient expectations about physical therapy’s treatment ability were more important than tear structural factors regarding therapy success versus conversion to surgery [113].

Operative¶

Indications: The primary indication for surgical intervention is significant pain [57]. Chronic full-thickness tears that have failed to respond to nonoperative management may be treated surgically [57]. Full-thickness acute tears should be repaired early because the disease process is accelerated in this setting [57]. Surgery reliably decreases pain and improves motion and function [57]. For partial-thickness tears, surgical treatment with either rotator cuff repair or debridement is indicated for patients in whom nonoperative treatment fails [21]. Most surgeons agree that tears involving more than 50% of tendon width are best treated with repair and those involving less than 50% with debridement and potential decompression [21]. A higher failure rate of debridement has been suggested for partial-thickness bursal-sided rotator cuff tears compared to articular-sided rotator cuff tears, leading some surgeons to favor repair in even low-grade bursal-sided tears [21]. For tears with poor-quality tendon remaining and involving more than 80% of tendon thickness, debridement is favored [21].

Surgical Approach / Technique: The operative approach has evolved from a classic open approach to a "mini-open" or deltoid-sparing approach and now to an all-arthroscopic technique [57]. The current standard of care is arthroscopic repair, although the superiority of arthroscopic versus open or mini-open repair is still somewhat controversial [49]. Arthroscopic repair has been shown to have similar outcomes and failure rates, with decreased short-term pain and more rapid return to activity compared to open or mini-open repair [49]. Advances in arthroscopic equipment and increased surgeon familiarity with shoulder arthroscopy have made arthroscopic surgery the preferred method of rotator cuff repair for many shoulder surgeons [119]. Arthroscopy allows a more comprehensive assessment of intra-articular pathology and rotator cuff tear configuration by viewing from multiple angles [119]. Tendon mobilization is facilitated by precise releases of adhesions that limit tendon excursion, leading to an improved ability to anatomically reduce the edge and create a tension-free repair [119]. Injury to the deltoid muscle is minimized in arthroscopic repair, and the acromial deltoid origin is preserved, eliminating the risk of deltoid dehiscence [119]. A key theoretical benefit of arthroscopic repair is decreased postoperative pain secondary to less soft tissue trauma, which aids in postoperative rehabilitation [119].

Regardless of the technique, the rate-limiting step for recovery is biologic healing of the rotator cuff tendon to the humerus, which is estimated to require a minimum of 8 to 12 weeks [57]. The goal of rotator cuff repair is to restore the tendon to its anatomic footprint to encourage healing [49]. Anatomic footprint restoration is now possible in arthroscopic repair, with fixation at both the suture-tendon interface and the anchor-bone interface that approximates traditional open transosseous repairs [119]. Routine acromioplasty is no longer recommended during rotator cuff repair [57]. If anatomic repair cannot be achieved without significant tension, medialised repair can be performed [6]. Strong fixation of the repair is essential to prevent gapping of the tendon [6]. Intraoperative prognostic healing factors for rotator cuff repairs include tendon and bone quality and the ability to anatomically reduce and repair the tendon to its normal footprint on the tuberosity without undue tension [6].

For partial-thickness tears, whether articular-side tears should be treated with débridement or repair remains controversial [57]. Articular-sided tears in which more than 7 mm of bone lateral to the articular margin is exposed, which represents 50% of the tendon insertion, should be considered significant [57]. Patients with a preponderance of impingement findings and a tear of less than 50% thickness may benefit from débridement and subacromial decompression [57]. If delamination of the tear is present in delamination-type tears of the articular side, a transtendinous repair is indicated [21]. The arthroscopic transtendon repair of partial articular-sided rotator cuff tears is an effective procedure that leads to significant improvement in pain and shoulder function, with high patients' satisfaction rate, while the complication rate is low [155]. There is no difference in functional outcome scores or re-tear rates between in situ rotator cuff repair and completion to a full-thickness rotator cuff tear with subsequent repair [21]. At a minimum of 2-year follow-up, there was no difference between treatment groups in a randomized control trial of 74 patients with PASTA tears treated with transtendon repair or completion and repair [22].

Intratendinous tears that can be identified on MRI must be localized through preoperative planning and use of a spinal needle to identify the tear site [21]. The tear can be opened using an arthroscopic knife and the edge debrided back slightly to promote local healing [21]. Extensive debridement is unnecessary for intratendinous tears [21]. Intratendinous tears are repaired side-to-side using arthroscopic technique [21].

Implant Selection: Surgical techniques have evolved to include double-row and suture-bridge fixation techniques, which have improved biomechanical strength in vitro; clinical correlation remains controversial [57]. The double-row technique has been advocated as a better biomechanical construct and a more anatomic repair strategy [119]. Controlled laboratory studies have generally shown superiority of double-row techniques over single-row in terms of initial and ultimate failure strength, decreased gap formation, decreased strain and suture cut-through, and improved vascularity in transosseous-equivalent double-row repair [49]. While in biomechanical studies, the double-row repair outperforms single-row repair in failure strength, superior clinical results with double-row fixation over single-row fixation is still controversial [119].

Other Considerations: Factors known to be associated with failure of rotator cuff repair include muscle degeneration (fatty infiltration and atrophy), tear size, chronicity, advanced age, and other environmental factors [49]. Factors associated with failure after rotator cuff repair include larger tears, greater retraction, advanced Goutallier grade, older age, smoking status, osteoporosis, diabetes mellitus, hypercholesterolemia, and more aggressive rehabilitation protocols [6]. The best potential for healing was in patients younger than 70 years with acute, small tears (<3 cm) and a healthy tendon-bone interface who are compliant with sling wear and are able to undergo an extended rehabilitation program of 6 to 9 months [6]. Carefully selected patients older than 70 years did well after rotator cuff repair and functionally improved as much as younger patients [6]. Goutallier stages III and IV tears, if accompanied by a tendinous stump of less than 15 mm and a positive tangent sign, have a 90% failure rate [6]. Tears with Goutallier grades III and IV usually are deemed irreparable and are treated with alternative strategies such as debridement, tendon transfer, superior capsular reconstruction, or reverse shoulder arthroplasty [6].

Blood flow to the repaired rotator cuff is achieved from the peribursal tissue and bone anchor site; vascularity has been shown to increase with exercise [57]. Patient-reported outcomes and pain are not correlated with rotator cuff healing on ultrasonography or MRI [59]. Postoperative strength is better in individuals with healed rotator cuffs versus those with defects after repair [59]. This study established a correlation between improved structural integrity of the repaired cuff tendon and enhanced structural outcomes in rotator cuff muscles [156]. Recovery of fatty infiltration and muscle atrophy would rarely occur with current rotator cuff repairs, suggesting further studies and advances in repair strategy are necessary [27]. In nonretracted cuff tears, fibrous tissue bound the tendon-to-bone junction with healing [183]. Inhibition or stimulation of muscle inflammation may be a potential target to enhance the outcome of the repaired torn rotator cuff [140]. Statin medication could potentially help improve outcomes for patients with rotator cuff tears, though further studies are necessary [145].

Massive and Irreparable Tears: The failure rate for repair is higher in large and massive tears; tissue failure is most common [57]. Irreparable tears are more likely to occur when the acromiohumeral distance appears shorter (<7 mm) on AP radiograph [57]. Larger, more retracted tears (>40 mm length/width) are characterized by fatty atrophy, supraspinatus width of less than 5 mm at glenoid margin [57]. Salvage options for irreparable cuff tears include SCR, tendon transfers, and RTSA in properly selected and appropriately counseled patients [122]. In the setting of larger tears, some biologic adjuncts such as PRP, bone marrow aspirate concentrate, and patch augmentation will have an evolving role as research continues [122]. Augmentation strategies may improve outcomes in rotator cuff repairs, particularly in high-risk cases; however, there is a lack of consensus among surgeons on the most effective strategies for each scenario [84]. Patch augmented cuff repair leads to a significant improvement of functional and structural outcomes [80]. LDTT is an effective treatment for massive, irreparable posterosuperior rotator cuff tears and leads to substantial clinical improvement [126]. Arthroscopic rotator cuff repair of massive rotator cuff tears with advanced mobilization techniques can lead to reversal of preoperative pseudoparalysis in 90% of patients who have not had previous surgery [192]. In massive rotator cuff tear, the pectoralis major and latissimus dorsi muscles are effective in improving glenohumeral kinematics and reducing acromiohumeral pressures [56]. The article highlights the need for better, well-designed studies truly comparing the outcomes for each of the treatment options used for massive rotator cuff tears, as current evidence is based on low levels of evidence [25]. Studies of high level of evidence and long-term follow-up are needed to explore the most suitable conditions for each LHB reuse method and the best method for each specific rotator cuff tear condition [43].

Specific Procedures and Outcomes: ARCR appears to be an effective and safe option to treat the symptoms of rotator cuff tears and to provide successful clinical results durable with time [13]. The clinical and structural outcomes of ARCR in patients 70 or older with symptomatic full-thickness rotator cuff tear are comparable with those in patients younger than 70 with at least 1-year follow-up [9]. Rotator cuff repair increases deltoid force requirements and joint load, particularly when combined with glenosphere lateralization, suggesting the rotator cuff muscles act as antagonists after reverse total shoulder arthroplasty [81]. All patients with cuff tear arthropathy have a significantly superior position of the humerus compared to the control group [194]. Subscapularis (SSc) tendon tears are found in up to 30% often alongside posterosuperior rotator cuff tendon tears [55]. The SSc is the largest rotator cuff muscle and provides stable support for glenohumeral movement comprising the anterior portion of the rotator cuff force couple [55]. Even isolated repair in large to massive rotator cuff tears has been shown to improve motion and function [55].

Complications¶

Re-tear and Structural Failure¶

Tear size demonstrates a stronger association with re-tear at six months post-surgery than tissue quality or concomitant shoulder pathology [16]. Healing rates after double-row repair decrease with increased age and longer follow-up duration [72]. At ten years, 68 to 81% of tendons have healed, with tears exhibiting posterior extension carrying a higher risk of retear [154]. Goutallier stages III and IV tears accompanied by a tendinous stump of less than 15 mm and a positive tangient sign carry a 90% failure rate [6]. In chronic full-thickness tears managed nonoperatively, the risk of tear progression is approximately 50% at 2 years [6].

Muscle Degeneration and Atrophy¶

Fatty infiltration and muscle atrophy do not improve after rotator cuff repair and correlate with poor functional outcome [15]. Within one year of successful tendon repair, fatty infiltration does not recover, while atrophy improves only partially; if the repair fails, both atrophy and fatty infiltration progress significantly [178]. The ability of rotator cuff muscles to develop tension correlates with both atrophy and the degree of fatty infiltration [178]. With current repair techniques, atrophy and fatty infiltration appear irreversible despite successful tendon repair [178]. Medium fatty infiltration appears on average 2.5 years after symptom onset, and severe fatty infiltration appears at an average of 4 years [86]. Chronic massive rotator cuff tears in rats resulted in a 30% reduction in supraspinatus muscle force and a 35% reduction in infraspinatus muscle force compared with the uninjured side [91]. Histological evidence confirms degeneration and fatty replacement of muscle tissue in chronically torn rotator cuff muscles [92]. Muscle shortening negatively impacts shoulder function, highlighting implications for surgical repair strategies and postoperative recovery [14].

Stiffness and Functional Limitations¶

Metformin reduces the incidence of shoulder stiffness after arthroscopic rotator cuff repair, with an absolute risk reduction of 12% to 16% at 6 months and 1 year, though it does not significantly improve long-term functional scores [160]. Common complications associated with arthroscopic rotator cuff repair include retear, failure to heal, stiffness, failure to recognize concomitant pathology, and infection [70].

Concomitant Pathology and Diagnostic Challenges¶

About one-third of patients with full-thickness reparable rotator cuff tears are likely to have long head of biceps tendon pathology [68].

Revision and Salvage Procedure Complications¶

Female patients with poor shoulder function and generalized muscle weakness prior to surgery have a greater likelihood of a poor clinical result after latissimus dorsi tendon transfer [20]. Over 63% of patients undergoing latissimus dorsi transfer for previously failed rotator cuff repairs reported undergoing 2 or more prior failed rotator cuff repairs [167].

Recovery¶

Long-term Outcomes of Repair: Arthroscopic rotator cuff repair (ARCR) is an effective and safe option for treating rotator cuff tear symptoms, providing successful clinical results that remain durable over time [13]. In patients aged 70 years or older with symptomatic full-thickness tears, clinical and structural outcomes are comparable to those in patients younger than 70, with data supporting this at least through 1-year follow-up [9]. For massive tears with short tendon length, patch augmented cuff repair yields significant improvements in both functional and structural outcomes [80]. Revision rotator cuff reconstruction also improves clinical outcomes and shoulder function at midterm follow-up [79].

Structural Healing and Re-tear: The degree of tendinopathy does not correlate with the morphological appearance of the tendon, patient outcome, or rotator cuff healing [200].

Muscle Degeneration and Atrophy: In a mouse model, significant atrophy and fatty infiltration of the supraspinatus and infraspinatus muscles occurred following delayed rotator cuff repair [17]. Conversely, a rabbit experimental study found that the delay before reattaching the tendon did not lead to an increase in muscle atrophy [199]. Although muscular condition predicts patient prognosis, quantitative evaluation of the rotator cuff muscles is not well established [11].

Functional Outcomes and Prognostic Factors: Concurrent procedures performed at the time of supraspinatus repair do not change functional outcomes [202].

Biomechanics and Kinematics: During high-velocity shoulder motions, the infraspinatus/teres minor was less involved than the subscapularis [1]. The subscapularis muscle exhibits a gradual formation of the musculotendinous junction and inserts into the humerus as both tendon and muscle [45].

Key Evidence¶

[L4] These results indicated that the infraspinatus/teres minor was less involved than the subscapularis during these high velocity shoulder motions. [1] (10.1016/s1058-2746(95)80189-8)
[L4] Patients who had repair of a massive posterosuperior rotator cuff tear maintained considerable improvements in clinical and radiographic outcomes at 10 years. [2] (10.2106/jbjs.17.01190)
[L1] Rotator cuff reconstruction with a dermal allograft demonstrated favorable structural healing rates and improved range of motion compared to maximal repair in the short term. [3] (10.1016/j.arthro.2019.11.030)
[L2] Subjective mechanical symptoms in the affected shoulder are a common complaint in patients with suspected rotator cuff pathology. [4] (10.1016/j.jse.2024.02.024)
[Case_report] Deltoid complications combined with rotator cuff pathology represent a rare but devastating complication with no well-described surgical option. [5] (10.1016/j.jse.2011.09.023)
[L3] Repair of a large or massive tear of the rotator cuff can have a satisfactory long-term outcome. [7] (10.2106/00004623-199907000-00012)
[L5] Fatty infiltration of the rotator cuff appears as early as 6 weeks after surgical detachment, starts near the musculotendinous junction, and progresses medially over time, worsening over the course of 1 year in the unrepaired rotator cuff. [8] (10.1016/j.arthro.2007.01.023)
[L3] The clinical and structural outcomes of ARCR in patients 70 or older with symptomatic full-thickness rotator cuff tear are comparable with those in patients younger than 70 with at least 1-year follow-up. [9] (10.1016/j.arthro.2018.02.047)
[Abstract] Although muscular condition predicts the prognosis of the patients, quantitative evaluation of the rotator cuff muscles is not well established. [11] (10.1016/j.jse.2016.11.032)
[L4] ARCR appears to be an effective and safe option to treat the symptoms of rotator cuff tears and to provide successful clinical results durable with time. [13] (10.1007/s00167-014-3234-8)
[L3] This suggests that muscle shortening negatively impacts shoulder function and highlights potential implications for surgical repair strategies and postoperative recovery. [14] (10.1016/j.jse.2025.03.002)
[L2] Muscle atrophy and fatty infiltration of the rotator cuff muscles, particularly of the infraspinatus, play a significant role in determining functional outcome after cuff repair. [15] (10.1177/0363546506297539)
[L3] Measures of rotator cuff tear size showed stronger associations with re-tear six months post-surgery than measures of tissue quality and concomitant shoulder pathology. [16] (10.1016/j.jse.2013.07.021)
[L5] [17] (10.1177/0363546518793403)
[L2] There was no influence of the rotator cuff fatty infiltration and muscle atrophy on the functional outcome after total shoulder arthroplasty. [18] (10.1016/j.jse.2017.12.021)
[L4] Arthroscopic-assisted latissimus dorsi tendon transfer provides satisfactory functional outcomes for irreparable massive rotator cuff tears. [19] (10.1016/j.jse.2015.08.043)
[L4] Female patients with poor shoulder function and generalized muscle weakness prior to surgery have a greater likelihood of having a poor clinical result. [20] (10.2106/jbjs.f.01160)
[L4] Fatty infiltration of the rotator cuff muscles is closely related to patient age, the extent of the tendon rupture, and the time to onset. [23] (10.1016/j.otsr.2009.05.001)
[L5] Emerging evidence suggests that isolated SLAP repairs are not always benign, with 1 in 10 people needing additional surgery within 3 years, often for disorders of the rotator cuff, biceps, and distal clavicle. [24] (10.1016/j.arthro.2016.07.004)
[L5] The article highlights the need for better, well-designed studies truly comparing the outcomes for each of the treatment options used for massive rotator cuff tears, as current evidence is based on low levels of evidence. [25] (10.1016/j.arthro.2017.01.007)
[L3] Despite good healing rates, not all patients with healed rotator cuffs experience good outcomes. [26] (10.1016/j.jse.2021.03.112)
[L4] Recovery of fatty infiltration and muscle atrophy would rarely occur with current rotator cuff repairs, suggesting further studies and advances in repair strategy are necessary. [27] (10.5397/cise.2019.22.2.59)
[L4] The repair of massive rotator cuff tears by a deltoid transfer produces acceptable clinical and radiological results. [28] (10.1007/s00167-005-0697-7)
[L5] Treatment of massive rotator cuff tears has evolved from conservative management to advanced surgical techniques including arthroscopic repair, muscle transfers, and reversed arthroplasty. [29] (10.1007/s00167-014-3470-y)
[L4] Pathologic conditions located in the supraspinatus tendon are very common and related to age and not to clinical status. [34] (10.1016/s1058-2746(99)90090-3)
[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. [35] (10.1016/j.arthro.2017.09.005)
[L3] Patients with painful shoulders, irrespective of having type 2 diabetes mellitus, seem to have abnormal shoulder muscles. [36] (10.1186/s12891-022-05627-9)
[L2] MRI, but not radiography, can be used to help discriminate between traumatic and nontraumatic rotator cuff lesions. [38] (10.1016/j.jse.2015.06.005)
[L3] MR imaging–derived RC muscle PDFF is associated with isometric strength independent of muscle atrophy and tendon rupture in shoulders with early and advanced degenerative changes. [40] (10.1177/0363546517703086)
[L3] [41] (10.1016/j.jse.2019.03.010)
[L1] Caution should be taken when deciding to inject a patient, and this treatment should be withheld if a rotator cuff repair is to be performed within the following 6 months. [42] (10.1016/j.arthro.2019.12.006)
[L5] Studies of high level of evidence and long-term follow-up are needed to explore the most suitable conditions for each LHB reuse method and the best method for each specific rotator cuff tear condition. [43] (10.1016/j.arthro.2024.09.019)
[L4] The degree of fatty infiltration, muscle atrophy and tendinopathy of the rotator cuff muscle on preoperative magnetic resonance imaging scanning is not associated with functional outcome score or functional movement at medium-term follow-up following total shoulder replacement. [44] (10.1177/1758573218811655)
[L5] The subscapularis muscle had a gradual formation of the musculotendinous junction and, in contrast to classical descriptions, inserted into the humerus as both tendon and muscle. [45] (10.1016/s1058-2746(09)80039-6)
[L4] Twenty-six different criteria described by multiple classification systems have been identified for the magnetic resonance assessment of rotator cuff after repair. [46] (10.1007/s00167-014-3486-3)
[L4] [52] (10.1007/s00167-017-4608-5)
[L5] None of the special tests for shoulder examination are absolutely diagnostic for any one pathologic entity, and many are poorly specific or unreliable if not performed precisely. [53] (10.1177/03635465030310011101)
[L4] [55] (10.1016/j.arthro.2019.01.034)
[L5] In massive rotator cuff tear, the pectoralis major and latissimus dorsi muscles are effective in improving glenohumeral kinematics and reducing acromiohumeral pressures. [56] (10.1016/j.jse.2013.11.030)
[L4] Chronic rotator cuff tendon tears and suprascapular neuropathy are both associated with fatty infiltration and muscle atrophy of the rotator cuff muscles, but the pattern of fatty infiltration is markedly different in the two situations. [65] (10.1016/j.jse.2013.01.028)
[L3] Magnetic resonance imaging is useful for the evaluation of patients who have pain and loss of function after a repair of the rotator cuff, particularly for identifying full-thickness tears, intact cuffs, ruptures of the biceps tendon, and detachments of the origin of the deltoid muscle, though it is less effective for partial-thickness tears. [66] (10.2106/00004623-199609000-00015)
[L4] About one-third of patients with full-thickness reparable rotator cuff tears are likely to have LHBT pathology. [68] (10.1016/j.arthro.2017.06.018)
[L5] This review outlines common complications associated with arthroscopic rotator cuff repair, including retear, failure to heal, stiffness, failure to recognize concomitant pathology, and infection. [70] (10.1016/j.csm.2017.12.013)
[L2] The physical therapy program was highly effective in alleviating patient symptoms despite the fact that patients continued to have tears of the rotator cuff. [71] (10.1016/j.jse.2016.04.030)
[L4] Increased age and longer duration of follow-up were associated with lower healing rates after double-row rotator cuff repair. [72] (10.1177/0363546510382835)
[L5] Ultrasound elastography, particularly shear wave elastography, is a promising tool for evaluating mechanical properties of musculoskeletal tissue in the shoulder, showing potential for detecting and monitoring pathologic processes such as fatty degeneration and tendon tears, though further research is needed to standardize techniques and clinical application. [73] (10.1016/j.jse.2017.08.001)
[L3] Shoulder strength deficits measured via isokinetic testing and shoulder function were weakly correlated in patients with rotator cuff tears overall. [74] (10.1016/j.jse.2019.03.015)
[L5] The commentary concludes that a recent case series makes the case that clinicians have been missing a significant number of rotator cuff tears by not routinely ordering MRI on patients with spontaneous proximal biceps tendon ruptures, while noting the need for further data on whether these findings change treatment. [76] (10.1016/j.arthro.2018.01.044)
[L5] This study provides evidence for the effective utilization of artificial intelligence advancements in the automated classification of fatty infiltration of rotator cuff muscles on MRI using in-domain transfer learning, feature fusion, and machine learning classifiers. [78] (10.1016/j.jseint.2025.06.020)
[L4] Revision RCR improves clinical outcomes and shoulder function at midterm follow-up. [79] (10.1177/0363546518786006)
[L4] Patch augmented cuff repair leads to a significant improvement of functional and structural outcomes. [80] (10.1016/j.jse.2023.03.037)
[L5] Rotator cuff repair increases deltoid force requirements and joint load, particularly when combined with glenosphere lateralization, suggesting the rotator cuff muscles act as antagonists after reverse total shoulder arthroplasty. [81] (10.1016/j.jse.2016.02.028)
[L3] Microscopic muscle atrophy appeared to negatively correlate with the movement of abduction leading to functional impairment, while shoulder pain did not show any relationship with microscopic changes. [82] (10.1186/s12891-023-06237-9)
[L4] Following a five months exercise protocol patients with irreparable rotator cuff tears showed increased function in their symptomatic shoulder, reduced pain and increased quality of life. [83] (10.1186/s12891-016-1116-6)
[L4] Augmentation strategies may improve outcomes in rotator cuff repairs, particularly in high-risk cases; however, there is a lack of consensus among surgeons on the most effective strategies for each scenario. [84] (10.2106/jbjs.rvw.25.00007)
[L4] [86] (10.1016/j.jse.2009.12.002)
[L5] [87] (10.1016/j.otsr.2023.103723)
[L4] [89] (10.1016/j.csm.2012.07.008)
[L3] [90] (10.1177/0363546518758313)
[L5] Chronic massive rotator cuff tears in rats resulted in a 30% and 35% reduction in muscle force of the supraspinatus and infraspinatus muscles, respectively, compared with the uninjured side. [91] (10.1016/j.jse.2014.04.016)
[L4] The study provides histological evidence for degeneration and fatty replacement of muscle tissue in chronically torn rotator cuff muscles. [92] (10.1016/j.jse.2016.07.070)
[L4] Using these data a clear relationship between shoulder volume and the torques they produce was established in all three rotational degrees-of-freedom. [97] (10.1016/j.jbiomech.2014.04.049)
[L4] The supraspinatus and deltoid muscles are equally responsible for producing torque about the shoulder joint in the functional planes of motion. [101] (10.2106/00004623-198668030-00013)
[L4] Human throwing capabilities largely result from several derived anatomical features that enable elastic energy storage and release at the shoulder. [104] (10.1038/nature12267)
[L5] A larger contribution of force from the supraspinatus was required near the beginning of motion, whereas the middle deltoid was more important near the end of glenohumeral abduction in the scapular plane. [105] (10.1016/s1058-2746(05)80052-7)
[L5] The supraspinatus has a greater mechanical advantage versus the other tested muscles in the neutral arm position. [108] (10.1016/j.jse.2008.10.021)
[L5] The elevation moment arms were larger, making the muscles more efficient, in the coronal plane than in the scapular or sagittal planes. [111] (10.1016/s1058-2746(97)70049-1)
[Paper] The results showed that the subscapularis and pectoralis major were substantial actuators for shoulder internal rotation. [123] (10.1067/mse.2000.105135)
[L4] LDTT is an effective treatment for massive, irreparable posterosuperior rotator cuff tears and leads to substantial clinical improvement. [126] (10.1016/j.jse.2007.02.128)
[L5] The rotator cuff provided substantial anterior dynamic stability to the glenohumeral joint in the end-range of motion as well as in the mid-range. [129] (10.2106/00004623-200006000-00012)
[L4] The supraspinatus and middle deltoid are active in both rotations. [130] (10.1016/s1058-2746(95)80190-1)
[L4] Despite global tear extension, the single most important predictor for preserved shoulder function is the integrity of the inferior subscapularis insertion. [133] (10.1016/j.jse.2014.05.026)
[L5] Inhibition or stimulation of muscle inflammation may be a potential target to enhance the outcome of the repaired torn rotator cuff. [140] (10.1016/j.jse.2020.08.028)
[L5] Statin medication could potentially help improve outcomes for patients with rotator cuff tears, though further studies are necessary. [145] (10.1016/j.jse.2014.06.048)
[L5] This study demonstrates the importance of the rotator cuff in actively stabilizing the humeral head against superior ascent. [147] (10.1016/s1058-2746(96)80475-7)
[L4] Ten years following rotator cuff tear repair, between 68 and 81% of tendons had healed, with tears having posterior extension showing a higher risk of retear. [154] (10.1007/s00167-018-4854-1)
[L4] The arthroscopic transtendon repair of partial articular-sided rotator cuff tears is an effective procedure that leads to significant improvement in pain and shoulder function, with high patients' satisfaction rate, while the complication rate is low. [155] (10.1007/s00167-015-3953-5)
[L3] This study established a correlation between improved structural integrity of the repaired cuff tendon and enhanced structural outcomes in rotator cuff muscles. [156] (10.1177/03635465241255944)
[L1] Metformin reduces the incidence of shoulder stiffness after arthroscopic rotator cuff repair, with an absolute risk reduction of 12% to 16% at 6 months and 1 year, though it does not significantly improve long-term functional scores. [160] (10.1177/03635465251380296)
[L5] A multicenter, prospective, observational cohort study is required to confirm or refute findings regarding statin dosing and rotator cuff repair outcomes, as current retrospective data are insufficient to change clinical practice. [165] (10.1016/j.arthro.2025.01.019)
[L4] [167] (10.1016/j.arthro.2019.07.034)
[L3] [169] (10.1186/s13018-025-05832-x)
[Paper] [172] (10.1002/jor.25321)
[L3] MRI findings of tendon retraction to or beyond the glenoid, increased inferior glenohumeral distance, and a positive tangent sign are associated with irreparability of large and massive rotator cuff tears. [177] (10.1007/s00167-013-2745-z)
[L4] [178] (10.1016/j.jse.2007.02.122)
[L5] In nonretracted cuff tears, fibrous tissue bound the tendon-to-bone junction with healing. [183] (10.1016/j.arthro.2021.06.025)
[L4] This research provides evidence for the effective utilisation of artificial intelligence advancements for the automated measurement of the fatty infiltration of the RC muscles using shoulder MRI images. [185] (10.1016/j.jisako.2025.100815)
[L4] Otsu's thresholding method offers a reliable, objective, and efficient approach for quantifying fatty change in rotator cuff muscles, outperforming the Goutallier classification in terms of inter-rater reliability. [186] (10.1016/j.jse.2025.04.026)
[Paper] The modified 5-stage CT classification of Goutallier et al is a useful method for the evaluation of experimentally induced rabbit supraspinatus and infraspinatus fatty degeneration. [188] (10.1067/mse.2000.105134)
[L4] [189] (10.1016/j.jse.2025.03.040)
[Letter] [190] (10.1016/j.jse.2007.06.003)
[L3] Supraspinatus muscle atrophy appreciated on MRI is independently associated with patient age, tendon retraction, and atrophy of the supraspinatus myofibers at the histologic level. [191] (10.1177/03635465231173697)
[L4] Arthroscopic rotator cuff repair of massive rotator cuff tears with advanced mobilization techniques can lead to reversal of preoperative pseudoparalysis in 90% of patients who have not had previous surgery. [192] (10.1016/j.arthro.2012.02.026)
[L4] All patients with cuff tear arthropathy have a significantly superior position of the humerus compared to the control group. [194] (10.1016/j.jseint.2023.11.005)
[L4] Increased infraspinatus fatty infiltration was correlated with the severity of an infraspinatus tear, but substantial fatty infiltration was also seen in the absence of a tear and correlated with worsening severity of a concomitant supraspinatus tear and atrophy. [196] (10.1016/j.arthro.2010.09.014)
[Abstract] Deep learning-based image segmentation provides a rapid, tireless and reliable automatic quantification of RC muscle atrophy, fatty infiltration, and overall muscle degeneration in patients undergoing preoperative CT planning prior to anatomic or reverse shoulder arthroplasty, with a higher reliability and similar accuracy compared with human observers. [197] (10.1016/j.jse.2022.01.030)
[Paper] On the other hand, the delay before reattaching the tendon did not lead to an increase in muscle atrophy. [199] (10.1016/s0736-0266(02)00208-5)
[L3] The degree of tendinopathy did not correlate with morphological appearance of the tendon, patient outcome, or rotator cuff healing. [200] (10.1177/0363546517746986)
[L4] Concurrent procedures performed at the time of supraspinatus repair do not change functional outcomes. [202] (10.1016/j.arthro.2016.01.027)

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