कंधे पर क्लिक, पॉपिंग और अस्थिरता

This is the clinical evidence summary written for health professionals. It is technical, and it lists the research this page was built from. You do not need to read it to understand your treatment or to make a decision about it.

Overview¶

Epidemiology and Presentation¶

• Multidirectional instability (MDI) has variable presentations and is difficult to quantify [11].
• MDI is characterized by inferior laxity in addition to anterior and/or posterior laxity [11].
• Symptoms of MDI include pain, weakness, ipsilateral paresthesias, popping or clicking of the shoulder, instability of the shoulder during sleep, difficulty with throwing, and pain when carrying heavy objects [11].
• Differential diagnoses for MDI include unidirectional shoulder instability, cervical disease, brachial plexitis, and thoracic outlet syndrome [11].

Pathoanatomy¶

• A patulous inferior capsule containing both the anterior and posterior bands of the inferior glenohumeral ligament is a commonly associated anatomic lesion in MDI [11].
• Functional deficiency of the rotator interval is a commonly associated anatomic lesion in MDI [11].
• Labral tearing may occur with repeated subluxations or a traumatic event in MDI [11].

Evaluation¶

• Assessment for generalized ligamentous laxity using Beighton criteria is part of the physical examination for MDI [11].
• A positive sulcus sign assesses the competency of the rotator interval in MDI [11].
• Rotator cuff tendinitis in an individual younger than 20 years should raise concern for MDI [11].

Non-Operative Management¶

• All patients with MDI should undergo extensive physical therapy for 6 to 9 months prior to consideration of surgical treatment [11].
• Physical therapy for MDI should focus on rotator cuff strengthening, scapular kinematics, and proprioceptive training [11].

Operative Management¶

• Surgery is appropriate for patients with MDI who have pain and instability interfering with normal or sport-related activity and have failed extensive nonsurgical treatment [11].
• Approximately 20% of patients with MDI fail nonsurgical management [11].
• Surgery is contraindicated for voluntary dislocators and patients who have not attempted physical therapy for MDI [11].
• Arthroscopic pancapsular plication with or without rotator interval closure is a surgical technique for MDI [11].
• If labral pathology is encountered during MDI surgery, anterior or posterior labral repair is indicated [11].
• Capsulorrhaphy for MDI should address inferior redundancy in a balanced fashion to avoid asymmetric tightening [11].
• Open anterior-inferior capsular shift is a surgical technique for MDI [11].
• Accurate identification of the mechanism of instability is essential for guiding management of dislocated reverse total shoulder arthroplasty [1].
• Outcomes for dislocated reverse total shoulder arthroplasty remain variable and recurrent instability continues to be a major challenge [1].
• Retroglenoid osteotomy with capsular shift for posterior shoulder instability resulted in clinical improvements in all patients, complete resolution of instability symptoms, and radiological correction of glenoid retroversion [2].
• At 2 years, 19.1% of patients with 270-360 degree panlabral tears experienced instability and 7.9% underwent reoperation for instability or dislocation [3].
• Open capsular shift with Achilles allograft augmentation for multidirectional shoulder instability demonstrated low rates of recurrent instability and improved clinical outcomes in patients with Ehlers-Danlos Syndrome [4].
• The arthroscopic Trillat procedure resulted in a stable and functional shoulder and patient satisfaction in 96% (20/21) of patients with recurrent anterior instability associated with massive irreparable cuff, with no patient losing active shoulder motion [5].
• The indications for an isolated soft-tissue procedure in anterior shoulder instability are narrower, with the ideal candidate presenting with minimal glenoid bone loss of 13.5% [6].
• Single-portal arthroscopic posterior capsulorrhaphy offers an efficient, reproducible procedure to address posterior shoulder instability pathology [9].
• Patients should be counseled pre-operatively on the expected outcomes over time following arthroscopic Bankart repair for anterior shoulder instability [10].
• The Bristow-Latarjet procedure was associated with significantly higher rates of full return to sport than Bankart repairs in anterior shoulder instability [17].
• The arthroscopic subscapular sling procedure is proposed as an alternative to existing surgical treatment options for recurrent anterior shoulder instability [19].
• Anterior labral reconstruction with biceps autograft for anterior shoulder instability has been performed in a small number of patients, and data are inadequate to report on clinical results and recurrent instability risk [21].
• The "pinch-and-tuck" arthroscopic technique is an alternative technique for capsular plication that effectively and safely addresses capsular laxity in patients with posterior shoulder instability [95].

Complications¶

• Recurrence of MDI occurs in 7% of cases for both open and arthroscopic techniques [11].
• Axillary nerve injury is a complication of MDI surgery [11].
• Stiffness is a rare complication of MDI surgery [11].
• Subscapularis insufficiency is a complication after open procedures for MDI [11].

Anatomy & Pathophysiology¶

Bony Anatomy¶

• The glenoid cavity is a shallow socket, approximately one third the size of the humeral head [46].
• The subchondral bone of the glenoid is relatively flat, with articular concavity augmented by cartilage and a circumferential labrum [47].
• The glenoid averages 5° of retroversion in relation to the axis of the scapular body [47].
• The humeral head averages 19° of retroversion and 41° of inclination (neck-shaft angle) [47].
• The articular head of the humerus is spherical with a diameter of 37 to 57 mm [45].
• The most superior portion of the articular surface of the humeral head averages 8 mm above the greater tuberosity [45].
• Humeral version averages 29.8 degrees, with a range of 10 to 55 degrees [45].
• The humeral head is inclined approximately 130 degrees with respect to the humeral shaft [45].
• The neck-shaft angle measures an average of 135 degrees [46].
• The humeral head is retroverted an average of 30 degrees [46].
• The glenoid is a convex structure of shallow depth shaped like an inverted pear [45].
• The acromion, the coracoacromial ligament, and the coracoid process form the coracoacromial arch, a rigid bony-ligamentous structure that imparts stability to the shoulder girdle [45].
• The superior shoulder suspensory complex (SSSC) is composed of the glenoid, the coracoid process, the coracoclavicular ligaments, the distal clavicle, the AC joint, and the acromion [47].
• The SSSC provides a stable connection between the scapula and the axial skeleton [47].
• The superior strut of the SSSC comprises the middle clavicle, and the inferior strut comprises the lateral scapular border/spine of the scapula [47].
• The clavicle is the first bone to ossify (fifth week of gestation) and is the only long bone to ossify by intramembranous ossification [47].
• The medial (sternal) epiphysis of the clavicle is the last ossification center to fuse, at age 20 to 25 years [47].
• The primary blood supply to the clavicle is periosteal, with no nutrient artery present [47].
• The scapula has only one true diarthrodial articulation, the acromioclavicular (AC) joint [47].
• Normal shoulder motion is approximately two-thirds glenohumeral and one third scapulothoracic [47].
• Ossification of the scapular body begins at the eighth week of gestation [47].
• The acromion has three ossification centers: the metacromion (base), the mesoacromion (middle), and the preacromion (tip) [47].
• Failure of fusion of the acromial ossification centers results in os acromiale [47].
• The coracobrachialis muscle and the short head of the biceps tendon originate from the coracoid process [47].
• The pectoralis minor muscle inserts onto the medial coracoid process [47].
• The proximal humerus has three centers of ossification: the humeral head (4 to 6 months), the greater tuberosity (1 to 3 years), and the lesser tuberosity (3 to 5 years) [47].
• The ossification centers of the proximal humerus fuse to the shaft at age 17 to 20 years [47].
• The greater and lesser tuberosities serve as attachment sites for the rotator cuff tendons [47].
• The anterolateral ascending branch of the anterior humeral circumflex artery provides the primary blood supply to the humeral head [47].
• The terminal intraosseous portion of the anterior humeral circumflex artery enters at the proximal aspect of the intertubercular groove as the arcuate artery [47].
• The bicipital groove lies between the greater and lesser tuberosities and serves as a pathway for the long head of the biceps [45].
• The distal aspect of the bicipital groove is internally rotated with respect to the proximal portion [45].
• The anatomic neck of the proximal humerus is located at the junction of the articular surface and the tuberosities [45].
• The surgical neck represents an indistinct region (metadiaphyseal junction) below the tuberosities but above the humeral shaft [45].
• Fractures involving the anatomic neck are prognostically worse than fractures involving other regions of the proximal humerus regarding potential disruption of vascular supply and development of avascular necrosis [45].
• The greater tuberosity is located in a posterior-superior location with respect to the humeral shaft and serves as the attachment site for the supraspinatus, infraspinatus, and teres minor tendons [45].
• The lesser tuberosity is located on the anterior aspect of the proximal humerus and serves as the attachment site for the subscapularis tendon [45].
• The proximal humerus receives its blood supply from the anterior and posterior humeral circumflex branches from the third division of the axillary artery [45].
• The posterior humeral circumflex artery travels with the axillary nerve, enters the quadrilateral space posteriorly, and anastomoses with a branch of the anterior circumflex to supply the posterior cuff [45].
• The anterior humeral circumflex artery arises from the axillary artery at the inferior border of the subscapularis and provides vascular inflow to the humeral head via its terminal anterolateral branch, the artery of Laing (arcuate artery) [45].
• The ascending branch of the anterior humeral circumflex artery courses parallel to the lateral aspect of the long head biceps tendon and enters the humeral head at the interface of the bicipital groove and greater tuberosity [45].
• Injury to the arcuate artery may result in osteonecrosis of the humeral head [45].
• Additional extraosseous collateral branches can permit humeral head perfusion despite complete ligation of the arcuate artery [45].
• The sternoclavicular (SC) joint is the only true diarthrodial articulation between the upper appendicular and axial skeletons [47].
• The posterior SC joint capsule and ligaments are the primary stabilizers to anterior and posterior translation of the medial clavicle [47].
• The AC joint is a small diarthrodial joint with an interposed fibrocartilaginous disk [47].
• The superior and posterior AC ligaments are the primary stabilizers to anterior and posterior (horizontal) translation of the clavicle [47].
• The coracoclavicular ligaments (conoid: medial; trapezoid: lateral) are the primary stabilizers to superior (vertical) translation of the distal clavicle [47].

Ligaments and Soft Tissue Stabilizers¶

• Dynamic stabilizers of the glenohumeral joint include the rotator cuff, which stabilizes the joint via joint compression [47].
• Positioning of the scapulothoracic joint contributes to dynamic stability of the glenohumeral joint [47].
• Static stabilizers of the glenohumeral joint include articular congruity, the glenoid labrum, concavity-compression, negative intra-articular pressure, and the glenohumeral capsule and ligaments [47].
• The glenoid labrum provides concavity and up to 50% of marginal glenoid socket depth [47].
• The rotator interval is defined medially by the base of the coracoid, superiorly by the supraspinatus tendon, and inferiorly by the subscapularis tendon [47].
• The rotator interval contains the coracohumeral (CH) ligament, the superior glenohumeral ligament (SGHL), and the intra-articular portion of the long head of the biceps tendon [47].
• Laxity of the rotator interval results in inferior laxity (the sulcus sign) [47].
• Contracture of the rotator interval is seen with adhesive capsulitis [47].
• The CH ligament restricts external rotation in adduction and is a static restraint to inferior and posterior translation in adduction and external rotation [47].
• The SGHL is a primary static restraint against anterior translation with the arm at the side [47].
• With the CH ligament, the SGHL forms a pulley that provides restraint against medial subluxation of the long head of the biceps tendon [47].
• The middle glenohumeral ligament (MGHL) is a primary static restraint against anterior translation with the arm in external rotation and 45° of abduction [47].
• The anterior band of the inferior glenohumeral ligament (AB-IGHL) is a primary static restraint against anterior-inferior dislocation of the glenohumeral joint in 90° of abduction and external rotation (position of apprehension) [47].
• The posterior band of the IGHL (PB-IGHL) is a primary static restraint against posterior-inferior translation in internal rotation and adduction [47].
• The superior transverse scapular ligament arises from the medial base of the coracoid overlying the suprascapular notch [47].
• The suprascapular artery runs superior to the superior transverse scapular ligament, and the nerve runs deep to the ligament [47].
• Entrapment of the suprascapular nerve at the superior transverse scapular ligament causes denervation of both the supraspinatus and the infraspinatus [47].
• The spinoglenoid ligament overlies the suprascapular nerve at the spinoglenoid notch [47].
• Entrapment, traction, or compression of the suprascapular nerve at the spinoglenoid notch causes denervation of the infraspinatus [47].
• The subscapular bursa lies between the subscapularis tendon and the neck of the scapula and communicates with the joint cavity between the superior and middle glenohumeral ligaments [48].
• The subscapular bursa protects the tendon of the subscapularis at the point where it passes under the base of the coracoid process and over the neck of the scapula [48].
• The subscapular bursa is linked to the coracoid process by a suspensory ligament [48].
• In 28% of specimens dissected by Colas and colleagues, the subscapular bursae merged with the subcoracoid bursae, forming a unique wide bursa [48].
• The subscapular bursa often houses loose bodies in the shoulder and is a region where synovitis of the shoulder may be most intense [48].
• DePalma described six common variations or types of recesses in the anterior capsule, which are variations in the opening of the subscapularis bursa [48].
• Type 1 anterior capsule recess (30.2%) has one synovial recess above the middle glenohumeral ligament [48].
• Type 2 anterior capsule recess (2.0%) has one synovial recess below the middle glenohumeral ligament [48].
• Type 3 anterior capsule recess (40.6%) has one recess above and one below the middle glenohumeral ligament [48].
• Type 4 anterior capsule recess (9.0%) has one large recess above the inferior ligament, with the middle glenohumeral ligament being absent [48].
• Type 5 anterior capsule recess (5.1%) has the middle glenohumeral ligament manifested as two small synovial folds [48].
• Type 6 anterior capsule recess (11.4%) has no synovial recesses, although all the ligaments are well defined [48].
• DePalma believed that if the capsule arises at the labrum or glenoid border of the scapula, few, if any, recesses would be present [48].
• If the capsule begins farther medially on the scapula or glenoid neck, the synovial recesses are larger and more numerous [48].
• DePalma believed that the end result of such recesses was a thin, weakened anterior capsule that could predispose the shoulder to instability [48].
• The rotator interval is defined as the region between the superior border of the subscapularis and the anterior border of the supraspinatus [48].
• The rotator interval includes the region of the superior glenohumeral ligament and coracohumeral ligament, in addition to the middle glenohumeral ligament [48].
• Plancher and colleagues found the average area of the rotator interval to be 20.96 mm [48].
• Some authors believe that enlargement of the rotator interval can cause instability in certain shoulders and that it should be surgically obliterated during stabilization procedures [48].
• Dynamic testing has shown that the subscapularis and supraspinatus dimensions as well as the total area of the rotator interval decrease significantly with internal rotation and open with external rotation [48].
• Imbrication procedures are performed with the arm in a neutral position to avoid loss of motion or insufficient tightening [48].
• A soft tissue sheath consistently covers the long head of the biceps tendon to the level of the proximal margin of the pectoralis major tendon and contributes to the roof of the bicipital tunnel [48].
• The fibro-osseous bicipital tunnel consists of three distinct anatomic zones [48].
• Zone 1 of the bicipital tunnel represents the traditional bony bicipital groove beginning at the articular margin and ending at the distal margin of the subscapularis tendon [48].
• Zone 2 of the bicipital tunnel extends from the distal margin of the subscapularis tendon to the proximal margin of the pectoralis major tendon and represents a "no man's land" because it is not viewable from arthroscopy above or from subpectoral exposure below [48].
• Zone 3 of the bicipital tunnel is distal to the proximal margin of the pectoralis major tendon and represents the subpectoral region [48].
• The sheath overlying Zone 2 of the bicipital tunnel can be robust [48].

Muscles and Nerves¶

• The rotator cuff consists of four muscles: the subscapularis, supraspinatus, infraspinatus, and teres minor muscles [46].
• The teres major is not a rotator cuff muscle [46].
• The cuff muscles serve as depressors of the humeral head to allow the deltoid to efficiently abduct the humerus [46].
• The infraspinatus and teres minor are external rotators, while the subscapularis is an internal rotator of the humerus [46].
• The deltoid and pectoralis major muscles, along with the rotator cuff, cause predictable displacement of fractures around the proximal humerus [46].
• The subscapularis inserts on the lesser tuberosity and causes medial displacement of fracture fragments [45].
• The supraspinatus and infraspinatus insert on the greater tuberosity and cause superior and posterior displacement of fracture fragments [45].
• The pectoralis major inserts on the humeral shaft and displaces it medially [45].
• The axillary nerve is a terminal branch coming off the posterior cord of the brachial plexus just proximal to the coracoid process [50].
• The axillary nerve passes beneath the conjoined tendon anterior to the subscapularis 3 to 5 mm medial to the musculotendinous junction and then adjacent to the inferior capsule before entering the quadrilateral space posteriorly [50].
• The axillary nerve splits into the anterior and posterior branches within the quadrangular space [50].
• The anterior and middle deltoid muscle receives sole innervation from the anterior branch of the axillary nerve [50].
• Posterior deltoid muscle innervation varies, with supply only from the anterior branch in 2.3% of cases, from the posterior branch in 8.5%, and from both branches in 89.1% [50].
• The posterior branch of the axillary nerve branches to supply the teres minor muscle and then terminates as the superior lateral brachial cutaneous nerve [50].
• In the anterior deltopectoral approach, the axillary nerve can be palpated by sweeping a finger inferiorly across the subscapularis muscle tendon interface [50].
• Nerve location can be confirmed by feeling the nerve with humeral internal rotation [50].
• Prior to transecting the subscapularis tendon, the nerve may be relaxed and the tendon pulled away laterally by humeral external rotation [50].
• The anterior motor branch of the axillary nerve emerges posterior to anterior on the deltoid undersurface with the accompanied posterior humeral circumflex artery [50].
• Flatow et al. described a "tug test" that helps confirm axillary nerve identity [50].
• In the anterolateral deltoid splitting approach, the axillary nerve crosses approximately 5 cm inferior to the anterolateral acromial corner [50].
• Burkhead et al. identified that 5 cm does not describe the absolute safe zone for axillary nerve passage and that shoulder abduction brings the nerve closer to the acromion landmark [5

Classification¶

• Posterior shoulder instability is categorized into first-time (Type A), dynamic (Type B), and static (Type C) [8].
• Type B posterior shoulder instability is further divided into functional (B1) and structural (B2) dynamic instability [8].
• The B1 subtype of posterior shoulder instability is characterized by pathological activation of the rotator cuff and periscapular muscles [8].
• The pectoralis major stabilizes the glenohumeral joint by resisting superior migration of the humeral head [8].
• The pectoralis major enhances scapulothoracic stabilization of the latissimus dorsi and deltoid muscles [8].
• Dysfunction of the pectoralis major may compromise glenohumeral stability [8].
• Existing literature primarily associates pectoralis major abnormalities with anterior or multidirectional shoulder instability [8].
• Historically, the absence of structural pathology on diagnostic imaging for dynamic-functional posterior instability led to the dismissal of the condition as attention-seeking or psychiatric behavior [8].
• Surgical stabilization is generally not recommended for dynamic-functional instability due to poor outcomes [8].
• The current gold standard for dynamic-functional instability focuses on normalizing pathological muscle activation patterns [8].
• Antero-inferior glenohumeral instability is associated with an abnormal position of the coracoid process [24].
• Coracoid morphology differs significantly in patients undergoing posterior shoulder stabilization compared to patients undergoing surgery for anterior instability or a comparison cohort [84].
• Current classification systems exhibit poor reliability in categorizing glenoid defects post-reverse shoulder arthroplasty removal [82].
• The Walch Classification is used to assess osteoarthritis grade at the time of conversion to shoulder arthroplasty following anterior shoulder instability surgery [87].
• Among patients requiring shoulder arthroplasty after anterior instability surgery, 55.1% exhibited A1-type osteoarthritis according to the Walch Classification [87].
• Among patients requiring shoulder arthroplasty after anterior instability surgery, 18.4% exhibited A2-type osteoarthritis according to the Walch Classification [87].
• Among patients requiring shoulder arthroplasty after anterior instability surgery, 16.3% exhibited B1-type osteoarthritis according to the Walch Classification [87].
• Among patients requiring shoulder arthroplasty after anterior instability surgery, 10% exhibited B2-type osteoarthritis according to the Walch Classification [87].

Clinical Presentation¶

History and Symptoms¶

• Multidirectional instability (MDI) symptoms include pain, weakness, ipsilateral paresthesias, popping or clicking of the shoulder, instability during sleep, difficulty with throwing, and pain when carrying heavy objects [11].
• The history for shoulder instability should define the mechanism of injury, including the position of the arm, the amount of force applied, and the point of force application [65].
• Injury with the arm in extension, abduction, and external rotation favors anterior dislocation [65].
• Electoshock, seizures, or a fall on the flexed and adducted arm are commonly associated with posterior dislocation [65].
• For recurrent instability, the history should define the initial injury, the position or action that results in instability, how long the shoulder stays out, whether radiographs are available with the shoulder out of joint, and what means have been necessary to reduce the shoulder [65].
• The history should solicit evidence of neurologic or rotator cuff problems after previous episodes of shoulder instability [65].
• Previous treatment of recurrent instability and the effectiveness of that treatment should be documented in the history [65].
• The evaluation of a patient suspected of having a bony Bankart lesion begins with a comprehensive history including the mechanism of injury, direction of force applied, direction of perceived instability, history of previous dislocations, whether manual reduction has ever been required, and any history of surgery for shoulder instability [14].
• In throwers, a detailed history with the chronology of symptoms is essential because athletes often describe only vague discomfort associated with throwing and a decrease in performance [75].
• Pitchers commonly complain of loss of pitch control and loss of velocity and describe symptoms distant from the shoulder joint [75].
• Swimmers often complain of pain during the catch or the recovery, when the shoulder is more often in the provocative impingement position [75].
• The history often suggests the direction of instability, with symptoms elicited with the arm in adduction and internal rotation suggesting posterior instability and symptoms reproduced by holding objects with the arms at the sides indicating inferior instability [75].
• The location of pain or instability, its duration, and response to prior treatment should be noted for all athletes [75].
• Unstable painful shoulder (UPS) is characterized by pain as the chief symptom, with no awareness of dislocation or subluxation but presenting imaging or arthroscopic findings indicative of anterior shoulder instability [33].
• Young athletes in collision sports often feel only pain without recognizing instability and continue to participate in sporting activities [33].
• Clinicians should maintain a high index of suspicion in young patients presenting with traumatic shoulder pain, even in the absence of perceived instability [32].
• The Western Ontario Shoulder Instability Index (WOSI) assesses physical symptoms including pain with overhead activities, aching or throbbing, weakness, fatigue, clicking/cracking/snapping, stiffness, neck discomfort, feeling of instability or looseness, compensation with other muscles, and loss of range of motion [15].
• The Western Ontario Rotator Cuff Index (WORC) assesses physical symptoms including sharp pain, constant nagging pain, weakness, stiffness, clicking/grinding/crunching, and neck discomfort [71].

Physical Examination¶

• An acutely dislocated shoulder is usually very painful, with muscles in spasm in an attempt to stabilize the joint [65].
• In anterior dislocation, the humeral head may be palpable anteriorly, and the posterior and lateral aspect of the shoulder shows a hollow beneath the acromion [65].
• The arm is held in slight abduction in anterior dislocation, and passive and active motions are limited by pain [65].
• Assessment of the neurovascular status of the upper extremity is an essential part of the physical examination of an anteriorly dislocated shoulder before reduction [65].
• Recognition of a posterior dislocation may be impaired by the lack of a striking deformity and by the fact that the shoulder is held in the traditional sling position of adduction and internal rotation [65].
• Classic features of a posterior dislocation include limited external rotation (often to <0 degrees) and limited elevation of the arm (often to <90 degrees) [65].
• Posterior dislocation presents with posterior prominence and rounding of the shoulder in comparison to the normal side, flattening of the anterior aspect of the shoulder, and prominence of the coracoid process on the dislocated side [65].
• Asymmetry of the shoulder contours can often best be visualized by viewing the shoulders from above while standing behind the patient [65].
• Motion is limited in posterior dislocation because the head of the humerus is fixed on the posterior glenoid rim by muscle forces, or the head might actually be impaled on the glenoid rim [65].
• Patients with old, unreduced posterior dislocations of the shoulder can have 30 to 40 degrees of glenohumeral abduction and some humeral rotation as a result of enlargement of the groove [65].
• Long-standing disuse of the muscles about the shoulder leads to atrophy, which accentuates the flattening of the anterior portion of the shoulder, the prominence of the coracoid, and the fullness of the posterior portion of the shoulder [65].
• Posterior dislocation may be misdiagnosed as a frozen shoulder for which vigorous therapy may be mistakenly instituted in an attempt to restore range of motion [65].
• The physical examination for multidirectional instability should assess for generalized ligamentous laxity using Beighton criteria [11].
• A positive sulcus sign assesses the competency of the rotator interval in the setting of multidirectional instability [11].
• Rotator cuff tendinitis in an individual younger than 20 years should raise concern for multidirectional instability [11].
• The physical examination for shoulder instability includes inspection for constitutional ligamentous laxity (e.g., Marshall test, Beighton score), neck range of motion and Spurling’s maneuver, shoulder range of motion and scapular symmetry, and strength testing of shoulder girdle muscles [77].
• Specific physical examination tests for shoulder instability include the lift-off and belly press tests, sulcus sign, anterior apprehension test, relocation test, load and shift (anterior and posterior), Jerk test, O’Brien’s active compression test, Hawkin’s and Neer’s impingement tests, and cross-body adduction [77].
• The patient should be draped appropriately to allow circumferential visualization of the sternoclavicular, acromioclavicular, glenohumeral, scapulothoracic, and scapular surface anatomy bilaterally [78].
• General inspection notes the patient’s general posture, any bone/soft-tissue deformity, incisions/scars, regions of swelling or erythema, muscle atrophy, and any asymmetry [78].
• The scapulae are examined bilaterally for resting attitude and winging/dyskinesia with movement of the shoulder through its range of motion [78].
• Palpation assesses anatomic landmarks for evidence of swelling, warmth, tenderness, deformity, crepitus, or instability [78].
• Palpation of the supraspinatus and infraspinatus fossae can reveal small amounts of atrophy that may not be obvious on inspection [78].
• Any crepitus with passive glenohumeral or scapulothoracic motion is noted during palpation [78].
• If palpation reveals pain, the examiner should clarify whether it reproduces the patient’s typical symptoms [78].
• The active range of motion of the shoulder is initially assessed with the patient in the upright position, observing forward elevation, abduction, external rotation (with the arm adducted), and internal rotation behind the back [78].
• To isolate glenohumeral motion, horizontal adduction and both internal and external rotation in 90° of abduction are measured with the patient in the supine position [78].
• Both shoulders are examined simultaneously, and differences in their rhythm and maximum range of motion are noted [78].
• Associated scapulothoracic motion is gauged with the patient standing, observing elevation, depression, protraction, and retraction [78].
• The passive range of motion of the glenohumeral joint is observed to note limitations or less commonly increased passive movements [78].
• Comparing any shoulder motion with that of the normal contralateral shoulder is advantageous [78].
• The supraspinatus muscle is evaluated with the empty can and champagne toast tests [78].
• The infraspinatus muscle is tested with the shoulder abducted 20° in the scapular plane and the elbow at 90° of flexion, with the patient attempting to externally rotate the arm from 45° of internal rotation against counterforce [78].
• A positive external rotation "lag" or "dropping" sign, where the arm spontaneously falls back by more than 10° of internal rotation, indicates insufficiency of the infraspinatus muscle [78].
• The teres minor muscle is isolated with the elbow flexed to 90° and the arm in 90° of external rotation and 90° of abduction [78].
• A positive "hornblower" sign, defined by spontaneous internal rotation of the shoulder when the patient is asked to maintain an abducted and externally rotated position against gravity, indicates teres minor insufficiency [78].
• The subscapularis muscle can be tested with the belly-press, lift-off, and bear-hug tests [78].
• The belly-press maneuver is performed with the patient’s hand pressing on the upper abdomen, with the elbow anterior to the wrist in the coronal plane [78].
• The lift-off test is performed with the shoulder rotated internally and the dorsum of the patient’s hand resting against the patient’s ipsilateral sacroiliac joint [78].
• The bear-hug test requires the patient to place the palm of the hand on the opposite shoulder, with the elbow anterior to the body, while maintaining an internal rotation force against external rotation by the examiner [78].
• Clinical examination for dynamic posterior shoulder instability should assess range of motion in multiple planes, documenting forward elevation, external and internal rotation, and abduction [81].
• Particular attention should be given to posterior subluxation or dislocation occurring during forward elevation, as this clinical sign is highly relevant for surgical indication [81].
• A thorough clinical exam is the most important factor when determining indication for shoulder instability surgery [18].
• The evaluation of the overhead athlete requires the close integration of history and physical examination findings while utilizing a systematic approach [75].
• Many of the traditional examination tests of the shoulder have not been validated or critically evaluated to a significant extent and should therefore be used only as an adjunct to a wider global assessment [75].
• A sport-specific approach should be used when evaluating the shoulder in an athlete [75].
• It can be helpful to observe the athlete in a situation specific to their sport, but often this is not practical for the clinician [75].
• Coaches and athletic trainers can provide invaluable insight into the athlete’s practice or performance-related complaints [75].
• A preseason examination is critical to document baseline shoulder stability, strength, and range of motion, which can be used as a reference when evaluating a mid-season injury [75].
• Instability often exists in overhead athletes, but they do not present with symptoms of frank subluxation or dislocation [75].
• The throwing phase in which the pain occurs gives direct clues to the underlying pathoanatomy [75].
• Pain during cocking is often a result of instability or internal impingement with a type II SLAP lesion [75].
• Pain during follow-through arises from rotator cuff or posterior capsular problems [75].
• In swimmers, instability is often the principal culprit, exacerbating symptoms of impingement [75].
• Determining the onset of symptoms is critical because traumatic and atraumatic instability are treated differently [75].
• An athlete who plays a contact or collision sport might report a specific incident (such as a dislocation) that initiated the symptoms [75].

Diagnostic Imaging and Assessment¶

• Magnetic resonance imaging (MRI) and magnetic resonance arthrography are recommended to rule out associated pathology such as labral injuries or rotator cuff tears in dynamic posterior shoulder instability [81].
• Computed tomography (CT) provides accurate quantification of glenoid version using standardized methods, including Friedman and Hoenecke techniques [81].
• Posterior subluxation of the humeral head can be quantified with the glenohumeral and scapulohumeral indices [81].
• Complementary radiographic parameters, such as posterior acromial coverage, sagittal tilt, and the cross-sectional area (CSA), should be assessed to determine morphological contributors to instability [81].
• Radiographs and MRI are used as adjuncts to diagnosis, to determine whether a patient is a candidate for arthroscopic stabilization, and for preoperative planning [77].
• MRI has proven to be useful in identifying capsulolabral avulsions (HAGL and reverse HAGL lesions) and rotator cuff pathology [77].
• Rotator cuff pathology is common in patients over 40 years old with glenohumeral dislocation and at times coexists with a Bankart lesion [77].
• Plain radiography is able to capture any substantial bone loss on the glenoid and humerus [77].
• Computed tomography (CT) allows for a more precise quantification of bone loss than plain radiography [77].
• Using CT, the best views to evaluate the glenoid are sagittal cuts and three-dimensional (3D) reconstructed en face glenoid views with humerus subtracted [77].
• The inferior two thirds of the glenoid forms a circle, and any bone loss is liable to result in circumferential asymmetry [77].
• A 1.5-mm osseous lesion corresponds to 5% glenoid bone loss [77].
• Glenoid bone loss greater than 18% to 25% of the glenoid surface area increases risk of failure of nonoperative and operative management that does not address the bone loss [77].
• Recent analysis of the combined effects of glenoid and humeral head bone loss in bipolar lesions suggests 18% bone loss as the threshold for concern [77].
• In a series of high-demand military personnel following arthroscopic Bankart repair, unacceptably low Western Ontario Shoulder Instability (WOSI) scores were observed when the anteroinferior glenoid bone loss was greater than 13.5% [77].
• An examination under anesthesia is critical to the success of arthroscopic stabilization and is more sensitive for determining both the degree and direction of instability [77].
• The pattern of instability can be determined during examination under anesthesia without being affected by patient apprehension or guarding [77].
• The axial load test or load-and-shift test is conducted during examination under anesthesia, and the translation is noted in the anterior, inferior, and posterior directions [77].
• Grading of humeral head translation reflects the degree of instability: Grade 1+ corresponds to translation to the edge of the glenoid, 2+ if the humeral head can be subluxated over the glenoid rim but reduces spontaneously, and 3+ if a frank dislocation does not reduce spontaneously [77].
• Diagnostic arthroscopy is critical for finalizing the surgical plan and includes evaluation of the glenoid labrum, capsular redundancy and tissue quality, size of the humeral Hill-Sachs defect, anterior-inferior bony defects of the glenoid, osteochondral loose bodies, and glenohumeral ligament detachment [77].
• Detachment or tearing of the glenoid labrum can confirm the presence and indicate the direction of the dominant instability vector [77].
• Arthroscopic inspection of the intra-articular and bursal surfaces of the rotator cuff should be performed, particularly in older patients who tend to have a high prevalence of concomitant rotator cuff pathology [77].
• Approximately 20% to 25% of patients with instability undergoing arthroscopy have associated loose bodies, rotator cuff tears, biceps tendon pathology, or SLAP lesions [77].
• These associated lesions, if unrecognized or untreated, may compromise the surgical outcome [77].
• Arthroscopic examination can clarify the diagnosis in ambiguous cases [77].
• The risk factors associated with treatment failure (recurrent instability or functional deficits) include age, gender, presence of osseous Bankart and/or large Hill-Sachs lesions, participation in competitive collision or forced overhead sports, hypermobility, time lapse between dislocation and reduction, and the number of instability episodes prior to operation [77].
• A failed arthroscopic stabilization procedure often starts with the failure to identify red flags in the patient’s history and physical examination that might preclude a successful arthroscopic repair [77].
• The UPS group had a significantly greater glenoid width and depth than the ASI and control groups [33].
• Automated 3D analysis methods may improve prognostic analysis of anterior shoulder instability and will facilitate measurement on MRI, which rarely includes the contralateral shoulder [34].

Investigations¶

Clinical Assessment and Diagnostic Principles¶

• A thorough clinical examination is the most important factor when determining the indication for shoulder instability surgery [18].
• The history and physical examination are paramount in the diagnosis of a stiff shoulder, with ancillary studies being helpful in certain circumstances [22].
• The purpose of imaging the shoulder 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 [23].
• Surgeons need to develop a judicious approach to imaging that yields necessary information while avoiding the tendency to "over-image" [54].
• Unless a specific research protocol is in place, the temptation to "overimage" should be resisted, obtaining only the scans or reconstructions necessary for patient care [23].

Plain Radiography¶

• Standardized plain films are almost always sufficient to garner the information needed for shoulder evaluation [23].
• Proper radiographic technique is as important as proper surgical technique to achieve the desired outcome [23].
• The first key radiographic view is the anteroposterior (AP) view in the plane of the scapula, taken so that the x-ray beam passes through the glenohumeral joint [23].
• The AP view shows the superoinferior position of the humeral head relative to the glenoid, presence of osteophytes, narrowing of the joint space, degree of medial displacement of the humerus, quality of bone, presence of loose bodies, and humeral head collapse or deformity [23].
• The second key radiographic view is the axillary view taken with the arm in the functional position of elevation in the plane of the scapula [23].
• The axillary view is referred to as the "truth view" because it demonstrates glenohumeral relationships in the functional position of elevation [23].
• CT scans have the disadvantage of being taken with the arm in the adducted position, unlike the functional axillary view [23].
• The standardized axillary view can show posterior subluxation or "functional decentering" that is not evident in images taken with the arm at the side [23].
• The degree of posterior subluxation can be measured by the position of the center of the humeral head in relation to the plane of the scapula, the position of the center of the humeral head in relation to the glenoid face, or the point of contact of the humeral articular surface on the glenoid articular surface [23].
• The point of contact of the humeral articular surface on the glenoid articular surface reflects the degree of centering of the net humeral joint reaction force on the glenoid [23].
• Malcentering of the joint reaction force leads to posterior instability, posterior glenoid wear, and "rocking horse" loosening of prosthetic glenoid components [23].
• Initially, all patients are usually asked to have AP and lateral plain radiographs of the shoulder related to their chief report [56].
• Plain radiographs are often the only required studies needed for assessing acute shoulder trauma, including fractures or dislocations [56].
• Arthritis, calcific tendinitis, and osteolysis of the distal clavicle can be observed on plain radiograph [56].

Computed Tomography (CT)¶

• CT imaging is frequently used to evaluate fractures of the shoulder, to assess for bony lesions in recurrent instability cases, or for preoperative templating for shoulder arthritis [56].
• Although CT scans may offer a few degrees of increased precision in the measurement of glenoid version, this precision does not necessarily improve the quality of the surgery or the clinical outcome [23].
• Three-dimensional reconstructions based on CT scans of the arthritic shoulder are currently discussed regarding whether they help surgeons achieve better outcomes compared to imaging consisting only of two standardized plain films [54].
• In the future, CT is expected to be superseded by MRI in anterior shoulder instability [91].

Magnetic Resonance Imaging (MRI) and Arthrography¶

• MRI is the modality of choice for evaluating the rotator cuff, biceps, and subacromial/subdeltoid bursa [56].
• T1-weighted MRI can reveal Hill-Sachs lesions and is often used with magnetic resonance (MR) arthrograms to provide a more detailed picture of the joint surfaces [56].
• T2-weighted MRI provides better visualization of full thickness rotator cuff tears [56].
• MR arthrography is considered the benchmark for evaluation for labral tears and rarely is indicated for evaluation of rotator cuff pathology [56].
• When MRI or MR arthrography is contraindicated, such as in patients with a pacemaker or vascular clips, CT arthrography is indicated [56].
• 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 [56].
• MRI augmented with a novel artificial intelligence system is superior to CT in shoulder instability [91].
• Automated 3D analysis methods for glenoid bone loss may improve prognostic analysis of anterior shoulder instability and facilitate measurement on MRI, which rarely includes the contralateral shoulder [34].
• Including the whole scapula on MRI, especially in advanced levels of tear retraction, may allow a more representative assessment [89].
• The study investigated whether unstable painful shoulder (UPS) and anterior instability (AI) are associated with differences in scapula morphology using magnetic resonance imaging (MRI) [97].

Ultrasonography¶

• Ultrasonography is a low-cost alternative to MRI and arthrography for evaluating both skeletal and soft-tissue structures of the shoulder [56].
• Ultrasonography can provide immediate, real-time visualization of the rotator cuff, biceps tendon, and calcific deposits [56].
• Ultrasonography can be used to measure the subacromial space and detect atrophy of rotator cuff muscles [56].
• As a result of providing images in real-time, ultrasonography can evaluate impingement in various positions and motions [56].
• 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 [56].

Treatment¶

Non-Operative Management¶

• All patients with multidirectional instability (MDI) should undergo extensive physical therapy for 6 to 9 months prior to consideration of surgical treatment [11].
• Nonsurgical treatment for posterior shoulder instability should always be attempted first [76].
• After a single traumatic posterior shoulder injury, the arm should be immobilized in neutral rotation with the elbow in adduction for 1 to 2 weeks, followed by therapy [76].
• NHL team physicians strongly favor nonoperative management in-season for initial posterior instability events of the shoulder [7].
• Surgery for MDI is contraindicated for voluntary dislocators and patients who have not attempted physical therapy [11].
• Surgery for posterior shoulder instability is contraindicated for voluntary dislocators [76].

Operative Management: Anterior Instability¶

• In recurrent instability of the shoulder, the Latarjet procedure leads to similar functional outcomes and failure rates in patients with or without hyperlaxity [20].
• Shoulder stabilization using the Latarjet procedure is effective in patients over 50 years old without associated cuff damage, despite a higher complication rate than in the younger population [40].
• The arthroscopic Trillat procedure resulted in a stable and functional shoulder with patient satisfaction in 96% (20/21) of patients with recurrent anterior instability associated with massive irreparable cuff, with no patient losing active shoulder motion [5].
• Patient-reported outcomes decline over time following arthroscopic Bankart repair for anterior shoulder instability, necessitating pre-operative counseling on expected outcomes [10].
• Anterior labral reconstruction with biceps autograft for anterior shoulder instability has been performed in a small number of patients, with data inadequate to report on clinical results and recurrent instability risk [21].
• Subscapularis and capsule augmentation is a safe and relatively easy technique for the treatment of shoulder instability associated with capsule-labral deficit [85].
• A thorough clinical exam is the most important factor when determining indication for shoulder instability surgery, as outcomes for posterior instability surgery showed no difference between patients with normal versus pathological radiologist-reported magnetic resonance arthrogram studies [18].

Operative Management: Posterior Instability¶

• Retroglenoid osteotomy with capsular shift for posterior shoulder instability resulted in clinical improvements in all patients, with complete resolution of instability symptoms and radiological correction of glenoid retroversion [2].
• Soft-tissue stabilization alone may not be sufficient in patients who present with substantial bone loss to the posterior glenoid and/or the anterior humeral head [12].
• Recurrence is the most common complication of posterior instability surgery, reported at 8.5% in the general population [76].
• Recurrence rates for posterior instability surgery are highest in overhead athletes [76].
• Posterior glenoid bone loss greater than 20% should be considered a contraindication to arthroscopic soft-tissue stabilization alone [76].
• Overtightening of the posterior capsule can lead to anterior subluxation or coracoid impingement [76].
• Shoulder stiffness or adhesive capsulitis is a concern with rotator interval plication during posterior instability surgery [76].
• The single-portal arthroscopic posterior capsulorrhaphy technique offers an efficient, reproducible procedure to address posterior shoulder instability pathology [9].
• Postoperatively for posterior instability, the shoulder should be placed in a rigid immobilizer with the arm abducted to 30° in neutral rotation [76].
• Strengthening for posterior instability patients should begin at 12 weeks postoperatively [76].
• Patients may return to heavy labor or contact sports 6 months after posterior instability surgery [76].
• The pooled published rate of return to any sport after posterior instability surgery is 91% [76].
• The pooled published rate of return to preinjury level of sport after posterior instability surgery is 67% [76].

Operative Management: Multidirectional Instability (MDI)¶

• Surgery for MDI is appropriate for patients with pain and instability that interferes with normal or sport-related activity who have failed extensive nonsurgical treatment [11].
• Capsulorrhaphy for MDI should address the inferior redundancy in a balanced fashion to avoid asymmetric tightening [11].
• Recurrence of MDI is reported at 7% for both open and arthroscopic techniques [11].
• Subscapularis insufficiency is a complication of open MDI procedures [11].
• Open capsular shift with Achilles allograft augmentation demonstrated low rates of recurrent instability and improved clinical outcomes in patients with MDI, including those with Ehlers-Danlos Syndrome [4].
• The zip-tie technique for multidirectional instability allows for progressive tightening of knotless anchors, addressing shortcomings of traditional suture-based methods regarding premature capsular tightening and tension control [30].
• Anterior capsulolabral allograft reconstruction can be a reproducible way to improve shoulder stability and obtain good postoperative outcome measures for patients with recurrent MDI [94].

Operative Management: Other Instability Pathologies¶

• At 2 years, 19.1% of patients treated arthroscopically for 270-360 degree panlabral tears experienced instability, and 7.9% underwent reoperation for instability or dislocation [3].
• Accurate identification of the mechanism of instability is essential for guiding management of dislocated reverse total shoulder arthroplasty, though outcomes remain variable and recurrent instability continues to be a major challenge [1].
• The triple anatomical technique for acromioclavicular joint reconstruction enables early recovery and return to sports by biologically restoring joint anatomy and kinematics [25].
• The acromioclavicular harness has been used with good results in treating twenty cases of acromioclavicular dislocation, maintaining reduction and bringing about permanent healing [43].
• There was no evidence regarding the effectiveness of surgical management for post-traumatic chronic shoulder instability in a systematic review with a network meta-analysis [66].
• Removal of the torn or degenerated intra-articular disk along with a capsulorrhaphy can improve pain and eliminate mechanical symptoms of popping and grating in chronic dislocation [74].
• Complications of stabilizing an anterior injury include recurrent instability, loss of motion, and pain [74].
• In Kim's lesion treatment, 93% (14/15) of patients undergoing fixation successfully resumed sports with little or no restrictions at a mean follow-up of 31 months [28].
• One patient with a Kim's lesion who initially returned to sport developed recurrent subluxation over 12 months and was unable to continue competing at the collegiate level in swimming [28].
• Significant improvements were reported in the University of California Los Angeles shoulder scale, American Shoulder and Elbow Surgeons index, Rowe score, and mean pain score following Kim's lesion fixation [28].
• Internal rotation decreased by an average of 2 vertebral levels following Kim's lesion fixation [28].
• Internal rotation at 90° of flexion improved from a deficit of 11° to 4° following Kim's lesion fixation [28].
• Nonoperative management for Kim's lesion is supported by previous investigations, warranting a grade-C recommendation due to limited evidence on return-to-activity rates and timing [28].
• New trauma drives recurrent shoulder instability following primary stabilization surgery in adolescent patients [93].

Complications¶

Recurrent Instability and Failure Rates¶

• In patients with 270-360 degree panlabral tears treated arthroscopically, 19.1% experienced instability at 2 years [3].
• In patients with 270-360 degree panlabral tears treated arthroscopically, 7.9% underwent reoperation for instability or dislocation at 2 years [3].
• In a high-risk population with traumatic posterior glenohumeral dislocations, 19 out of 33 shoulders (58%) experienced structural failure such as recurrent dislocation or revision surgery [39].
• Recurrent instability continues to be a major challenge in the management of dislocated reverse total shoulder arthroplasty [1].
• Patient-reported outcomes decline over time following arthroscopic Bankart repair for anterior shoulder instability [10].
• Surgical stabilization is generally not recommended for dynamic-functional posterior instability, as it is associated with poor outcomes [8].

Specific Complications and Pathologies¶

• Frozen shoulder is a common epidemiological affliction that does not resolve spontaneously in a large number of patients [13].
• Adolescent athletes who present with a history of anterior shoulder instability have a high incidence of bipolar bone loss [90].
• The Latarjet procedure for recurrent anterior shoulder instability in patients over 50 years old is associated with a higher complication rate than in the younger population [40].
• A previously undescribed group of patients presents with chronic shoulder instability even after surgery to correct this problem, characterized by an axillary index-scar [16].

Outcomes and Efficacy in Specific Populations¶

• The Latarjet procedure leads to similar functional outcomes and failure rates in patients with or without hyperlaxity for recurrent shoulder instability [20].
• Retroglenoid osteotomy with capsular shift for posterior shoulder instability resulted in complete resolution of instability symptoms and radiological correction of glenoid retroversion in all patients [2].
• A local vascularized scapula bone graft for posterior glenohumeral instability resulted in a posteriorly stable glenohumeral joint and a persisting vital bone graft at two-year follow-up [37].
• Shoulder stabilization using the Latarjet procedure is effective in patients over 50 years old without associated cuff damage [40].
• Contemporary studies show comparable instability and functional outcomes between arthroscopic and open Bankart repair for anterior shoulder instability [44].
• Historical instability differences between arthroscopic and open Bankart repair were driven primarily by earlier studies [44].

Management Considerations¶

• Patients should be counseled pre-operatively on the expected outcomes over time following arthroscopic Bankart repair of anterior shoulder instability [10].
• Addressing cartilage injury in the setting of first-time anterior shoulder instability can be beneficial and may alter recovery and longer-term shoulder joint outcomes [42].
• Data are inadequate to report on clinical results and recurrent instability risk for anterior labral reconstruction with biceps autograft for anterior shoulder instability [21].

Recovery¶

Operative Outcomes and Recurrence¶

• Accurate identification of the mechanism of instability is essential for guiding management of dislocated reverse total shoulder arthroplasty, but outcomes remain variable and recurrent instability continues to be a major challenge [1].
• At 2 years following arthroscopic treatment of 270-360 degree panlabral tears, 19.1% of patients experienced instability and 7.9% underwent reoperation for instability or dislocation [3].
• Following the arthroscopic Trillat procedure for recurrent anterior instability associated with massive irreparable cuff, 96% (20/21) of patients had a stable and functional shoulder and were satisfied with the procedure, with no patient losing active shoulder motion [5].
• The Latarjet procedure leads to similar functional outcomes and failure rates in patients with or without hyperlaxity for recurrent instability of the shoulder [20].
• A local vascularized scapula bone graft to treat posterior glenohumeral instability resulted in a posteriorly stable glenohumeral joint and a persisting vital bone graft at two-year follow-up [37].
• Postoperative radiographic evaluation at 7-month follow-up for anterior capsular reconstruction with dermal allograft augmentation for multidirectional shoulder instability demonstrated a concentrically reduced glenohumeral joint [41].
• Contemporary studies show comparable instability and functional outcomes between arthroscopic and open Bankart repair for anterior shoulder instability, whereas historical differences were driven primarily by earlier studies [44].

Patient-Reported Outcomes and Counseling¶

• Patients should be counseled pre-operatively on the expected outcomes over time following arthroscopic Bankart repair for anterior shoulder instability, as patient-reported outcomes decline over time [10].

Non-Operative Management and Natural History¶

Pathomechanism and Surgical Indications¶

• Dynamic-functional posterior instability (Type B1) is characterized by pathological activation of the rotator cuff and periscapular muscles, including the pectoralis major, which stabilizes the glenohumeral joint by resisting superior migration of the humeral head [8].
• Surgical stabilization is generally not recommended for dynamic-functional instability, as it is associated with poor outcomes [8].

Cartilage and Long-Term Considerations¶

• Cost-effectiveness analyses comparing distal tibial allograft versus the Latarjet procedure for anterior shoulder instability do not account for long-term outcomes such as the development of glenohumeral arthritic changes, which may influence the relative value of each procedure over time [98].

Key Evidence¶

• [L4] Accurate identification of the mechanism of instability is essential for guiding management, but outcomes remain variable and recurrent instability continues to be a major challenge. [1] (10.1177/17585732261472448)
• [L4] This study showed clinical improvements in all patients, with the complete resolution of instability symptoms and radiological correction of glenoid retroversion. [2] (10.1186/s12891-026-09524-3)
• [L3] At 2 years, 19.1% of patients experienced instability and 7.9% underwent reoperation for instability or dislocation. [3] (10.1177/2325967126s00513)
• [L4] The study demonstrated low rates of recurrent instability and improved clinical outcomes in this high-risk population. [4] (10.1016/j.jse.2026.05.024)
• [L4] Overall, 96% (20/21) of the patients had a stable and functional shoulder and were satisfied with the procedure; no patient lost active shoulder motion. [5] (10.1016/j.jseint.2024.08.149)
• [Paper] The indications for an isolated soft-tissue procedure in anterior shoulder instability are now narrower; the ideal candidate presents with minimal glenoid bone loss (13.5%). [6] (10.2106/jbjs.rvw.26.00033)
• [L4] NHL team physicians strongly favor nonoperative management in-season for initial posterior instability events of the shoulder. [7] (10.1177/23259671261440208)
• [L5] [8] (10.1016/j.xrrt.2026.100861)
• [L5] All in all, this technique offers an efficient, reproducible procedure to address posterior shoulder instability pathology. [9] (10.1016/j.eats.2022.05.004)
• [L3] Patients should be counseled pre-operatively on the expected outcomes over time following ABR of anterior shoulder instability. [10] (10.1177/2325967126s00552)
• [L5] Soft-tissue stabilization alone may not be sufficient in patients who present with substantial bone loss to the posterior glenoid and/or the anterior humeral head. [12] (10.2106/jbjs.rvw.23.00243)
• [L4] Frozen shoulder is a common epidemiological affliction that does not resolve spontaneously in a large number of patients. [13] (10.3389/fmed.2021.663703)
• [L4] [14] (10.2106/jbjs.rvw.23.00200)
• [L5] The authors define a previously undescribed group of patients who present with chronic shoulder instability, even after surgery to correct this problem, and who accordingly present with an axillary index-scar. [16] (10.1016/s0020-1383(00)00127-3)
• [L3] The Bristow-Latarjet procedure was associated with significantly higher rates of full RTS than Bankart repairs in anterior shoulder instability, despite variability in patient indications across procedures. [17] (10.1177/23259671261450204)
• [L3] A thorough clinical exam is the most important factor when determining indication for shoulder instability surgery. [18] (10.1016/j.xrrt.2026.100675)
• [L5] The authors propose the arthroscopic subscapular sling procedure as an alternative to existing surgical treatment options for recurrent anterior shoulder instability. [19] (10.1016/j.eats.2021.03.027)
• [L4] In recurrent instability of the shoulder, the Latarjet procedure leads to similar functional outcomes and failure rates in patients with or without hyperlaxity. [20] (10.1016/j.jseint.2024.08.174)
• [L4] This technique has been performed in a small number of patients, and the data are inadequate to report on clinical results and recurrent instability risk. [21] (10.1016/j.eats.2024.102935)
• [L3] [24] (10.1016/j.jseint.2026.101785)
• [L5] It enables early recovery and return to sports by biologically restoring joint anatomy and kinematics. [25] (10.1016/j.eats.2025.103595)
• [Paper] [28] (10.2106/jbjs.rvw.25.00126)
• [L5] [30] (10.1016/j.eats.2025.103762)
• [L3] Clinicians should maintain a high index of suspicion in young patients presenting with traumatic shoulder pain, even in the absence of perceived instability. [32] (10.1177/23259671251414851)
• [L4] [33] (10.1016/j.xrrt.2026.100810)
• [Paper] Such methods may improve prognostic analysis of anterior shoulder instability and will facilitate measurement on MRI, which rarely includes the contralateral shoulder. [34] (10.1016/j.jseint.2025.101506)
• [L5] The two-year follow-up of the performed surgical procedure led to a posteriorly stable glenohumeral joint and a persisting vital bone graft. [37] (10.1016/j.xrrt.2026.100772)
• [L4] The study found a high failure rate in both cohorts, with 19 out of 33 shoulders (58%) experiencing structural failure such as recurrent dislocation or revision surgery. [39] (10.1016/j.jseint.2026.101773)
• [L4] Despite a higher complication rate than in the younger population, shoulder stabilization using the Latarjet procedure is effective in patients over 50 without associated cuff damage. [40] (10.1016/j.jseint.2025.101518)
• [L5] Postoperative radiographic evaluation at 7-month follow-up demonstrated a concentrically reduced glenohumeral joint. [41] (10.1002/atn2.70104)
• [L5] The authors conclude that addressing the cartilage injury can be beneficial and may alter recovery and longer-term shoulder joint outcomes. [42] (10.1002/arj.70461)
• [L4] The acromioclavicular harness has been used with good results in treating twenty cases, maintaining reduction and bringing about permanent healing. [43] (10.2106/00004623-195234010-00032)
• [L4] Publication period subgroup analysis suggests that historical instability differences were driven primarily by earlier studies, whereas contemporary studies show comparable instability and functional outcomes between approaches. [44] (10.1177/03635465261443999)
• [L1] There was no evidence regarding the effectiveness of surgical management for post-traumatic chronic shoulder instability. [66] (10.1136/bjsports-2017-098539)
• [L5] [81] (10.1002/atn2.70026)
• [Paper] Current classifications exhibit poor reliability in categorizing glenoid defects post-reverse shoulder arthroplasty removal. [82] (10.1016/j.jseint.2024.08.170)
• [L3] Coracoid morphology differs significantly in patients undergoing posterior shoulder stabilization when compared to patients undergoing surgery for anterior instability or a comparison cohort. [84] (10.1177/03635465261421534)
• [Paper] The subscapularis and capsule augmentation is a safe and relatively easy technique for the treatment of shoulder instability. [85] (10.1016/j.eats.2024.103313)
• [L4] [87] (10.1177/23259671261451245)
• [Paper] Including the whole scapula on MRI, especially in advanced levels of tear retraction, may allow a more representative assessment to the [89] (10.1016/j.jseint.2024.08.135)
• [L4] Adolescent athletes who present with a history of anterior shoulder instability have a high incidence of bipolar bone loss. [90] (10.1177/2325967126s00146)
• [L4] In the future, we expect CT to be superseded by MRI in anterior shoulder instability. [91] (10.1016/j.jseint.2025.101440)
• [L4] This value is on the lower end of the currently reported range and we believe this to be very accurate as this study contains the largest and most heterogenous population of pediatric shoulder instability patients in the literature. [93] (10.1177/2325967126s00536)
• [L5] This technique can be a reproducible way to improve shoulder stability and obtain good postoperative outcome measures for patients with recurrent MDI. [94] (10.1016/j.eats.2025.103500)
• [L5] The article presents an alternative technique for capsular plication that effectively and safely addresses capsular laxity in patients with posterior shoulder instability. [95] (10.1016/j.eats.2025.103794)
• [L3] The study investigated whether unstable painful shoulder (UPS) and anterior instability (AI) are associated with differences in scapula morphology using magnetic resonance imaging (MRI). [97] (10.1016/j.jse.2026.04.009)
• [Paper] Notably, this analysis does not account for long-term outcomes such as the development of glenohumeral arthritic changes, which may influence the relative value of each procedure over time. [98] (10.1177/2325967126s00557)

References¶

[1] Management of the dislocated reverse total shoulder arthroplasty: A tertiary centre experience. Shoulder & Elbow. 2026. DOI: 10.1177/17585732261472448

[2] Retroglenoid osteotomy with capsular shift for posterior shoulder instability: technical note and short-term results. BMC Musculoskeletal Disorders. 2026. DOI: 10.1186/s12891-026-09524-3

[3] Poster 217. Outcomes of Arthroscopic Treatment of 270-360 Degree Panlabral Tears. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00513

[4] Open Capsular Shift with Achilles Allograft Augmentation for Multidirectional Shoulder Instability: Long-Term Outcomes and Implications for Patients with Ehlers-Danlos Syndrome. Journal of Shoulder and Elbow Surgery. 2026. DOI: 10.1016/j.jse.2026.05.024

[5] The Arthroscopic Trillat Procedure Is A Valuable And Durable Treatment Option For Recurrent Anterior Instability Associated With Massive Irreparable Cuff. JSES International. 2024. DOI: 10.1016/j.jseint.2024.08.149

[6] Current Approaches to Arthroscopic Management of Anterior Shoulder Instability. JBJS Reviews. 2026. DOI: 10.2106/jbjs.rvw.26.00033

[7] Treatment of Posterior Shoulder Instability in National Hockey League Players: A Survey of NHL Team Physicians. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671261440208

[8] Posterior stabilization and subtotal pectoralis major release for combined dynamic functional and structural posterior instability: A Case Report. JSES Reviews, Reports, and Techniques. 2026. DOI: 10.1016/j.xrrt.2026.100861

[9] Single‐Portal Arthroscopic Posterior Capsulorrhaphy for Recurrent Shoulder Capsule Laxity and Instability. Arthroscopy Techniques. 2022. DOI: 10.1016/j.eats.2022.05.004

[10] Poster 260. Patient-Reported Outcomes Decline Over Time following Arthroscopic Bankart Repair for Anterior Shoulder Instability. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00552

[11] Aaos Comprehensive Orthopaedic Review 3. The Unstable Shoulder > V. Multidirectional Instability.

[12] Management of Bone Loss in Posterior Glenohumeral Shoulder Instability. JBJS Reviews. 2024. DOI: 10.2106/jbjs.rvw.23.00243

[13] A Comprehensive View of Frozen Shoulder: A Mystery Syndrome. Frontiers in Medicine. 2021. DOI: 10.3389/fmed.2021.663703

[14] Bony Bankart Lesion. JBJS Reviews. 2024. DOI: 10.2106/jbjs.rvw.23.00200

[15] Classifications And Scores Of The Shoulder. 19.15 The Western Ontario shoulder instability index (WOSI) [70]*.

[16] Orthopaedic variant of Munchausen's Syndrome: shoulder instability. Injury. 2001. DOI: 10.1016/s0020-1383(00)00127-3

[17] High Rates of Return to Sport After Surgical Stabilization for Anterior Shoulder Instability in Athletes: A Systematic Review and Meta-analysis. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671261450204

[18] No difference in outcomes for posterior shoulder instability surgery in patients with a normal vs. pathological radiologist reported magnetic resonance arthrogram study. JSES Reviews, Reports, and Techniques. 2026. DOI: 10.1016/j.xrrt.2026.100675

[19] Dynamic and Static Stabilization of Anterior Shoulder Instability With the Subscapular Sling Procedure. Arthroscopy Techniques. 2021. DOI: 10.1016/j.eats.2021.03.027

[20] Similar Outcomes After Latarjet Procedure For Recurrent Instability In Hyperlax Versus Non-Hyperlax Patients. JSES International. 2024. DOI: 10.1016/j.jseint.2024.08.174

[21] Anterior Labral Reconstruction With Biceps Autograft for Anterior Shoulder Instability. Arthroscopy Techniques. 2024. DOI: 10.1016/j.eats.2024.102935

[22] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > SUMMARY.

[23] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > Radiographic Evaluation.

[24] Antero-inferior glenohumeral instability is associated with an abnormal position of the coracoid process. JSES International. 2026. DOI: 10.1016/j.jseint.2026.101785

[25] The Triple Anatomical Technique for Acromioclavicular Joint Reconstruction: A True Anatomical Reconstruction Technique Using Synthetic Ligaments With Acromioclavicular Ligament Reconstruction. Arthroscopy Techniques. 2025. DOI: 10.1016/j.eats.2025.103595

[28] Kim's Lesion of the Shoulder. JBJS Reviews. 2025. DOI: 10.2106/jbjs.rvw.25.00126

[30] Zip‐tie Multidirectional Instability: A Technique for Progressive Tightening of Knotless Anchors in Multidirectional Instability. Arthroscopy Techniques. 2025. DOI: 10.1016/j.eats.2025.103762

[32] Unperceived First-Time Anterior Shoulder Subluxation: The Role of MRI in Detection and Characterization of Pathoanatomy. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671251414851

[33] Analysis of scapular morphology as a key factor in unstable painful shoulder: an magnetic resonance imaging-based study. JSES Reviews, Reports, and Techniques. 2026. DOI: 10.1016/j.xrrt.2026.100810

[34] Automated 3D Analysis of Glenoid Bone Loss for Anteroinferior Instability Assessment Using Deep Learning. JSES International. 2026. DOI: 10.1016/j.jseint.2025.101506

[37] A local vascularized scapula bone graft to treat posterior glenohumeral instability—an innovative surgical technique. JSES Reviews, Reports, and Techniques. 2026. DOI: 10.1016/j.xrrt.2026.100772

[39] The Natural History of Traumatic Posterior Glenohumeral Dislocations in a High-Risk Population. JSES International. 2026. DOI: 10.1016/j.jseint.2026.101773

[40] Long-Term Outcomes of the Open Latarjet Procedure for Recurrent Anterior Shoulder Instability in Patients Over 50 Years Old. JSES International. 2026. DOI: 10.1016/j.jseint.2025.101518

[41] Anterior Capsular Reconstruction With Dermal Allograft Augmentation for Multidirectional Shoulder Instability. Arthroscopy Techniques. 2026. DOI: 10.1002/atn2.70104

[42] Regarding “Glenoid Labral Articular Disruption Lesions in the Setting of First‐Time Anterior Shoulder Instability”. Arthroscopy. 2026. DOI: 10.1002/arj.70461

[43] TREATMENT OF ACROMIOCLAVICULAR DISLOCATION BY MEANS OF A HARNESS. The Journal of Bone & Joint Surgery. 1952. DOI: 10.2106/00004623-195234010-00032

[44] Arthroscopic vs Open Bankart Repair for Anterior Shoulder Instability: A Systematic Review and Meta-analysis. The American Journal of Sports Medicine. 2026. DOI: 10.1177/03635465261443999

[45] Rockwood And Matsen S The Shoulder. Shoulder and Elbow Specialty Clinic Workers’ Survey > ANATOMY.

[46] A Lange Medical Book Current Diagnosis Treatment In Orthopedics Fifth Edition. 2Musculoskeletal Trauma Surgery > SHOULDER AND ARM INJURIES.

[47] Aaos Comprehensive Orthopaedic Review 3. Anatomy of the Shoulder, Arm, and Elbow > I. Shoulder.

[48] Rockwood And Matsen S The Shoulder. Developmental Anatomy of the Shoulder and Anatomy of the Glenohumeral Joint > Bursae.

[50] Rockwood And Matsen S The Shoulder. Developmental Anatomy of the Shoulder and Anatomy of the Glenohumeral Joint > EDITOR COMMENTARY.

[54] Rockwood And Matsen S The Shoulder. Developmental Anatomy of the Shoulder and Anatomy of the Glenohumeral Joint > SENIOR EDITOR COMMENTARY.

[56] Orthopaedic Knowledge Update 13 Ebook Without Multimedia. Shoulder Anatomy and Biomechanics, Clinical Evaluation, Imaging > Clinical Evaluation > Imaging.

[65] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > Clinical Findings.

[66] Treatment after traumatic shoulder dislocation: a systematic review with a network meta-analysis. British Journal of Sports Medicine. 2018. DOI: 10.1136/bjsports-2017-098539

[71] Classifications And Scores Of The Shoulder. THE WESTERN ONTARIO ROTATOR CUFF INDEX (WORC).

[74] Rockwood And Matsen S The Shoulder. Shoulder and Elbow Specialty Clinic Workers’ Survey > Chronic Dislocation.

[75] Rockwood And Matsen S The Shoulder. Arthroscopic Management of Prearthritic and Arthritic Conditions of the Shoulder and the Postarthroplasty Shoulder > EVALUATION OF THE OVERHEAD ATHLETE.

[76] Aaos Comprehensive Orthopaedic Review 3. The Unstable Shoulder > IV. Posterior Instability.

[77] Rockwood And Matsen S The Shoulder. Fractures, Dislocations, and Acquired Problems of the Shoulder in Children > DIAGNOSIS AND DIAGNOSTIC ARTHROSCOPY IN SHOULDER INSTABILITY.

[78] Aaos Comprehensive Orthopaedic Review 3. Physical Examination of the Shoulder and Elbow > I. Shoulder.

[81] Acromial Osteotomy for Dynamic Posterior Shoulder Instability. Arthroscopy Techniques. 2026. DOI: 10.1002/atn2.70026

[82] Glenoid Defects In Revision Reverse Shoulder Arthroplasty: Are Current Classification Systems Appropriate?. JSES International. 2024. DOI: 10.1016/j.jseint.2024.08.170

[84] Coracoid Morphology and the Risk of Posterior Shoulder Instability: A Magnetic Resonance Imaging Study. The American Journal of Sports Medicine. 2026. DOI: 10.1177/03635465261421534

[85] Subscapularis Tendon Augmentation in Patients With Anterior Shoulder Instability Associated With Capsule‐Labral Deficit. Arthroscopy Techniques. 2024. DOI: 10.1016/j.eats.2024.103313

[87] Rate of Shoulder Arthroplasty After Anterior Shoulder Instability Surgery: A Systematic Review. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671261451245

[89] Pre-Shaped And Pre-Drilled Cortical Bone Allograft Provides Comparable Results To Coracoid Autograft In Treatment Of Instability With Glenoid Bone Loss. JSES International. 2024. DOI: 10.1016/j.jseint.2024.08.135

[90] Bipolar Bone Loss in Adolescent Anterior Shoulder Instability. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00146

[91] MRI augmented with novel artificial intelligence system is superior to CT in shoulder instability. JSES International. 2026. DOI: 10.1016/j.jseint.2025.101440

[93] Poster 242. New Trauma Drives Recurrent Shoulder Instability Following Primary Stabilization Surgery in Adolescent Patients. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00536

[94] Anterior Capsulolabral Allograft Reconstruction for Revision Multidirectional Instability Surgery. Arthroscopy Techniques. 2025. DOI: 10.1016/j.eats.2025.103500

[95] “Pinch‐and‐Tuck” Arthroscopic Technique for Capsular Laxity in Posterior Shoulder Instability. Arthroscopy Techniques. 2025. DOI: 10.1016/j.eats.2025.103794

[97] Scapula morphologic analysis using magnetic resonance imaging in unstable painful shoulder and anterior shoulder instability. Journal of Shoulder and Elbow Surgery. 2026. DOI: 10.1016/j.jse.2026.04.009

[98] Poster 265. Cost-Effectiveness of Distal Tibial Allograft vs The Latarjet Procedure for Anterior Shoulder Instability: A Markov Analysis. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00557