Multidirectional instability of the shoulder

INTRODUCTION — Multidirectional instability (MDI) of the shoulder is defined as symptomatic laxity of the glenohumeral joint. Patients with this disorder have excessive laxity of the joint capsule in more than one or in all directions (anterior, inferior, and posterior) and have difficulty maintaining the head of the humerus centered within the glenoid fossa.

The clinical presentation, diagnosis, and management of MDI of the glenohumeral joint will be reviewed here. The general evaluation of adults with undifferentiated shoulder complaints, shoulder dislocation, and other common shoulder ailments, such as impingement or rotator cuff tendinopathy, are discussed separately. (See "Evaluation of the adult with shoulder complaints" and "Shoulder dislocation and reduction" and "Subacromial (shoulder) impingement syndrome" and "Rotator cuff tendinopathy" and "Presentation and diagnosis of rotator cuff tears".)

DEFINITIONS: DISTINGUISHING LAXITY AND INSTABILITY — In the medical literature, a number of definitions exist for multidirectional instability (MDI) of the shoulder, making classification of these patients difficult. To clarify, glenohumeral laxity and instability are not synonymous [1]. Instability implies dysfunction. It can be voluntary or involuntary, unidirectional or multidirectional, and traumatic or nontraumatic. Patients with ligamentous laxity often have no complaints and require no intervention, while those with instability are by definition symptomatic.

The distinction between laxity and instability applies to physical examination findings as well. A patient whose shoulder can be subluxated in one or multiple directions but is asymptomatic has laxity without instability and requires no intervention. In contrast, a patient who presents with shoulder or proximal upper extremity pain, weakness, fatigue, or paresthesias may have laxity with instability. Patients with MDI of the glenohumeral joint often have laxity in both the asymptomatic and symptomatic shoulder, but only the symptomatic shoulder is classified as having instability.

ANATOMY AND BIOMECHANICS — The basic anatomy and biomechanics of the shoulder complex are reviewed separately. (See "Evaluation of the adult with shoulder complaints", section on 'Anatomy and biomechanics'.)

EPIDEMIOLOGY AND ETIOLOGY — Multidirectional instability (MDI) of the glenohumeral joint may occur in patients with congenital joint laxity who have sustained repetitive minor injuries or one or more major injuries to the shoulder [2,3]. The incidence of generalized or asymptomatic joint laxity ranges from approximately 10 to 30 percent. Laxity in a single joint appears to be more common than generalized hypermobility. Joint laxity decreases steadily in boys but peaks around age 15 in girls. (See "Clinical manifestations and diagnosis of hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder".)

The precise incidence of MDI of the glenohumeral joint is unknown. Among sedentary individuals, the condition is more common in young women with poor muscular development and patients with large rotator cuff tendon tears, due to deficiencies in the muscles that stabilize the humeral head. MDI can develop in athletic or active individuals without generalized joint laxity, who participate in sports or work requiring repetitive overhead movements, such as gymnasts, tennis players, and throwers [4,5]. Frequent overhead activity can lead to repetitive microtrauma of the structures that stabilize the glenohumeral joint.

However, the extent to which MDI accounts for shoulder problems in overhead athletes is not clear. According to a report based upon questionnaire results, the incidence of traumatic shoulder injuries among gymnasts is related to generalized ligamentous laxity but not MDI [6]. In addition, although many observers believe that swimmers have increased glenohumeral laxity compared to non-swimmers, the literature on the subject is mixed [4,7-11]. An observational study comparing elite and recreational swimmers reported that a combination of inherent and acquired factors contribute to greater glenohumeral laxity among elite swimmers [4]. Another study of competitive swimmers found that male swimmers had greater joint laxity but younger females less than age and gender matched non-swimmer controls [7]. An observational study using ultrasound measurements found no significant increase in glenohumeral joint displacement among 42 elite swimmers compared to non-swimmer age-matched controls [8].

Regardless of the sport, MDI is more common in athletes under the age of 40. After the age of 40, the condition is uncommon due to the natural stiffening of tissues around the shoulder.

The asymptomatic shoulder of patients with MDI is frequently as mobile as the affected shoulder, suggesting that factors in addition to laxity are important in pathogenesis. These factors may include structural deformation, focal muscle weakness, and neuromotor dysfunction [12]. Balance between the forces exerted upon the glenohumeral joint by the scapulothoracic stabilizers and the rotator cuff is important for maintaining normal function of the joint [13]. Some researchers speculate that imbalances in these forces can develop when an individual's arm fatigues from repetitive overhead activity or when the shoulder is forcefully traumatized [14]. Examples of the former scenario might include repetitive minor trauma from pitching a baseball, swimming, or serving in tennis; examples of the latter scenario might include a tackle during a rugby or American football match that produces an anterior dislocation of the glenohumeral joint.

The initial inciting event, particularly repetitive overhead activity, frequently does not cause an identifiable episode of instability, but does produce pain, which leads the individual to guard the affected shoulder. Over time, such guarding results in muscle weakness and changes in neuromuscular coordination [15,16]. This creates a vicious cycle whereby the patient becomes increasingly prone to shoulder instability and worsening pain as the shoulder becomes weaker and more dysfunctional.

CLINICAL PRESENTATION AND HISTORY — The symptoms of multidirectional glenohumeral instability are often vague and nonspecific unless the condition is preceded by specific trauma or complicated by subacromial impingement or rotator cuff pathology [14]. The patient may complain of shoulder looseness or "giving way," a noisy shoulder that "pops" or "clicks," anterolateral shoulder pain, which is often similar to the pain associated with rotator cuff tendinopathy, or some combination of these symptoms. In addition to instability and pain, patients may complain of transient neurologic symptoms in the affected upper extremity, such as numbness, tingling, or weakness. (See "Rotator cuff tendinopathy", section on 'Clinical presentation and examination'.)

Symptoms of shoulder instability tend to occur with glenohumeral motion, often during everyday activities, ultimately leading patients to avoid the extremes of glenohumeral motion [14]. Identifying the movements that precipitate symptomatic instability can provide insight into the patient's pathology. Patients who complain primarily of the shoulder "slipping out" when the arm is in a throwing position (shoulder abducted and externally rotated) most often have anterior instability. Symptoms, possibly including paresthesias, that occur when patients carry a heavy object at their side suggest inferior instability. Posterior instability is suggested by symptoms that develop when the shoulder is loaded posteriorly (eg, pushing against a heavy door, performing a pushup). Recurrent dislocations at night are characteristic of a severely decompensated shoulder (which is often less amenable to conservative management).

Patients who participate in repetitive overhead activities, such as swimming, gymnastics, tennis, or weight training may develop subacromial bursitis or rotator cuff impingement. Repetitive microtrauma from such impingement can lead to a pathologic chain of events eventually leading to multidirectional instability (MDI) [17]. (See "Subacromial (shoulder) impingement syndrome", section on 'Clinical presentation and examination'.)

Sometimes, patients with MDI may be able to relate the onset of the problem to a specific traumatic event. However, the trauma that produces multidirectional glenohumeral instability is typically less severe, and therefore less memorable, than trauma that produces unidirectional shoulder instability from a major injury (eg, anterior shoulder dislocation) [14]. More typically, patients either cannot recall an inciting event or the episode was trivial or involved a period of overuse or muscle fatigue.

Obtaining a detailed history is important as many patients with MDI have seen multiple doctors and been given multiple diagnoses. This is frequently the case with young patients with persistent symptoms following surgical repair of unidirectional shoulder instability [18]. These patients may present following significant shoulder trauma or may participate in a sport that predisposes them to MDI. They may complain of periods of fatigue or overuse associated with decreasing performance.

PHYSICAL EXAMINATION

Overview of approach and general shoulder examination — Examination of the patient with multidirectional instability (MDI) of the glenohumeral joint requires a systematic approach. Particularly in patients with a history of trauma, it is important to examine the cervical spine and peripheral nerves to rule out referred pathology. Inspection of the shoulders, neck, and torso may reveal important findings, such as muscle asymmetry or atrophy, scapular winging, or surgical scars. The examination of the shoulder is complex and described in detail separately; a general approach and specific guidance related to MDI of the shoulder is described here. (See "Physical examination of the shoulder".)

After visual inspection, ask the patient to demonstrate any voluntary instability or "double jointedness," as many patients describe having this capacity. You may ask the patient to reach behind their head and touch their elbow to the opposite ear, or have them reach behind their back with one hand and over the opposite shoulder with the other and clasp hands. Some patients may be able to voluntarily subluxate or dislocate and relocate their shoulder. Such findings demonstrate increased laxity of the glenohumeral joint.

Next, assess the patient for any generalized ligamentous laxity. Patients with generalized laxity (predisposing them to shoulder instability) will demonstrate laxity in joints, such as the thumb (can extend and touch the forearm), elbow (hyperextension), or knee (excessive recurvatum) [3,19]. The Beighton score is commonly used to evaluate hypermobility of the joints (table 1). This score evaluates four joint maneuvers and the spine. (See "Clinical manifestations and diagnosis of hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder".)

Following inspection and assessment of shoulder and generalized joint laxity, palpate the shoulder and surrounding structures. Palpation may reveal a step-off between the acromion and the humeral head in patients with MDI of the shoulder. (See "Physical examination of the shoulder", section on 'Palpation'.)

Assess glenohumeral range of motion looking in particular for limitations in active and passive motion, as well as pain or apprehension with testing. Remember to examine and compare shoulders. Scapular dysfunction is common among patients with MDI of the shoulder, and thus, it is important to perform a careful evaluation of scapular motion during shoulder abduction and flexion. The examination of glenohumeral and scapular movement are described separately. (See "Physical examination of the shoulder", section on 'Range of motion' and "Physical examination of the shoulder", section on 'Scapulothoracic motion and strength'.)

Next, evaluate rotator cuff function and strength, including internal and external rotation and abduction. Testing for subacromial impingement (Hawkins and Neer tests), bicep tendinopathy (Speeds and Yergasons tests), and pathology at the acromioclavicular joint (cross body adduction test) is performed to rule out these alternative diagnoses.

Following the general shoulder examination, there are a number of specialized tests can be performed to help identify MDI.

Determining the presence of instability — As discussed above, distinguishing between laxity and instability is central to diagnosing MDI of the glenohumeral joint. Therefore, provocative testing of the shoulder designed to elicit symptoms as well as detect joint instability is an important element of the physical examination. Remember to examine and compare both shoulders. (See 'Definitions: distinguishing laxity and instability' above.)

The tests used to make the diagnosis of MDI include the sulcus sign, the load and shift test, and the apprehension and relocation tests. Patients with multidirectional shoulder instability generally manifest the signs described below in response to these tests. The techniques for performing these tests and their characteristics (eg, sensitivity) are described separately. (See "Physical examination of the shoulder", section on 'Special tests for shoulder instability'.)

●Sulcus sign – Inferior laxity is assessed with the sulcus sign. This sign is present when downward traction applied to the upper arm causes translocation of the humeral head inferiorly in the glenoid fossa (picture 1 and movie 1 and movie 2). Some patients demonstrate a voluntary sulcus sign by placing the hand of the affected arm under their bent leg and pulling upward, thereby creating a sulcus just below the acromion. (See "Physical examination of the shoulder", section on 'Sulcus sign'.)

●Load and shift test – This test measures anterior and posterior glenohumeral laxity. This test is positive if there is significant translocation of the humeral head anteriorly or posteriorly in the glenoid fossa when applying a force in the respective direction (picture 2). (See "Physical examination of the shoulder", section on 'Load and shift test'.)

●Apprehension relocation test – Apprehension (more specific and sensitive for MDI than pain) when placing the glenohumeral joint at extremes of motion (generally external rotation and abduction) that is then relieved with pressure relocating it in the center of the glenohumeral joint (picture 3). (See "Physical examination of the shoulder", section on 'Apprehension, relocation, and release tests'.)

When performing these maneuvers, the examiner will often note varying degrees of crepitation ("popping" in the joint as it moves). Pain may also occur, but the site and timing of such pain varies depending upon the cause of shoulder instability and the presence of concomitant injury (eg, rotator cuff tendinopathy).

Positive results from tests assessing movement of the humeral head in relation to the glenoid, while useful in assessing joint laxity, are not necessarily predictive of shoulder instability. Positive findings with the apprehension, relocation, and anterior release tests more accurately predict subsequent arthroscopically evident instability [20,21].

Concomitant subacromial impingement or rotator cuff tendinopathy — Variable degrees of impingement or rotator cuff tendinopathy may accompany or contribute to shoulder instability. This can be assessed using the Neer test (picture 4), Hawkins-Kennedy test (picture 5), painful arc maneuver (picture 6), and other appropriate tests of rotator cuff muscle function (supraspinatus (picture 7) and external rotators (picture 8)). Examination techniques for diagnosing subacromial impingement and rotator cuff tendinopathy are discussed separately. (See "Physical examination of the shoulder", section on 'Special tests for shoulder impingement' and "Physical examination of the shoulder", section on 'Examination for rotator cuff pathology'.)

DIAGNOSTIC IMAGING

Plain radiography — Plain radiographs (including AP (image 1), external rotation, Y-outlet (image 2), and axillary (image 3) views) are frequently normal in patients with multidirectional instability (MDI) [22]. However, it is reasonable to obtain these studies in patients with persistent pain to look for bony injuries or lesions.

Ultrasonography — Several small clinical studies suggest that ultrasound is a reliable tool for assessing the degree of shoulder instability and may provide additional information when evaluating glenohumeral laxity [5,23,24]. Ultrasound is also useful for identifying any associated rotator cuff pathology. (See "Rotator cuff tendinopathy", section on 'Musculoskeletal ultrasound'.)

CT and MR arthrography — More specialized radiographic testing is rarely necessary, although computed tomography (CT) and magnetic resonance arthrography (MRA) are useful for assessing the integrity of the glenoid labral cartilage (eg, for thinning or tears), determining the presence of early osteoarthritis of the glenohumeral joint, and identifying soft tissue abnormalities associated with instability [25,26]. These studies are most commonly indicated in patients who fail to respond to conservative therapy, have persistent motion deficits, or manifest persistent crepitation with shoulder circumduction. CT is often used to study the bony architecture when glenoid abnormalities are identified on plain film [27]. MRA is useful to identify capsular redundancy, labral injury, and rotator cuff pathology [28].

DIAGNOSIS — The diagnosis of multidirectional glenohumeral instability is made clinically based upon a suggestive history and characteristic findings on physical examination. Shoulder looseness or weakness is a common complaint, particularly among young active individuals engaged in overhead activities and in sedentary patients with hypermobile joints. The prevalence of multidirectional instability (MDI) appears to be higher among patients who participate in overhead sports, such as gymnastics, volleyball, and tennis [18]. Common examination features include glenohumeral joint instability and apprehension when the joint is placed in positions at the extremes of motion. The most useful tests to elicit these findings are the sulcus sign, load and shift test, and apprehension relocation test. Although the diagnosis is primarily clinical, plain radiographs may be helpful in some cases to rule out other pathology; specialized radiographic testing is rarely necessary. Note that MDI differs from unidirectional instability, which should be referred for assessment by an orthopedist. (See 'Clinical presentation and history' above and 'Physical examination' above and 'Indications for orthopedic referral' below.)

DIFFERENTIAL DIAGNOSIS — The differential diagnosis for multidirectional instability (MDI) of the shoulder includes rotator cuff disease (tendinopathy or tear), subacromial impingement, unidirectional instability of the shoulder, cervical neuropathy, brachial plexopathy, and thoracic outlet syndrome. Although MDI of the shoulder can occur concomitantly with rotator cuff disease or impingement, the presence of MDI can usually be determined on the basis of a suggestive history (eg, repetitive overhead activity, sensation of shoulder giving way in particular positions, history of recurrent subluxation or dislocation) and examination findings of excessive glenohumeral motion, including focused testing of shoulder laxity (eg, positive sulcus sign, positive load and shift test, positive apprehension and relocation tests).

Patients with rotator cuff disease, impingement, or bursitis without MDI generally complain of pain with overhead activity but without the sensation of giving way. They may describe preceding trauma (possibly minor), pain at night, or weakness with daily activities involving the shoulder. Examination of the patient with impingement may reveal positive impingement signs (eg, Hawkins and Neer tests) but no abnormalities with the load and shift, sulcus, or apprehension relocation tests. Patients with significant rotator cuff tears may have positive painful arc and drop arm tests and weakness with testing of abduction, internal, or external rotation. Skilled practitioners can use ultrasound to help distinguish MDI from rotator cuff disease. (See "Subacromial (shoulder) impingement syndrome" and "Rotator cuff tendinopathy" and "Presentation and diagnosis of rotator cuff tears".)

Distinguishing unidirectional instability from MDI is important, as the former may do better with surgical intervention. In contrast to MDI where joint laxity is present in more than one direction and the patient often has global ligamentous laxity, the patient with unidirectional instability has laxity in only one direction with testing. An example would be a patient with a positive load and shift test only anteriorly following a traumatic anterior shoulder dislocation who has no signs of global ligamentous laxity. Unidirectional instability may reflect a labral tear. The presence of a labral injury is suggested by the history (eg, fall onto the shoulder, lifting a heavy object, traumatic dislocation, and overuse from overhead sports or heavy work) and positive provocative testing (eg, Active compression, Crank, and Speeds tests). Advanced imaging studies or possibly arthroscopy are required to make a definitive diagnosis. (See "Clinical manifestations and diagnosis of hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder" and "Physical examination of the shoulder", section on 'Special tests for labral (SLAP) pathology'.)

It is important to differentiate MDI of the shoulder from cervical neuropathy or brachial plexopathy. Patients with either condition often have paresthesias in the affected upper extremity. Sensory deficits, atrophy of affected muscles of the shoulder girdle, and scapular winging may be present. In patients with cervical neuropathy, a Spurling's test may be positive. Although MDI patients with MDI frequently manifest some scapulothoracic dysfunction, the findings associated with neuropathy described here are generally absent. (See "Clinical features and diagnosis of cervical radiculopathy" and "Brachial plexus syndromes".)

MANAGEMENT — Although rigorous studies to determine the relative benefits of exercise-based management compared with surgery are lacking [29], based on clinical experience, many patients with nontraumatic multidirectional instability (MDI) of the shoulder are treated effectively with a focused rehabilitation program designed to strengthen the stabilizing muscles of the shoulder and improve neuromuscular coordination of glenohumeral and scapulothoracic movement [30,31]. Those who do not respond well to physical therapy may require surgical repair. Surgical options for stabilizing the glenohumeral joint in patients with MDI include open and arthroscopic capsular plication, rotator interval closure, and labral augmentation [32-36].

Initial treatment — Patients should initially be advised to rest and restrict overhead activities, such as reaching, pushing, pulling, and lifting. Daily applications of ice (15 minutes every four to six hours) and a short course (eg, two to three days) of antiinflammatory medication (eg, ibuprofen) help to relieve pain in patients with concomitant bursitis or rotator cuff tendinopathy.

Physical therapy — The goal of physical therapy for patients with MDI of the shoulder is to improve the dynamic control and positioning of the humeral head in the glenoid. A rehabilitative exercise program that focuses on correcting scapulothoracic dyskinesia and strengthening the dynamic stabilizers of the glenohumeral joint is often effective in achieving these ends [18,37-39]. Data are limited, but observational studies and abundant clinical experience suggest that most compliant patients have good results with an appropriate rehabilitation program, as determined by diminished pain and improved stability over time [30].

When treating the overhead athlete, many clinicians incorporate stretching exercises into the rehabilitation program with the goal of maintaining a normal range of motion equal to the contralateral shoulder while correcting for the increased external rotation commonly seen in the dominant arm [40]. (See "Throwing injuries: Biomechanics and mechanism of injury" and "Throwing injuries of the upper extremity: Clinical presentation and diagnostic approach" and "Throwing injuries of the upper extremity: Treatment, follow-up care, and prevention".)

Strengthening the scapular stabilizers, including the trapezius, rhomboids, and serratus anterior, increases scapular stability, which is required for proper rotator cuff function [17,41,42]. The results of a small randomized trial comparing MDI rehabilitation protocols suggest that correcting scapulothoracic dyskinesia is an important part of rehabilitation [39]. Once proper scapulothoracic control is achieved, the program begins to incorporate rotator cuff strengthening exercises. (See "Rehabilitation principles and practice for shoulder impingement and related problems", section on 'Step one: Improve scapular stability'.)

When performing rotator cuff strengthening exercises, higher loads may be beneficial. In a randomized trial of rehabilitation for 100 patients with multidirectional shoulder instability, a supervised twice-weekly program using heavier resistance exercises led to significantly greater improvements in function at 16 weeks compared with patients using lighter resistance [43]. The study was limited by its small size and short follow-up period. (See "Rehabilitation principles and practice for shoulder impingement and related problems", section on 'Step two: Strengthen the rotator cuff'.)

When appropriate strength is achieved in the scapulothoracic stabilizers and the rotator cuff, the patient begins a functional training program designed to simulate the stresses the patient's shoulder will encounter during their usual athletic and work activities. An example of one exercise progression that might be used in such a program consists of pushups against a wall followed by standard pushups and ultimately pushups on a tilt board. The instability created by the tilt board helps the patient to improve proprioception and dynamic joint stability [44,45]. Once rehabilitation is completed, most patients need to continue performing exercises to maintain shoulder strength and function.

Persistent symptoms — Patients with concurrent symptoms attributable to subacromial impingement or rotator cuff tendinopathy may benefit from a short course of nonsteroidal antiinflammatory therapy or a subacromial glucocorticoid injection (figure 1). The resulting reduction in pain often allows patients to participate more actively in their rehabilitation program. (See "Rotator cuff tendinopathy", section on 'Glucocorticoids'.)

Indications for orthopedic referral — The natural history of multidirectional shoulder instability is to improve slowly as the tissues gradually stiffen with age. Nevertheless, referral to an orthopedic surgeon for consideration of surgical correction is warranted in patients with persistent pain or recurrent episodes of dislocation despite full participation in a well-designed physical therapy program for 6 to 12 months. Recurrent dislocation in particular must be managed appropriately to avoid the development of premature glenohumeral osteoarthritis. (See "Clinical manifestations and diagnosis of osteoarthritis", section on 'Shoulder'.)

In addition, patients with unidirectional (eg, posterior) shoulder instability, particularly those who are not improving with physical therapy, should be referred to an orthopedic surgeon for evaluation. In many cases, the pathology responsible for unidirectional instability is amenable to surgical repair [46].

Coordinated care by a team of specialists (eg, genetics, rehabilitation medicine, orthopedic surgery) is generally needed for patients with shoulder instability due to a connective tissue disorder, such as Ehlers Danlos or Marfan syndrome, since these individuals appear to be less responsive to standard conservative therapy [14,47]. These patients are challenging surgically and frequently require activity and lifestyle modifications for a satisfactory outcome. (See "Clinical manifestations and diagnosis of Ehlers-Danlos syndromes" and "Genetics, clinical features, and diagnosis of Marfan syndrome and related disorders".)

In addition, patients with instability as a result of shoulder trauma and athletes who participate in overhead sports often have a less favorable outcome with conservative management and require surgical repair [14,18,48]. Conversely, patients with hypermobility syndromes (eg, voluntary dislocators) typically experience poor outcomes following surgery.

Surgical options include an open capsular repair and arthroscopic repair. The open procedure historically has been associated with a long-term success rate of 90 percent or better among appropriately selected patients. Arthroscopic techniques and technology have improved considerably, and appropriately selected patients treated in this manner return to activity and sport at a high rate [32,49]. With either technique, approximately 5 to 10 percent of patients lose some shoulder mobility in rotation or overhead reaching.

According to a 2015 systematic review of 24 studies comparing open repair (capsular shift), arthroscopic treatment, and conservative management, 21 percent of patients (52 of 253) managed initially with physiotherapy went on to surgical intervention, while the overall redislocation rate among all treatment groups was 10 percent (61 of 608) [50]. In a subsequent study, 68 patients with atraumatic shoulder instability were randomly assigned at the time of arthroscopy to no treatment or to surgical repair (arthroscopic capsular shift), followed by identical postoperative rehabilitation [51]. At six months, scores on two validated shoulder function scales were improved for both groups, but scores plateaued thereafter with both groups experiencing comparable, persistent pain at 24 months. This study supports prior observational literature reporting that capsular repair in the subset of patients with atraumatic instability does not confer significant improvements in longer term function or pain.

A meta-analysis of studies of surgical management for multidirectional instability reported significantly higher recurrence rates for patients treated with thermal capsular shrinkage, suggesting that such treatment is best avoided [52].

PREVENTION — Evidence about methods to prevent injury due to shoulder laxity is scant. A prospective observational study in which 33 male Australian rules football players served as their own controls, found that taping of the shoulder did not reduce joint laxity [53].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Shoulder soft tissue injuries (including rotator cuff)".)

SUMMARY AND RECOMMENDATIONS

●Definitions – Multidirectional instability (MDI) of the shoulder is defined as excessive laxity of the glenohumeral joint in more than one direction (anterior, inferior, and/or posterior), which results in the inability to keep the head of the humerus centered within the glenoid fossa. This in turn causes recurrent episodes of shoulder instability and pain. (See 'Introduction' above and 'Definitions: distinguishing laxity and instability' above.)

●Epidemiology – MDI of the glenohumeral joint may occur in patients with congenital joint laxity who have sustained minor injuries from repetitive trauma or one or more major injuries to the shoulder. It is more common in young woman with poor muscular development, patients with large rotator cuff tendon tears (because of a loss of muscular support), and select athletes under the age of 40, particularly overhead athletes, such as throwers. (See 'Epidemiology and etiology' above.)

●Clinical presentation – The symptoms of glenohumeral instability are vague and nonspecific unless the condition is complicated by rotator cuff tendinopathy. The patient generally complains of shoulder looseness, a noisy shoulder (crepitation), or anterolateral shoulder pain similar to rotator cuff tendinopathy. (See 'Clinical presentation and history' above.)

●Physical examination – Examination of the shoulder generally reveals the following abnormal signs:

•Translocation of the humeral head inferiorly in the glenoid fossa when downward traction is applied to the upper arm ("sulcus sign") (movie 1 and movie 2)

•Translocation of the humeral head anteriorly or posteriorly in the glenoid fossa when applying a force in the respective direction ("load and shift sign") (picture 2)

•Apprehension when placing the glenohumeral joint at extremes of motion (generally external rotation and abduction) (picture 3)

•Variable degrees of crepitation, or "popping"

•Variable degrees of pain from accompanying subacromial bursitis or rotator cuff tendinopathy

Examination techniques used to diagnose the condition are described in greater detail separately (see "Physical examination of the shoulder", section on 'Special tests for shoulder instability')

●Diagnosis and imaging – The diagnosis of glenohumeral instability is made clinically based upon a suggestive history and characteristic findings on physical examination. Plain radiographs can be helpful to identify bony lesions in some cases; specialized radiographic testing is rarely necessary. (See 'Diagnosis' above and 'Diagnostic imaging' above.)

●Differential diagnosis – The differential diagnosis for MDI includes rotator cuff disease (tendinopathy or tear), subacromial impingement, bursitis, unidirectional instability of the shoulder (including labral injury), cervical neuropathy, brachial plexopathy, and thoracic outlet syndrome. (See 'Differential diagnosis' above.)

●Management – Many patients with multidirectional shoulder instability are treated effectively with a focused rehabilitation program designed to strengthen the stabilizing muscles of the shoulder and improve neuromuscular coordination of glenohumeral and scapulothoracic movement. Referral to an orthopedic surgeon is indicated for patients with persistent pain or recurrent episodes of dislocation despite appropriate conservative treatment. (See 'Management' above and 'Indications for orthopedic referral' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Bruce Anderson, MD, who contributed to an earlier version of this topic review.