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Shoulder Instability, Anterior

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Ovid: 5-Minute Sports Medicine Consult, The


Shoulder Instability, Anterior
Tricia Beatty
Basics
Description
  • A symptomatic anteroinferior subluxation or dislocation of the glenohumeral (GH) joint
  • Synonym(s): Glenohumeral dislocation; Glenohumeral subluxation; Dead-arm syndrome
Epidemiology
  • The most dislocated joint in the body. In a study of 8,056 dislocations, 45% involved the GH joint.
  • Anterior GH dislocations are the most common. In a study of 394 shoulder dislocations and separations, 84% were anterior GH dislocations.
  • Recurrence rate for athletes under age 25 is over 85% in those who have suffered an initial traumatic event.
Risk Factors
  • History of previous dislocation
  • Younger patients
  • Athletes participating in repetitive overhead activities such as throwing or volleyball
Diagnosis
History
  • Patients usually give a history of prior dislocation/subluxation event. The symptoms will be reported to occur when the arm is placed in the provocative position of abduction and external rotation.
  • Patients also may complain of a “dead arm,” which typically occurs with subluxation.
Physical Exam
  • Patients note the feeling of impending dislocation with the arm in a provocative position. Pain itself is generally not a sign of pure dislocation.
  • A thorough exam of the cervical spine, proximal humerus, and scapula should be performed when evaluating anyone with shoulder pain. If multidirectional instability is suspected, an assessment of ligamentous laxity should be addressed. A complete neurologic exam should be performed to identify any central or peripheral neuropathy.
  • Apprehension test: Arm is placed at 90 degrees of abduction and gently externally rotated. A sense of “impending” dislocation is regraded as a positive test.
  • Relocation test: With the patient supine, the apprehension test is repeated. A posteriorly directed force is applied to the proximal humerus with the scapula stabilized by the examiner's opposite hand. If symptoms abate, the test result is positive.
  • Load and shift test: The patient is seated while the examiner stabilizes the scapula with one hand and with the thumb and forefinger of the free hand on the proximal humerus attempts to sublux the head anteriorly and posteriorly. In general, this test works better with thinner patients and requires a fair amount of patient relaxation.
Diagnostic Tests & Interpretation
Imaging
  • Imaging studies should include orthogonal views to rule out associated bony injuries and to ensure that the humeral head is reseated within glenoid.
  • Radiography: The initial series includes an anteroposterior (AP), true shoulder AP, axillary lateral, and scapular Y. Additional views, if necessary, may include the Westpoint view (good for identifying a bony Bankart/anteroinferior glenoid rim fracture) and Stryker notch view (good for identifying a Hill-Sachs lesion/posterolateral humeral head compression fracture).
  • Velpeau view (if required to stay in sling) if initial radiographs are inconclusive or patient is unable to be appropriately positioned.
  • MRI can identify rotator cuff tears, biceps abnormalities, and occasionally lesions associated with humeral avulsion of the GH ligament. Because of the normal variation of the labrum and GH ligaments, most studies overestimate the frequency of labral tears.
  • Postreduction views are necessary for the acute treatment of a shoulder dislocation to ensure relocation and assess for possibility of a fracture.
Differential Diagnosis
  • Diagnoses that can mimic anterior instability include multidirectional instability, acromioclavicular instability, superior labral anteroposterior (SLAP) lesions, biceps tendon subluxation, and subscapularis tear.
  • One always should rule out referred pain from the cervical spine.

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Treatment
Additional Treatment
Additional Therapies
  • Early treatment consists of brief immobilization of up to 3 wks for younger patients, followed by early protected ROM and strengthening. The anterior capsular structures must be protected throughout rehabilitation, and therefore, all stressors to the anterior structures should be limited.
  • Rotator cuff strengthening: Initial strengthening should begin in the plane of the scapula. Internal and limited-range external rotation exercises can be begun with light free weights or therabands.
  • Scapular stabilization: Exercises include rowing, modified push-ups with maximal protraction, scaption (elevation of the humerus in external rotation in the scapular plane), modified flies and press-ups (later stage).
Surgery/Other Procedures
  • Indications for surgery include more than 3 dislocations per year, dislocation at rest, or failed nonoperative therapy.
  • Relative indications for surgery depend on patient demand, such as 1st-time dislocations in young (<30 yrs) athletes or laborers.
  • Surgical technique: Repair the traumatic lesion by reattaching the torn labrum and GH ligaments. Avoid compromised motion by not overtightening the capsule.
  • Arthroscopic stabilization: Has advantage of easier postoperative rehabilitation and less restriction of motion secondary to scarring; has disadvantage of a higher recurrence rate of 12%. To reduce rate of recurrence, capsular laxity must be addressed with either capsular imbrication or thermal capsulorrhaphy.
  • Open stabilization (Bankart procedure): Has more successful outcome, with recurrence rates of <5%; Has the disadvantage of slowed rehabilitation secondary to injury to the subscapularis tendon.
Ongoing Care
Follow-Up Recommendations
  • Any patient with recurrent anterior dislocations or a young, athletic, 1st-time dislocator should have the opportunity to discuss all options, including surgery, and therefore may be referred to an orthopedic surgeon for evaluation.
  • Any patient failing nonoperative modalities also should be referred.
Additional Reading
Bankart AS. Recurrent or habitual dislocation of the shoulder. BMJ. 1923;2:1132–1133.
Bedi A, Ryu RK. The treatment of primary anterior shoulder dislocations. AAOS Instructional Course Lectures. 2009;58:293–301.
Cave EF, Burke JF, Boyd RJ. Trauma management. Chicago: Year Book Medical, 1974.
Jobe FW, ed. Operative techniques in upper extremity sports injury. St. Louis: Mosby Year Book, 1996.
Kazár B, Relovszky E. Prognosis of primary dislocation of the shoulder. Acta Orthop Scand. 1969;40:216–224.
Ludewig PM, Reynolds JF. The Association of Scapular Kinematics and Glenohumeral Joint pathologies. J Ortho & Sports Phys Ther. 2009;39:90–101.
Matthews LS, Pavlovich LJ. Disorders of the shoulder: diagnosis and management. Philadelphia: Lippincott Williams & Wilkins, 1999.
Neviaser RJ, Neviaser TJ, Neviaser JS. Anterior dislocation of the shoulder and rotator cuff rupture. Clin Orthop Relat Res. 1993;291:103–106.
Ochoa E, Burkhart SS. Glenohumeral bone defects in the treatment of anterior shoulder instability. AAOS Instructional Course Lectures. 2009;58:323–333.
Rowe CR, Patel D, Southmayd WW. The Bankart procedure: a long-term end-result study. J Bone Joint Surg Am. 1978;60:1–16.
Codes
ICD9
718.81 Other joint derangement, not elsewhere classified, involving shoulder region
Clinical Pearls
  • In general, surgery is required only when physical therapy has failed. Most young patients (<30 yrs of age) require surgical intervention.
  • In the hands of a good arthroscopist with experience in shoulder stabilizations, the success rate of arthroscopy probably has improved beyond the previously reported rate of 85%. The open procedure is still the “gold standard,” with a success rate of 95%.


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