High Yield Topics

Shoulder Instability, Multidirectional

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Ovid: 5-Minute Sports Medicine Consult, The


Shoulder Instability, Multidirectional
David E. J. Bazzo
Tara Robbins
Basics
Description
  • Multidirectional instability (MDI) is an increase in glenohumeral translation in more than one direction causing either subluxation (any partial loss of normal articulation) or dislocation (a complete loss of glenohumeral articulation) in more than one direction, such as anterior, inferior, superior, or posterior.
  • The extent of laxity can be described objectively by the measured amount in millimeters of which the humeral head can be translated on the glenoid. Some individuals may be symptomatic with minimal millimeters of laxity, whereas others may have minimal symptoms with 3+ laxity.
  • Hallmark pathology of MDI is a large, patulous inferior capsule, although this is not always the case.
Epidemiology
  • MDI is much more common than previously realized but still represents <5% of all shoulder instability.
  • Most patients are in their 3rd decade of life but range in age from teenagers to middle age.
Risk Factors
  • Repetitive microtrauma (especially overhead motion): Butterfly and backstroke swimmers, gymnasts, baseball pitchers, and weight lifters
  • Generalized ligamentous hyperlaxity
Etiology
Etiology is thought to be multifactorial, with current theories focusing on anatomic, biochemical, and neuromuscular abnormalities.
  • Anatomic:
    • Patients with MDI have been shown to have a large, patulous inferior pouch and wide rotator interval that are both common manifestations of inferior instability.
    • Pathologic changes in labral height and Bankart lesions also are observed in patients with MDI (1).
  • Biochemical:
    • Patients with MDI have been shown to have alterations in the type and quantity of collagen, specifically types III and IV collagen, as seen in Ehlers-Danlos syndrome (1).
  • Neuromuscular:
    • Loss of strength or neuromotor coordination of rotator cuff and scapular stabilizing muscles also contributes to MDI.
    • Recent studies have shown that when compared with controls, patients with MDI have altered functioning of the musculature of the shoulder girdle and the dynamic stabilizers of the glenohumeral joint during movement.
    • Loss of proprioception also can contribute to MDI because proprioceptive feedback is important in maintaining stability.
    • It still needs to be elucidated whether the proprioceptive defect is a cause or effect of the instability (1).
Diagnosis
History
  • MDI is associated with recurrent or “low-energy” trauma.
  • Unilateral versus bilateral shoulder problems: 30–70% of patients with MDI have symptoms in the opposite shoulder as well.
  • MDI of the humeral head reduces spontaneously or is self-reduced.
  • Previously unsuccessful shoulder reconstruction for presumed unidirectional instability may indicate MDI.
  • Patients with emotional problems who can purposely cause repeated dislocation typically will not benefit from surgery until their emotional problems are resolved. However, patients who dislocate voluntarily and do not have emotional problems may benefit from surgery.
Physical Exam
  • Most common complaint is vague pain radiating to the deltoid insertion, initially occurring after activity and progressing to pain at rest, and in late stages, patients may develop night pain.
  • Transient neurologic symptoms, such as numbness (“dead arm”) or tingling owing to transient subluxation, usually affecting ulnar > median nerve distribution
  • Rotator cuff weakness
  • Inferior instability: Pain, numbness, tingling while carrying briefcase or heavy suitcase; this is caused by traction on the brachial plexus.
  • Posterior instability: Pain while arm in forward-flexed, internally rotated position (eg, pushing open a heavy door, performing push-ups or bench press, blocking in football, or during pull-through phase of rowing stroke)
  • Anterior instability: Pain with arm in overhead, abducted, externally rotated position (eg, during wind-up or early acceleration of a throw)
  • Often general ligamentous laxity is present (eg, thumb to forearm), elbow hyperextension, metacarpophalangeal joint hyperextension, genu recurvatum, patellofemoral subluxation (40–75%)
  • Sulcus test involves inferior traction on the arm while at the side. Inferior translation of at least 1–2 cm causing concavity of skin inferior to acromion (positive sulcus sign) indicates inferior instability.
  • Anterior and posterior load and shift test and/or drawer test usually result in anterior and posterior displacement (graded trace to III). Always remember to stabilize the scapula with one hand while the patient remains in either a seated or supine position.
  • Apprehension test involves placing the shoulder in the position of instability (throwing position: abduction and external rotation for anterior instability; adduction, flexion, and internal rotation for posterior instability). A positive test is seen when the patient senses pending subluxation or has involuntary guarding. It is apprehension that is most reliable in confirming shoulder instability, not pain.
  • Relocation test involves relief of apprehension and symptoms when applying a stabilizing counterforce (posterior force on humeral head for anterior instability; anterior force on humeral head for posterior instability) to the arm in the provocative position with the scapula stabilized.
  • Cervical range of motion, upper extremity strength, sensory function (including axillary nerve), and reflexes also should be evaluated.
  • Muscle guarding may make the examination difficult, and repeat exams may be necessary for confirmation of diagnosis.
Diagnostic Tests & Interpretation
Imaging
  • MDI is a clinical diagnosis based on the history and physical exam; orthogonal plain radiographs should be obtained to evaluate for bony defects such as Bankart and Hill-Sachs lesions as well as glenoid dysplasia.
  • Stryker notch: Patient supine, cassette under shoulder, arm flexed, palm to head, elbow pointing straight upward, beam 10 degrees cranially centered over coracoid; reported to show defect in 90% of 20 patients studied
  • Axillary view: Clear delineation of glenoid-humerus relationship; evaluation of anteroposterior displacement of humeral head on glenoid and Hill-Sachs lesions as well as larger glenoid rim and humeral head compression fractures
  • West Point (reverse axillary lateral): Patient placed prone on table, involved shoulder place on raised (8 cm) pad, head and neck rotated away, cassette against superior aspect of shoulder, beam centered at axilla with 25 degrees down/25 degrees medial angulation; allows view of anteroinferior glenoid rim; this view is usually used for traumatic anterior dislocations.
  • Weight-bearing traction films typically not performed routinely because diagnostic yield is quite low
  • More sophisticated imagery is now accepted as routine preoperatively or for persistent symptoms. Most shoulder surgeons prefer an MRI arthrogram to help detect capsular redundancy, but MRI remains more useful in ruling out other pathology. Double-contrast CT arthrography may show increased capsular volume.

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Differential Diagnosis
  • Unilateral instability (anterior, posterior, inferior)
  • Acute dislocation or subluxation
  • Voluntary dislocator
  • Primary impingement
  • Thoracic outlet syndrome
  • Cervical disc disease
  • Brachial plexitis
Treatment
  • Analgesia: NSAIDs can decrease pain and inflammation acutely, but long-term analgesic usage typically is not necessary.
  • Reduction: Usually reduce spontaneously or self-reduce
  • Immobilization:
    • Usually immobilize with a sling for 3 wks for young (<30 yrs of age) acute, 1st-time true dislocation. There has not been a well-demonstrated association between length of immobilization and recurrence.
    • Immobilization for recurrent dislocators is of less value, although some authorities suggest short-term immobilization for each occurrence.
    • Use caution in immobilizing older patients, who are more likely to develop adhesive capsulitis.
Additional Treatment
Additional Therapies
  • 1st-line treatment is prolonged course of physical therapy/independent exercise program with emphasis on strengthening anterior deltoid and rotator cuff muscles for at least 6 mos and probably up to 1 yr. Symptomatic relief is gradual.
    • 2 phases have been suggested: Phase I focuses on strengthening the anterior deltoid and rotator cuff muscles and usually lasts 6–12 wks. Phase II focuses on continuing to strengthen deltoid and rotator cuff muscles with the addition of strengthening scapular stabilizers and improving proprioception (1)[B].
    • Recent data suggest that most patients will begin to improve within 3 mos of physical therapy (2)[B].
  • It is important to continue a maintenance exercise program indefinitely.
  • If patient is pain-free with normal strength after 6 mos, prior activity may be resumed.
  • May develop secondary impingement syndrome, which can be relieved by a subacromial injection of a steroid preparation, if necessary, to allow continuation of physical therapy
  • May need to change prior activity (ie, a butterfly stroke swimmer may need to choose a different stroke or a pitcher may need to change his or her delivery or position)
Surgery/Other Procedures
  • Surgery is indicated only for symptomatic, painful shoulders after the patient fails aggressive, prolonged physical therapy (usually minimum 6 mos) (1)[C].
  • Laxity alone is not a typical indication for surgery.
  • Some authorities advocate earlier surgery if there is a documented glenohumeral ligament avulsion on double-contrast CT or MRI arthrogram.
  • Neer et al. described the open inferior capsular shift repair technique with good success in 1974, and it continues to be a reasonable choice of surgical interventions for MDI.
  • Recently, several arthroscopic approaches have been described, including transglenoid capsular shift and capsular plication with bone anchors and adjunctive thermal capsulorrhaphy and/or rotator interval closure. The arthroscopic techniques produce clinical results equivalent or superior to open techniques. Arthroscopic treatment results in less surgical time and presumed less morbidity (1,3)[B].
  • Thermal capsulorrhaphy (capsular shrinkage through laser or radiofrequency energy) has been used to treat shoulder instability for centuries; however, clinical studies have not shown favorable results. In isolated thermal capsulorrhaphy, a high failure rate and complications of glenohumeral chondrolysis and axillary nerve injuries have been reported. However, thermal capsulorraphy may be useful as adjunctive therapy (4)[B].
  • Note: Probably the earliest “sports surgery” was thermal capsulorraphy for anterior instability in ancient Egypt, where warriors with instability were treated with a hot poker to thermally shrink anterior structures to try to allow them to throw a spear.
Ongoing Care
Follow-Up Recommendations
  • Most patients with MDI should be referred for physical therapy. Patients who fail physical therapy can be referred to an orthopedist for consideration of surgical treatment.
  • Asymptomatic, pain-free voluntary dislocators with emotional problems who purposely dislocate their shoulder repeatedly for shock value do not benefit from surgery and may need a psychiatric referral.
References
1. Bahu MJ, Trentacosta N, Vorys GC, et al. Multidirectional instability: evaluation and treatment options. Clin Sports Med. 2008;27:671–689.
2. Miniaci A, Codsi MJ. Thermal capsulorrhaphy for the treatment of shoulder instability. Am J Sports Med. 2006.
3. Caprise P, Sekiya J. Open and arthroscopic treatment of multidirectional instabilty of the shoulder. Arthroscopy: J Arthroscopic Related Surg. 2006;22:1126–1131.
4. Mahaffey BL, Smith PA. Shoulder instability in young athletes. Am Family Phys. 1999;59:2773–2782.
Additional Reading
Foster CR. Multidirectional instability of the shoulder in the athlete. Clin Sports Med. 1983;2:355–368.
Misamore GW, Sallay PI, Didelot W. A longitudinal study of patients with multidirectional instability of the shoulder with seven- to ten-year follow-up. J Shoulder Elbow Surg. 2005;14:466–470.
Schenk TJ, Brems JJ. Multidirectional instability of the shoulder: pathophysiology, diagnosis, and management. J Am Acad Orthop Surg. 1998;6:65–72.
Yamaguchi K, Flatow EL. Management of multidirectional instability. Clin Sports Med. 1995;14:885–902.
Codes
ICD9
  • 718.81 Other joint derangement, not elsewhere classified, involving shoulder region
  • 755.59 Other congenital anomalies of upper limb, including shoulder girdle
  • 831.00 Closed dislocation of shoulder, unspecified site
Clinical Pearls
  • Regardless of whether the treatment is conservative physical therapy or surgery, the time until resumption of full sports generally is 6 mos. If surgery is required, then postoperative immobilization with a sling is typically for 3–6 wks, with early supervised range-of-motion exercises. Light sports and throwing can start at ∼4 mos postoperatively if strength is at least 90% and full range of motion is achieved.
  • ∼10–13% of patients require bilateral surgical repair.


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