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Glenohumeral Joint Disability - G2.1

Defintion of condition:  Glenohumeral joint instability is a symptomatic clinical situation where there is abnormal movement between the humeral head and the glenoid cavity.[Resnick, D. (1995).  Diagnosis of bone and joint disorders, 3rd ed., p. 2989.  Philadelphia W.B. Saunders]

Issue statement: Diagnosing a shoulder problem may be difficult because of the variety of potential shoulder injuries and the similarity between them.  When determining the cause of shoulder instability, factors such as predisposition, etiology and mechanism of injury must be considered.

WCB-Alberta position

Work relationship criteria

A work relationship may be established if shoulder instability is caused by:

• a traumatic episode at work, such as forced abduction and external rotation of the shoulder causing an anterior subluxation or dislocation, resulting in anterior instability.  Posterior dislocations do occur but are uncommon.

Multidirectional instability is more difficult to attribute to work related causes.  It often occurs in individuals with generalized ligamentous laxity; symptoms or signs of subluxation at other joints are common.  Spontaneous or minimal trauma (lifting, rotation) may bring on subluxation/dislocation because of underlying laxity.

In order to determine work relationship, the degree of involvement of the following medical and physiological risk factors should be considered:

• a history of acute or recurrent subluxation/dislocations; the length of time since the previous episode, the severity and frequency of subluxations/dislocations with or without surgery
• hereditary factors such as shoulder joint laxity and developmental/anatomic variations such as glenohumeral joint and humeral head variation
• previous trauma or acquired variations.

Clinical criteria

Instability differs from joint laxity although they can coexist.  Instability is pathological while joint laxity may be normal and is asymptomatic.

Anterior instability ("TUBS" - Traumatic onset, Unidirectional and anterior with a Bankart lesion responding to Surgery)

• sudden onset of acute shoulder pain following a forceful abduction/external rotation shoulder stress; "slipped out of place" feeling
• when shoulder is "out" the arm is held in a guarded manner in flexion & internal rotation.  Any external rotation causes pain.
• weakness, numbness of the affected arm
• positive anterior apprehension test with abduction and external rotation of the affected shoulder only
• positive anterior drawer test

Multidirectional instability ("AMBRI" - Atraumatic etiology, Multidirectional, Bilateral shoulders responding to Rehabilitation and rarely surgery in the form of Inferior capsular shift)

• may be asymptomatic until considerable heavy lifting or repeated activities in extreme ranges of motion
• positive sulcus sign
• positive anterior/posterior drawer and apprehension tests and positive load and shift tests which may be bilateral
• often evidence of generalized ligamentous laxity (e.g. most commonly hyperextension of metacarpal phalangeal, knee and elbow joints)

Diagnostic criteria

Imaging studies

If there is a frank dislocation, pre-reduction x-rays are required to rule out fractures.  A post reduction film following first time dislocation is recommended.

Plain films are recommended if instability is present and may be ordered with stress film. Supportive findings include subluxation and a Hill-Sachs defect in the posterior humeral head.

MRI may identify glenolabral tears or detachments and capsular/tendinous tears (e.g. Bankhart lesions)

Arthroscopy is an ancillary diagnostic tool but may have a role in defining Hill-Sachs defect or glenolabral tears and detachments.

Recommended Management

If a dislocation is present reduction is necessary. Initial management should focus on control of acute inflammation and avoidance of aggravating activity.

Education

The attending physician should fully discuss the following with the worker:

• anatomy, natural history, and prognosis of shoulder instability
• diagnosis and expected outcome of treatment
• self care including exercises
• proper use of medication
• restriction and avoidance of those activities known to precipitate a recurrence of the original problem:
  -with anterior instability (TUBS), avoid extreme abduction/external rotation
  -with multidirectional instability (AMBRI), avoid extreme ranges of motion in any direction as well as heavy downward traction on the arm such as heavy lifting.

Physical methods of treatment

Primary dislocation:

1. Reduction
2. Immobilization where appropriate.
3. With TUBS, continuous immobilization in abduction and internal rotation for an average three weeks in the active fit worker under 45.
4. Isometric strengthening of the shoulder girdle mechanism especially during immobilization.
5. Muscle groups should respond to reconditioning within one month.  Recovery of adequate range of motion and function should continue.  Further improvements from formal active therapy are unlikely beyond one month of such treatment post-immobilization.  Further improvement of strength and range can be expected through regular use of the arm.

Recurrent Dislocation:

1. General strengthening of the shoulder girdle.
2. Restriction of shoulder motion with a shoulder harness may decrease frequency of dislocation especially in TUBS.

Drugs

Optional:

• a short course of analgesics/NSAIDs may be useful following an acute traumatic dislocation to manage pain

Referrals to Specialist:

Emergent:

• referral is indicated for irreducible shoulder dislocations and for neurologic or vascular compromise

Discretionary: 

Anterior instability (TUBS):

Orthopaedic referral if:

• recurrent dislocation or impingement syndrome with failure of an exercise and strengthening program, and
• there is interference with work and activities of daily living.

Multidirectional instability (AMBRI):

Surgical correction of multidirectional instability is generally not recommended.  Strengthening of the shoulder girdle is the preferred mode of therapy. 

If conservative treatment fails and a firm diagnosis of shoulder instability is made, referral to an orthopedist for further evaluation may be indicated.

Fitness to work criteria

Most cases should have healed or have been declared as surgical candidates within one month post-immobilization. 

Loss of work is not necessarily anticipated following shoulder dislocation.  Length of disability depends on factors such as the type and frequency of dislocation, the severity of trauma and symptoms, age, length of immobilization, type of work and arm dominance.

Modified work duties may be necessary, work restrictions may be temporary or permanent.

Permanent Clinical Impairment criteria

Impairment assessment is primarily based on loss of ROM.  A judgment award may be assessed for instability

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