Shoulder Instability

Normal Anatomy

• The fossa is relatively shallow and deepened by the glenoid labrum

• The ratio of the humeral head to glenoid fossa is similar to a golf ball on a tee

• Glenoid labrum acts to deepen the glenoid fossa to increase static stability

• Shoulder relies on dynamic stability

Pathophysiology

• Excessive movement of the humerus on the glenoid which can result in dislocation or subluxations

Mechanism Of Injury

• Acute Anterior Dislocation– Forceful external

rotation in an abducted position

– Falling on an outstretched arm

– Direct blow to the shoulder in a posterior anterior direction

Mechanism Of Injury

• Acute Posterior Dislocation– Rare and usually missed– Caused by fits, seizures

or electrocutions– Falling onto an

outstretched arm

Mechanism Of Injury

• Congenital Laxity– Connective tissue

abnormality– Poor motor control of

dynamic stabilisers– Laxity becomes

instability as soon as it becomes pathological

Mechanism Of Injury

• Acquired laxity– Chronic repetitive stress– Usually on top of laxity

Associated Pathologies

• Hill Sachs Lesion– Compression fracture of

humeral head

• Bankart Lesion– Tearing of inferior

glenohumeral ligament complex from labrum

Associated Pathologies

• Internal Impingement• SLAP Lesions• External Impingement

Subjective – Acute Anterior Dislocation

• Usually traumatic• Mechanism of injury as stated above• Usually attended A&E where relocation was

completed and X-rays taken• Immobilisation by A&E

Subjective – Acute Posterior Dislocation

• Usually traumatic• Mechanism of injury as stated above• Usually attended A&E where X-rays taken• Commonly missed• Immobilisation by A&E

Subjective – Congenital Laxity

• History of recurrent dislocations• History of hypermobility or connective tissue

disease• Vague aching around the shoulder

Subjective – Acquired Laxity

• Overhead sports or activities• Symptoms consisted with associated

pathology

Objective – Acute Anterior Dislocation

• Step deformity if seen acutely

• Protective posturing• Spasm and guarding • Significant pain• Global loss of range of

movement• Loss of abduction and

external rotation after immobilisation due to capsular scarring

Objective – Acute Posterior Dislocation

• Anterior flattening if seen acutely

• Protective posturing• Spasm and guarding • Significant pain• Global loss of range of

movement• Loss of internal rotation

and horizontal adduction after immobilisation due to capsular scarring

Objective – Congenital Laxity

• Excessive ROM Globally• Poor Dynamic Control• Beighton Score 4/9 or

greater

Objective – Acquired Laxity

• Signs consistent with associated pathology

• i.e internal impingement, SLAP, external impingement

• Scapular Dyskinesis

Special Tests

• Inferior Sulcus Test• Apprehension Sign• Relocation Test• Load and shift

Further Investigation

• X- Ray• MRI

Conservative – Acute Dislocations

• See Wilk et al., 2006 for more detail• Relocation• Sling for comfort• Immobilization to allow scaring of capsule

Conservative – Acute Dislocations

1. Restore Normal Mobility– Pain free passive mobilisations

2. Immediate Isometrics and Rhythmic Stabilisations– As pain allows– Closed chain more comfortable for anterior

dislocations

3. Restore Normal Strength– Once ROM allows start scapular, external and internal

rotation strength

Conservative – Congenital Laxity

• See Wilk et al., 2006 for more detail• Avoid aggravating activities

1. Minimal to zero stretching2. Restore normal motor control and strength• Closed Chain• Rotator Cuff and Scapular Stabilisers

3. Restore Proprioception4. Return to Sport/Activity Specific Exercises

Conservative – Acquired Laxity

• See Wilk et al., 2006 for more detail• Avoid aggravating activities• Manage associated pathology

– Restore Normal Mobility• Reduced Swelling and Inflammation• Reduce soft tissue trauma• Reduce capsule restrictions if present

– Restore Normal Motor Control and Strength• Closed Chain• Rotator cuff, scapular stabilisers

– Restore Proprioception– Return to Sport/Activity Specific Exercises

Surgical - Management

• Always dependent on the client and the surgeon

• Young sports people with repetitive dislocations usually considered for surgery

• Arthroscopic repair• Open Repair• Capsular Shift