| | Classification
| The shoulder is the most mobile of joints and yet is structurally insecure.
Instability
Instability occurs with the shoulder completely out of it’s socket (dislocation), or with lesser degrees of slipping where the shoulder is not completely out of joint (subluxation). Usually anterior or antero-inferior (seldom posterior or multidirectional).
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| | Mechanism of injury
| Anterior Instability
The shoulder is most at risk for anterior instability when the arm is placed in abduction/external rotation (such as a fall on the outstretched hand or tackling a player). In other cases there is no traumatic event but involvement in upper limb overhead sports.
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| | | Frank anterior dislocation is obvious but instability can have slipping; pain with the arm in abduction/external rotation; apprehension using the arm overhead or a dead arm feeling with a tackle or overhead action (Fig. 30).
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| | Clinical features
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Treatment | Acute Dislocation
Exclude nerve or vascular injury. Closed reduction (Figs 31 & 32) can be achieved in the emergency room. In cases (where there is a high risk of recurrence) an acute arthroscopic assessment and repair may be offered. The risk of recurrent instability is highest (60 - 85%) in patients younger than 25 years returning to violent contact or upper limb sports.
Recurrent Dislocation
For those patients with recurrent instability treatment is to modify or avoid the known precipitating event; undergo physiotherapy rehabilitation programme or consider a reconstruction of the shoulder.
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| | Mechanism of injury | Posterior Instability
Traumatic posterior dislocations are uncommon (4%) and occur in electrocution or grand mal convulsion. Posterior subluxation is being recognised more frequently occurring in athletes involved in sports such as baseball.
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| | Clinical features
| The diagnosis of is often missed (Fig. 33). The patients may have pain and an inability to externally rotate the arm. The axillary x-ray view is diagnostic (Fig. 34). | |
| | Treatment | Reduce early. If the dislocation is longer standing or a large portion of the humeral head is damaged then surgical reconstruction of the humeral head is required; rarely total shoulder replacement.
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| | Clinical features | Multidirectional Instability
Signs of ligamentous laxity are present. Patients often have pain and weakness with a shoulder that subluxes anterior, posterior and inferior. Examination shows a loose shoulder with a sulcus sign on inferior stress testing (Fig. 37).
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| | | The majority of patients will respond to physiotherapy. Rarely surgery is indicated.
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| | Treatment | |
| | | Tendinitis and Impingement
Tendinitis can occur due to rotator cuff overload/fatigue, trauma, and age related degenerative changes. Crowding of the cuff tendons in the subacromial space leads to impingement.
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| | Mechanism of injury
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| | Clinical features | Pain aggravated with overhead activities. Night pain in advanced cases. Tenderness is over the greater tuberosity and impingement signs are present (Figs 38). X-rays may show an anterior acromial spur.
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| | | An injection of corticosteroid and local anaesthetic into the subacromial space is often diagnostic, and therapeutic. Activity modification, NSAID’s, and physiotherapy. Consider surgery in 6 months.
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| | Treatment | |
| | | Rotator Cuff Tears
In the younger patient from trauma. In the older patient from underlying degenerative changes.
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| | Mechanism of injury | |
| | Clinical features | Pain with overhead use of the arm and at night. There may be weakness, only massive rotator cuff tears loose active range of motion. X-rays often show an acromial spur. Investigations include either an arthrogram, ultrasound or M.R.I.
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| | Treatment | In the younger patient surgery, in the older patient a short trial of activity modification, NSAID’S, physiotherapy and corticosteroid injection is reasonable and later surgery.
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| | | Acromioclavicular Joint Injuries
Usually relayed to a fall onto the point of the shoulder. Pain, tenderness and deformity.
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| | Mechanism of injury | |
| | Treatment | RICE and sling, with surgery for major dislocations in active patients (Fig 40).
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| | | Labral Tears & Loose Bodies
Often associated with direct trauma or instability
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| | Mechanism of injury | |
| | Clinical features | Pain, clicking or locking. Instability may be present. Diagnosis difficult (Fig. 41).
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| | Treatment | Arthroscopy.
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| | | Outer Clavicular Osteolysis
From a direct blow or fall but often found in individuals who work out in the gymnasium on overhead machines or benchpress.
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| | Mechanism of injury | |
| | Clinical features | X-rays show irregularity of the outer clavicle with osteolysis.
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| | Mechanism of injury | Sternoclavicular Dislocation
Usually a fall onto the side with another player failing on top causing compression of the shoulder. Can be anterior or posterior.
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| | Clinical features | Anterior dislocation has a painful prominence, (Fig 42); posterior dislocation may cause pressure on structures in the neck with dysphagia, dyspnoea or great vessel compression. (This can be a surgical emergency.) X-rays are often difficult to interpret. A CT scan may be necessary.
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| | Treatment | Anterior dislocations may be reduced closed or left. Posterior dislocations should be reduced urgently if there is compromise of mediastinal structures. Muscle Ruptures
Usually occurs on contraction of muscle against an unexpected resistance. Muscles include: pectoralis major; long head of biceps; and subscapularis (Fig. 43). Biceps Tendinitis
May occur with anterior instability or rotator cuff tears.
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| | Mechanism of injury | Nerve Injuries Can occur secondary to instability or direct trauma. Traction to the arm can cause a neuropraxia. Nerves involved often include: Circumflex Axillary; Suprascapular; Musculocutaneous; Long Thoracic and Radial nerve (Fig. 44). Brachial plexus palsy (partial or complete) occur with high energy trauma.
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| | Treatment | In most cases the injury is a neuropraxia and will recover with time. EMG studies are recommended. Rarely exploration and repair. | | |
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