Dislocation of the shoulder ( Shoulder Dislocation)
-Shoulder is the commonest joint in the human body to dislocate.
-It occurs more commonly in adults.
-Anterior dislocation is much more common than posterior dislocation.
-Shoulder instability: head of the humerus is not stable in the glenoid.
-A fall on an outstretched hand with the shoulder abducted and externally rotated, is the most common mechanism of injury.
-Occasionally, it results from a direct force pushing the humerus head out of the glenoid cavity.
-A posterior dislocation may result from
1.a direct blow on the front of the shoulder, driving the head backwards.
2.More commonly as a consequence of an electric shock or an epileptiform convulsion.
head of the humerus comes out of the glenoid cavity and lies anteriorly.
further classified into three subtypes – Preglenoid, Subcoracoid, Subclavicular
Pathological changes in anterior dislocation
-Dislocation causes stripping of the glenoidal labrum along with the periosteum from the anterior surface of the glenoid and scapular neck.
-The head comes to lie in front of the scapular neck, in the pouch thereby created.
-In severe injuries, it may be avulsion of a piece of bone from anteroinferior glenoid rim, called bony Bankart lesion.
-a depression on the humeral head in its posterolateral quadrant
-caused by impingement by the anterior edge of the glenoid on the head as it dislocates.
Rounding off‘of the anterior glenoid rim:
Occurs in chronic cases as the head dislocates repeatedly over it.
-Fracture of greater tuberosity
-Rotator cuff tear,
-patient enters the casualty with his shoulder abducted and the elbow supported with opposite hand
-There is a history of a fall on an outstretched hand followed by pain and inability to move the shoulder.
-The patient keeps his arm abducted
-The normal round contour of the shoulder joint is lost, and it becomes flattened.
-On careful inspection, one may notice fullness below the clavicle due to the displaced head. This can be felt by rotating the arm.
Signs, associated with anterior dislocation
1.Dugas’ test: Inability to touch the opposite shoulder.
2.Hamilton ruler test:
-Because of the flattening of the shoulder, it is possible to place a ruler on the lateral side of the arm that touches the acromion and lateral condyle of the humems simultaneously.
-The diagnosis is easily confirmed on an anteroposterior Xray of the shoulder
-An axillary view is sometimes required.
-usually occurs following a convulsion.
-This injury is often missed even on Xray
-A clinical examination eliciting loss of external rotation
-CT scan may be diagnostic.
-reduction under sedation or general anaesthesia, followed by immobilisation of the shoulder in a chestarm bandage for three weeks.
-After the bandage is removed, shoulder exercises are begun.
Techniques of reduction of shoulder dislocation:
This is the most commonly used method.
The steps are as follows
1.traction—with the elbow flexed to a right angle steady traction is applied along the long axis of the humerus
-the arm is rotated externally
-the externally rotated arm is adducted by carrying the elbow across the body towards the midline
internal rotation –
3.the arm is rotated internally so that the. hand falls across to the opposite shoulder.
-surgeon applies a firm and steady pull on the semiabducted arm.
-He keeps his foot in the axilla against the chest wall.
-The head of the humerus is levered back into position using the foot as a fulcrum.
Early complications: Injury to the axillary nerve
-result in paralysis of the deltoid muscle.
-result in a small area of anaesthesia over the lateral aspect of the shoulder.
-result in inability to abduct the shoulder.
Treatment is conservative, and the prognosis is good.
Late complications: recurrent dislocation
-Shoulder is the commonest joint to undergo recurrent dislocation.
Recurrent shoulder dislocation
-anatomically unstable joint
-inadequate healing after the first dislocation
-an epileptic patient.
Operations for Recurrent shoulder dislocation
-Double breasting of the subscapularis tendon is performed
-It prevents external rotation and abduction, thereby preventing recurrences.
-glenoid labrum and capsule are reattached to the front of the glenoid rim.
-In this operation, the coracoid process, along with its attached muscles, is osteotomized at its base and fixed to lower half of the anterior margin of the glenoid.
-The muscles attached to the coracoid provide a dynamic anterior support to the head of the humerus.
4.Arthroscopic Bankart repair
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