Dislocation of shoulder
shoulder joint is vulnerable for dislocation more often than any other joint in the body. the extreme mobility it enjoys jeopardizes its stability. the shoulder has an “Achilles point” at the inferior part of the capsule providing the joint with a potential weak spot, so much so that 99% of the anterior shoulder occurs here.
Classification
- Anterior dislocation of shoulder joint
- Subcoracoid
- Subglenoid
- Subclavicular
- Intrathoracic
- Posterior dislocation of shoulder joint
- Subacromial
- Subglenoid
- Subspinous
- Inferior dislocation of shoulder joint ( Laxatio Erecta )
ANTERIOR DISLOCATION OF SHOULDER JOINT
it is the most common type of shoulder dislocation. it could be due to either direct or indirect forces.
direct force- blow from the posterior aspect of the shoulder
indirect force- due to outstretch fall while abduction external rotation and extension
clinical features
- the patient complaints of severe pain and inability to use the shoulder joint.
- flat shoulder, rounded anterior prominence and the arm held in a position of abduction and external rotation.
- the loss of sensation on the outer aspect of the upper arm, known as the “regiment badge” sign, occurs due to injury to the axillary nerve.
- clinical tests =
- HAMILTON’S RULER TEST: place a ruler between the acromion and the lateral epicondyle.
- CALLAWAYS TEST: the circumference of the axilla
- BRYANTS TEST: anterior axillary fold is at the lower level
- DUGA’S TEST: patient is unable to touch the opposite shoulder.
Treatment
in an emergency, immediate reduction is necessary for anterior shoulder dislocation. kocher’s method is the most common, involving the application of longitudinal traction along the humerus line, external rotation, adduction, and internal rotation of the arm under general anesthesia. open reduction becomes necessary in cases of failed closed reduction, soft tissue interposition, greater tuberosity displacement, fracture displacement >1cm after reduction and large glenoid rim fracture
After treatment
following reduction, it is essential to securely fasten the arm to the chest with a body bandage for a minimum period of 3 weeks. failure to do so results in the development of recurrent shoulder dislocation due to faulty healing of the capsular rent
Posterior dislocation of the shoulder joint
posterior dislocation of the shoulder are seen in a small percentage of the patients say about 5% of the cases. they are occasionally due to the violent muscle contractions from electric shock or epileptic fits. it is due to the strength imbalance of the rotator cuff muscles. patient typically presents with a deformity of holding their arm internally rotated and adducted, there is flattening of the anterior shoulder with a prominent coracoid process.
Inferior dislocation ( Luxatio Erecta )
A rare injury results from a hyperabduction force, causing the head of the humerus to be positioned below the glenoid cavity, and the humeral shaft to point overhead. the shoulder becomes locked in 100 to 160 degree of abduction with the forearm positioned behind the head