Shoulder Dislocation - Basics

DISLOCATON : Is complete loss of contact between to articular surfaces forming the joint.

SUBLUXATION :Is partial dislocation

Acute joint dislocations are medical emergency because of chances of injuries to surrounding blood vessels and nerve.

Shoulder Dislocation

•By the virtue of its anatomy & biomechanics, shoulder joint is one of the most unstable joint in body

•It has an excellent range of mobility, but at the cost of stability

•It constitutes bout 50% of all dislocations

ANATOMY

•The head of the humerus is 3 times that of glenoid cavity area wise

•It forms an 135 degree angle with the axis of the shaft of humerus & an angle of 30 degree with the frontal plane

•The anatomical neck makes an angle of 45 degree with the horizontal plane

•Glenoid labrum deepens the joint by 50% & increase the humeral contact by 75%

STABILITY FACTORS

•ANATOMIC factors

1.Labrum increases socket depth

2.Labrum bonding strength

3.Adhesions

•Dynamic Factors

1.Supraspinatus

2.Subscapularis

3.Infraspinatus

4.Long head of biceps

•Static Factors

1.Superior glenohumeral ligament

2.Middle glenohumeral ligament

3.Inferior glenohumeral ligament

4.Coracohumeral ligament

Arterial supply

•Ant. Circumplex humeral artery

•Post. Circumflex humeral artery

•Suprascapular artery

•Circumflex scapular artery

Nerve supply

From posterior cord of brachial plexus & from suprascapular, axillary & lateral pectoral nerve

CLASSIFICATION

•On basis of frequency

1.Acute

2.Recurrent

3.Chronic (fixed)

4.Habitual

•On basis of etiology

1.Trumatic

2.Atraumatic

3.Congenital

4.Neuromascular (erb’s palsy, seizures, cerebral palsy)

•On the basis of direction of dislocation

1.Anterior

2.Posterior

3.Inferior

4.Superior