Shoulder Instability

Shoulder instability refers to a condition where the structures surrounding the shoulder joint are unable to maintain its proper position, leading to frequent dislocations or subluxations.

Shoulder is the most common joint in the body to dislocate. Due to its ball and socket design we have a great deal of mobility within the shoulder, which is directly at the cost of stability.

Shoulder joint socket is formed by bony glenoid and labrum attached to it, while ball is formed by head of humerus (arm bone). Shoulder dislocates anteriorly far more commonly than posterior. Glenoid labrum is crucial stabilizing factor that tears when shoulder dislocates. It is known as Bankart tear or Bankart lesion. When shoulder dislocates it leads to cuticle depression injury on posterolateral portion of head of humerus known as Hill sach’s lesion.

Traumatic shoulder dislocation usually recurs leading to shoulder instability. Occur frequently in young patients. If age at first dislocation is in second or third decade chances of recurrence are high. After first traumatic dislocation there is 50-60% possibility of recurrence, while after second episode that increases to more than 90%. With every dislocation it damages Labrum and anterior portion of glenoid bone. It is usually predisposed by activities like throwing where shoulder is abducted and rotated externally.

Diagnosis

MRI – it is a investigation of choice in diagnosing Bankart’s tear.
X ray – It is investigation of choice in diagnosing acute dislocation. Specific views help in assessing extent of hill sach’s in recurrent shoulder instability.
CT Scan – may be needed in planning of treatment to assess extent of bone loss.

Treatment

Acute shoulder dislocation needs to be reduced by orthopaedic surgeon under suitable anaesthesia.
Rest in sling, ice , medicines and physical therapy are important
In recurrent shoulder instability surgical intervention is needed depending on age, dislocations and bone loss.
Arthroscopic Bankart repair – it is a keyhole surgery where anterior labrum can be repaired to glenoid with the help of suture anchors.
Latarjet procedure – this procedure is required if significant bone loss is present. Coracoids process (part of bone scapula) along with its muscle attached is fixed to glenoid rim.