It is one of the most unstable and most commonly dislocated joint.
Definition – excessive translation of the humeral head that results in complete separation of the articular surfaces of the glenohumeral joint. 50% of all dislocations.
Why More susceptible-
- Shallowness of the glenoid socket
- Only one fourth of the large humeral head articulates with the glenoid at any given time.
- Capsule is lax and thin and, by itself, offers little resistance or stability
Structures important for joint stability
- Glenoid labrum-
It deepens the glenoid by 20%, may protect bone and probably assists lubrication
Accounts for 50% of the glenoid surface area
Increases the humeral contact to 75%.
- Muscles- The humeral head is compressed into the glenoid by the muscles of the rotator cuff and other scapulohumeral and thoracohumeral muscles.
- Glenoid Ligament-
Mechanism of injury-
- 96% of acute shoulder dislocation are traumatic in origin
- Labral lesions (Bankart lesions)
- Bony glenoid lesions – Osseous anterior glenoid rim fractures (44%), bony Bankart lesions, fracture of the greater tuberosity
- Ligamentous lesions – Anterior band of the IGHL
- Capsular abnormalities – Separation of the capsule from the anterior glenoid rim (85%)
- Hill-Sachs lesions
- Intra-articular loose body
- Rotator cuff lesions – Supraspinatus or subscapularis tears
What is Bankart lesion?
Due to a direct injury to back of shoulder or fall on elbow directed backward and outward , humeral head is forced forward out of the glenoid cavity and tears not only labrum from anterior half of glenoid rim but also capsule and periosteum from anterior surface of the neck of the scapula – BANKART’S LESION
- Most authors agree that the bankart lesion is the most commonly observed pathological lesion in recurrent dislocation but it is not the essential lesion
- Humeral head defect (Hill Sachs lesion)
Examination – Tests are done to identify instability.
Radiology- X rays can help diagnose a acute dislocation and also help in finding a bony glenoid and humeral head lesion. MRI is the investigation of choice.
Rationale for Treatment-
Indications:Failed nonoperative, Recurrent dislocation at young age, Irreducible dislocation, Open dislocation, Unstable reduction, 1st time YOUNG dislocation with HIGH demands (TUBS).
- Arthroscopic – Most commonly done. Minimum scar, minimum damage to the tissues, quick rehabilitation, faster recovery.
- Open with soft tissue repair – may be needed in very old cases.
- Failed arthroscopic or very old lesions with much bony changes and instability – Open with bony augmentation eg Latarjet.
Phase I-Rest and Immobilization (30 degrees ER), Pain control with NSAID and Ice applied to the shoulder
Phase II-Isometric strengthening, Isotonic strengthening
Phase III-Endurance building along with strengthening exercises. Goal: the patient reaches 90% strength in the injured shoulder compared with the uninjured shoulder
Phase IV-Increase activity to sport- or job-specific activities