Recurrent shoulder dislocations
Dislocations of the shoulder can be classified by time (acute, recurrent, chronic); mechanism (traumatic, atraumatic) and by activity (voluntary, habitual). Each of these may intersect with each other. Nevertheless, the most common of these are the recurrent, habitual, traumatic dislocations. This describes a clinical entity where a person, usually a young adult, is involved in an acute injury and has torn the anterior part of his glenoid labrum (Figure 1), resulting in a Bankart lesion. The shoulder is now no longer stable and becomes readily dislocated. This entity should not be confused with the recurrent, voluntary dislocation which usually happens in a person with hyperlaxity (“double-jointedness”) who can voluntarily pop out a joint (often as a party trick).
Figure 1. In recurrent shoulder dislocations, a relative small injury (ie. the detachment of the anterior glenoid labrum, a) results ina shoulder that becomes unstable and continually dislocates or pops out. This is readily appreciated on MRI as a detached anterior labrum (arrowed in b). Many operations have been devised in the past but the re-attachment of this labrum has now become the procedure of choice. This is usually done arthroscopically (a) with a stab incision in the back of the shoulder to introduce the camera (eye) and another stab in the top and front to introduce the instruments (tool).
The recurrent dislocation with a Bankart lesion is best thought of with the mnemonic TUBS (it is Traumatic, results in Unidirectional instability, is associated with a Bankart lesion, and is Surgically treated). An MRI is usually required to confirm the presence of the Bankart lesion (Figure 2) and to ensure one is not dealing with a voluntary dislocator. The procedure is relatively straightforward with an arthroscope introduced through the back of the shoulder into the joint and the instruments through the front of the joint (2 portal technique).
The voluntary dislocator is a person who should not be treated surgically as captured by the mnemonic AMBRI (it is Atraumatic, results in Multidirectional instability, is frequently Bilateral, should be treated with Rehabilitation or physiotherapy focusing on muscle coordination, and exceptionally requires an Inferior capsular shift). The inferior capsular shift involves tightening the lower recesses of the shoulder capsule and is prone to failure.
Results of Bankart repair surgery is excellent with most patients returning to the pre-injury level of activity.
Figure 2. Having introduced the camera and instruments, the Bankart lesion (or tear of the anterior labrum) is readily visualised (right panel), and can be reattached using the suture anchors. We prefer this 2-port technique although a similar 3-port technique is also performed by some surgeons.
Figure 3 (video). This patient, an avid surfer dislocated his shoulder many years before and was unable to return to sport. His shoulder would dislocate in specific situations (habitual dislocation). The MRI confirmed the presence of a Bankart and Hill-Sach lesion and he underwent arthroscopic reconstruction with a prompt return to sport at 3 months after surgery.