Bankart lesions are another type of labral tear. They occur as a result of a shoulder dislocation or multiple dislocations. When the ball (humeral head) dislocates out of the socket (glenoid), the ligaments that normally hold these two structures together will either stretch or tear. When they tear it is called a Bankart Lesion. In this case the inferior (i.e. lower) glenohumeral ligament pulls the inferior labrum away from the glenoid. Less commonly the ligament will pull the labrum with a piece of bone—this is known as a bony Bankart lesion. Most shoulder dislocations have to be forcefully relocated (i.e., put back in place) by a doctor, sometimes with sedation. Next, the patient is placed in a sling for immobilization that allows some scarring and healing of the damaged ligament, labrum and /or bone. In many cases, however, these structures do not heal in the correctly. Studies have shown variable results with non-surgical treatment. Many published studies have noted re-dislocation rates of 75-90% in patients under the age of 25 with a first time dislocation. This risk is greatest for dominant arms of active individuals.
The lesion is associated exclusively with anterior shoulder dislocations. When it is driven from the glenohumeral cavity, the relatively soft head of the humerus impacts against the anterior edge of the glenoid. The result is a divot or flattening in the posteromedial aspect of the humeral head (typically referred to as a 3 to 6 o’clock lesion for the right humeral head if seen from the bottom). The mechanism which leads to shoulder dislocation is usually traumatic but can vary, especially if there is history of previous dislocations. Sports, falls, seizures, assaults, throwing, reaching, pulling on the arm, or even just turning over in bed can all be causes of anterior dislocations.