The degree of instability is also an important component of the classification. During a dislocation, the ball partially leaves the socket, but then goes back into place. C. Chronology - The timing of the dislocation is also a part of the classification. D. Etiology - The cause of the instability is important because it implies different management. A dislocation or partial dislocation may be traumatic or atraumatic.
Traumatic dislocations occur as a result of a significant injury.
Unidirectional instabilities of the shoulder occur anteriorly, toward to front of the body, or posteriorly, toward the rear of the body, with acute anterior instability historically being the most common. Inferior instability, toward the feet, and anterior instability, upward, along with anterior and posterior are the most common MDIs. However, instability in all three directions may occur. A Bankart lesion is a tearing away of this labrum from the glenoid rim. Bankart lesions typically result from recurrent partial or full anterior dislocations of the shoulder and are a major cause of shoulder instability.