Multidirectional instability of the glenohumeral joint.

The concept of multidirectional instability (MDI) was introduced as an important clinical entity in 1980. Previously, it had received little mention in the literature and was not considered to be clinically relevant. MDI is a symptomatic glenohumeral subluxation or dislocation occurring in more than one direction. The basic pathology of this condition is a loose and redundant joint capsule. Most patients with MDI can be treated successfully by conservative methods, such as patient education, a shoulder girdle strengthening program, or modification of the patient's routine activity.