Multidirectional Instability (MDI) of the shoulder is defined as instability in more than one direction:  anterior, posterior, and/or inferior.  There is a common misconception that MDI is limited to young, inactive patients with generalized ligamentous laxity in many joints, bilateral symptoms, and without a history of trauma.  Although this comprises a group of these patients, shoulders with MDI are often seen in athletic patients, including gymnasts and butterfly swimmers, many of whom have had injuries. 

Patients with MDI may present in a variety of ways.  The instability may have occurred without significant injury and spontaneously reduced or self-reduced.  Extremely hypermobile shoulders can become symptomatic without unusual trauma, even with activities of daily living.  A typical presentation is a person with a relatively loose shoulder who stresses it repetitively in athletic activities or work-related events.  There is a subgroup of patients with MDI who have a family history of hypermobility.  Patients with connective tissue disorders, such as Ehlers-Danlos syndrome, or those who have biochemical abnormalities and ligamentous laxity syndromes may all be affected. 

The patient’s symptoms may provide some evidence of directional component to the instability.  Inferior instability may be associated with pain when carrying a heavy suitcase or bag.  Pain associated with pushing open heavy or revolving doors could suggest posterior instability.  Discomfort in the abducted, overhead, externally rotated position can suggest anterior instability (when throwing a ball).

Following diagnosis, a prolonged course of rehabilitation is recommended with emphasis on strengthening the muscles around the shoulder.  Patients may have an associated synovitis or secondary impingement syndrome accompanying their shoulder instability.  Nonsteroidal anti-inflammatory medication and/or a subacromial injection might be helpful in this instance.

If the patient has persistent involuntary instability symptoms that have not responded to conservative treatment, including a supervised physical therapy regimen and NSAIDs, then surgery is recommended.  Surgery may be considered sooner if a documented anatomic defect, such as a glenohumeral ligament avulsion is identified on the MRI.

• Shoulder Pain