Multidirectional Instability
What is it: Multidirectional instability (MDI) is inferior and anterior and/or posterior instability of the shoulder.
How does it present: MDI is often seen in athletes or patients that do repetitive overhead motions. It may be more common in patients that have general ligamentous laxity (those with a positive thumb to forearm sign or genu recurvatum). Patients will often come in with complaints of rotator cuff injuries.
Common exam findings: In patients presenting with rotator cuff injuries, stability should be tested with the Sulcus Sign, Anterior Load and Shift Test, and Apprehension and Relocation Test to determine if an underlying MDI is contributing to the injury. These patients may be at greater risk of shoulder subluxation or dislocation and may have had past occurrences of these conditions.
Tests and treatment: X-rays may be taken to evaluate for any bony pathology. In the case of previous dislocation, a Hill-Sachs lesion could be present on the humeral head. MRI +/- arthrogram or ultrasound may be indicated if there is further need to evaluate for labral or rotator cuff injury. Most rotator cuff injuries associated with MDI are treated with physical therapy to improve strength of the rotator cuff muscles and therefore improve stability. In resistant cases, orthopedic referral may be indicated to consider surgical intervention.