What is Multidirectional Instability?
Instability may be described by the direction in which the humerus is subluxated or dislocated from the glenoid. When it occurs in several directions it is referred to as multidirectional instability. There may be one predominant direction of instability, but in this condition the ball can move in multiple planes. It is often associated with ligamentous laxity of the joint (loose ligaments around the shoulder). Some people are born with a tendency to have loose ligaments, but it can also occur progressively over time if the ligaments become progressively more stretched out, for example with repetitive overhead activities.
Symptoms of Multidirectional Instability
You may feel instability or looseness of your shoulder joint. Some people may even have the ability to use their own muscle to move the shoulder out of joint (voluntary instability). Other symptoms include:
- Vague pain in your shoulder which is aggravated by certain activities or arm positions
- Difficulty performing overhead activities
- Weakness of the arm
- Clunking of the shoulder in certain positions or with certain movements
Diagnosis of Multidirectional Instability
Your doctor will review your medical history and perform a physical examination to assess the instability of your shoulder and identify its cause. Joint laxity and the strength of the rotator cuff muscles are assessed. Multidirectional instability is diagnosed with the help of specific tests. Imaging tests such as an X-ray or an MRI scan help visualize the shoulder joint and its supportive structures.
Treatment of Multidirectional Instability
Your physical therapist will plan an exercise program which may include:
- Strengthening exercises for the rotator cuff muscles and the muscles that stabilize the shoulder blade
- Exercise to help you return to daily activities and sports
Conservative treatment methods and rehabilitation help most people with multidirectional instability.
Surgery is considered only if your symptoms persist, and/or if there is clear evidence on an MRI that there is structural damage in the joint. It may involve arthroscopy or open surgery.
Arthroscopy involves the insertion of a thin device with a camera to view the shoulder joint on a monitor and perform the necessary surgical procedure. Open surgery involves a larger incision, and the procedure is performed under direct visualization. The most common surgery performed for multidirectional instability is a capsular shift where the capsule and ligaments enclosing the shoulder joint are tightened to reduce redundancy and help stabilize the joint again.