Multidirectional and Global Shoulder Instability

Description

Most shoulder instability has a direction: the ball slips out the front after a tackle, or out the back after years of pushing. This guide is about the shoulders that are loose in more than one direction, usually without any real injury at all. These are different problems with a different plan, and they are common in teenagers, especially swimmers, gymnasts, dancers, volleyball players, and anyone who is naturally flexible.

Three terms come up, and it helps to keep them apart:

• Laxity is a loose joint without symptoms. Many healthy teenagers can slide the ball partway out of the socket, and many flexible people have loose shoulders, elbows, and knees. Laxity by itself is not a diagnosis and does not need treatment.
• Multidirectional instability (MDI) is a shoulder that is loose in two or more directions and causes symptoms: pain, slipping, a dead-arm feeling, or weakness. It is usually in both shoulders, usually starts without an injury, and the joint capsule is baggy all the way around.
• Global instability is the far end of the same spectrum: a shoulder that can slip in every direction, front, back, and down, often very easily. It is most often seen with a connective tissue condition such as Ehlers-Danlos syndrome or Marfan syndrome, or in a shoulder whose muscles have learned to fire in the wrong pattern, so the joint moves out of place during ordinary reaching. Some teenagers can pop the shoulder out on purpose; that is a muscle-pattern problem, not a surgical one.

How it happens (the mechanism)

The shoulder socket is shallow, so the joint depends on soft tissue and muscle to stay centered. In MDI, the capsule that wraps the joint is larger and more elastic than usual, sometimes from birth and sometimes stretched by years of overhead sport. The ligaments that normally tighten at the end of each motion do not tighten until the ball has already drifted. The rotator cuff and the muscles of the shoulder blade then have to do all the work of keeping the ball centered, and when they tire or fire late, the ball slides and the shoulder hurts.

In global instability from a connective tissue condition, the ligaments themselves are made of tissue that stretches more than it should, so every joint is affected to some degree. In the muscle-patterning type, the big muscles around the shoulder (especially the pectoralis major and the latissimus) pull the ball out of place during movement, and the problem is in the timing rather than the tissue.

Symptoms

• Aching in the shoulder with overhead activity, carrying bags, or at the end of a long day.
• A feeling of the shoulder slipping, especially when carrying something heavy at the side (the ball drops down) or reaching across the body.
• Dead-arm episodes: a sudden loss of power and a tingling arm that passes in minutes.
• Clicking, clunking, or a sense that the shoulder is "not in the right place."
• Usually both shoulders, often with loose elbows, knees, and fingers too.
• In the global type, the shoulder may come out with little or no force, or on purpose.

Doctor examination and imaging

I look for looseness in each direction: pulling the arm down to see the ball drop (a sulcus sign), and loading it forward and backward. I check the other shoulder and the other joints with a simple nine-point flexibility score, and I ask about skin, bruising, and family history when a connective tissue condition is possible. I watch the shoulder blade while the arm moves, because scapular control is almost always part of the problem. X-rays are usually normal. An MRI with dye may show a roomy capsule and sometimes a labrum tear from repeated slipping, but the diagnosis is made on the exam, not the scan.

Treatment

Therapy, and plenty of it. This is the opposite of a one-time dislocation. The treatment for MDI is a long, structured strengthening program, usually six months at minimum, that rebuilds the rotator cuff and retrains the shoulder blade so the muscles keep the ball centered. It takes patience, and it works: most teenagers with MDI improve enough with therapy that surgery never comes up. My home program for shoulder instability and scapular dyskinesis describes the stages. For the muscle-patterning type, the therapist's job is to retrain timing, and biofeedback is sometimes used.

Activity changes. Avoiding the end-range positions that let the ball slide until the muscles can control them, and in some sports, a brief change of event or position.

Surgery. Reserved for the shoulder that still slips and hurts after a genuine six-month program. The usual operation is an arthroscopic capsular plication, which tightens the baggy capsule with stitches, and it is combined with a labrum repair if there is a tear. Results are good when the problem is the tissue, and poor when the problem is muscle patterning or a connective tissue condition, which is why the exam matters so much before anyone operates. A sling for about six weeks, therapy for six months, and a return to overhead sport at about nine months.

Recovery and long-term outlook

Most teenagers with MDI do well with therapy and grow into adults with stable shoulders, especially as the natural looseness of adolescence settles. The program has to become a habit, because the capsule does not tighten on its own. Global instability with a connective tissue condition is managed over the long term, with strengthening as the mainstay and surgery used very selectively.

When to call the doctor

Call if the shoulder dislocates and does not go back, if there is numbness or weakness in the arm, if the shoulder is slipping more often despite therapy, or if other joints are also dislocating, which is a reason to look for a connective tissue condition.

Learn more

OrthoInfo (AAOS), Chronic Shoulder Instability: orthoinfo.aaos.org (opens in a new tab)

My guides to anterior shoulder instability, posterior shoulder instability, scapular dyskinesis, and Ehlers-Danlos syndromes.

This information is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. For specific concerns about your child, consult a board-certified, fellowship-trained pediatric orthopaedic surgeon.