The shoulder is the most mobile joint in the human body, with a complex arrangement of structures working together to provide the movement necessary for daily life. Unfortunately, this great mobility comes at the expense of stability.
Several bones and a network of soft tissue structures (ligaments, tendons and muscles) work together to produce shoulder movement. Each of these structures makes an important contribution to shoulder movement and stability. Certain work or sports activities can put great demands upon the shoulder, and injury can occur when the limits of movement are exceeded and/or the individual structures are overloaded.
Shoulder instability develops in two ways: it can be traumatic (injury related) or atraumatic in onset. Generally, traumatic onset instability begins when an injury causes a shoulder to develop repeated dislocations. The patient with atraumatic instability has generalized laxity or looseness in the joint that eventually causes the shoulder to become unstable.
Traumatic shoulder instability is most common in younger, athletic people. The younger and more active the patient is when the first dislocation occurs, the more likely it is recurrent instability will develop. For example, if the first dislocation occurs during the teenage years, there is a greater than 80 percent chance recurrent dislocations will develop. However, people over 40 with a first dislocation have less than a 20 percent risk of developing chronic instability. Treatment strategies are designed to suit each patient’s age and lifestyle.
When younger patients dislocate their shoulder typically the damage occurs to the ligaments and soft tissues around the rim of the socket. In patients over the age of 40 or 50 who dislocate, the damage is more likely to occur in the tendons (rotator cuff) or may even cause a fracture in one of the bones around the shoulder.
Initial treatment for recurrent instability of the shoulder centers on physical therapy. Strengthening the rotator cuff and scapular muscles may give stability to the joint. The goal of physical therapy is to help the muscles provide stability to the shoulder that the torn ligaments can no longer supply. Often, physical therapy can help regain lost motion, reduce apprehension and restore shoulder function.
Surgery is recommended if recurrent instability cannot be controlled with physical therapy and activity modification. Currently, the state of the art for surgically managing dislocations and instability is through arthroscopy. This involves minimally invasive, video-assisted techniques through small incisions that have revolutionized our understanding and treatment of this disorder and have dramatically improved the recovery post-operatively. Fortunately, with modern techniques, shoulder instability is a relative bump in the road rather than a career or activity ending injury.
Dr. Tom Hackett is an orthopedic surgeon who specializes in the arthroscopic management of shoulder and elbow disorders at the Steadman Hawkins Clinic in Vail.
