By Dr. Eric W. Edmonds
Most joints in the body function as complex hinges, however the shoulder experiences a large degree of freedom in motion. With this freedom comes the risk for instability. A dislocation is the act of a bone coming out of socket (or, a joint completely coming apart). Yet, not all instability events have to be traumatic dislocations.
Some instability events can actually be quite minute in nature. But, even the smallest events can be problematic if they occur on a recurrent basis. Most children are born with a good amount of flexibility and joint laxity or looseness. It is important to distinguish between flexibility and laxity.
Flexibility refers to the muscle tightness whereas the laxity refers to looseness of ligaments around a joint. Lacking flexibility in the presence of joint laxity is actually one of the greatest risk factors for joint injuries during sports. With maturity and skeletal growth the flexibility decreases and the joint looseness goes away in most children.
Some children continue to have joint laxity and the shoulder is notorious for this problem, especially in girls. Some people can voluntarily dislocate their shoulders. Usually, this represents a pathologic state of the shoulder termed multidirectional instability, or MDI. MDI can be non-painful and non-problematic to many people; and yet, some teenagers suffer terribly. Having a shoulder that can move more than average can be OK, and in fact can be necessary to be good at certain sports like gymnastics, swimming or volleyball. But, having shoulder pain that limits activities of daily living is not normal.
If the excessive motion of your child’s shoulder is associated with pain, then it is reasonable to seek medical intervention. The first line of treatment for these kids, after confirming that there is no fracture or other cause for the pain, is to enroll in physical therapy.
As previously mentioned, a bad combination is joint looseness and muscle tightness. Another bad player in this combination is muscle weakness. If the muscle mechanics are poor, then the entire foundation of the shoulder is on shaky ground. Physical therapy can help improve the muscle mechanics and thereby resolve the pain that comes with shoulder motion.
Surgery is rarely required for MDI, and traditionally, it was always frowned upon. However, recent evidence has demonstrated that young people with painful MDI that fail to fully improve with physical therapy may benefit from surgery that tightens the joint lining, removing the laxity. Results have been very promising, but expectations should be tempered since younger patients are at risk to loosen the shoulders with time even after a successful surgery.
Prevention of MDI is not really possible, as most experts believe that genetics plays a large role in shoulder laxity. However, it is possible to limit the pain that can be associated with this problem. If your child starts to experience pain with shoulder motion, it will be important to limit their activities.
Dr. Eric W. Edmonds is a pediatric and adolescent orthopedic sports medicine specialist at Rady Children’s Hospital-San Diego and an assistant professor of orthopedics at UC San Diego. He can be reached at sports@rchsd.org.