By Dr. Eric W. Edmonds
A child’s bone grows at specific locations called growth plates. The growth plates provide the changes in length that we see in our kids’ arms and legs with maturity. The main growth plates are near the ends of the bones. But, directly on the ends of long bones is a second area of growth that contributes more to the shape of the joint than the length of the bone.
On the outer side of the elbow is an area of upper arm bone called the capitellum. This is an important part of the elbow joint, as it is the base on which the forearm rotates giving us supination and pronation.
Normally a rounded surface, when the capitellum becomes flattened in children it is termed Panner’s disease. Many specialists believe that Panner’s disease results from an injury to the secondary area of growth at the capitellum. The injury results in a loss of blood supply causing the nearby bone to soften and then collapse.
This is most often seen in boys, but can occur in girls, between the ages of 5 and 10. Almost without fail, it is the dominant arm that is affected. The most likely cause of injury in this youthful group is repeated mild injuries that have a cumulative effect on the capitellum. For example, the young 8-year-old baseball pitcher may not have a single event that causes trauma, but repetitive throwing with the susceptible arm may cause Panner’s disease to appear.
The symptoms of Panner’s disease may include many nonspecific findings. The most common findings is elbow pain, particularly on the outer side that is worsened with activity and improves with rest. Occasionally, there also may be a limitation in elbow motion.
Ultimately, Panner’s disease tends to be a diagnosis based on X-ray findings. Usually, the capitellum has lost its round shape and looks flat, which indicates that bone collapse has occurred. Advanced studies (such as MRI or CT scans) are not usually necessary.
A period of rest from sports that use the elbow and throwing activities is the treatment of choice. This needs to be done until the X-rays and the pain have improved. Over one to two years, the bone will remodel itself and the flattened capitellum will get back its normal round shape. In the interim, not only is physical therapy rarely needed, but most children recover with very little treatment.
It is important to distinguish this relatively benign problem from osteochondritis diseccans (OCD) of the capitellum, which occurs in older kids and may require surgery to resolve. Some specialists believe that OCD of the capitellum could start as untreated Panner’s disease, so it is important to monitor your child’s progress.
The goal is to return your child to his or her sport as quickly and safely as possible. Elbow pain in this young group should not be ignored, especially if it lasts more than a few days.
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.