Multiple cartilaginous exostoses (MCE) is an overgrowth of bone called exostosis or exostoses (plural form). In MCE, there are many bony projections or exostoses. They are covered or capped by cartilage. The bones affected most often are the long tubular bones of the forearm and lower leg. Sometimes flat bones, vertebrae, ribs, and short tubular bones can be affected, too.
The condition is inherited and is present in childhood. Deformity of the bones in the lower leg is often accompanied by an ankle problem called ankle valgus. Valgus refers to the way the side of the ankle that is closest to the other leg drops down toward the floor. This happens because the tibia (larger of the two lower leg bones) is tapered at the bottom. At the same time, the fibula (smaller bone on the outside of the lower leg) is shortened. When the bones shift in response to these changes, ankle valgus occurs.
In mild cases. MCE occurs as a stand alone problem. But when MCE is severe, there is a problem in the lower leg and deformity of the forearm. the bones in the forearm (radius, ulna) are deformed and/or shortened. These changes can affect motion and function.
If the problem is caught early enough, the ankle (valgus) joint deformity can be corrected. The goal is to prevent ankle arthritis later. Some surgeons try to correct the ankle deformity by performing a partial ankle fusion. The bones on the medial side of the ankle (closest to the other ankle) are fused together. A fusion helps hold the bones in place and stabilize the ankle. The procedure is called a partial epiphysiodesis.
Your pediatrician is a good place to start. Treatment may depend on the severity of the problem. A referral to an orthopedic surgeon may be needed. Your pediatrician will guide you through this process.