Osteochondritis dissecans (OCD) is a problem that affects the end of the femur (thigh bone) at the knee. The joint surface is damaged and doesn’t heal naturally. The problem occurs where the cartilage of the knee attaches to the bone underneath.
The area of bone just under the cartilage surface is injured, leading to damage to the blood vessels of the bone. Without blood flow, the area of damaged bone dies. This area of dead bone can be seen on an X-ray and is sometimes referred to as the osteochondritis lesion. A bone fragment with the layer of articular cartilage covering it detaches from the bone.
Six months of conservative care with activity restriction and casting or bracing for the first six to 12 weeks is the standard approach to this problem. If the lesion is small and stable (no disruption of the cartilage), the chances of healing are much greater than if there is a big chunk of bone and attached cartilage that has pulled away from the bone.
Your orthopedic surgeon will advise you regarding progression of activity. His or her decision is based on your son’s symptoms and results of imaging studies. Don’t be surprised if you are asked to get X-rays and MRIs several times over the next six months.
Serial images every six to eight weeks is the best way to assess healing in lesions of this type. And both X-rays and MRIs offer a different view of the healing structures. They are both essential in the diagnosis, treatment, and follow-up.
Young children who are still growing must be watched very carefully. Any disruption of the growth plate can disturb bone growth leading to a leg-length discrepancy. MRIs are especially helpful in showing changes in the signal intensity between the lesion and the growth plate. This information will be used to guide treatment. If the lesion is too severe and/or not showing any signs of healing, then surgery may be the next step.