Osteochondritis Dissecans is a relatively common childhood problem in the knee. The name means bone and cartilage breaking away from the underlying bone. It most commonly heals by itself, but in adults, or adolescents over the age of 14, it seems more likely to break off than to heal. It is less common in girls, but the upper age cutoff for might be lower.
<12 years of age – almost definitely will heal with activity modification
>12 & open physes – possibly will heal & can wait if few symptoms
closed physes – surgery is required if symptomatic, or sclerosis on XR
Other ways of classifying the problem are with an MRI scan, or arthroscopic surgery. The lesions likely to heal don’t have fluid underneath them, don’t have a defect in the joint surface, and are in younger patients. MRI is a good investigation to prove that surgery isn’t critical in the younger patients, or how complex the surgery needs to be in older patients.
This image shows a “fracture line” of osteochondritis dissecans (OCD) in yellow. In contrast, the growth plates around the knee cross the whole bone. The medial femoral condyle is the most common location for OCD.
Surgery to fix the OCD fragment depends on the age of the patient, whether the fragment is loose within the joint, and whether there is free fluid underneath the fragment. The most common situation is that the fragment is still in position, and although mobile. The typical surgery for these cases is the “drill” the lesion and stabilise it with bioabsorbable pins (“Smart Nails”). This is done arthroscopically (camera controlled, keyhole surgery), usually as day surgery. Typically three months off sport will see the OCD lesion heal, and although crutches might be used for the first week or so, they are not required beyond this.
This MRI image (side on view) show the Smart Nail tracks are disappearing, and the OCD fragment has healed.
In patients with significant fluid under the defect, sometimes screws and bone grafting is necessary.