Osteochondritis dissecans (OCD) of the knee is a problem where a small patch of bone just under the joint cartilage loses its blood supply, softens and can start to crack loose. It is not related to obsessive-compulsive disorder. It mostly affects active children and teens, usually between about 10 and 20.
The good news for growing children: if the patch is stable, MORE THAN HALF heal without surgery, with a few months off running and jumping sports.
Teens near the end of growth and adults do less well. Unstable or loose fragments usually need surgery, and return to sport after surgery typically takes about 4 to 6 months.
What it is and who gets it
The patch is called a lesion. In the knee it most often sits on the end of the thighbone, usually on the inner side. OCD can occur in other joints, but the knee is the most common.
- Age: most common between about 12 and 19
- Sex: boys are affected more often than girls
- Activity: it is common in young athletes who train hard and often, especially in running and jumping sports
- Cause: not fully known. Repeated stress on the bone over time is thought to play a big part, and some families seem more prone to it
Symptoms
- Vague knee ache during or after sport, that is hard to pinpoint
- Swelling after activity
- A limp, or walking with the foot turned out to ease the pain
- Catching, locking or giving way, which can mean the fragment is loose
Early OCD is easy to miss because the pain is mild and comes and goes. Knee pain that keeps coming back with sport in a young athlete deserves an X-ray. It is often mistaken for more common teenage knee pain. See runner’s knee and jumper’s knee.
Children versus adults
Growth plates are the zones of growing bone near the ends of the long bones. Whether they are still open is the single biggest factor in how OCD behaves.
- Still growing (open growth plates): the bone has a good blood supply and a strong ability to heal. Many stable lesions heal with rest alone
- Finished growing (closed growth plates): healing is slower and less reliable, fragments are more likely to loosen, and surgery is needed more often
Stable versus unstable lesions
- Stable: the fragment is still firmly attached, and the cartilage over it is intact. This is the kind that can heal on its own
- Unstable: the fragment is loose, cracked around its edge, or has come off and is floating in the joint. This kind rarely heals without surgery
An MRI scan is usually used to tell the two apart and to measure the size of the lesion.
Pain-free is not the same as healed. In OCD, the X-ray or MRI decides when the knee is ready, not how the knee feels.
Treatment without surgery
This is the usual first step for a stable lesion in a child who is still growing.
- Stop running and jumping sports for a period, usually several months. Everyday walking is usually fine
- Crutches or a brace for a few weeks if walking hurts
- Keep moving in other ways: gentle cycling, swimming and strength work for the hips and thighs, as your doctor allows
- Repeat X-rays or MRI every few months to check that the bone is filling in
Many children feel better within 2 to 4 months, but full healing on imaging can take 6 months or longer.
When surgery is needed
- The fragment is unstable or loose
- A stable lesion isn’t healing after several months of proper rest
- The growth plates are closing and the lesion is large or painful
Options include drilling small holes into the lesion to bring in fresh blood supply, pinning or screwing a loose fragment back in place, or, when the fragment can’t be saved, filling the gap with new cartilage and bone. See cartilage repair surgery recovery.
Return to sport timeline
- Without surgery: once the knee is pain-free, strength is back, and imaging shows the bone has healed. This usually means several months, and sometimes longer
- After drilling or fixation: crutches for about 6 weeks, then a few months of physical therapy. Most return to sport after about 4 to 6 months
- After cartilage restoration: usually longer, depending on the procedure
A note for parents
You did not cause this, and neither did your child’s coach.
The hardest part is usually the waiting. A teenager who feels fine after 6 weeks will want to play. Coming back before the bone has healed risks turning a stable lesion into a loose one, which is much harder to fix. Keep them active in ways that spare the knee, and let the scans set the timeline.
The OrthoInfo guide to osteochondritis dissecans explains the treatment options clearly.
Get urgent medical help if
- The knee locks and won’t straighten
- The knee suddenly swells up and becomes very painful
- The knee is hot, red and swollen, and your child has a fever. That needs checking the same day
See your doctor if
- Knee pain keeps coming back with sport for more than a few weeks
- Your child limps, especially if they also have pain in the hip or thigh. In children, hip problems can show up as knee pain
- Pain returns after going back to sport
In a growing knee, rest does much of the healing. The scan, not the pain, says when it’s done.