Overview
what it is and why it mattersOsteochondritis dissecans (OCD) is when a small patch of bone and the cartilage covering it loses its blood supply, dies, and can break loose into the joint. In the knee, it almost always sits on the inner knuckle at the end of your thigh bone (the medial femoral condyle). It hits active teens and young adults the most. Why it starts isn't fully understood, but repeated small impacts on growing bone seem to be the trigger.
If the fragment is still stuck in place, simply stopping the activity that aggravates it and taking weight off the knee often lets it heal on its own. If it's lifted off the bone or floated free, you need surgery to put it back or replace it.
Symptoms
what you may notice- Vague knee pain with activity — an ache deep in the knee that's hard to pinpoint at first, worse with running, jumping, or stairs.
- Intermittent swelling — the knee puffs up after activity, then settles with rest.
- Catching or locking — if a fragment has broken loose, the knee may catch mid-stride or lock in a bent position until you shift it free.
- Stiffness after rest — the knee feels tight after sitting for a while, loosening up once you start moving.
Diagnosis
exam first, imaging secondVague knee pain that flares with activity, sometimes with swelling or a catching/locking feeling if a piece has broken free. X-rays show a dim spot on the end of the thigh bone where the lesion sits. An MRI is the key test — bright fluid tracking behind the fragment means it's unstable. Whether your growth plates are still open matters a lot, because younger bone has a much better chance of healing on its own.
Treatment Path
how care progresses at OSI1
Activity modification & unloading
When the fragment is stable and the growth plates haven't closed yet, the plan is crutches, no high-impact activity, and repeat MRIs every few months to confirm the bone is filling back in. Younger bone heals well on its own when given the chance.
2
Physical therapy
Once the lesion has healed, physical therapy rebuilds the thigh muscles around the knee so you can return to activity safely.
Surgical Options at OSI
if non-operative care isn't enoughSurgery is the answer when MRI shows the fragment is loose, when a piece has already broken off and is floating in the joint, when months of activity restriction haven't worked, or when the growth plates have closed and the bone has lost its built-in ability to heal itself.
Providers Who Treat Osteochondritis Dissecans
sports-medicine team
Further Reading
authoritative sourcesExternal patient-education references and related OSI pages for additional background: