Can patellar dislocation cause knee cartilage injury?

The injury can happen as the kneecap leaves its groove and again as it returns. The same force may bruise the underlying bone or release a cartilage-and-bone fragment into the joint. Not every dislocation produces the same damage, so the knee needs an assessment after the kneecap has moved out of place.

Articular cartilage forms the smooth gliding surfaces on the underside of the patella and along the femoral groove. A dislocation pushes these surfaces against an edge of bone. A shallow scuff may irritate the joint, while a deeper osteochondral injury includes the bone beneath the cartilage.

Swelling, pain at the front of the knee, catching, locking, or difficulty fully straightening the leg can follow. Those features do not reveal the exact size or location of an injury. Examination and imaging are used to check kneecap alignment, ligaments, bone, and cartilage; a plain X-ray and an MRI answer different questions.

If the kneecap still looks displaced, keep the knee supported in the most comfortable position and seek urgent medical help. Do not force it back yourself. If it returned by itself, the injury still merits timely review because cartilage damage, a loose fragment, or ligament injury may not be obvious from appearance alone.

Until you receive advice, limit twisting and impact, use cold therapy with a cloth barrier for swelling, and follow instructions about weight bearing or bracing. Rehabilitation commonly restores movement, quadriceps control, and kneecap tracking in stages. Surgery may be discussed when imaging shows a repairable loose fragment or when significant instability continues; it is not required for every cartilage injury.

Go for urgent assessment if the kneecap remains out of position, the knee is visibly deformed, you cannot safely bear weight, or swelling builds quickly after the injury. A cold or pale foot, new foot numbness, or inability to move the toes requires emergency care because circulation or nerves may be affected.

Contact an orthopaedic or sports medicine clinician promptly if the knee repeatedly locks, will not fully straighten, keeps giving way, or remains markedly swollen. These problems can reflect a loose fragment or continuing instability and should guide how soon imaging and treatment occur.

You can ask whether imaging shows a cartilage or osteochondral fragment, whether the fragment is stable, and whether the stabilising ligament was injured. Clarify how long to use any brace, when weight bearing and bending may progress, which exercises fit the current healing stage, and what symptoms should bring you back sooner.