Subluxation is another word for partial dislocation of a bone. Patellar subluxation is a partial dislocation of the kneecap (patella). It’s also known as patellar instability or kneecap instability.

Patellar tendonitis is a common injury or inflammation of the tendon that connects your kneecap (patella) to your shinbone (tibia). Your pain may be mild or severe. Anyone can get patellar tendonitis.