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.

Clonus is a neurological condition that creates involuntary muscle contractions. This results in uncontrollable, rhythmic, shaking movements. It’s usually brought on by excessive muscle stretching.