Patellar Dislocation and Subluxation
Patellar dislocation occurs when the patella (kneecap) slips out of its normal position. Patella dislocation may be due to malalignment or a sudden twist of the leg while the foot is planted in a flexed position. It presents as a sudden sharp pain and inflammation with a mass (typically lateral) that is the patella (knee cap) located outside of its usual position.
It is common for many surrounding soft tissues to also be damaged in the process, including the muscles and tendons that attach to the patella as well as the articular (joint) surfaces of the patella and femoral condyle, located at the bottom of the femur.