Unstable Patella

The kneecap (patella) forms a very important part of your knee joint. It sits in a groove on the front of your femur (thigh bone). On its under surface, the patella has a thick layer of cartilage that allows your kneecap to glide smoothly as you bend and straighten your knee.

The thigh muscle (quadriceps) is attached to the kneecap, which is then attached to the top of the shin bone (tibia) by the patella tendon.

The groove that the kneecap sits in is called the trochlea. Normally, it sits snugly in the center of this groove, and as the knee bends and straightens, it should travel straight up and down the trochlea.

In people with an unstable patella, the kneecap doens't travel in a straight line. Instead it travels unevenly in the trochlea or rides out of it.

Other names

  • patella subluxation
  • patella maltracking
6 August, 2011