Patellar Luxation

Patellar Luxation


My small breed dog will frequently pull up lame while running, but soon will return to normal.  What causes this condition?

It may be a condition called Patellar Luxation where the kneecap will move out of place.  The kneecap, the petella in medical terms, guides the up and down action of the thigh bone (femur), and accompanying muscle, using bony ridges built into the femur.  While more frequent in small breeds it is also found in larger breeds.

Occasionally, because of a malformation of the femur or because of a trauma, too shallow of a grove exists and the patella will move causing the leg to “lock up”.  It will usually return to its normal position once the muscles again relax and lengthen.  Without treatment the groove will usually continue to become more shallow and leads to osteoarthritis and associated pain and could cause them to eventually stop using the limb.

There are four degrees and all but the first level will usually require surgery to correct:

    1.  Knee cap returns to its normal position spontaneously
    2.  Knee cap leaves the groove occasionally and can be replaced in the groove by manipulation
    3.  Knee cap leaves the groove most of the time but can be replaced in the groove via manipulation
    4.  Knee cap rides out of its groove all the time and cannot be replaced inside the groove


The surgery will usually correct the problem and the dog should have normal function of its leg returned within 30 days.

Please visit the following web sites for more in depth discussion of Patellar Luxation

Orthopedic Foundation for Animals (OFA)