Patellar Luxation Surgery for Pets

Trochlear Wedge Recession & Tibial Crest Transposition

The quadriceps muscle pulls the knee cap (patella) up and down in a groove at the knee. Luxation means the patella slips out of the groove and goes to the side.Slipping to the inside of the knee is more common (80%) and occurs in small breed dogs. Large breed dogs luxate the patella to the outside of the knee. The most common cause for luxation is poor conformation. Small breed dogs have bow-legged conformation and large breed dogs have a knock-knee appearance. Both conformations result from curved and rotated femur or tibia bones. The point of the knee where the quadriceps attaches is called the tibial crest. If the crest is too far on the inside of the tibia, the patella slips to the inside when the quadriceps muscle pulls it.

The seriousness of the luxation is graded. Grade 1 patellar luxation does not require surgery because it is intermittent. Grade II luxation is more frequent. Grades III and IV require surgical correction to allow use of the leg without constant luxation.

Surgery not only corrects the luxation but helps prevent the arthritis associated with persistent luxation. The earlier correction is performed, the better because more arthritis and pain can be prevented. Surgical techniques to keep the patella in the groove include making the groove deeper (Trochlear Wedge Recession) and moving the attachment of the patella to a more normal position (Tibial Crest Transposition). The soft tissues surrounding the knee are also sutured to allow more normal knee function. The surgery is often necessary on both knees. After surgery, most pets do well because the function of the knee is more normal and less painful. Radiographs help evaluate arthritis and healing. Confine pets for two months while healing.