Medial Patellar Luxation Repair

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A patellar luxation occurs when a dog’s kneecap slips out of its proper position and becomes unable to fully glide down the groove of the femur. A medial patellar luxation (MPL), the most common type, occurs when the kneecap slides to the inside of knee. This is normally caused by a congenital abnormality like a misshapen femur or tibia, shallow femoral groove or hip dysplasia, or as a result from knee trauma. Small breeds are especially prone to MPL, but it can occur in larger dogs as well.

If left untreated, medial patellar luxations can result in osteoarthritis, weakness on rear legs, chronic limping, cartilage damage and ligament tears.

Medial patellar luxations are graded according to severity and frequency of displacement:

Grade I: Occasional patella displacement, but remains in the groove the majority of time. Symptoms may include skipping or kicking out of the leg.
Grade II: Frequent patella displacement characterized by a persistent skipping gait and a mild degree of lameness; patella can be manipulated back into the groove.
Grade III: Patella is always displaced, frequent lameness; patella can be manipulated into the groove but will pop out immediately.
Grade IV: Patella is always displaced and cannot be manipulated back into the groove, constant lameness, signs of physical deformity and a bow-legged appearance. The knee cannot be extended.

Diagnosis and Treatment

Patellar luxations are often discovered during annual physicals and other general examinations. If an MPL is suspected, your Bethany Family Pet Clinic veterinarian will examine your pet’s knee for signs of displacement.

Surgery is recommended to treat MPL grades III and IV, and select grade II cases. The procedure aims to realign patella using a number of techniques including deepening the femoral groove, altering the alignment of the patellar ligament, readjusting the leg bones and fixing the joint attachments. Pre-surgical radiographs (x-rays) are taken to determine the exact surgery technique needed for each individual patient.


Patellar luxation surgery is a major surgical procedure that requires an initial recovery period of 8 weeks to allow for bone healing at the osteotomy site. Patients require exercise restriction during this period. After this initial period patients are able to have gradually increasing amounts of exercise based on how they are doing. Our veterinarian will advise you about the amount of exercise your pet can have at various stages of healing. Pain relief medications are prescribed following the procedure to manage discomfort. Pets must wear a collar to prevent licking the incision for the first two weeks following surgery. Regular veterinary postoperative checkups including follow-up x-rays will monitor your pet’s recovery. The cost of your pet’s postoperative recheck examinations and postoperative x-rays are included in the price of TTA surgery. We want you to call us if you have any questions after your pet’s surgery at Bethany Family Pet Clinic.