- Grade I – The patella occasionally pops out of its groove and then immediately pops back in. The patella is in the groove more than it is out of it. It may be that the only time the patella is out of the groove is when it is manipulated out of place by a veterinarian during an examination. Signs may range from none to occasional skipping or kicking out of the leg.
- Grade II – Pets may show a more persistent skipping gait, may intermittently hold the leg up, and may have a mild degree of lameness. The patella tends to be out of the groove more than it is in the groove. It is easily manipulated back into the groove.
- Grade III – The patella is always out of the groove, can be manipulated back into the groove, but will immediately pop out again. Pets have a more persistent lameness with increasing conformational abnormalities.
- Grade IV – These pets have a patella that rides out of the groove all the time and cannot be manipulated back into place. They have significant lameness, show outward signs of physical deformity and may walk with a "bow-legged" appearance. The knee usually cannot be extended.
How Is Patellar Luxation Diagnosed?
Patellar luxation is diagnosed through orthopedic examination and radiographs. The condition may be first detected, however, during a routine examination.
How Can Patellar Luxation Be Treated?
Pets with patellar luxation that exhibit no clinical signs should be monitored and do not typically warrant surgical correction. Surgery is dependent on clinical signs, age, and grade of patellar luxation. Surgery is usually considered once the condition is a Grade II or above. Surgical treatment seeks to realign the patella in its groove through basic surgical techniques. More advanced techniques can be employed to correct conformational abnormalities as needed, depending on the grade of patellar luxation.
Surgical corrections include:
- Deepening the groove over which the patella slides so that it can glide in its proper position.
- Changing the alignment of the patellar ligament attachment to prevent the pull of the quadriceps either to the inside or to the outside of the leg.
- Tightening or loosening the joint capsule attachments depending on the pull of the joint capsule on the patella.
- Cutting and properly aligning one or both bones to correct any abnormal bending or twisting action of the femur or tibia. (Usually required only for more severe cases.)
What To Expect After Surgery
When your pet returns home from surgery, confine the pet to a small area or room. For the first six weeks after your pet’s surgery, restrict exercise to short leash walks only. Increases in the duration of leash walks will depend on how quickly your pet recuperates from surgery. Pain medications for your pet will be provided as needed by your veterinarian. Physical therapy is generally recommended in order to provide the best post-surgical outcome.
Does Patellar Luxation Need To Be Treated?
If left untreated, the patella will continue to damage the cartilage of the joint, leading to the development of osteoarthritis. Patellar luxation can also contribute to the development of other conditions, such as cranial cruciate ligament rupture.