Grade one pets do not experience pain. Their kneecap pops out of place intermittently and can be easily massaged back into place when the leg is fully extended.
Grade II pets have less stable knees. The kneecap can be massaged back into its groove - but it pops back out again once the knee is manually flexed or after the pet has taken a few steps. With time, many of these pets will develop knee pain and arthritis associated with their problem.
Those in which the problem seems more pronounced or when persistent pain or arthritic changes are already present are placed in grade III.
These are pets whose kneecap will not stay in its groove even for short periods. These dogs have a hard time walking. Dogs that have suffered this degree of joint damage for more than a year or two usually have pain, developing arthritis and degenerative joint disease. They usually walk with a crouching stance and stand knock-kneed with their toes turned inward.
In contrasted with cruciate ligament or hip surgery , patellar surgery is less invasive, less expensive and generally has much better outcomes. When patellar surgery is performed before arthritic changes have occurred in the knee, the surgery is usually very successful. Once arthritic changes have developed, surgery is much less likely to produce a pain-free leg.
What needs to be done depends on what structures in your pet?s knees are abnormal and how abnormal they are. No two cases are exactly alike. There are three surgical procedures that are used to treat patellar luxation. Most cases can be cured with the first. If your veterinarian decides that ligamental reinforcement (lateral imbrication) will not be sufficient, the vet will add the second procedure, deepening of the trochlear groove. If that will not be sufficient, the surgeon may move the point where the patella's ligament attaches to the tibia (tibial crest transposition).
In many mild cases, it is sufficient to simply reinforce the weak lateral ligaments that keep the kneecap in alignment. When the inner or medial ligament has contracted or pulls too hard to the inner side of the knee, that ligament can be ?stretched? (medial desmotomy) at the same time to allow the patella to glide in its groove in a straighter course.
Your pet?s patella rides in a channel on the face of the femur. Sometimes, this channel or groove is not deep enough in toy breeds to hold the patella in track (course). This track is coated with a slippery cartilage that allows for smooth motion. In this surgery, this cartilage (hyaline cartilage) is carefully lifted off to one side while the notch is deepened, or a wedge of bone and cartilage are removed and then replaced in a deepened channel.