Rebah is a 20 month old Shih Tzu cross who has been visiting our clinic ever since she was a puppy. Rebah's owner has recently noticed that Rebah skips on her right hind leg when she goes for a walk. So Rebah's owner booked an appointment to see Dr. Nathalie. After thoroughly examining Rebah, Dr Nathalie found that she had a luxating patella.
The patella is a knee cap, which is located in the centre of the knee joint. A luxating patella is when the knee cap moves out of place.
What causes the patella to luxate?
The patella slides in a groove on the lower end of the femur (the bone that runs between the hip and the knee). There is a ligament called the "patellar ligament" which runs from the bottom of the patella to the tibia, (the bone just below the knee joint). This ligament keeps the patella in place. The thigh muscles are attached to the top of the patella. When the thigh muscles contract, the force is passed through the patella and through the patellar ligament, which results in straightening of the knee joint. The patella can luxate because the point where the patellar ligament attaches to the tibia can sometimes be attached too far inward. As the thigh muscles contract, the force pulls the patella against the inner groove that it is sitting in. After several months, the inner side of the groove wears down and the patella is free to move out of the groove or luxate. This can be quite painful when this happens and the dog may have difficulty putting weight on the leg. After a while, some dogs learn to kick the leg and push the patella back in place. However, because the groove is gone, the patella can easily move out of place again. Some dogs can tolerate this problem for a while, but the joint may become arthritic and painful.
Can a luxating patella be fixed?
A surgery called, "Medial Luxating Patella Repair", can be performed.
There are three steps to the surgery:
1. The point where the patellar ligament is attached is moved and surgically fixed to its proper location.
2. The groove where the patella sits is deepened so the patella will stay in place.
3. The capsule around the knee joint is tightened.
It is important to have this surgery performed before arthritis occurs in the joint. If there is no arthritis, the dog should regain full use of its leg. If there is arthritis in the joint already, the joint can still be painful, especially in the cold weather.
Rebah's Owner had noticed this problem early and surgery was performed soon after. There was no arthritis in Rebah's joint, which means she should recover from the surgery quite well without any more joint pain. Rebah's post - operative care includes keeping her quiet with restricted exercise for 6 weeks after surgery. This is to allow her knee joint to heel correctly. Too much exercise too early such as running around in the backyard or running in the house can result in an unsuccessful repair of the joint. Rebah visits us weekly so Dr Nathalie can assess how she is doing.