Graceful, athletic creatures, cats have bodies that are naturally flexible and can withstand a great deal of stress. Even so, cats can experience traumatic injury or develop degenerative joint disease, either of which can have severe negative effects on a cat's quality of life. Although some bone fractures can be pinned into place without issue, in other instances -- such as severe damage to the hip or pelvis -- femoral head ostectomy (FHO) is required. FHO is a radical procedure that cannot be reversed; however, most cats adapt well to life after surgery.
Femoral Head Ostectomy Surgery
Femoral head ostectomy is a radical and irreversible surgery intended to restore leg function to a debilitated or injured cat. The veterinary surgeon removes the round head of the hip bone, the acetabulum, by severing the slanted piece of bone that holds it to the femur. While the femur, the long bone that forms the upper leg, no longer has any means of fitting into the hip socket, muscle tissue holds it in in place near the hip. Although the head of the femur is not replaced after this surgery, the neck removal prevents bone-to-bone contact between the pelvis and the femur. Eventually, fibrous scar tissue forms, creating a new attachment. This attachment has considerably less strength and stability than the original hip joint had.
Range of Motion
Post-surgical care requires physical therapy, which a cat owner can perform at home. The owner must commit to flexing and extending the cat's leg several times a day to ensure that the muscles are being manipulated until the cat is capable of using the leg himself. Early range-of-motion exercises have an effect on the amount of function the cat retains after recovery. Even with early range-of-motion exercises being performed, the hip muscles may atrophy and reduce mobility. Atrophy can also lead to instability in the knee joint.
Running, Jumping and Climbing
Some loss of function can occur due to the limb being shortened following surgery. However, cats are typically capable of walking with relative comfort a week following surgery. Full use of the leg often returns within two or three months, at which time a normal recovery should be complete. Regular range-of-motion exercises and anti-inflammatory medications can aid in the recovery of function, as well. Some difficulty in running, jumping and climbing can occur if the muscles holding the femur in place later atrophy.
Most cats are light enough that their weight causes minimal complications after FHO surgery. While there is no conclusive evidence that weight has an effect on recovery from FHO surgery, obesity can have deleterious effects even on healthy joints.
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