Kevin, is a 20 month Rag Doll Kitty belonging to our own Dr. Henderson who woke up one night screaming in pain. After the initial pain reduced a bit, Kevin was no longer bearing weight on his right leg. Being an indoor kitty, Dr. Henderson was hard placed to figure out what could be causing Kevin so much pain. She immediately brought Kevin into the hospital to evaluate him. On physical exam, the pain was isolated to the right hip, however there was also pain in the left hip. On palpation of the hind legs, it became apparent that the muscles on both legs had atrophied a bit which went unnoticed at home due to his long hair and sedentary nature.

We sedated Kevin and took radiographs of the hips.

Examining the radiographs, we could see an obvious, dislocated fracture of the neck of the femur on the right. The left leg has a fracture as well, but you can’t see the bones distracted from one another. This condition is a syndrome affecting large young cats known as atraumatic physeal fracture syndrome. In this syndrome, the growth plates, which are the cartilaginous areas of the bone where growth takes place during the first year of life, fail to close and become.

solid bone. The cartilage is strong enough to support the cat up to a point, however, when they get heavy enough or perform strenuous exercise or jumping, the cartilage breaks and the pieces slide apart.

When there is an injury like this, there are two basic approaches to fixing it. The first, is to remove the fractured ball of the femur and smooth out the neck of the femur. This is known as an FHO surgery (Femoral Head Ostectomy). By doing this, we remove the source of the pain, which is the bone on bone contact. Most animals, especially small cats will do very well after this surgery. Their gaits will not be normal, and they may not be able to jump as well as normal cats, but their day to day life goes on very nicely. Once the bones are removed, the remaining portion of the femur, will form a “false joint” with the hip (acetabulum) through the deposition of scar tissue. The strong muscles of the thigh and hip will keep the leg in alignment.

The second approach to this problem would be to do a total hip replacement, similar to the surgery performed in humans. In this surgery, the head and neck of the femur are removed, a hole is drilled in the femur and a titanium prosthesis is cemented into the femur to replace the head and neck of the normal femur. The normal hip socket is replaced with a synthetic receptacle matched to the leg prosthesis. This surgery returns the pet to a relatively normal leg and since there is no biological joint, there is minimal pain associated with it.

Dr. Henderson felt that Kevin would do better over the course of his life with new hip implants, and so she took Kevin to the local specialty surgeon to have the first hip replaced.

The referral specialists are very accomplished surgeons, but when they called after the surgery, they had bad news to report. When they were trying to cement the implant into the leg, the cement dried too quickly and they were unable to get the implant placed. Instead, they performed the FHO surgery on the right side. Needless to say, Dr. Henderson was disappointed, but Kevin recovered well and began gradually using the leg at home. Since the left side was also broken, Dr. Henderson was in a quandary as to whether or not to try again on the other side. Ultimately, she decided to give it a try so that Kevin would have at least one good leg to stand on.

Two weeks later, Kevin was re-anesthetized and this time the surgery was a success. The new hip was placed appropriately and he was returned to her care after a few days in the hospital. You can see in the radiographs below the results of both surgeries.

Kevin has been home for 3 weeks now and is still recuperating. He is walking with some discomfort but we are using medications to mitigate the pain. It will probably take 12 weeks before he is fully using the new hip, but after that, he should have a very comfortable hip for years to come.