Excision Arthroplasty in Cats

Excision arthroplasty is a surgical procedure used to excise, or remove, a joint. This is usually performed if a joint is not capable of healing on its own, or if preserving it proves impossible. Conservative treatment is almost always recommended as a first course of treatment. Excision arthroplasty will usually be considered if the underlying condition does not respond to medical treatment.

The hip joint is the most common joint in a cat’s body which will require excision arthroplasty. This procedure is then known as femoral head and neck ostectomy (FHO). During excision arthroplasty of the hip, the surgeon will remove one or both of the femoral head and neck of the hip joint, which are located on either side of a cat’s pelvis. Fibrous tissue will grow in their place, and will support the hip.

Cats undergoing excision arthroplasty will be prohibited from eating, typically for twelve to twenty-four hours, prior to surgery. Owners should follow preoperative dietary changes carefully.

1. First, the surgeon or veterinarian will conduct preoperative blood tests to confirm anesthetization is safe for the cat.
2. The surgeon will administer anesthesia prior to placing a catheter and breathing tube.
3. The hip will be shaved, cleaned, clipped, and draped.
4. Analgesics will be administered intravenously throughout the surgery.
5. Using a scalpel, the surgeon will make the initial skin incision.
6. The surrounding subcutaneous tissue and muscles will be retracted, or gently separated along their natural edges, so that the surgeon can visualize the hip joint.
7. The surgeon will make an incision into the joint capsule.
8. The femoral neck will then be identified and removed using an osteotome, or bone cutter.
9. Prior to removing the femoral head, the surgeon will ensure no rough or sharp edges remain.
10. The round ligament and femoral head are then removed.
11. A sterile saline solution is used to flush the surgery site.
12. The muscles and subcutaneous tissues will then be sutured prior to closure of the incision site.
13. Postoperative x-rays will be taken to ensure the entire femoral head and neck were removed.

Excision arthroplasty is often used to treat congenital hip dysplasia. However, this condition should not be treated with surgery until the bones have fully developed, around nine or ten months of age. It should be noted that the affected limb will be slightly shorter following surgery. This is normal, but does not usually affect walking or limb function. 

It is imperative that cats undergo proper rehabilitation. A poor range of motion in the affected hip will result from improper rehabilitation. Owners should follow their surgeon’s rehabilitation instructions and/or recommendations carefully.

Complications with FHO and excision arthroplasty are rare, but possible. Sciatic nerve damage is a possible complication. Infection may also occur, although this is considered extremely rare in orthopedic surgery.