Femoral Head Ostectomy (FHO) in Dogs

What is a femoral head ostectomy?

A femoral head ostectomy (FHO) is a surgical procedure that removes the head and neck of the femur (the long leg bone or thighbone) to help restore pain-free mobility to a diseased or damaged hip.

How does FHO change the hip?

The hip is a simple ball-and-socket joint. The joint consists of two parts: the acetabulum, which is a cup-shaped depression in the pelvis that forms the “socket,” and the head of the femur (thighbone), which forms the “ball. The head of the femur fits within the acetabulum, allowing the hip to move freely in all directions.

When the hip becomes damaged or diseased, this mobility can be affected. If the acetabulum and the head of the femur do not fit together properly, this poor fit can limit the joint’s range of motion. In addition, poor joint fit can lead to chronic pain and inflammation.

An FHO restores mobility to the hip by removing the head of the femur (the ball of the ball-and-socket joint), leaving just an empty socket. The muscles of the leg will initially hold the femur in place and, over time, scar tissue will form between the acetabulum and the femur, creating cushioning between the bones that is referred to as a “false joint.” Although this joint is anatomically very different from a normal hip joint, it provides pain-free mobility in most patients.

Is my dog a good candidate for FHO?

FHO is primarily recommended for small dogs (under about 45 pounds). The false joint created in an FHO works well to support the weight of small animals but may be less effective in large-breed dogs. There are exceptions, however, and veterinarians may recommend an FHO for a dog over 45 pounds if the specifics of the case indicate that doing so would be appropriate.

Active dogs often experience better results with FHO than less active dogs. The muscle mass they have built up through activity helps to stabilize the joint, allowing them to regain pain-free mobility more quickly. Inactive dogs have less muscle mass around the joint, which can make the joint less stable after surgery and lead to longer recovery times.

Why is FHO performed?

The primary goal of an FHO is to remove bone-on-bone contact, restoring pain-free mobility. The most common reasons for FHO include:

Fractures involving the hip. When a fracture involves the hip joint and cannot be repaired surgically, either due to patient considerations or cost considerations, an FHO may provide the best option for pain-free mobility.

Hip luxation or dislocation (associated with trauma or severe hip dysplasia). In some cases, a hip that is out of the socket cannot be put back into place through manipulation or other medical means. Surgical repair of hip luxations can be costly and is not always successful, so many dog owners choose FHO for small dogs with hip luxation.

Severe arthritis of the hip. In chronic, end-stage arthritis, the cartilage that protects both the head of the femur and the acetabulum can erode, leading to painful bone-on-bone grating whenever the hip is moved. An FHO can remove this point of contact and alleviate pain.

Legg-Calve-Perthes disease (also known as avascular necrosis of the femoral head). This uncommon condition, most frequently seen in miniature and toy-breed dogs, causes the bone in the femoral head to begin to die at an early age. The bone collapses due to these degenerative changes, leading to severe pain. Removing the femoral head through FHO removes the source of pain.

What can I expect on the day of surgery?

FHO is performed under general anesthesia. In most situations, you will take your dog to the veterinary clinic early in the morning on the day of surgery. Your veterinarian will likely instruct you to withhold food the morning of surgery to prevent vomiting that may occur under anesthesia.

After surgery, your dog will remain in the hospital for several hours to several days, depending on the specific circumstances of your dog’s health and surgery. When you pick your dog up from the hospital, they will probably not bear any weight on the leg that had surgery. An incision will be visible around the hip, and this incision may or may not have visible external sutures. Some veterinarians use dissolving sutures that are placed under the skin. Your dog will likely be wearing an Elizabethan collar (cone) to prevent them from licking the surgical site.

What care will my dog need after an FHO?

Care varies based on the needs of the specific patient but, in general, the post-operative recovery can be divided into two phases.

Phase 1: Pain control and restricted activity. In the first several days after the operation, your dog will be healing from the surgical procedure. Because bones and muscles are cut during this procedure, the focus during this period is on pain control. Give all medications and treatments as prescribed by your veterinarian (e.g., warm and cold packing). Your veterinarian may also recommend laser therapy to reduce inflammation and encourage healing.

Your veterinarian will recommend activity restrictions during the first several days after surgery. Confine your dog to a crate or a small area in the house, with only very brief leashed walks outside for bathroom breaks. After a few days, you can attempt passive range-of-motion (PROM) exercises, if your dog tolerates them, gently moving the hip forward and backward through its range of motion. Do not do these exercises if they cause your dog pain.

Phase 2: Rebuilding muscle mass and strength. Your veterinarian will likely recommend introducing more physical activity approximately one week after surgery. During this phase of recovery, the focus shifts to rebuilding muscle mass and strength. Keeping your dog mobile will help keep the scar tissue in the false joint from forming too tightly, allowing your dog to remain flexible. Good exercises during this period include:

• Walking (especially up stairs)
• Holding the front portion of your dog’s body in the air while allowing them to “walk” on their hind legs
• Walking through water

Walk slowly to encourage your dog to bear weight on the affected leg. When running, your dog will be more tempted to lift the affected leg. In the first 30 days after surgery, it is important to avoid rough play or any activity that encourages sudden twists and turns. These high-impact motions can slow healing that is occurring within the joint and muscles.

When will my dog fully recover from surgery?

Most dogs show signs of complete recovery approximately six weeks after surgery. At this point, your dog can resume regular activities. Healing may be more rapid in dogs that had normal function until just before the FHO (e.g., a dog that had a sudden, traumatic injury to the hip) and may be slower in dogs with longstanding, chronic issues, because these issues often lead to muscle atrophy, which takes time to resolve.

If your dog does not show significant improvement six weeks after surgery, consider a formal rehabilitation or physical therapy program. Ask your veterinarian for recommendations.

What is the prognosis after an FHO?

Most dogs recover fully after an FHO and regain essentially normal function of the affected leg. Although the leg may have a slightly decreased range of motion or decreased limb length after surgery, these impacts are typically minimal and do not affect the dog’s quality of life.