What is Femoral Head and Neck Ostectomy (FHO)?
Femoral head and neck ostectomy (FHO) for cats and dogs is a surgical procedure that involves permanently removing the femoral head and neck to treat a diseased or damaged hip. The femoral head and neck are part of your pet’s hip joint, serving as the ball that connects to the acetabulum, the socket, to form the ball-and-socket joint.
FHO is generally performed to treat irregular bone-on-bone contact caused by injury or conditions such as Legg-Perthes disease, osteoarthritis, and advanced hip dysplasia. If the acetabulum and femoral head cannot fit together normally, it may cause friction between the bones, limiting the hip’s mobility and flexibility and causing symptoms such as chronic pain, inflammation, stiffness, and lameness.
FHO is a permanent salvage procedure that aims to restore your pet’s mobility and comfort by removing the femoral head and neck. This allows your pet’s leg muscles to support the femur throughout recovery. Over time, scar tissue forms between the acetabulum and the femur to create a ‘false joint’, or pseudarthrosis, composed of fibrous tissue that supports your pet’s mobility.
We recommend restricting your pet’s physical activity for a few days after surgery. After this, your vet may gradually introduce controlled movement and rehabilitation exercises to rebuild muscle mass and strength. This helps stabilise the affected limb and supports gradual recovery. This phase also prevents the scar tissue within the false joint from forming too tightly, which helps maintain your pet’s range of motion and flexibility.
Conditions That May Require FHO Surgery
Your pet may be a suitable candidate for FHO surgery to treat hip conditions that impact its mobility and comfort.
Femoral Head/Neck Fracture
A fracture to the femoral head or neck may occur after an injury to your pet’s hip joint. If the hip joint cannot be surgically repaired, FHO surgery may be recommended to relieve your pet’s pain and restore their mobility.
Hip Dysplasia
Hip dysplasia is an inherited developmental condition characterised by a hip joint deformity, which causes laxity and instability. Over time, this condition causes the bones to rub against each other, gradually wearing down cartilage that results in painful osteoarthritis and inflammation. If hip joint laxity cannot be treated with manipulation or surgical approaches, your pet may be a suitable candidate for FHO surgery.
Hip Luxation/Dislocation
Hip luxation or dislocation typically occurs due to traumatic injury to the hip joint, where the femoral head is displaced from the acetabulum. The force of the trauma is significant enough to tear the joint capsule and other ligaments that secure the hip joint. If your pet has hip dysplasia, they may potentially be predisposed to hip luxation. FHO surgery may be recommended if the hip joint cannot be reduced (realigned) or luxation recurs.
Legg-Perthes Disease
Also known as aseptic, or avascular, necrosis of the femoral head, this condition is characterised by disrupted blood flow to the femoral head in one or both hind limbs. The femoral head gradually undergoes bone and tissue death, preventing its normal function and leading to pain, lameness, and muscle loss from lack of use. Its exact cause is still being investigated, although it may have a hereditary component that frequently occurs in small dog breeds, as well as cats. FHO surgery may be recommended to remove the femoral head, in order to help alleviate symptoms and restore mobility.
Severe Hip Arthritis
Chronic osteoarthritis is characterised by inflammation and cartilage degeneration in the hip joint, causing painful bone-on-bone friction whenever your pet moves the affected limb. Some breeds are genetically predisposed to developing arthritis, such as Maine Coons in cats and Labradors in dogs, while older pets may also be at high risk due to wear and tear on the hip joints.
Slipped Capital Femoral Epiphysis
Slipped capital femoral epiphysis is a degenerative, progressive condition in which the proximal femoral metaphysis detaches from the capital femoral epiphysis through the growth plate. This means your pet’s growth plate located in the femoral head slips and becomes displaced. The condition is often idiopathic, meaning your pet has no prior history of trauma or injury but may gradually develop symptoms. It typically affects younger pets under 2, and overweight, neutered male pets may be predisposed.
Physeal Fracture
A physeal fracture generally occurs in pre-adolescent and adolescent pets when injury or trauma damages or fractures the growth plates. At such a young age, growth plates tend to break easily. A physeal fracture may alter bone growth, which can affect the length or angulation of a developing bone. If this happens, FHO surgery may be necessary.
Is Every Dog or Cat a Good Candidate for FHO?
FHO surgery is generally suitable for small dogs weighing approximately 45 pounds (~20kg) and most cats. Active pets with good muscle tone before surgery typically recover better than sedentary pets, since strong muscles help stabilise the hip joint and support the return of mobility.
While a false joint may support the weight of small animals, results may vary with large-breed dogs since more body weight places greater stress on the joint. However, if FHO surgery is still appropriate, larger dogs may need more intensive postoperative rehabilitation to improve weight-bearing on the affected leg.
How FHO Surgery Is Performed
A pre-surgical examination is first performed to determine if your pet is suitable for FHO surgery and to assess your pet’s mobility and pain levels. Imaging scans, typically using X-rays, are also performed to assess your pet’s hip joint and the extent of damage that will be addressed during surgery.
Additionally, the initial consultation provides information about the FHO surgery process, potential risks and complications, and other important considerations. You may also use this time to ask questions and clear up any concerns you may have.
During the surgery, the veterinary surgeon will administer general anaesthesia to keep your pet comfortable and pain-free throughout the procedure. From there, they will perform a controlled incision at a predetermined location on your pet’s hip to allow surgical access to the hip joint. The surgeon will remove the femoral head and neck from the femur to relieve bone-on-bone pain, followed by the smoothing of bone edges to reduce irritation. With the femoral head and neck removed, the surgeon will move the muscles and skin back into position before closing the incision with sutures.
After surgery, your pet will receive postoperative pain management and monitoring to support gradual recovery. This is essential to allow your pet to recuperate and prepare for eventual rehabilitation and physiotherapy after surgery. The vet may provide additional postoperative care instructions if your pet is discharged, including prescription medications and activity restrictions to support recovery.
FHO Recovery Timeline: What Changes at Each Stage?
Your pet’s postoperative recovery is divided into several distinct phases.
Immediate Post-Surgery Phase
In the first few days after FHO surgery, your pet may feel tired and unsteady as it recovers from the effects of the anaesthesia. Your pet’s medical care will focus on pain control, adequate rest, and close monitoring to help the surgical site heal properly. The vet will recommend activity restrictions to minimise the risk of pain, discomfort, or other complications affecting your pet’s hip joint. As such, you may need to confine your pet to a crate or room, with very short leash walks for bathroom breaks only.
The vet may allow passive range-of-motion (PROM) exercises after a few days, moving your pet’s hip forward and backwards repeatedly. These exercises should not be performed if they cause pain or discomfort in your pet.
Early Recovery Phase
Approximately 1 to 2 weeks after FHO surgery, your vet may allow controlled movement and early rehabilitation exercises under their guidance. The objective of these activities is to slowly rebuild muscle mass and strength while preventing the scar tissue from forming too tightly to preserve your pet’s flexibility.
Some activities your vet may suggest include walking up and down stairs, going from a standing to sitting position, and walking through water. Maintain a slow, comfortable walking pace to encourage your pet to bear weight on the affected limb. Avoid high-impact activities, sudden movements, and rough play at this time.
Rehabilitation Phase
Approximately 2 to 6 weeks after FHO surgery, activity and therapeutic exercises can be gradually increased based on your pet’s recovery progress. The vet may focus on improving hip range of motion, continuing muscle strengthening, and encouraging normal use of the affected limb. Your vet may allow your pet to go on controlled walks for longer periods as part of the gradual increase in activity. Pets that enjoy swimming may be allowed to return to the pool, as this low-impact exercise may support muscle mass rebuilding without placing significant stress on the developing false joint.
Long-Term Recovery Phase
Your pet may show substantial functional improvement by around the sixth week after surgery, though full recovery can take longer, especially in larger dogs. During the follow-up evaluation, the vet will advise you on whether your pet can safely resume its regular activities. If your pet’s condition does not show significant improvement, see a vet immediately for further support.
To learn more about FHO surgery and whether your pet may be eligible for it, visit Westside Veterinary Emergency and Referral Hospital today and speak to our team.
