Femoral Head and Neck Ostectomy

 

Key Points

The femoral head and neck ostectomy (excision) is a salvage procedure used to treat painful hip conditions

This surgery has the best outcome in small to medium breeds of dogs and cats and dogs that are very active.  For an optimal recovery, rehabilitation therapy at home, ideally in conjunction with therapy at an animal rehabilitation center, is recommended

Anatomy

The pelvis is made of four bones: the ilium, acetabulum, pubis, and ischium.

Hip Anatomy

In the immature animal, these bones are not fused together.  As the pet matures these bones fuse into one confluent bone.  The ilium joins the pelvis to the lower part of the spine called the sacrum.  The hip joint consists of a ball (femoral head) which is at the end of the femur bone and socket (acetabulum). This joint joins the hind limb to the pelvis. The joint is held together with a very strong round ligament (sometimes called the teres ligament) and the joint capsule. The muscles that surround the hip joint also provide very good support to the joint. 

 Diseases Treated by Femoral Head and Neck Excision

·            Hip dysplasia is a very common disease that affects large breed dogs. This disease is caused by the abnormal development of the hip as a puppy grows. Bad genetics are a major contributing factor. Sometimes the dam and sire of the affected puppy have no physical evidence of hip dysplasia. If this occurs, the parents likely have hidden genes for the disease. Hip dysplasia results in looseness of the hip joints. Clinical signs of hip dysplasia can be seen by 4 months of age but some dogs develop signs of hip dysplasia when they are a couple of years old and others in the geriatric years. Warning signs of hip dysplasia may first start out as exercise intolerance. Bunny hopping, stiffness on rising after a rest, lameness on a limb, and atrophy of the muscles of the hind limbs are other typical clinical signs. 

·            Dislocation of the hip is another condition that requires surgery. If signs of arthritis are present with dislocation the hip or if the dislocation is chronic, then the hip should not be placed back into the socket. Instead, total hip replacement or femoral head and neck excision should be performed. 

·            Severe fractures of the acetabulum or of the head or neck of the femur sometimes that cannot be repaired likely will require femoral head and neck excision. 

·            A form of degeneration of the hip joint, called Legg-Calve-Perthes disease that is found in small breed dogs, is due to damage of blood supply to the femoral head. This disease causes the femoral head to collapse and pain results. The more economical treatment is FHO, but total hip replacement is now available for this size of dog. 

Preparation for surgery 

The pet should be fasted prior to surgery, as instructed by the surgical team. Water is usually permitted up to the time of admission to the hospital. The surgical team should be informed of any medications that your pet is currently receiving. The pet should not receive any aspirin within 1 week of surgery, as this medication will thin the blood and increase the risk of bleeding. Just prior to surgery, your pet will receive a sedative, have an intravenous catheter placed for the administration of intravenous fluids and intravenous medications, be induced under general anesthesia with medication(s), and have a breathing tube (endotracheal tube) placed to allow delivery of oxygen and gaseous anesthesia. The surgical site will be clipped and cleansed with an anti-septic solution in preparation for surgery. Pain will be controlled both during and after surgery with analgesics (pain-controlling medication); we routinely perform a lumbosacral epidural for administration of spinal local anesthetics and narcotics during surgery. Please note that each surgical and anesthesia team may elect to choose a different, but effective analgesia protocol. 

 

Treatment 

The pet will be anesthetized and the entire limb and hip to be operated will be clipped. An incision is made over the hip region. The hip is exposed and the femoral head and neck is removed. The muscle, fat and skin layers are then closed. If deemed necessary, the femoral head is submitted for microscopic evaluation (histopathology) by a pathologist. After the surgery, fibrous tissue will form in the region of the hip joint which prevents bone rubbing on bone. The muscles hold the hip in place. The operated limb will be slightly shorter than prior to surgery, but this does not cause any functional problems. This illustration shows the normal hip and operated hip (FHO).

Unilateral FHO

In this radiograph, the dog has had both femoral heads removed.  Take note of the femoral head and neck excision site on the right (R) which was recently done; the excision is very clean and prevents the bone from rubbing on the hip socket (called the acetabulum) of the pelvis.  Also take note that the left hip has also had the FHO procedure, but this one was operated years ago and new bone has grown on the site of the FHO; it is not contacting the pelvis and is not causing any clinical problems.

bilateral FHO Radiograph

After Care and Convalescence

A prescribed analgesic medication should be administered in the postop period at home. Nonsteroidal anti-inflammatory medications are very beneficial to reduce pain at the surgical site and encourage weight bearing. In some cases, antibiotics may be prescribed.

Activity is not limited after surgery. In fact, exercise will help to maintain a good range of motion of the hip joint. The owner should do rehabilitation therapy using the surgeon's recommendations until the pet is using the limb normally. Flexion and extension of the hip joint is essential in the recovery period. Rehabilitation therapy will help prevent adhesions from forming, thus maintaining a good range of motion of the hip region. If possible, swimming should be started after the incision has healed. It is also highly recommended (though not required) that rehabilitation therapy sessions be scheduled with a professionally trained therapist.

Most dogs will start to bear a small amount of weight on the limb within 2 weeks after surgery. Within 4 to 6 weeks the pet should bear a moderate amount of weight on the limb. By 2 to 3 months after surgery, recovery is complete. The pet should be examined 2 weeks and 2 months after surgery to ensure that the hip region is healing well.

Most small pets do well following femoral head and neck excision surgery. Larger dogs can also do well, but some weakness on that limb frequently can be seen. This is due to the muscles supporting the region of the hip instead of the actual joint. As a result, heavy exercise can cause the pet to become stiff or lame. Anti-inflammatory medication can be given to give your pet relief if needed. If your pet is a medium to large breed dog, total hip replacement is the preferred technique over the femoral head and neck excision surgery.

Complications

As with any surgery, complications may arise. Even though rare, anesthetic death can occur. With the use of modern anesthetic protocols and extensive monitoring devices (blood pressure, EKG, pulse oximetry, and respiration rate), the risk of problems with anesthesia is minimal. Infection is also an unusual complication, as strict sterile technique is used during the surgery. Poor range of motion of the hip joint can occur and is usually due to a lack of rehabilitation therapy. If your pet is not using the limb very well after 2 to 3 weeks, anti-inflammatory therapy should be continued for another 2 to 4 weeks. Sciatic nerve damage is a rare complication of FHO surgery, but frequently is a transient problem.

Due to the false joint that is created, the leg will be slightly shorter than the other leg and the pet may have a mechanical limp which is very different from a limp due to pain.  This is of no concern other than cosmetics.  The goal of this procedure is to give your pet good range of motion with a pain free hip and it is hard to achieve a completely normal gait with this salvage procedure.  

Credit due for pictures and portion of text to Animal Surgical Center of Michigan, Flint Michigan