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FHO (femoral head ostectomy)

FHO was first described by Gathorne Robert Girdlestone(1881–1950) in 1945. He originally designed the procedure for treating tuberculosis and other disorders of the hips. This has led to the procedure also being known as a “Girdlestone operation”. Other surgeons added various modifications to the procedure to improve recovery and outcomes. FHO was first described in veterinary science in 1961 by J.S.A. Spreull. It can be suggested however that the technique was developed concurrently at other locations.

Small breeds of dog, cats and small horses, donkeys and ponies have all had the procedure performed successfully. Hip dysplasia, an extremely painful congenital condition found in many dog breeds and some cats, is an example of such a condition where this procedure may be used. It is also performed in cases of trauma where the head of the femur is badly broken or severed, or in response to other diseases of the hip bone, such As Legg-Calve-Perthes’ disease. It is sometimes the procedure of last resort when other methods have failed and or sepsis of the joint has occurred, but it can be indicated when the hip joint is severely affected or if arthritis In the joint is serious enough. It can also be indicated in small animals with pelvic fractures, particularly fractures of the acetabulum (socket of the pelvis).


The procedure exposes the head section of the femur bone (the ball of the ball and socket joint), and then the head is removed using a small saw or a bone hammer and chisel. Rarely both sides are done in one operation, most times one side is done and allowed to heal before the other side is done.

Unlike most other hip surgeries, the head of the femur is not replaced, but is allowed to heal and develop its own fibrous scar tissue so that the joint is no longer bone-to-bone, a pseudoarthrosis (also called a “false joint”). The neck of the femur is usually removed at the same time as the head. This prevents the post operative complication of bone rubbing on bone and continued pain. This has led to the procedure often also called “Femoral head and neck ostectomy”.

Animals who have had FHO surgery are required to maintain a lower weight throughout their lives to compensate for the loss of skeletal integrity, and generally have less mobility than normal.

The clinical signs can occur in one or both rear limbs but are usually bilateral (occurring in both legs). Lameness often appears suddenly after prolonged exercise or after a brisk walk. This is the result of tears or injuries to the abnormal joint tissue. The dog may be slow upon rising and may take a few minutes to warm out of joint stiffness. Occasionally, stifle (knee) ligaments are injured when the dog tries to protect the hip by overextending the stifle joint.
In the chronically affected hip, the joint capsule (which is normally paper thin) is markedly thickened. Subsequently, extension Severe osteo- End-stage arthritic changes osteoarthritis (portion of cartilage (no cartilage) remaining) shorter, choppy steps when the dog is running. Due to discomfort and pain, the dog sits rather than stands when he or she stops. When rising, he or she does so slowly and with some degree of difficulty. The dog may be reluctant to chase, jump, or run a long distance. Finally,
when pain has restricted limb use for weeks to months, muscle atrophy and loss of muscular support in the rear limbs becomes severe. At the same time, weight is shifted to the forelimbs and the shoulder muscles enlarge.
Once the patient has radiographic (x-ray) evidence of degenerative arthritis (Figures it is no longer a candidate for a triple pelvic osteotomy. Over time, many of these dogs will become less responsive to analgesic medications and surgical therapy should be considered.

Call Dr. Mauer with any questions regarding
FHO Surgery