Hip Salvage

INTRODUCTION
The hip is a "ball and socket" type of joint. In the normal dog and cat, the head of the femur, femoral head (the "ball" portion) sits tightly into the acetabulum of the pelvis ("socket" portion).

In cases of disease, irreparable fractures, or the advanced stages of crippling osteo-arthritis (secondary to an old injury or hip dysplasia), surgical procedures may be required to salvage pain free use of the affected leg.

EXCISION ARTHROPLASTY
One such salvage procedure is called Excision Arthroplasty or Femoral Head Ostectomy (FHO). In this procedure, one part of the arthritic hip joint, the femoral head (the "ball" portion), is cut and removed. This is known as excision or ostectomy. The joint is then reconstructed with regional muscles and tendons so that the patient can use the leg without pain (arthroplasty).

Heavy animals do not do as well with this procedure, thus we prefer to limit this surgery to patients weighing less than 40 pounds or in dogs requiring a revision due to a complication of a total hip replacement. Smaller patients can usually be expected to have up to 80% of normal leg usage. The success of this procedure is largely dependent on the pet's size and the owner's willingness and ability to perform physical therapy exercises. Slow leash walks up slopes and stairs as well as range of motion exercises are necessary 2-3 times per day.

TOTAL HIP REPLACEMENT
In dogs greater than 45 pounds, especially large, active, athletic dogs, we strongly recommend Total Hip Replacement (THR) to salvage pain free use of the leg. This procedure not only involves precision removal of both sides of the abnormal hip joint, but also reconstruction and replacement of the entire hip joint using a stainless steel/titanium ball and plastic/teflon cup. The prostheses (implants) may be cemented or screwed (non-cemented) into place.

The non-cemented screw-in prosthesis developed in Switzerland ("Zurich Hip") may be the more suitable system for many dogs especially very young dogs needing a Total Hip Replacement.

Patients begin to place weight on the leg within days of surgery! Crate and pen confinement is required for 8 weeks. When they are out of the pen or crate, leash control is required. A sling may be required to support their weight during short walks to urinate and defecate.

Patients can generally begin to return to normal activity after 8 weeks of strict rest. Some control of activity is required for 6 months. If both hips need to be operated, the second side is generally staged 4-6 months after the first.

Radiographs are required at 6 weeks, 16 weeks and 1 year after surgery. Annual radiographs are needed for patients with the cemented hip prostheses. Radiographs do require sedation or light general anesthesia.

Dislocation of the artificial hip joint is the most common immediate post-operative complication. It is a devastating complication and most likely occurs within the first six weeks after surgery, generally when patients slip and fall. Thus, dogs must be confined to a crate/pen, slippery surfaces must be avoided and leash control enforced for 6 weeks.

In patients with the cemented prosthesis, infection of the implant is another serious complication. Complete physical examination and laboratory tests are performed to screen for any underlying infections within the body. In addition, extra precautions are recommended in the future when routine procedures such as prophylactic dentistry are performed.

The most common complication associated with the cemented Total Hip Replacement is loosening of the artificial prosthetics over the years. This loosening may occur within 5-7 years following surgery and is a cause of progressive lameness and pain. Many complications including disclocation, loosening or breakage of the implants require additional surgeries such as revision or explantation (removal and conversion to an excision arthroplasty.)

The Total Hip Replacement procedure is very successful in allowing dogs to regain a normal life without the pain of chronic hip arthritis.

This highly specialized procedure can only be performed at a few referral centers on the west coast. The Veterinary Medical and Surgical Group is one such facility.

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