Canine Hip Dysplasia - part 2 of 2
by Dr. Gaea Mitchell, DVM Surgical treatment of dogs with Canine Hip Dysplasia has evolved over the years to include several highly technical procedures. A young dog in the very early stages of the disease may be good candidate for triple pelvic osteotomy (TPO). This procedure depends on a good acetabular brim, not worn down or roughened with osteophytes. The surgeon exposes the acetabular area of the pelvis, and cuts each of the three bones of the pelvis that meet in the acetabulum, freeing the entire acetabular area from the rest of the pelvis. A special bone plate is used to re-attach this to the ischium, the pelvic bone behind the joint. The plate places the acetabulum at a new angle which incorporates more of the femoral head within the socket, with the acetabular brim holding the femur into place. The result is to avoid subluxation, thereby relieving the abnormal slipping of the bones which will cause DJD. Total hip replacement has become a more successful procedure, and may be indicated if the acetabulum is too shallow or the brim too worn to allow for TPO. In this procedure the top of the femur is removed and acetabulum drilled out to allow insertion of a socket in the pelvis and a rod that runs down the center of the femur and holds the ball part of the replacement joint. While there is some risk of implant failure if the dog returns to activity too soon, many dogs return to excellent function following this procedure. A new approach is called the Shelf Arthroplasty. In this procedure a groove is cut into the pelvis just above the acetabulum, and filled with an artificial bone graft substance, which serves as a base for formation of new bone above the joint. The theory is to provide a shelf that will keep the femur from being able to slip out of the acetabulum and ride higher on the pelvis. There was some discussion of this procedure at the AVMA Convention in Boston last summer. The current wisdom seems to be that there are not nearly enough cases that have gone several years following the surgery, to evaluate the long term benefit of the procedure. Given time, it will be accepted, modified or rejected on the basis of long term success. The last currently recognized surgery for a severely dysplastic dog is Femoral Head Ostectomy (FHO). This is generally viewed as a salvage procedure when none of the others are deemed appropriate, or when the cost of hip replacement places it out of reach. FHO entails surgical removal of the femoral head and neck, and closure of the joint capsule. The dog must then be kept quiet until initial healing can begin, then physical therapy and forced exercise are used to continually stretch the healing scar tissue, to counteract its tendency to contract. The end result is a scar tissue false joint, the range of motion of which depends largely on the success of the physical therapy. FHO has traditionally been recommended only for dogs under 40 lbs., but recently I have seen it done on a Labrador of 80 lbs. at our Vet school teaching hospital. My own Frigga has walked well for almost 9 years on two such false joints, so I never discount it as an option.