FEMORAL HEAD AND NECK EXCISION (OSTECTOMY)
Surgical options for the treatment
of canine hip dysplasia have, for the most part, been adaptations of human
orthopedic procedures. In 1943, a Lancet article (British medical journal)
described a surgery done in 1929 to relieve the pain caused by a tubercular
hip joint in a human. This was possibly one of the first complete excisions
of the femoral head and neck seen-- at least it was the first example we
have been able to find in the literature. Since its inception, this procedure
has been modified and used extensively by veterinary surgeons. Often considered
an alternative to total hip replacement, the femoral head ostectomy is sometimes
the only affordable surgical option available to many dog owners. While there
is significant potential for long-term complications, femoral head ostectomy
should be carefully considered within its narrow recommended parameters.
A prolonged recovery, muscle atrophy and "bed sore"- type ulcers are frequent
problems associated with this procedure. Best results are achieved and fewer
complications are encountered when the dog weighs less than 50 pounds. Some
clinicians feel that the procedure is most effective for dogs less than 35
pounds.
For dogs weighing more than 50 pounds, the femoral head ostectomy has been
modified to include a muscle "sling" to support and cushion the femoral shaft.
The sling is formed from the biceps femoris muscle (biceps muscle of the
thigh). Two other options include using a part of the gluteal muscle (buttocks
muscle) to pad the area between the excised femoral shaft and the pelvis,
or using the joint capsule itself to accomplish this. These "pads" are sewn
into place to fix their position. Over time, the muscle pad is transformed
to a fibrous mass that is better able to absorb the impact of the forces
exerted by the femor. Nothing will replace the near-frictionless and hydrostatic
dampening of the cartilage of the original joint when it was in good condition,
but if forces are limited, the muscle pad has been shown to serve well in
this function in many cases.
Once the femoral head and neck have been removed, the surgeon takes the joint
through a complete range of motion. This ensures that there are no obstructions
to normal articulation. The muscle pad is sewn into place so it will attach
securely to the acetabulum. The clinician also checks for crepitus, which
is a dry, crackly sound. Ovary crepitus may indicate that not enough of the
femoral neck was removed or that bony fragments are still at the excision
site. Both conditions would cause loss of function and pain after surgery.
It is much better to reduce the problem at the time of surgery than to have
to go back into the joint a second time.
As mentioned before, femoral head excision tends to be more effective and
fewer complications are encountered when the dog weighs less than 50 pounds.
A study published in 1988 evaluated the use and efficacy of the biceps femoris
muscle sling. Sixteen dogs with normal hips were given the biceps femoris
muscle sling surgery and six normal dogs were given the conventional excision
of the femoral head and neck. While both control and treatment animals had
similar post-surgical limb functions, there was marked edema and swelling
of the affected limb in half of the dogs with slings and not in the control
dogs. Four of the sling dogs developed post-operative infection and all of
the treatment animals had elevated temperatures after the procedure. Their
results indicated that the added risk of infection and complications was
not justified and that further clinical trials needed to be run before the
efficacy of this adjunct treatment could be established.
For those considering this type of surgery, it should be noted that this
is a strictly end-stage salvage procedure. Only those animals demonstrating
severe bony changes in the coxofemoral joint and clinical signs of pain should
be considered for this procedure. Also, excisions without adding a prosthesis
shortens the leg, which affects the gait, and the biceps sling can cause
a slight adduction (drawing in toward the center line) of the affected limb
during exercise. On the positive side, this procedure has worked well over
the years and is still the standby short of total hip replacement.
Source: Canine Hip Dysplasia Susan
Thorpe-Vargas Ph.D., John Cargill MA, MBA, MS
The above information is simply informational. It's intent is not
to replace the advice of a veterinarian nor to assist you in making a diagnosis
of your pet. Please consult with your own veterinarian for confirmation of
any diagnosis. Your pets life may depend on it.