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TRIPLE PELVIC OSTEOTOMY
Overview
Triple Pelvic Osteotomy (also called Pelvic Osteotomy or abbreviated TPO) is one of the treatment options for hip dysplasia, a developmental disease of the hip joints most commonly seen in large and giant breed dogs. See the ACVS Health Conditions topic Canine Hip Dysplasia in this section for a more detailed description of the disease and other treatment options.
The object of a TPO is to change the orientation of the shallow hip socket (acetabulum) to allow better coverage of the head of the femur. This increases the depth of the acetabulum causing it to “capture” the head of the femur and not allow it to slip out of the socket. Increasing the stability of the joint helps to minimize the development of degenerative joint disease (arthritis) as the dog gets older..
Indications
Triple Pelvic Osteotomy is a procedure that is generally done on young dogs that are showing pain in the hips, but have not yet developed significant radiographic changes in the joints. Unfortunately, the early changes of hip dysplasia are subtle and some dogs do not show signs indicating that they have the disease until after they have already developed changes in the joint that make performing a TPO inadvisable. For this reason, many veterinarians recommend doing routine palpation and X-ray screening of the hips in all large and giant breed dogs at about 6 months of age. (Figure 1a, b) If caught at the early stages, TPO is a very successful procedure with few complications. For this reason, any young large or giant breed dog that demonstrates lameness in one or both rear legs, reluctance to run and play, tires easily, shifts the weight to the forelimbs, shows loss of muscle mass in the rear limbs, shows pain when the hips are manipulated, or has a “popping” sensation felt over the hip joints, should be evaluated by your veterinarian.
Figure 1a. A radiograph of a dog with normal hips showing NO laxity of the hip joints
Figure 1b. A radiograph of a dog with hip dysplasia, showing subluxation of the right hip joint (on the left side of the picture). The left side was also subluxating but appears normal in this film.
Signs and Symptoms (of Hip Dysplasia)
Dogs may show clinical signs at any stage of development of the disease, although many dogs with hip dysplasia do not show overt clinical signs. Some dogs are painful at 6 to 8 months of age but recover as they mature. As the osteoarthritis progresses with age, some dogs may show clinical signs similar to people with arthritis such as lameness after unaccustomed exercise, lameness after prolonged confinement, and worse problems if they are overweight. The development of hip dysplasia has an important genetic component (i.e. it is at least partially an inherited disease) however, rapid growth rates and over nutrition have important modifying effects on the disease as well.
When to seek Veterinary Advice
As mentioned above, if hip dysplasia is found during the early stages before significant degenerative joint disease (arthritis) has formed, Triple Pelvic Osteotomy can be very helpful in minimizing the development of arthritic changes. If significant arthritic changes have already developed, TPO is no longer a good option for management of the problem. (See the discussion on Total Hip Replacement on this website for another option) Large breed rapidly growing dogs should be evaluated by your veterinarian for hip dysplasia at 6 months of age or earlier. Any dog that that demonstrates lameness in one or both rear legs, reluctance to run and play, tires easily, shifts the weight to the forelimbs, shows loss of muscle mass in the rear limbs, shows pain when the hips are manipulated, or has a “popping” sensation felt over the hip joints, should be evaluated by your veterinarian. Your veterinarian may want to refer you to an ACVS Veterinary Surgeon in you area for a second opinion or evaluation of your dog’s hips. To find an ACVS veterinary surgeon in your area, click here: Find a Surgeon.
Exam, Screen Tests, Imaging
The diagnosis of hip dysplasia, especially at an early age, requires careful examination of the dog both awake and with sedation or anesthesia. Initial examination is done with the dog awake and consists of manipulation of the hip joint through a full range of motion looking for signs of discomfort or a palpable popping sensation which indicates laxity in the hip joint. In a young animal with no signs of hip problems, this may be sufficient exam, or you veterinarian may want to take X-rays of the pelvis to evaluate the hip socket conformation. In animals with any signs of possible hip problems (see above) X-rays of the pelvis under anesthesia, as well as careful palpation of the hip joints is indicated. (Figure 1a, b) It is important to realize that X-rays alone are not a reliable indicator of hip laxity. The x-rays show the position of the femur in the hip socket for only about 1/30th of a second (the time it takes to make the X-ray exposure). It is very possible for hips with significant laxity to have very normal looking hips on the standard pelvic X-ray views. Specialized X-ray procedures such as the PennHip have shown some promise in diagnosing hip laxity at an early age, and nearly eliminate the problems occasionally seen with the standard views. While the dog is under anesthesia, a trained veterinarian can carefully palpate the hip joints and can generally evaluate whether there is laxity in the joint or not. If significant laxity is present in the hip joints, the dog may be a candidate for a TPO even if he has not started to show any signs of hip problems yet. It is also important for the surgeon to evaluate the hips of a potential TPO candidate. Determination of the degree of rotation of the acetabular segment required in order to correct the hip laxity is made by palpation of the hips with the dog under anesthesia.
An Overview of the Surgical Procedure:
The basic concept of Triple Pelvic Osteotomy is to change the orientation of the shallow hip socket (acetabulum) to allow better coverage of the head of the femur. This increases the stability of the joint and helps to minimize the development of degenerative joint disease (arthritis) as the dog gets older. In order to accomplish this it is necessary to cut the pelvis in three separate locations, hence the name, Triple Pelvic Osteotomy. (Figure 2). Generally the first incision is made over the ischium (the back portion of the pelvis next to the base of the tail. The muscles are elevated from the bone on both sides and the ischium is cut with a power saw or an osteotome to the level of the obturator foramen. The second cut in the pelvis is made on the inside of the leg in the groin. The pecten of the pubic bone is cut through this incision. Some surgeons prefer to remove a segment of the bone rather than make a simple cut. The third and largest incision is made on the side of the pelvis in front of the hip joint. The large gluteal muscles are elevated from the bone and the body of the ilium is then cut. Once this last osteotomy has be made the hip socket (acetabulum) can be rotated as needed in order to make the hip socket deep enough that it will “capture” the head of the femur. The body of the ilium is stabilized in the rotated position with a special stainless steel plate designed for this purpose (Figure 3), or with a standard bone plate that the surgeon has twisted to the desired shape. Some surgeons prefer to perform this procedure on only one side at a time and address the second side (if necessary) several weeks or months later. Other surgeons prefer to do both sides at the same time in one long surgical procedure. (Figures 4 and 5)
Figure 2. A pelvis from a dog, showing the three areas where the bone must be cut in order to rotate the hip joint (acetabulum)
Figure 3. A special plate is used to hold the rotated acetabular segment in the desired degree of rotation until the ilium has healed back together.
Figure 4. X-rays taken of the pelvis immediately after surgery show the rotation of the acetabulum on each side and the plate and screws holding the acetabulum in the desired degree of rotation.
Figure 5. An X-ray taken of the pelvis at 8 weeks after surgery shows that the ilial osteotomy is now healed.
Potential Complications following TPO
TPO is a major orthopedic procedure, particularly when performed bilaterally. Most dogs are fairly reluctant to walk for several days following the procedure and will require pain management. Hospitalization is generally several days. Care of the surgical wounds is required as infection is always a potential problem. The most common wound problem involves the ischial incision (near the tail) because the dogs tend to sit on this area, and it is easily contaminated with fecal matter as well.
TPO can be successful in markedly diminishing the amount of degenerative joint disease (DJD, arthritis) that the dog develops. It is rarely successful in completely eliminating the problem. Long term follow ups on patients that have had a TPO show that arthritic changes DO develop over time. In many cases, however, they are mild enough to be sub-clinical and no further treatment is required. Some animals may require an anti-inflammatory medication (NSAID) to help with the signs of developing arthritis as they get older.
Occasionally TPO is not successful in adequately rotating the acetabular segment enough to allow capture of the femoral head. This can happen particularly in cases where the degree or rotation required is extreme. In these cases, a Total joint replacement is still a viable alterative. See the ACVS Health Conditions topic Total Hip Replacement in this section for a more detailed description of this procedure.
Aftercare
Your surgeon will recommend appropriate exercise restriction in order to allow the multiple osteotomies a chance to heal. The first week or so after surgery can require significant care, however, even with bilateral procedures, most dogs are walking without assistance within two weeks. Exercise must be restricted to leash walking only until X-rays confirm that the ilial body osteotomy is adequately healed. Overactivity risks loosening of the screws and loss of rotation of the acetabular segment, potentially causing failure of the procedure to correct the hip problem. Once the x-rays confirm adequate healing, exercise can be increased to normal or even athletic performance levels. (Figure 5)
Prognosis
Triple Pelvic Osteotomy performed by an adequately trained surgeon on a carefully chosen patient can result in excellent hip joint function with complete resolution of hip problems for many years. The most important factor regarding prognosis is ultimately entirely dependent on early recognition of the problem.
—William Daly, DVM
Diplomate ACVS
Posted 4/18/2007
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