Are You “Hip” to Joint Replacement?

Total hip replacement has been available as a surgical treatment for canine hip dysplasia and degenerative osteoarthritis for 30+ years in veterinary medicine. There have been many improvements and modifications that have occurred during that time in implant design and surgical technique that have resulted in a 90% overall success rate in clinical cases performed by skilled joint replacement surgeons.

Dr. Terri Schiller, Dip ACVS, has 20 years of experience with total hip replacement. During her time at North Carolina State University she was involved in the development of a canine cementless total hip replacement system (Canine PCA) that was designed as a research model by a human orthopedic company. For the canine patient this system was highly successful and the company subsequently allowed its use for clinical canine patients. Unfortunately, this system was never commercially produced and once the initially made implants ran out the company initiated no further production. In 2004, Biomedtrix released a canine cementless total hip prosthesis for use. This system was patterned after the Canine PCA system.

A cementless joint replacement system offers a huge benefit over a cemented system as it is stabilized within the patient’s bone via bone ingrowth versus cement fixation. This provides a living or vital form of fixation which theoretically provides a better long term outcome as implant loosening due to cement degradation does not occur. Aseptic loosening in cemented hips occurs in approximately 30% of cases. The development of aseptic loosening has been noted at variable times following surgery, but typically occurs between 2-5 years after surgery. It results in return of pain and dysfunction and requires some form of hip revision procedure. Another potential benefit of a cementless total hip replacement is decreased risk for implant related infection at the time of surgery.

In the past 5 years Dr. Schiller has performed approximately 200 BFX cementless total hip replacements at Canada West Veterinary Specialists and other surgical referral hospitals in North America. As an outside consultant for the Biomedtrix company she has also been heavily involved in the training of other joint replacement surgeons in North America, Europe and the UK in the successful use of the BFX cementless total hip system.

Biomedtrix recently made a new system for small dog and cat total hip replacement available. The MicroHip is an option to consider to preserve hip joint function in our smaller patients (5-10kg) as an alternative to femoral head and neck excision. Preliminary data collection on this system through North America has shown it to be very successful. Patient’s recover rapidly from the procedure and show excellent return of function following their surgical recovery. In the past year Dr. Schiller had the opportunity to perform a MicroHip procedure on “Lucas” a 2 year old Maltese suffering from Legg Perthes disease. “Lucas” recovered extremely quickly from surgery and has returned to normal function. Dr Schiller is very pleased to offer this procedure now to small dogs and cats.

The first total knee replacement (TKR) procedure in Canada was also performed at this hospital this past year by Dr. Schiller. “Tollie” received a left TKR in November of 2008. Canine TKR is a new and emerging area of joint replacement. The number of knee replacements performed in people in North America annually now exceeds the number receiving total hip replacements. Knee replacement is performed in patients with advanced knee osteoarthritis. Many of these patients will have been treated chronically for some type of cruciate ligament instability, medically and/or surgically, have cartilage erosion or loss secondary to meniscal injury or have medical reasons for inflammatory joint disease which results in joint degeneration over time. Our canine patients suffer from similar problems and often develop advanced stifle osteoarthritis as they age secondary to ligamentous and cartilage injuries and inflammatory joint disease. TKR certainly provides an option for treatment for some of these patients.

The Biomedtrix company is also actively exploring total elbow replacement. We all see a large patient population effected by degenerative osteoarthritis of the elbows. Medical therapy has been the mainstay of treatment for these patients, but it often becomes ineffective over time and these patients struggle with pain and dysfunction. The TATE Total Elbow Replacement (TATE TER) system was launched commercially in the past year at a few selected surgical referral hospitals, including Canada West Veterinary Specialists. A limited number of cases have been performed across North America with mixed results. Some patients have recovered well from the procedure and have shown improved comfort level and function. Others however have failed to respond as expected and have developed surgical complications requiring further surgical intervention. “Cleo” underwent the TATE TER procedure in Dec 2008. Initially, “Cleo” recovered well from her procedure but subsequently developed loosening of her implants which resulted in loss of function and discomfort. “Cleo” recently underwent a revision procedure to remove her joint replacement and an arthrodesis of her elbow was performed. Finding an elbow replacement system that will achieve the success rates of a total hip replacement system will be a challenging task over the coming years. Modifications to the current implant system are already underway based upon what we have learned so far which should improve its potential successful application. In a few years, this type of joint replacement may be a regularly considered option for the treatment of elbow osteoarthritis.

If you have any questions about joint replacement, be it hips, knees or elbows don’t hesitate to call Dr. Schiller at the hospital.