Clean Run - March 2012 - 34

If you build it... they can run!

patient will be appropriate for both options. Many patients benefit best from a combination of a cementless acetabular cup with a cemented stem. This is termed a hybrid hip.

What are the pros and cons of a cemented and cementless implant?
Cemented hips have been utilized for decades in both humans and dogs, and have the most research available supporting their use and long-term efficacy. The biggest advantage of the cemented system is that it offers maximum strength shortly after implantation, thus has few short-term complications. It is also ideal for patients with more brittle bone or straight shaft femurs, like those typically seen in the older Shepherd breeds. One of the negative aspects of a cemented hip is that with time, the cement mantle can separate from the bone. This is termed aseptic loosening and can be caused by a number of factors the cause inflammation at the bone-cement interface. The risk of infection is also higher in a cemented hip, as bacteria can harbor in the cement, making treatment potentially challenging. However, the risk of infection is still generally less than 1-2 % of cases. Cementless hip systems rely on bone ingrowth or ongrowth of the implants for longterm stability. This system theoretically offers a long-term advantage of decreased aseptic loosening, and carries a smaller risk of infection. However, perioperative complications are reported to be higher than with a cemented hip, and long-term data is currently not available to document the true life span of these implants. In our hospital, we prefer to implant either a completely cementless hip, or a hybrid hip, depending on what is most appropriate for the individual patient.

Once my dog has a hip replacement, what is the expected outcome?
Almost all patients will be weight bearing on the operated limb within 24 hours of surgery. In our hospital we have an overall implant retention rate with good to excellent function in 98% of patients. Of this 98%, about 7-8% will experience some sort of complication, which usually necessitates an additional surgery to correct. The most common complications are luxation of the hip, with femoral fracture, loosening of the implants prior to bone integration, and aseptic loosening and infection are also possible. With an appropriate revision, long-term outcome still remains very positive. Once a patient has healed properly, there are no restrictions on physical activity, agility included!

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Is there another option besides a hip replacement for dogs with hip dysplasia?
Yes. A femoral head and neck ostectomy is a salvage procedure in which the ball and neck of the femur is removed with a surgical saw. With this procedure, the bone on bone contact of the worn femoral head and acetabulum is eliminated, as the bones no longer touch. This procedure relies on scar tissue and muscle to support the body weight of the patient. The biggest advantage to this procedure is that it has few complications, as no implants are present. However, preservation of muscle mass and range of motion are absolutely critical for a successful outcome. The majority of patients will not bear weight on the limb for 3-5 days following surgery and rehabilitation therapy is imperative for a functional outcome. Recovery is usually longer than that experienced with a THR. While patients with this procedure typically have a residual gait abnormality, they are usually pain free and can maintain an acceptable level of activity. However, I would not recommend this surgery for an agility dog that is expected to return to competition. Unfortunately, hip dysplasia is a common condition affecting many dogs. Ideally the veterinary community will eventually determine the specific genetics of this condition so that with responsible breeding we can hopefully see a decline in this life long condition. The good news is that there are now many more treatment and management options available to help alleviate the discomfort associated with this disease. If finances are not a factor, a total hip replacement will offer the appropriate patient the most normal, long-term function. D

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Dr. Peter Lotsikas is a Diplomate of the American College of Veterinary Surgeons. He graduated with a BS degree in Biology from Virginia Tech and a DVM degree from the Virginia-Maryland Regional College of Veterinary Medicine. He then completed a general small animal internship at Kansas State University, followed by a surgical internship at Dallas Veterinary Surgical Center. Dr. Lotsikas received his formal surgical residency training at Iowa State University. He now practices at the Veterinary Orthopedic & Sports Medicine Group (VOSM) in Annapolis Junction, Maryland. Additional information about Dr. Lotsikas is available at www.VOSM.com. 34 Clean Run | March 12

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Clean Run - March 2012

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