Total Hip Replacement
At the Dallas Veterinary Surgical Center (DVSC), we have used the Biomedtrix cemented total hip system for many years (Figures 1 and 2). It has proven reliable and with complication rates comparable to those seen elsewhere in the US. Infection rate is about 2%, long term implant loosening rate about 4%, and rate of various other complications such as dislocation and fracture combine for about 2-3%. Over 90% of patients recover remarkably quickly, have very low morbidity, and client satisfaction is very high. In those patients with complications, there are almost always options for revision, that in most cases improve their conditions to near what is expected in uncomplicated hip replacements.

The surgeons at the DVSC are currently being trained in the application of the two most commonly used uncemented total hip replacement systems, BFX and Kyon (Figures 3, 4, 5 and 6). These may be used in dogs that are considered high risk for complications with the more commonly implanted cemented hip system. These may include dogs with autoimmune disorders, concurrent infection, dogs with hip conformations not suited to the cemented system, dogs less than one year of age, or even certain dogs that are suffering complications from cemented hip implantation.

Criteria for Uncemented Systems
Uncemented total hip replacement systems may be used in dogs for a variety of reasons, such as dogs with:

• autoimmune disorders,
• concurrent infection,
• hip conformations not suited to the cemented system,
• dogs suffering complications from cemented hip implantation, or
• dogs less than one year of age.

The majority of hip replacement cases are those diagnosed with hip dysplasia (Figure 7), but it can be used to reliably alleviate pain from other hip diseases as well such as recurrent luxation, femoral head/neck fracture, or autoimmune hip arthritis. It has even been used in a very small number of cases to temporarily alleviate pain from neoplasia of the femoral head/neck, or acetabulum, although we do not routinely recommend hip replacement for neoplastic disease. The only reasonable surgical alternative for patients with these conditions is femoral head ostectomy, but most hip replacement cases are larger dogs, usually with advanced degenerative disease and concurrent hind limb muscle atrophy. FHO does not produce reliably good results in patients such as this.

The limitations to total hip replacement in dogs are mainly related to body size, and age. While implants are made for mid sized dogs, the complication rates are higher in these patients, and the DVSC currently is not recommending hip replacement in dogs less than 45 lbs body weight. Complication rates used to be higher in skeletally immature dogs. With the Kyon system it could be considered in dogs as young as 9 months. Counseling the client considering hip replacement in dogs this young is of paramount importance.

The biggest impediment to consideration of canine hip replacement is it’s cost, but for those clients that own large dogs with painful hips, that are willing to consider a surgery that reliably restores comfort and function, total hip replacement continues to fill that need.

View/download this topic in our newsletter, Cutting Edge, Summer 2008.