The replacement of diseased hips with pros-theses has been in development for nearly

100 years. In the early 20th century the surgery was

plagued with problems related to the materialsused, and the lack of awareness of surgical prin-cipals that we take for granted today. In the1950s joint replacement was revolutionized withthe development of polymethylmethacrylate(“bone cement”). Since that time there has beenan evolution in cemented system designs and

implant materials, but the cement itself hasremained largely unchanged.

With cemented systems, the short and longterm stability is related to the cement interfacewith the implants and the bone, and initialstability (at time of surgery) was excellent.Loosening of implants was seen years afterimplantation in humans however, and infectionwas catastrophic to a cemented total jointreplacement, requiring explantation andpseudoarthrosis formation.

In the late 1980s joint replacement inhumans began to move away from cementedsystems, and towards uncemented systems. Thisprincipal involves initial stability from drivingthe implants into the bone forcibly, and longterm stability from bone growing into poroussurfaces on the implants themselves. The hopewas that infection would cease to be such acatastrophic problem (the incidence was low,but consequences unacceptable). Sure enough,

infection became less of a problem, but implantloosening became a greater problem, especiallyin the first few months after the surgery. Itappeared that one potential complication wasbeing traded for another, which spurred thedevelopment of “hybrid” joint replacement, inwhich one component of the prosthesis wascemented, and the other uncemented. Currentlyin human medicine there is not standardmethod. Different surgeons have different pref-erences, and the jury is still out as to what is the

optimum configuration.Veterinary medicine, as it

often has been done historically

in other areas, has mirrored human medicine inthe development of joint replacement. The vastmajority of canine total hips have, and continueto be cemented, but in recent years uncementedsystems have been developed. While they arestill in the minority, uncemented hips are gain-ing popularity in part because infection is

The vast

majority of

canine total hip

replacements

continue to be

cemented.

In recent years

uncemented

systems have

been

developed.

CUTTING EDGEa publication of the Dallas Veterinary Surgical Center Summer 2008

www.DFWVetSurgeons.com

TOTAL HIP REPLACEMENT

DVSCDVSCThe highest quality surgical care for the well-being of your pet.

continued on page 2 . . .

After-Hours Emergency Pager

214.246.2819 or 214.289.3215

Figure 1: Biomedtrix system

Criteria forUncementedSystems Uncemented total hipreplacement systems may beused in dogs for a variety ofreasons, such as dogs with:

3 autoimmune disorders,

3 concurrent infection,

3 hip conformations not suited to the cementedsystem,

3 dogs suffering complica-tions from cemented hipimplantation, or

3 dogs less than one yearof age.

less feared, in part because the uncementedsystems are being modified to improveperformance, and in part because “it’s whatdoctors do in humans”.

At the Dallas Veterinary SurgicalCenter, we have used the Biomedtrixcemented total hip system for many years(Figures 1 and 2). It has proven reliable andwith complication rates comparable tothose seen elsewhere in the US. Infectionrate is about 2%, long term implant loosen-ing rate about 4%, and rate of variousother complications such as dislocation andfracture combine for about 2-3%. Over90% of patients recover remarkablyquickly, have very low morbidity, andclient satisfaction is very high. In thosepatients with complications, there arealmost always options for revision, that inmost cases improve their conditions to nearwhat is expected in uncomplicated hipreplacements.

The surgeons at the DVSC arecurrently being trained in the application

of the two most commonly useduncemented total hip replace-ment systems, BFX and Kyon(Figures 3, 4, 5 and 6). Thesemay be used in dogs that areconsidered high risk for compli-

cations with the more commonlyimplanted cemented hip system. Thesemay include dogs with autoimmune disor-ders, concurrent infection, dogs with hipconformations not suited to the cementedsystem, dogs less than one year of age, oreven certain dogs that are suffering compli-cations from cemented hip implantation.

The majority of hip replacement casesare those diagnosed with hip dysplasia(Figure 7), but it can be used to reliablyalleviate pain from other hip diseases aswell such as recurrent luxation, femoralhead/neck fracture, or autoimmune hiparthritis. It has even been used in a verysmall number of cases to temporarily allevi-ate pain from neoplasia of the femoralhead/neck, or acetabulum, although we donot routinely recommend hip replacementfor neoplastic disease. The only reasonablesurgical alternative for patients with these

conditions is femoral head ostec-tomy, but most hip replacementcases are larger dogs, usually withadvanced degenerative diseaseand concurrent hind limb muscleatrophy. FHO does not producereliably good results in patientssuch as this.

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www.DFWVetSurgeons.com

Figure 3: Kyon uncemented hip

Figure 2: Biomedtrix system

Figure 4: Kyon uncemented hip

The limitations to total hip replacement in dogs are mainly related to body size and age.

The DVSC WelcomesDr. Greg ArnoldDr.Arnold graduated from the College

of Veterinary Medicine at Texas A&M

University in May of 2001.After complet-

ing an internship at Kansas State

University, he practiced in general and

emergency medicine at Sherrill Veterinary Hospital and

the North Texas Emergency Pet Center in the Coppell/

Carrollton area of Greater Dallas for two years.At that

time, he left private practice to do a surgical fellowship in

osteoarthritis, gait analysis, and physical rehabilitation at

the University of Tennessee in Knoxville,TN.

Since that time, he has completed an ACVS accredited sur-

gery residency program at North Carolina State University

where his primary interests included fracture management,

the BFX cementless hip replacement system, oncologic

surgery and general soft tissue surgery.After finishing his

residency in June 2008, he has decided to return to the

Dallas area to join the DVSC and

be around his friends and family.

Dr.Arnold grew up in the Dallas

area and is active in his church. He

enjoys exercise, NHL ice hockey,

cooking and acoustic guitar.The

area has changed a lot in the last

four years and he’s looking

forward to establishing a host of

new contacts and friends.

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

The biggest impediment to consideration of canine hipreplacement is it’s cost, but for those clients that own largedogs with painful hips, that are willing to consider a surgerythat reliably restores comfort and function, total hip replace-ment continues to fill that need.

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www.DFWVetSurgeons.com

DVSCDVSCGreg Arnold, DVMSmall Animal Surgery

Robert D. Barstad, DVM, MSSmall Animal Surgery

Scott G. Bertrand, DVMDiplomate American College of Veterinary Surgeons

Joanne N. Franks, DVMDiplomate American College of Veterinary Surgeons

Darryl E. McDonald, DVM, MSDiplomate American College of Veterinary Surgeons

Robert M. Radasch, DVM, MSDiplomate American College of Veterinary Surgeons

H. Fulton Reaugh, DVM, MSDiplomate American College of Veterinary Surgeons

Brent E. Wilkens, DVMDiplomate American College of Veterinary Surgeons

Katherine L. Wells, DVMSmall Animal Surgery

Our Doctors

Figure 5: BFX uncemented hip

Figure 7:Hip dysplasia

Figure 6: BFX uncemented hip

In early July 2008, the DVSC Southlake location is relocating to our new facility in Grapevine, theAnimal Emergency Hospital and Veterinary Specialty Center. The new address is:

2700 West Highway 114Grapevine, TX 76051

tel 817.379.5444 (same phone)

The new state-of-the-art facility includes a variety of specialty practices: Surgery, InternalMedicine, Dermatology, Ophthalmology, Physical Therapy and a 24-hour Emergency Hospital.

Physical Therapy is expanding to offer full rehabilitation services with state of the art equipmentincluding an underwater treadmill. The physical therapy practice is owned by Angie Faver, PT and isavailable to treat not only DVSC cases, but patients referred from general practices as well.

The DVSC continues to increase surgeon staffing to accommodate your cases promptly. Ourservices also will expand through the addi-tion of a CT scanner and minimallyinvasive surgery: arthroscopy andlaparoscopy.

Please stop by for a visit, to see ournew facility, and to meet with the DVSCsurgeons.

WELCOME TO THE DVSC IN GRAPEVINE

DVSCDVSCD a l l a s V e t e r i n a r y S u r g i c a l C e n t e r

Dallas4444 Trinity Mills Rd., Suite 203Dallas, Texas 75287T 972.267.8100 F 972.267.8700

Grapevine2700 W. Highway 114Grapevine, Texas 76051T 817.379.5444 F 817.379.0222

Mesquite4651 N. Belt Line Rd.Mesquite, Texas 75150T 972.226.3399 F 972.226.0800

Plano10225 Custer Rd.Plano, Texas 75025T 214.667.2233T 214.667.2250

If you need

a surgeon

after-hours,

please page

214.246.2819.

If no response

in 15 minutes,

feel free

to call

214.289.3215.

NN

www.DFWVetSurgeons.com