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Michael Conzemius, Veterinary Clinical Sciences, (515) 294-9562
Teddi Barron, News Service, (515) 294-4778

Michael Conzemius
Michael Conzemius

AMES, Iowa -- The first, total-elbow replacement joint for dogs has proven successful in year-long follow-ups on clinical cases at Iowa State University's College of Veterinary Medicine.

The patented implant and surgical procedure were developed by orthopedic specialist Michael Conzemius, an associate professor of veterinary clinical sciences.

In dogs, the elbow joint functions much like the human knee, absorbing the stress of walking, climbing and running.

Arthritis common in some breeds
Arthritis in the elbow joint often causes pain and lameness. It is common in many breeds of dogs, such as Labrador retriever, rottweiler and German shepherd. Available treatments can't curtail the disease or alleviate the limping, Conzemius said.

Although surgery to replace diseased hips in dogs has been successful for several years, such an option hasn't existed for elbow joints.

Conzemius said that an estimated 1,000 dogs per year will undergo the total-elbow replacement surgery when it becomes widely available in the United States. Currently, the procedure is performed only at Iowa State.

Conzemius and his colleagues at Iowa State implanted their total-elbow replacement joint in 20 dogs. Using computerized gait analysis, they monitored the dogs' recovery for one year. About 80 percent had good or excellent outcomes. Their evaluation was reported at the recent Veterinary Orthopedic Society meeting.

Implant refined over 5 years
Conzemius' team refined the implant design and surgical procedure during a period of five years. They tried more than 15 different design modifications before attempting clinical cases.

"The elbow is a complex joint. It's a three-bone system and everything has to meet up perfectly or the dog ends up with instability, pain or uneven wear of the cartilage in the joint," he said.

"We spent a great deal of time studying the mechanics and the anatomy of the elbow and the variations we'd need for different breeds. We also studied all parts of the bones that make the joint, because most joint replacements have stems that go up into the bones," he said.

The total-replacement joint was designed in four sizes to accommodate different breeds. It consists of two implants made from traditional implant materials. One is a medical-grade polymer. The other is machined from stainless steel for use in the study dogs. If mass produced, it would be manufactured of cobalt chromium, Conzemius said.

The surgical procedure takes about two hours. The dogs remain in the hospital for three to five days following the surgery.

Dogs swim during rehab
"They're usually up and about right away. Within seven to ten days, we enroll them in an aquatic rehabilitation program," said Conzemius, who pioneered aquatic therapy for dogs.

"Swimming helps maintain and regain range of motion, which is really important after this type of major joint surgery. I won't do the surgery unless the owners can find a place where the dogs can swim after surgery," Conzemius said.

Although the dogs are in reasonably good condition three months after the surgery, they continue to improve for up to a year. That's because by the time dogs need elbow replacement surgery, they're in fairly bad shape, Conzemius said.

"They have very little range of motion -- the limb moves only 10 or 15 degrees prior to the surgery, for example. There's also profound muscle atrophy from years of limited use. So, it takes a long time for the dogs' function to return to the point that they can walk or run for long periods of time without a limp," he said.

"In surgery, we break down all the scar tissue and get back about 70 to 90 degrees of the range of motion. That's enough for them to have near normal function," Conzemius said. "But if they don't swim during rehab, the scar tissue is just going to re-form. They'll lose the range of motion again and just have an expensive implant that doesn't move."

Conzemius evaluated the recovery of 20 dogs of different breeds. He used force-platform gait analysis, a computerized device that measures the amount of weight a dog places on each limb while walking. One year after the surgery, 16 dogs had a good or excellent outcome, with limb function increasing by at least 25 percent when compared to preoperative function.

Surgery a success
"Although this probably can be improved upon, we consider this successful because these dogs had no treatment options prior to the surgery," Conzemius said.

The Iowa State University Research Foundation holds the patent. Conzemius expects the total-elbow replacement joint will be licensed in the next year for commercial manufacturing.

When the implant and surgery become widely available, the total cost could range between $2,500 and $5,000, he said.

The research and development of the total-elbow replacement joint was funded by the American College of Veterinary Surgeons and Iowa State University's College of Veterinary Medicine and Center for Applied Technology Development.


Note to editors: Downloadable print-quality photos of Dr. Conzemius are at http://www.public.iastate.edu/~nscentral/photos.html.

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