Carpal Spavin Surgery, Fine-Tuned

Several years ago, Spencer Barber, DVM, Dipl. ACVS, of the Western College of Veterinary Medicine (WCVM) achieved a first in equine surgery when he developed a successful arthrodesis (surgical fusion) technique for treating a debilitating arthritic condition in horses called carpal spavin.

This degenerative disease affects the carpometacarpal joint--the lower joint space of the knee in a horse's front leg. Carpal spavin is most commonly diagnosed in middle-aged to older horses--especially in the Arabian and Quarter horse breeds.

Unfortunately, the pain associated with carpal spavin can't be controlled with normal intra-articular medication used for other arthritic conditions in horses. As a result, affected horses usually become so severely lame that most patients are humanely euthanized within two to three years after diagnosis.

Barber's surgical procedure offered horse owners a much more attractive option. By inserting a drill bit into a horse's carpometacarpal joint in several places, Barber used a "fanning" motion to destroy cartilage and bone, helping the joint fuse together during the horse's recovery. Once the joint fused, his patients were able to walk normally without any pain.

While the procedure seemed to work well, it was very invasive and required four or five different entry points. The technique was also subjective, and it was challenging for other surgeons to successfully repeat the procedure in their patients.

As an alternative, Barber devised a new, less invasive technique using two entry points and three drill tracts into the joint. The concept is based on a similar arthrodesis procedure developed for the equine tarsus (or hock)--another "low motion" joint.


Luca Panizzi

Dr. Luca Panizzi

Here's the drill

And that's where Luca Panizzi, DVM, enters the story. Not long after the large animal surgical resident arrived at WCVM in 2006, Barber asked him if he wanted to test the minimally-invasive technique in a research study as part of his Master of Veterinary Science (MVetSc) program.

"I'm interested in orthopedics so I thought, 'Why not?'" says Panizzi, now in the third and final year of his residency and graduate degree. "If this technique proves to be as good as the one that Dr. Barber first developed, it will mean that we can use a less invasive approach and get the same result: a sound horse that's still usable."

Panizzi, Barber and summer research student Hayley Lang began the research trial during the spring of 2007. After initially testing and perfecting the modified arthrodesis technique on the limbs of equine cadavers, Panizzi performed the surgery in six healthy horses that were selected for the research project. One carpometacarpal joint of each horse underwent the treatment.

Through two points of entry, Panizzi drilled three tracts to destroy some of the cartilage and subchondral bone in the joint: two tracts were drilled through one entry point while the second entry was used to drill the third tract. "We're trying to cause a counterbalance between not causing too much damage to the cartilage and bone--but enough to cause the joint to fuse," explains the resident.

Unlike Barber's initial technique, this method is standardized with particular measurements and angles for the drill bit passes. During the procedures, Panizzi also used the veterinary college's C-arm fluoroscope unit to guide and measure his movements.

Fast-tracked fusion

All of the horses received anti-inflammatory drugs for the first few days after their surgeries, and as expected, the animals were still noticeably lame two to three months later. "After that point, they became progressively better," says Panizzi. He adds that it usually takes about six to eight months for the joint to completely fuse.

The research team took radiographs of the horses' treated carpometacarpal joints one day after surgery, and then took further X rays at four, six, eight, and 12 months post-surgery. Panizzi and Barber also used the veterinary college's force plate to determine each horse's grade of lameness: those evaluations took place before surgery and at six, eight, and 12 months post-surgery.

By the eight-month mark, Panizzi says four of the six horses appeared to be sound without any lingering issues from the surgical procedure. Additional analyses must be completed in the next few months before the research team can make any concise conclusions about the new technique. However, after spending watching the horses' progress in the past year, Panizzi believes the new procedure should help horses heal faster than the previous technique.

"Being minimally invasive means creating less pain and less damage, and hopefully the joint will fuse in a shorter amount of time with minimal pain."

Since the lower carpal joint doesn't move very much, Panizzi says surgical fusion shouldn't affect the locomotion of the horse: treated horses should be able to walk, trot and even gallop.

"When you flex the knee in a horse, that joint doesn't open up. It's just a very minimal motion, but apparently it's enough to create pain when the cartilage is damaged," he says.

Apart from the study, Panizzi says the research team used the new arthrodesis procedure on two clinical patients that were diagnosed with carpal spavin at WCVM's Veterinary Teaching Hospital last summer.

"We performed surgery on one case around the same time as the research project's surgeries. Since then, the owner was in touch with us and she said the horse is doing fine," points out Panizzi.

Will the new arthrodesis procedure prove to be the best alternative for treating patients diagnosed with carpal spavin? Panizzi says that can only be determined after it's used in more clinical cases and develops a track record. But ultimately, results from this research project will help to fine tune the fusion process: "The idea is that if this arthrodesis technique works in normal horses, there's a good chance that's it's going to work in horses that have the disease."



The photo at left shows a horse�s leg after surgical fusion of its carpometacarpal joint. The noticeable bump (see arrow) is caused by new bone that forms during fusion. The carpometacarpal joint (CMC) is evident in this close up of an equine skeleton�s left front limb. Using the new, minimally-invasive arthrodesis procedure, Dr. Luca Panizzi inserted a drill bit into the joint space through two different entry points and drilled three tracts to destroy some of the cartilage and bone--but only enough to encourage fusion.

David Shield has written for many Saskatchewan-based publications including Planet S Magazine, U of S On Campus News, Pulsepoint Magazine and Eagle Feather News. He also works as a casual reporter for CBC Radio News in Saskatoon, Sask.


Reprinted with permission of Horse Health Lines, publication for the Western College of Veterinary Medicine's Equine Health Research Fund. Visit for more information.

About the Author

David Shield

David Shield has written for many Saskatchewan-based publications including Planet S Magazine, U of S On Campus News, Pulsepoint Magazine and Eagle Feather News. He also works as a casual reporter for CBC Radio News in Saskatoon, Sask.

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