Fetlock Arthrodesis Advances Provide Options for Injured Horses

If pressed to pinpoint a single Achilles heel in the racehorse, it's probably a fair bet to assume many would zero in on the fetlock–the intricate joint mechanism that in a racehorse travelling at top speed proves especially vulnerable to system failure. Indeed, 19 of the 22 horses that suffered catastrophic musculoskeletal injuries at Santa Anita during its benighted winter-spring meet nearly two years ago had sesamoid fractures.

In most cases, the prognosis for horses who suffer severe fetlock breakdowns is grim, but a procedure pioneered at the end of the 1970s called the fetlock arthrodesis suddenly provided a viable avenue to save some horses that would otherwise be euthanized.

Due to costs and limited range of activities for horses post-surgery, the fetlock arthrodesis–a procedure to stabilize the ankle, preventing joint movement by fusing it into a normal position for the leg–has been traditionally performed on horses with residual paddock value.

Perhaps the widest known fetlock arthrodesis recipient is Barbaro, the 2006 GI Kentucky Derby winner who suffered a complicated series of fractures to and around his right hind fetlock at the start of the 2006 GI Preakness S. In the end, Barbaro succumbed to these injuries, though only after an extended struggle.

But a program in California that has been underway for about a year has the aim of making the procedure a practical consideration for a wider net of injured horses.

“We have to recognize that there are times when we make decision based on finances,” said Ryan Carpenter, a SoCal-based veterinarian who performs the arthrodesis surgeries at Santa Anita. “So, we're taking the approach that if you remove finances from the equation, what is the best course of action for this horse?”

As a rule of thumb, in the event an owner or trainer cannot afford the cost of surgery and convalescence–roughly $20,000 in total–expenses are shared between The Stronach Group (TSG), the Thoroughbred Owners of California (TOC) and the horse's owner and/or trainer, said TSG Chief Veterinary Officer Dionne Benson. In some cases, TSG has picked up the entire tab, she said.

But the program–also employed at other TSG facilities in California, like Golden Gate Fields–has courted certain concerns. For one, the procedure is intricate and invasive, with the potential for a number of post-surgery complications. That horses who receive it are essentially paddock-bound raises long-term economic considerations.

Some have also suggested the program could be used to skew state fatality statistics, an assertion both Carpenter and Benson strongly deny.

“I would never do anything that I wouldn't do on another horse,” said Carpenter, who added that the results of the program thus far are encouraging. Of the eight horses that Carpenter has performed fetlock arthrodesis surgery on over the past year, six have proven successful, he said.

“If American Pharoah needed the procedure, and we say it's right and ethical and humane for American Pharoah to receive the procedure, then I think you have to say it's right, ethical and humane for the $10,000 claimer to receive the procedure,” Carpenter added. “It's either ethical or not, irrespective of value.”

What is Fetlock Arthrodesis?…

There are two primary candidates for fetlock arthrodesis, experts say: horses crippled with degenerative arthritis, and in racehorses, those that suffer a closed biaxial proximal sesamoid fracture (when both sesamoid bones break in the same leg).

The initial portion of the surgery concerns the removal of cartilage between the bones, to make the fusion as tight and stable as possible. “That's the most important part of the procedure that's often not done correctly,” warned Carpenter. “You need that bone-on-bone interface so that it can heal properly.”

A plate is placed across the front of the fetlock, which holds the whole joint in place. This plate is secured with screws that can be inserted into the fetlock, pastern, cannon bone and, when necessary, the sesamoids.

A “tension band,” which is essentially a wire that goes behind the fetlock joint, provides another layer of joint stabilization.

“When the sesamoid bones break, you have nothing that supports it back there, and the fetlock drops,” said Carpenter, of the need for this mechanism.

Not every horse that suffers a traumatic fetlock fracture is a candidate for the surgery. Compound fractures come with too great a threat of infection, for example.

Existing laminitis in the opposite limb is a serious problem, and “usually enough of a red flag that we would not proceed,” wrote Dean Richardson, chief of surgery at The University of Pennsylvania School of Veterinary Medicine's New Bolton Center, in emailed answers to questions.

Most importantly, there needs to be a good flow of blood to the foot. “When a horse fractures its sesamoid bones and it drops its fetlock, they stretch the blood vessels,” said Carpenter, explaining the link between fetlock injuries and curtailed blood flow to the lower limb. “They don't have a tremendous amount of collateral circulation when it comes to the foot, and that's why tissue perfusion [the lack of adequate blood supply] is a big issue.”

Fetlock arthrodesis–pioneered by acclaimed veterinarian, Larry Bramlage–is long and complicated. In the course of perfecting the procedure, Carpenter reckons that he has shaved about an hour off the time he takes to complete the surgery, with it now taking him roughly two hours.

Because of the intensive nature of the procedure, coupled with the relative scarcity of viable equine candidates, there's a limited number of surgeons across the country with the necessary skill sets to take the surgery on, experts say.

At the same time, “The procedure has evolved a lot from the way Bramlage first described it,” said Carpenter, pointing to the development over the years of locking compression plates, where the screws fix to the plate, making it a very “fixed, stable construct.”

And how successful is the fetlock arthrodesis surgery? In a 2008 article, Bramlage is quoted as saying that, “In the first group of horses we presented, the success rate of the primary treatment approached 70%.” For other kinds of injuries, such as degenerative arthritis, “It's as high as 80%,” he added.

Likewise, Richardson said that success is inextricably linked to the severity of the original injury.

“Certain types of injuries such as complete disruption of the distal sesamoidean ligaments are much more difficult and the prognosis for success as defined above is probably only 50-60%, whereas fetlock arthrodesis in horses that need the joint fused for problems not related to being an active racehorse results in essentially a 100% success rate,” Richardson wrote.

Post-surgery, most horses are reasonably comfortable quickly after the fetlock is stabilized, say experts, though this is still the time when the risk of complication is high. “If you're going to fail, you're going to fail very quickly,” said Wayne McIlwraith, founder of the Orthopaedic Research Center at Colorado State University.

Laminitis and local infection are common medical hurdles to overcome in the short term–further down the road, experts warn of potential residual problems with the pastern region.

“The fetlock is meant to bend a lot for a reason,” said Carpenter. “Now that it can't, you're transitioning the stress to the other joints.”

For the first few months of convalescence, horses are restricted to box rest. After that, a process of light exercise can begin, leading eventually to a point where the horse can be turned loose in the paddock. This can take roughly six months, said Carpenter.

Though the overwhelming majority of horses will only ever be pasture or breeding-sound, Richardson said that a “small percentage” have been ridden at “low level work,” like trail riding. That these horses are essentially pasture-bound is not a reflection of pain in the fused joint, Richardson explained–rather, it's due to the practicalities of a high-motion joint being fixed, immobile.

“Fusing it inexorably results in a marked asymmetry of gait that feels terrible when you sit on the horse,” Richardson wrote. “It is not painful to the horse but it looks bad and feels bad to the rider.”

Nevertheless, among some in the industry, the procedure carries a stigma. “When we started this, there were a lot of memories from these surgeries in the early days–how challenging they were, and how often they went poorly,” admitted Benson.

Several industry figures who spoke on the condition of anonymity also raised concerns about a lack–especially in the early days of the program–of clear guidance to determine which horses receive the surgery, and how the economics is structured.

According to Benson, TSG is in the process of developing standardized protocols to guide its California program. These primarily surround the funding mechanism, she said, but also include avenues to ensure others, like the attending veterinarian, weigh in on each case.

When asked if the CHRB, the state industry's regulatory body, is overseeing the shape of these standards, equine medical director Rick Arthur said that, “I have certainly encouraged them to standardize protocols so all the horsemen understand what's available, and what they're being asked to do, and what they're expected to do.”

The American Association of Equine Practitioners' euthanasia guidelines outline five main points to assist veterinarian in making “humane decisions regarding euthanasia of horses.” These points are as follows:

A horse should not have to endure continuous or unmanageable pain from a condition that is chronic and incurable.

A horse should not have to endure a medical or surgical condition that has a hopeless chance of survival.

A horse should not have to remain alive if it has an unmanageable medical condition that renders it a hazard to itself or its handlers.

A horse should not have to receive continuous analgesic medication for the relief of pain for the rest of its life.

A horse should not have to endure a lifetime of continuous individual box stall confinement for prevention or relief of unmanageable pain or suffering.

The program, Benson said, has provided an opportunity to showcase the surgical advancements that have been made to the procedure over the years. “We've had far more successes, fortunately, than we've had issues,” she said, adding that ultimately, “Any decision that's made on the medical side is made in the best interest of the horse.”

“Dr. Carpenter and the vets on our team are independent of the financial decision. They're there to help make a medical decision for the horse,” added Benson. “And, if they say, 'the horse has a reasonable chance of pasture soundness,' then we turn it over to the people in the racing office to arrange the financial piece.”

Not Just Committed In The Short Term…

A not-inconsiderable sticking point to these surgeries is money. “I've long considered that if you've bred a horse and race it, or buy a horse and race it, you should be responsible for the welfare of that horse for the rest of its life” said McIlwraith. “Unfortunately, that's an ideal that not everybody holds to.”

Which leads to the long-term economic considerations of caring for a pasture-sound horse. California's aftercare program falls under the umbrella of the California Retirement Management Account (CARMA).

According to Madeline Auerbach, who founded the organization and remains on its board of directors, “CARMA's position is that if this is veterinary driven, and the vets have determined that this is within their guidelines to operate on the horse, we support that and we support trying to provide services for the horse.”

Has the selection process for horses to receive the surgery thus far been vet driven? “It has been,” Auerbach replied. “It's been vet driven in terms of: Is it worth trying or is it cruel and unusual punishment.”

Financially, CARMA is not “at this point struggling” to care for the horses, said Auerbach. But in the long-term, “We have to figure out a way that we get compensated for it,” she said, floating the idea of a fee or separate fund.

“We have not figured that out yet,” Auerbach said. “We're still in the process of putting a dollar amount to it and trying to figure out trying to make sure that we do not deplete the funds. This year has been horrific, obviously, in terms of financial support, because we get most of our money from the purse account.”

(This recent TDN story breaks down the hit California purses have taken due to the COVID-driven betting shift towards ADW)

When asked if TSG will step in to provide additional funding in the event a horse who has undergone fetlock arthrodesis surgery finds itself in a financially precarious situation in the future, Benson replied: “If there comes a time when a horse in one of these situations, or a horse really in any risky situation, we want to help be part of the solution, not pass it down the road and assume it's somebody else's problem…We're not just committed to the horses who race at our tracks for the short-term.”

Carpenter stressed the relatively small number of horses for which the surgery is applicable.

“If we have partnership from the industry to help decrease the financial burden to the owner, and we have well-respected lay-up facilities that are willing to take these horses on, maybe we find out that these horses can actually do more than we expected them to do, and we can place them at other places,” Carpenter said. “Then, this perceived burden may not be as big as it once was.”