Cover image courtesy of Colorado State University
Every yearling that has walked through a sales ring in Australasia has been subject to several sets of x-rays, and many have had some kind of joint surgery to correct rotation or remove fragments and lesions that could affect racetrack performance.
Older horses are routinely imaged during training and arthroscopic surgery is an accepted regular practice in the industry, but Dr Wayne McIlwraith remembers a time before it happened at all.
Graduating from Massey University with a Bachelor of Veterinary Science (with distinction) in 1970, McIlwraith’s interest in surgical interventions was sparked during an internship in Large Animal Surgery (which included a Diploma of Surgery) at the University of Guelph in Ontario. In the mid 1970s, the idea of surgically treating a horse with colic was entirely novel, but was becoming routine at the University of Guelph with a high success rate.
After the internship at the University of Guelph in 1975, he then went to Purdue University as a Resident in Large Animal Surgery. It was here that McIlwraith was assigned a Masters project on equine synovitis, and his interest in joint disease and surgery began in earnest.
The beginning of a revolution
“Arthroscopic surgery revolutionised our ability to fix horses and get them back to athletic activity, just as it did with humans,” McIlwraith explained. “Before then, we would have to make a large incision into their joints, and they just didn’t back to the same level of competition.”
“Arthroscopic surgery revolutionised our ability to fix horses and get them back to athletic activity.” - Dr Wayne McIlwraith
Until McIlwraith undertook his project in 1975, the scientific world believed at the time that you needed instability or a fracture in a joint for the horse, or human, to develop osteoarthritis. Treatment and imaging were both highly primitive; magnetic resonance imaging was in its infancy in the seventies and the first body scan of a human by MRI wouldn’t be done until 1977, so the surgical treatment for knee pain was based on location of symptoms and removal of the meniscus without pinpointing where the pain originated was quite common.
It was even more primitive for equine patients; pre-digital x-rays required much more bulky equipment and long processing times for each shot, and even then, there wasn’t much that could be done.
Dr Wayne McIlwraith | Image courtesy of Colorado State University
That would soon change with the dawn of the arthroscope; first, quite literally a long, thin scope that allowed a surgeon to see into a joint without making a large incision, looking directly into the eyepiece, and quite a number of years later, a camera would be attached to the scope, allowing the inside of a joint to be shown on a larger screen and recorded.
The arthroscope’s invention came much earlier in the 20th century, but it didn’t reach the western world until the sixties, and was still limited in its spread. Dr Lanny Johnson, then a professor of surgery at Michigan State University, was one of the pioneers of its use in the United States and it was his work that attracted McIlwraith’s attention.
“When I did my first year of surgical residency at Purdue, I read about the arthroscope and I read about Dr Lanny Johnson,” McIlwraith recalled. “He was putting on courses teaching human orthopaedic surgeons to do a diagnostic arthroscopy of the knee joint. So I called him up and I said, ‘Dr Johnson, I'm a veterinary surgery resident’. Basically, I was a cheeky New Zealander and otherwise I wouldn't have called him.
“I said, ‘I'd love to come to your course’, and he said, ‘oh, I'd love to have you. I won't charge you registration’.
“So I got in my Ford Pinto and drove to Michigan, and 100 human orthopaedic surgeons and me learned how to do a diagnostic arthroscopy of the human knee. What we could do then is go in with the arthroscope, distend the joint (with sterile fluid), and you look and you have a view of the inside of the joint. In 1975, it wasn't crystal clear like now, but it was good enough so you could ascertain in the human case if there was a meniscal tear or another injury, and if it was treatable.”
“What we could do then is go in with the arthroscope, distend the joint (with sterile fluid), and you look and you have a view of the inside of the joint.” - Dr Wayne McIlwraith
McIlwraith could immediately see the application of the device in horses; if much smaller incisions were made in the joint, veterinary surgeons risked far less interference with joint structures and they could far more easily remove whatever was causing a problem.
“I came back to Purdue and I said to my supervisor, ‘you need to buy me an arthroscope’.”
Triangulating the problem
“We were 80 miles from Chicago and there were a lot of lame standardbreds with knee chips that were developing secondary osteoarthritis after surgery, and the arthroscope allowed us to decide if it was worthwhile to remove the chip fragments.”
There was a real opportunity here to make a difference.
McIlwraith first put an arthroscope into a horse’s knee in 1976, at first performing diagnostic arthroscopy to assess if there was enough cartilage left to support the joint if they removed chips. This is called triangulation, something that was being perfected in humans at that point.
“Triangulation means you've got the scope in one place and you're looking at the chip, or whatever is wrong, and then you make another hole so you can bring your instrument in and operate it under arthroscopic visualisation,” he said.
Arthroscopic surgery for horses | Image courtesy of Colorado State University
McIlwraith finished his Masters and a PhD at Purdue on the subject, before obtaining a faculty position at Colorado State University as an Assistant Professor in 1979. Soon after this, word had started to spread that he was using an arthroscope on horses, and he was contacted that year by a human orthopaedic surgeon who wanted to observe his work.
“We anaestheticised a horse and he gave some excellent advice on triangulation technique, and it really helped me to a point where I could remove knee chips and ankle (fetlock) chips,” McIlwraith said. In 1980, he started to offer the surgery in practice and added other joints. In 1984, he began to offer courses teaching the emerging techniques to other vets.
“Arthroscopic surgery is very routine now, but this was before the techniques were developed, and so we were developing the techniques for it. Once I got the numbers and had the results, I started being invited to do horses elsewhere.”
“Arthroscopic surgery is very routine now, but this was before the techniques were developed, and so we were developing the techniques for it.” - Dr Wayne McIlwraith
In 1983, McIlwraith met Dr Nancy Goodman, a race track vet who was interested in learning to use an arthroscope, when she called because she could not get in the course. Cameras for the scopes were still a long way away from being developed, so the course could only take 12 people at a time.
“She was the first woman to make it in race track practice,” McIlwraith shared. “She practiced at Los Alamitos, in Orange County, which was the premiere Quarter Horse race track in the United States, so I said, ‘I could come down and show you and Dr (Bart) Baker (her employer)’.”
Goodman lined up four horses for McIlwraith’s first visit Los Alamitos.
“I flew down from Denver on a Wednesday and arrived at seven, we started operating and we finished at two in the morning, sat around drinking Scotch until four, and I was on the plane by seven AM. Dr Goodman had four lined up again for the next weekend, and I kept coming back.”
“I flew down from Denver on a Wednesday and arrived at seven, we started operating and we finished at two in the morning, sat around drinking Scotch until four, and I was on the plane by seven AM.” - Wayne McIlwraith
McIlwraith married Goodman eventually, and she would become his main surgical partner in 2001 after retiring from race track practice. But before that, they were changing the face of Quarter Horse racing.
Dr Wayne and Dr Nancy McIlwraith | Image courtesy of Colorado State University
“Most of the Quarter Horses had more than one joint with chip fragments, and I could take chips out and clean up the cartilage, and they come back to full level. There was a horse called First Down Dash, he was the son of Dash For Cash and he had chips in six joints. We operated him and the next year he won the Champion Of Champions.”
First Down Dash’s (USA) (Dash For Cash {USA}) victory in the 1987 G1 Champion Of Champions earned him that year’s AQHA World Champion title, and the Quarter Horse world was sold on the idea of arthroscopic surgery. The Thoroughbred world followed quickly in California, but took a little more convincing in Kentucky.
Changing perceptions
“People knew I was doing it, and most vets accepted it pretty well,” McIlwraith said. “But owners and trainers were more skeptical.”
Even so, a steady stream of topline horses started to come McIlwraith’s way. Acceptance of the procedure was one of the largest advancements for the practice, it just wouldn’t come easy.
“If you have a fast horse and you can bring them back to the same level, then you still have a fast horse. Unfortunately, you aren’t going to change a slow horse with surgery!”
In 1985, the tide would be turned in Thoroughbreds by McIlwraith’s work on one in particular. Late in the previous year, he was asked to operate on a very special patient.
“In (late) 1984, I was asked to go down and take knee chips out of a horse called Spend A Buck, who was a good 2-year-old,” McIlwraith put it lightly. “He'd been third in the Breeders' Cup Juvenile. I did surgery on him in Miami, and six months later, he won the Kentucky Derby by six lengths, wire to wire. So that really put arthroscopic surgery on the map.”
“I was asked to go down and take knee chips out of a horse called Spend A Buck... and six months later, he won the Kentucky Derby by six lengths, wire to wire. So that really put arthroscopic surgery on the map.” - Dr Wayne McIlwraith
The win, and a subsequent victory in the G1 Jersey Derby, earned Spend A Buck (USA) that year’s Champion 3YO Colt and United States Horse Of The Year honours. Suddenly, joint surgery became very much in vogue.
There were still detractors, but McIlwraith had his ways of convincing them.
Spend A Buck (USA) | Image courtesy of Colorado State University
“I started doing arthroscopic surgery at one clinic in Kentucky and we had a high number of stifle OCDs in the progeny of a stallion known to throw them,” McIlwraith recalled. Osteochondritis dissecans (OCD) is a common problem in young thoroughbreds where abnormal bone has been laid down in the joint, leading to swelling and lameness.
“I was operating on these horses and they were doing great. Dan Rosenberg, who managed Three Chimneys Farm, was telling this pre-eminent vet about how I was doing surgery and we were having good results. He was skeptical, so Dan asked him to call me.
“This vet called me, and he said, ‘hi, Wayne, Dan Rosenberg tells me that you're having great success with stifle OCDs. Now, we have really well-bred thoroughbreds in Kentucky, they're not like the horses that you have there in Colorado, so I don't know how it compares’.
“I said, ‘well, actually, nearly all the horses in the series we've just published on were Kentucky-bred thoroughbred yearlings’, and he was just in shock. He wasn't even aware of my coming in and doing them.”
You've got to use data
McIlwraith was keen to point out he wasn’t alone in this march towards progress.
“We soon had other people doing it as well, it wasn't just me,” he said. “But I was the first and wrote the book (first edition published in 1984) and was giving the courses. But the thing that was great about it is that it enabled us to get horses back to their full potential.
“But the thing that was great about it (arthroscopy) is that it enabled us to get horses back to their full potential.” - Dr Wayne McIlwraith
“Now, did we get 100 per cent back? No. And then you start realising limitations, you get secondary disease, and so that's when I went back to the university and said,’ we need to do a research project on this, and do a research project on that’.”
The Orthopaedic Research Center, now the world’s largest equine orthopaedic research centre, was developed as a response to the complications and problems that McIlwraith recognised.
Horse treatment at Orthopaedic Research Center | Image courtesy of Colorado State University
“We started it based on recognising problems, and our research is at all levels, we look at cause and prevention of disease, use of corticosteroids, new treatments like orthobiologics, and biomarkers inertial sensors to predict injury.”
Retiring from his principal referral surgical practice in California in 2023, McIlwraith continues to be passionate about research and keeping on the frontier of orthopaedic development. Recent and current projects he has taken part in include the use of sensors to detect injury, improving the versatility of computed topography (CT), and analysing the truth behind yearling sales x-rays.
“We did a big radiographic study where we looked at the x-rays of 2600 yearlings from the 2016 Keeneland yearling sales, because that’s one of the big areas (of contention), looking at a yearling x-rays and seeing something and thinking that you shouldn't buy it,” McIlwraith said.
“We followed all the horses through their careers, and we were able to define what has the potential to cause problems. We showed that many of of the changes seen on yearling radiographs have no negative effects on the horses subsequent career and we were able to define the risk, or lack of risk, with large numbers.
“If you've got a yearling that's got an OCD with clinical signs, most of them can be treated very effectively with arthroscopic surgery and go on to race, and we've been doing it for a long time. I wrote my first paper on stifle arthroscopy for OCD with 300 cases and it was published in 1985.
“But then you get into other grey zones where it's very questionable (if you need to operate), and one of them is subchondral cystic lesions in the medial femoral condyle of the stifle. They show up on x-rays, but at least 80 per cent of them are never going to be lame (because of the lesion). Our study showed the proof.”
AgriFutures Australia and the University of Queensland did a similar exploration in 2023 and returned the same conclusion.
McIlwraith wants to see these studies start to make more of an impact on the thoroughbred industry; “Some people are making the decision (to operate) without looking at the data, and we have done the studies and published them. If people read those, they're going to be doing less surgery.
“Some people are making the decision (to operate) without looking at the data, and we have done the studies and published them. If people read those, they're going to be doing less surgery.” - Dr Wayne McIlwraith
“Five to 10 years ago, I had my opinion that many of these lesions wouldn't be a problem, but I didn't have proof until we did this study. And now we've got really good proof and we've got good figures, and it's like a lot of things, if you got to be successful, you've got to use data.
"This study was done by Drs Frances Peat, Chris Kawcak, Jeff Berk, Dave Keenan, and myself and was only possible with the financial support of Grayson Jockey Club Research Foundation, Keeneland, and Fasig-Tipton, as well as multiple generous individual donors in the Thoroughbred Industry. "
In Part 2, Dr McIlwraith turns his attention to what’s next - exploring the cutting-edge innovations that could transform equine care once again, and bring the sport closer than ever to an era of zero preventable fatalities.
