Improving Bone Chip Rehabilitation

If there is one thing most horsemen know well, it is the way things have always been done. The conventional paths to feeding, shoeing, training, and rehabilitating horses are processes that came to be tried-and-true for a reason: they usually accomplished the end goal. Today, the combination of research, technology, and, to some extent, an entrepreneurial spirit, has slowly eroded the bastions of tradition and made room for new ideas to become the standard by which others are measured.

Veterinary medicine has made huge strides, thanks in part to advances in diagnostic capabilities and treatment modalities. A unique research project that combines both might prove to be the best answer for horses with bone chips in their knee joints.

Arthroscopic surgery has become a common treatment for horses suffering lameness issues caused by bone chips in the knee. The standard rehabilitation program after that surgery involves a lot of rest. Wayne McIlwraith, BVSc, PhD, DSc, FRCVS, Dipl. ACVS, director of Orthopedic Research at Colorado State University, said, "Typically, horses recovering from this type of surgery get about two weeks of stall rest, followed by a few more weeks of hand-walking. Gradually, as the joint recovers, the horse can be walked for longer periods of time. It can be 60 days before the horse might be ready to go back to light work."

But time, especially for a Thoroughbred racehorse, is a golden commodity. The time allotted for resting the joint might see the horse lose much of the muscle tone and fitness required of an athlete. When the short duration of a Thoroughbred's racing career is taken into consideration, those months of healing and retraining can be extremely costly.

Identifying the Problem

 

Mark Dedomenico, MD, a heart surgeon, is the founder of PRO Sports Club in Seattle, Wash., the largest sports-medicine club for human athletes in the United States. A major focus at the club are the health and fitness programs Dedomenico and his colleagues have developed to benefit athletes recovering from injuries, people battling weight and blood pressure problems, and individuals suffering the effects of osteoarthritis.

For all his interest in human health endeavors, Dedomenico has a real passion for equine athletes. He has owned horses for most of his life and is dedicated to their welfare. He said, "When you love horses the way most people in the Thoroughbred business do, you want to do everything you can to help them perform well and stay sound doing it."

The impetus for Dedomenico's interest in research into equine recovery programs was the success of football superstar Terrell Owens. In 2005, just seven weeks before the Super Bowl, the Philadelphia Eagles' wide receiver sustained severe injuries to his right ankle and a fracture in the bone just below his right knee. Had these injuries occurred a decade earlier, they would certainly have ended his career. Instead, thanks to surgical expertise and a specialized rehabilitation program, Owens was on the field on that Super Bowl Sunday, making nine catches.

Owens' remarkable recovery led Dedomenico to discover that it was a combination of surgery and an aggressive rehabilitation program that brought the athlete back. "I really wanted to do the same thing for horses. I knew that many equine athletes with bone chips and fractures often do make it back to the track. Our aim will be to get increasing numbers of racehorses back to the racetrack at their previous level. I wondered if a program like the one that helped Owens would work for horses," Dedomenico explained.

 

Any kind of responsible research is an expensive proposition. Equine research is no exception. Once a specific problem is isolated, the study requires subjects with very similar issues, dedicated scientists, and a facility that is capable of providing all of the care and attention the subjects require. The money to do this at most research facilities comes from grants and a collection of donors. The research can usually take advantage of existing facilities at colleges and universities.

Dedomenico was fortunate in his quest in that he already had an established relationship with McIlwraith, who brought with him to the discussions a team of veterinarians and contacts that would help to establish the parameters of the eventual research protocol. Dedomenico had also developed Pegasus Equine Rehabilitation & Training in Redmond, Wash.

McIlwraith explained, "Kevin Haussler, DVM, DC, PhD, is an assistant professor at the Orthopedic Research Center at Colorado State University. He and I had been involved with Dr. Dedomenico in talks about this project for quite a while. We wanted to prove the value of the rehab protocol Dr. Dedomenico had in mind in a clinical setting. We had to pick a problem that we commonly address. We are looking at rehabilitation post surgery. We also need to get a certain uniformity in the cases, so we have chosen to look at fragments in the knees of Thoroughbred racehorses. They have to be chip fragments in the lower joint of the knee which are harder to come back from than chips in the upper joint. Bone chips in the upper joint are relatively forgiving compared to bone chips in the lower joint. Osteoarthritis is more likely with chips in the lower joint."

The goal is to have at least 24 horses accepted into the program by the end of this year. There will be two groups of 12 horses each. The horses can come from anywhere in the United States or Canada. Dedomenico, who is funding the research, has offered to absorb the cost of transporting the horses to the rehabilitation center as well as the costs for surgery and rehabilitation. Horse owners will be responsible only for a daily charge of $50 to $60 per day.

McIlwraith feels strongly that the bone fragments must be somewhat similar in size and effect on the subjects. Trainers and owners interested in participating should send X rays of their horses' knees so that they can be assessed for this protocol.

"I set up a system about 25 years ago for grading bone fragments," McIlwraith explained. "I just have four grades. We are not going to pick and choose on size for this protocol, but we will throw out really bad ones. If we are presented with a horse that has grade four damage with loss of bone, we will pass on it. It will not have a really good prognosis. We are looking for horses with a chip fragment either of the distal radial carpal bone or the proximal third carpal bone. It could be in the distal intermediate, but it has to be a chip fragment in the middle carpal joint or the lower joint in the knee."

 

Randomization is critical for the success of this study. McIlwraith explained, "The problem that messes up most protocols is bias. The horse owner has to realize that when their horse goes into the study, it has a 50/50 chance of getting the new treatment. On the other hand, if it gets in the other group, it is going to receive the care it would normally have received anyway, and getting it paid for. We are going to have to assign horses to these groups randomly. We will probably try to match the fragments somewhat so that if we have two horses with very similar chips, one will go into one group and the other horse will be in the other group to facilitate a randomized block design. I will know which they are, but there will be two other veterinarians, Drs. Jim Bryant and John Stenslie, participating in this program. Dr. Bryant will be treating the horse and will know what treatments they are receiving, and Dr. Stenslie will be doing weekly lameness and joint exams. He will not know which treatment the horse will have."

 

Developing the Protocol

 

Together, the veterinarians and Dedomenico developed two very specific rehabilitation protocols. Horses in both groups will have their knee chips removed arthroscopically by McIlwraith and his team. The first group will be in the control program, one that has been the standard of care following arthroscopic surgery for years. The horses will be confined to their stalls for two weeks. Following that, each horse will be hand-walked for five minutes a day. The walking time will increase by five minutes a week until the horses are walking 30 minutes a day at 60 days post surgery. The horses will be assessed for lameness and the knee joints will be monitored by X ray and biomarkers.

The horses in the second group will each receive treatments in a hyperbaric chamber starting three days prior to their surgery and continuing through day 32 post surgery. On day 15 post surgery, the horses will begin swimming. On day 30, exercise in an aqua-tred will begin as well. As with the first group, the horses receiving the new protocol will be carefully monitored for lameness and any signs of osteoarthritis.

"I am already a believer in rehabilitation therapies that include swimming and underwater treadmills for equine patients. I use them frequently for my patients in Southern California," McIlwraith explained. He added, "Currently, I do not have enough experience with hyperbaric therapy to have a belief or hypothesis as to its value. This project will allow us to prove the value of a combination of these modalities and, if it is positive, we will then need to differentiate the relative value of each."

The new research protocol is a bit more involved than most. Isolating only one treatment variable at a time is the norm, but McIlwraith said, "Dr. Dedomenico wants to test all his modalities. The horses are going to get a combination of hyperbaric therapy in the short term. Then they will go into swimming and an aqua-tred protocol. There will be two distinctly different treatments. For the horses on the protocol, the treatments will overlap to a degree. We will be taking joint samples. We will be doing things that can, hopefully, give us some idea if the hyperbaric therapy is worthwhile because only half the horses will be getting it. At the end of the study, if the horses come back quicker or they come back better, then we will have to separate out those three different techniques in further studies. Dedomenico wanted to do all of them first. He realizes that we will have to do another study, and that's fine."

Both groups of horses will be turned over to Pegasus trainer Mike Puhich at 60 days post surgery. Puhich has been training horses since 1984, and will have the job of bringing all the horses from rehabilitation to the end goal of two 5/8th-mile works.

"Mike is an experienced trainer," McIlwraith said. "He will take over after the protocol. He will not know which horses came from which group. They will receive the same training and we will be monitoring both groups equally. We will be doing blind lameness exams and various tests that Dr. Haussler has put together. He is the expert in that area. Then we will look at the various outcome parameters."

The researchers hope the horses receiving the new protocol will have more success in the short term and last longer on the track in the long term. McIlwraith said, "We hope this will become a pretty regular program. These modalities are available certainly at Pegasus, but also in Southern California where I do most of my arthroscopic surgery, and in a few other places through the United States. Some people will just not do it, though. There is still this opinion that the best thing for a horse is to turn it out in a pasture. That is not always the case with injuries of this nature. These horses definitely need a structured exercise program. We hope to demonstrate that this is a superior program."

Dedomenico and his staff welcome inquiries and visitors. People with horses that might qualify for the research protocol should contact the staff at Pegasus at 425/898-1060.--Robin Stanback

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