At one time, a condylar fracture in a horse’s cannon bone was a death sentence. With veterinary advances, such injuries became non-fatal but career ending. Now, that’s no longer the case, with new veterinary technology helping more horses return to competition after surgery.
Most commonly seen in thoroughbred racehorses and occasionally polo ponies or eventing horses, a condylar fracture is a repetitive strain injury that results in a fracture to the cannon bone above the fetlock due to large loads transmitted during high-speed. On a radiograph, a condylar fracture appears as a crack that goes from the fetlock joint up the cannon bone.
Lateral fractures many times exit the bone usually one-third of the way up the bone. Medial fractures will oftentimes spiral up to the hock or knee, and are much more common in the hindlimb than the forelimb. It is the spiral fractures that are more difficult, due to the fact that the extent of the spiral cannot be identified radiographically. If the surgeon cannot identify the fracture, then that part of the fracture cannot be repaired.
“A condylar fracture is a disease of speed,” said Dr. Robert Brusie, a surgeon at Florida’s Palm Beach Equine Clinic. Brusie estimates that he repairs between 30 and 50 condylar fractures per year.
“A fracture to the left lateral forelimb is most common in racehorses as they turn the track on a weakened bone and increased loading on the lateral condyle,” he said.
Condylar fractures are further categorized into two classes. An incomplete and non-displaced fracture means that the bone fragment is not separated from the cannon and is still intact with its original position. A complete and displaced fracture means the fragment has detached from the cannon bone and this fracture can often be visible under the skin. Displaced condylar fractures have a somewhat lower prognosis due to the fact that soft tissue structures, such as the joint capsule, become torn. When these structures heal, they are thicker, which makes the joint less flexible.
PBEC surgeon Dr Weston Davis said most lateral condylar fractures were fairly simple to fix. “Medial condylar fractures tend to be more complicated configurations because they often spiral up the leg. Those require more advanced imaging and more advanced techniques to fix.”
The first step to effectively treating a condylar fracture through surgery is to accurately and quickly identify the problem. At the Palm Beach Equine Clinic, Radiologist Dr Sarah Puchalski said stress remodeling can be detected early and easily on Nuclear Scintigraphy before the horse goes lame or even develops a fracture.
“Early diagnosis of stress remodeling allows the horse to be removed from active race training and then return to full function earlier. Early diagnosis of an actual fracture allows for repair while the fracture is small and hopefully non-displaced,” Puchalski said.
Depending on surgeon preference, condylar fracture repairs can be performed with the horse under general anesthesia, or while standing under local anesthesia and sedation. During either process, surgical lag screws are used to reconnect the fractured condyle with the cannon bone.
“For a very simple and small non-displaced fracture, we would just put in one to two screws across the fracture,” Davis said. “The technical term is to do it in ‘lag fashion’, such that we tighten the screws down heavily and compress the fracture line. Many times the fracture line is no longer visible in x-rays after it is surgically compressed. When you achieve good compression, the fractures heal very quickly and nicely.”
More complicated fractures, or fractures that are fully displaced, may require more screws to align parts of the bone. For the most severe cases of condylar fractures, a locking compression plate with screws is used to stabilize and repair the bone.
In simpler, non-displaced condylar fractures, the horse can be operated on while standing, taking away the risk of anesthesia. It also means a shorted recovery time, of only 90 days.
In such cases, surgeon Dr Jorge Gomez said he sedates the horse and blocks above the site of the fracture.
“Amazingly, horses tolerate it really well, and it is very convenient for medial condylar fractures. In these cases, the fracture can spiral all the way up through the cannon bone, and they have a tendency to develop complete catastrophic fractures that can happen at any time after the injury. That risk can be significantly increased by the recovery from general anesthesia. Our goal is always to have the best result for the horse, trainers, and us, as veterinarians.”
Renovations are under way at the Palm Beach Equine Clinic to give surgeons a new approach to fix condylar fracture repairs. A set of stocks and surgeon’s pit have been added with the ability to give the surgeon eye-level access to the fracture with the patient standing and subsequently simplifying the procedure by reducing the risk from recumbent recovery.
One of the most common questions regarding an equine injury is, “Will the horse return to work?” Thanks to advanced imaging and surgical techniques, the answer to that question when involving a condylar fracture is most likely, “Yes.”
Diagnostic imaging plays a major role in assisting to diagnose, surgically map, and follow up on condylar fractures. After primary use to diagnose a condylar fracture, digital radiographs are also used after surgery to ensure that a fracture repair was completely successful. Scanning two planes during and after surgery gives a full view of the fracture and repair techniques, immediately indicating the success of the procedure before moving the horse on to recovery.
“A condylar fracture was once considered the death of racehorses, and as time and science progressed, it was considered career-ending,” Brusie said. “Currently, veterinary medical sciences are so advanced that we have had great success with condylar fracture patients returning to full work. Luckily, with today’s advanced rehabilitation services, time, and help from mother nature, many horses will come back from an injury like this.”