Condylar fractures—the number one fracture affecting racing Thoroughbreds - DVM
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Condylar fractures—the number one fracture affecting racing Thoroughbreds
Could this common fracture eventually be a thing of the past?



"In order to get out in front of the fracture outcome, we've been looking at scintigraphy and in some cases MRI," Judy says. MRIs are being performed in some racehorses "that come up sore in their ankles." Equine veterinarians are seeing tiny nondisplaced cracks right at the articular surface. "These tell us that something may be going on in the ankle, and we recommend backing off on those horses training a lot earlier than we might have in the past," Judy says. "Those horses have not gone on to fracture those legs after we've given them a period of rest."

There is definitely a population of horses that have condylar sclerosis as seen in MRI results. "We think those horses may be at an increased risk for fractures," Judy says. "We don't have any hard numbers yet, but it is sure suggestive that that may be true." Trainers have started backing off of the horses with a lot of condylar sclerosis, trying to get the bones retrained to tolerate the stress and not become so brittle.

"The treatment for condylar fractures is pretty straightforward these days," Judy says. The screw fixation has been quite successful, not only for keeping these horses alive but also for getting many of them back to the racetrack. "The only debate is whether you take the screws out or leave them in, and everybody has their own opinion about that."

"As far as the repair goes, it is straightforward," Hogan agrees. "It really hasn't changed a lot, though we now realize that we don't have to put 10 screws in a bone. We just need to secure the joint surface. Most routine fractures are repaired with one or two screws."

"I know of one horse that actually had three condylar fractures in its racing career and actually broke three different condyles in three different legs," Judy says. "And after each one, he went on to race and win."

Lining up the fractured bone exactly with the parent bone is something most experienced surgeons can do quite nicely, particularly with the help of digital radiography or fluoroscopic control. "The biggest concern with all of these, particularly displaced fractures, is the damage to the backside of the joint, where the cartilage is lost, because of the small fragments that develop there," Nixon says. "Those crumbly fragments might be only a couple of millimeters across, but they are a key element to returning horses to their true athletic function and should be removed."

The fragments can be difficult to get out or even visualize. And while the bigger fragments can be locked back into position with the screw repair, the smaller comminuted pieces lead to progressive arthritis and need to be removed. "Once you get them out, you're going to get a better response," Nixon says. "Doing the screw insertion is only a small part of the surgery; the key is cartilage repair. I think when we get better at doing cartilage cell grafts, or stem cell grafts, in these areas we'll get a better outcome.

"The surgery ought to be a three-step process," Nixon adds. "First is fracture reduction and screw insertion. Second, fragment removal—the small fragments that are so loose and rattling around in the back of the joint. And the third phase should be a cartilage or stem cell graft after the fragments have been removed. The big issues right now are trying to get better quality cartilage repair at the back of the fetlock."

"One thing I've learned over the years, by using arthroscopy, is that there is a lot more going on than just the resultant fracture," Hogan says. "Early on, I used to just fix the fracture and never look in the joints. But I started to scope every single one because some fractures that I thought would do very well ended up still having some low-grade soreness problems that I really didn't understand." When she started to arthroscopically evaluate the joints, she found out more, and it solidified her opinion that the condylar fracture is just one part of a chain of events occurring in the ankle.

"I found that when I looked in the back of the joint, in about 80 percent of the horses, there was concurrent cartilage erosion or injury of the lateral sesamoid bone—even in the simplest of fractures with no previous history of joint disease," Hogan says. "So that tells me that there is some undue biomechanical stress on that joint. The cartilage is going to show evidence of that first, and then the bone is going break. It's a combination of factors that contributes to the bone breaking. I always arthroscopically evaluate the joint now and consider what the joint looks like on the inside when formulating my prognosis. If the horse has preexisting joint disease, it has overloading in that joint for some reason and will likely continue to do so to some degree."


Source: DVM360 MAGAZINE,
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