Page 56 - Barrel Stallion Register 2017

STIFLE INJURIES IN
WESTERN PERFORMANCE
AND BARREL HORSES
“The stifle has been a challenging joint in that we’ve had to figure things out via the school of hard knocks.”
by Heather Smith Thomas
The stifle is a large, complex joint composed of
3 bones, 2 menisci (crescent-shaped discs of fibro-cartilage attached to the joint surface) and 14 ligaments. It is actually 3 separate joints. One is between the femur (the large bone from stifle to hip) and the patella (similar to the human kneecap) at the front of the stifle. The other 2 joints are between the femur and the tibia (the bone from stifle to hock), one on the inside (medial) and outside (lateral). These joint compartments are filled with lubricating f luid.
The stifle is one of the strongest and most well supported joints in the body, but it occasionally becomes injured by a direct blow or suffers dam-
age during athletic stress. Horses that compete in strenuous competitions like barrel racing sometimes develop stifle problems. Stifle injuries may involve soft tissues, the bones, or both--which can sometimes make diagnosis and treatment challenging. Dr. David Frisbie at the Equine Orthopedic Research Center, Colorado State University, has worked with many stifle problems. These range from subchondral bone cysts to soft tissue tears.
BONE CYSTS IN THE STIFLE
“Bone cysts may have an osteochondrosis origin in young horses, but most often occur in adult horses after trauma—which is something that many people don’t realize. We are now finding that many of these lesions are actually due to trauma rather than devel- opmental problems,” says Frisbie.
“Radiographic appearances vary. In some cases, a radiograph will show a big hole in the bone—maybe 3/4-inch in diameter. These typi- cally occur in the medial
femoral condyle of the
stifle. These lesions can
vary from just a flatten-
ing of the condyle, to a
crescent-shaped divot, to
a divot that’s 5 mm deep,
to a full-blown cyst,”
Frisbie says.
we looked at repository films, and many of these horses were not lame. One particular study looked at cutting horses, and we found a fairly high inci- dence of cysts,” he says.
“We looked at long-term performance outcomes in 3- and 4-year-old horses and didn’t see a really high association with flattening on the condyle based on the repository findings,” says Frisbie. The paper on this study was recently accepted for publication in JAVMA (Journal of the American Veterinary Medical Association).
When people see these changes on the condyle on the pre-purchase radiographs, however, they may not understand that these might not be a problem. “So, this is something that has changed in our general knowledge in the last 8 years, realizing that not all abnormalities on the condyle will become a problem,” he says.
“Subsequently, we’ve been able to develop a new technique for dealing with these. Instead
of simply scooping out those cysts when they do become a problem, we actually go around the periphery of the cyst with an injection. There’s a lining that produces chemicals that retards heal- ing of the bone. If we decrease the metabolism
of that lining, depending on the expertise of the person doing the surgery, we can actually get 80 to 90% of those horses back to full work within 2 or 3 months,” he explains. This is a good progno- sis for most of the horses.
In an earlier paper discussing this technique, there were 2 surgeons who had success rates of
89% or greater. “They had a rehab protocol with these horses that was either 60 or 30 days. Whether it was the surgeon/technique or the rehab that contributed to the success (several variables), we know that it worked.” When you look at the overall picture and the success rates of 7 surgeons who
“We see these bone cysts/flattenings some- times on pre-purchase films, and they are not very often associated with lameness. We’ve done some work in which
Dr. David Frisbie of the Equine Orthopedic Research Center at Colorado State University
54 SPEEDHORSE
EQUINE HEALTH