Insight

Fall 2008

Equine 3-D modeling

In the fields of engineering, architecture and human medicine, but now researchers at the Equine Orthopaedic Research Center (EORC) are using 3-D modeling with diagnostic imagery to better understand how joint shape in horses may impact the risk of injury.

The study has evolved from work originally funded by the Colorado Racing Commission. During the last 12 years, deceased Colorado racehorses have been brought to Colorado State University for necropsy and researchers have noticed a pattern correlating injury to joint shape. Horses with significant fetlock damage seemed to have abnormally shaped condyles and minimal support from the soft tissues, including tendons and ligaments, and a compromised supply of blood.

“Looking at pictures of the cannon bone, we can see that where the fetlock joint has a significant amount of damage there is usually an abnormal shape to the condyles,” said Dr. Chris Kawcak, an Associate Professor in the Department of Clinical Sciences and member of the EORC team. “We began to ask if we could develop parameters for using the shape of the joint to help determine the risk of injury. Having that knowledge ahead of time may help us prevent catastrophic injuries in racehorses by proactively treating those horses or taking them off the race track altogether.”

The condyle is the bulbous bottom of the cannon bone that fits into the fetlock joint. Condylar fractures can be repaired surgically, Dr. Kawcak noted, but the prognosis for survival and a return to racing soundness depends on the severity of injury. Asymmetry in the condyles seems to increase the risk of condylar fracture, compromising the fetlock joint, cannon bone and other structures in the front limbs. Last year, the EORC research team received a grant from the Grayson-Jockey Club Research Foundation to study a large group of racehorse specimens to further examine the pattern of abnormal geometry in the condyles. Working cooperatively with Dr. Kenton Morgan at the University of Liverpool, England, and Dr. Tim Parkin at the University of Glasgow, Scotland, Dr. Kawcak’s team is studying 150 fetlocks from racehorses, 50 of which had condylar fractures, 50 with arthritis, and 50 normal specimens.

“The English have an amazing library of specimens and recordkeeping, along with epidemiological information, so using their samples and our studies we are able to put together a picture of the relationship between injury and joint shape,” said Dr. Kawcak. “They send us CAT scans of the fetlock joints, and we’ve built a software program that takes the scans and builds a three-dimensional model. We can apply special modeling to look at bone density, examine joint surfaces, look at the curvature of the back of the fetlock, and see how a number of different factors relate to bone abnormality.”

On the computer modeling forefront, Dr. Kawcak’s team is drawing from a number of experts in the field. Dr. Christian Puttlitz, an Associate Professor in the Department of Mechanical Engineering at CSU, is on the grant, as is Dr. Marcus Pandy from the University of Melbourne, Australia, who is a leader in musculoskeletal modeling in humans. Graduate Student Katrina Easton is working with the Biomedical Engineering Program at CSU to help build the model, working to calculate different stresses going through the joint and the muscle forces around the joint.

“A lot of this computer work is way outside of our (EORC) expertise,” said Dr. Kawcak. “We knew what we wanted, but didn’t have the knowledge or the technology to get there. Drs. Pandy and Puttlitz, and Katrina, are building us a very robust model that not only has applications in equine medicine, but also has promising applications in humans where abnormal joint shape can also lead to common problems in the knees and hips. This work simply wouldn’t be possible without them.”

In the short term, the gold standard for determining at-risk horses remains biomarkers and blood tests that reveal early indicators of injury. Dr. Kawcak hopes that eventually the joint shape model can be used clinically to give veterinarians the information they need to determine the chance of a fracture and make the best decisions for the health and well-being of the horse from there.