Man vs. Machine on Post-Nerve-Block Lameness Evaluation

Man vs. Machine on Post-Nerve-Block Lameness Evaluation

Inertial sensor systems, like the one being applied here, have enabled veterinarians to obtain more objective lameness measurements.

Photo: Courtesy Equine Sports Medicine

Which limb is lame? Even practitioners who handle lameness cases day in and day out second-guess each other’s assessments (and even their own) when pinpointing a mild lameness. While developments of tools such as inertial sensor systems (ISS) have enabled more objective lameness measurements, veterinarians are still determining if they can use these tools effectively in the field and combine them with subjective assessment and, if so, how.

Indeed, agreement among clinicians about where a mild lameness is tends to be poor (only 50-60%). So Josh Donnell, DVM, equine sports medicine and rehabilitation resident at Colorado State University's Orthopaedic Research Center, in Fort Collins, was curious if an ISS would improve lameness assessment post-blocking and could be used outside the confines of a veterinary clinic. He presented the results from the research he and professor of Equine Surgery and advisor David D. Frisbie, DVM, PhD, Dipl. ACVS, ACVSMR, completed at the 2015 American Association of Equine Practitioners Convention, held Dec. 5-9 in Las Vegas.

“Regionalization of pain ‘blocking’ is the gold standard (for lameness diagnosis), but there is fair to poor agreement between clinicians,” he said. “There are some objective devices that are being used and sought after, but currently there’s a lack of repeatable methods.”

In the experiment he dubbed “man vs. machine,” Frisbie being the man they pitted against the ISS, experienced lameness clinicians evaluated 36 horses 181 times (five lameness exams, plus or minus three, per horse) in the field—specifically, they ran the experiment out of Frisbie's practice Equine Sports Medicine (in Pilot Point, Texas) while at national and international events.

“Every horse had a baseline exam (while) simultaneously, ISS data was collected when horses were moving in a straight line,” he said. Next, “diagnostic regional anesthesia was performed … and then the (blinded) clinician reported what they thought their percent improvement was.

“Sixty percent of the time the blinded clinician and the ISS agreed on which was the primary lame limb” in the baseline exam, he said, and they found an 81% agreement when the clinician was unblinded in later exams. Agreement of blinded clinician and the ISS was similar to reports of agreement between clinicians on the presence of mild lameness (for example, the one described in Subjective vs. Objective Lameness Identification Methods).

When they combined unblinded clinician opinion with ISS, they saw an 80% agreement, potentially suggesting an improvement in choosing the primary limb.

“The correlation between ISS and the blinded clinician is strong for estimating lameness change post-nerve-block,” he added. “This information could benefit all clinicians,” regardless of experience level.

He added that the clinician has the advantage of clinical experience, a complete musculoskeletal exam, and a case history. But because subjective viewpoint and bias do affect their assessments, the input of the ISS could be helpful.

Finally, Donnell and Frisbie reported that while the horse cannot speak up, telling us what hurts, and a true gold standard for lameness diagnosis remains elusive, certainly the ISS can be a useful tool to help diagnose mild lameness, even for the experienced clinician.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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