Hind-Limb Flexion Test Times Compared (AAEP 2012)

"A thorough lameness exam usually includes limb flexion tests to evaluate for gait changes when joints are stressed in a flexed position," remarked Amy Armentrout, DVM, MS, Dipl. ACVS, of Burleson Equine Hospital, in Texas. Holding the hind limb up for a protracted time can be tough on the practitioner's body, and horses aren't always compliant, she noted, so recently she and colleagues sought to determine if veterinarians could use shorter hind-limb flexion times.

Veterinarians generally believe it necessary to hold a hind leg in upper-limb flexion (ULF) for 60-90 seconds before trotting the horse off to watch for increased lameness, said Armentrout. The research team compared a shorter-duration ULF of five seconds to the longer 60-second duration, and she presented their results at the 2012 American Association of Equine Practitioners' (AAEP) Convention, held Dec. 1-5 in Anaheim, Calif.

In a previous study on fetlock flexion, researchers identified that a 30-second flexion did not always yield a positive result in lame horses, whereas a 60- to 90-second flexion did. Armentrout wanted to identify if there could also be a difference between longer and shorter duration upper limb flexion testing.

All 34 client-owned lame horses in the study sported a solid coat color over their entire body to eliminate any artifacts in videotaping. Limb markings could otherwise confuse the evaluator. Both the person leading the horse and the practitioner flexing the horse wore the same outfits during each evaluation. The practitioner flexed all horses as maximally as possible, such that the cannon bones were parallel to the ground. The research team placed the camera a consistent 3 meters (9.84 feet) behind the horses for recording, and they repeated 10 of the flexion tests to identify if the practitioners would make the same assessment on the same horses. Fifteen blinded practitioners, each with an average of 20 years of equine lameness experience, reviewed each of the videos. Armentrout asked them to interpret the flexion as positive or negative as compared to the baseline lameness.

Armentrout noted that the reviewers frequently reported individual variability: "About 74% of the time, the results of 5 vs. 60 seconds were interpreted the same. The initial flexion was more likely to be called positive than the second flexion." She said the reviewers were more likely to judge the 60-second flexion as positive 54% of the time as compared to the 5-second flexion being positive 36% of the time. As for the 10 horses that had repeat flexion testing, the reviewers interpreted 5- and 60-second flexion test results the same way 75% of the time.

In summary, Armentrout advised practitioners to perform their own trials since clinical assessment is often very subjective. Some practitioners reach the same interpretation 74% of the time, whether the horse was flexed for 5 or 60 seconds. But in this particular study, the short and longer flexions did not yield the same results.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.