Reports from the world of equine science
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For many years, opinions on the value of flexion tests in assessing equine lameness have been divided. Now, new research looks set to provide an objective approach to what has always been regarded as a subjective process.
The study, recently published in the Equine Veterinary Journal (EVJ) in partnership with the American Association of Equine Practitioners, has shown that a system based on a wireless, inertial sensor can be used to measure the horse’s response to a flexion test.
Flexion tests are used routinely in horses with subtle lameness, to accentuate the problem and make it apparent to the observer. The test involves applying a short period of pressure to the joints of the limb before re-
However, the process is subjective, relying on the ability of the observer to identify and interpret changes in the horse’s gait. Considerable variation in interpretation between observers is seen.
The research was conducted by orthopaedic surgeons based at the Weipers Centre Equine Hospital at the University of Glasgow's School of Veterinary Medicine. The aim of the investigation was to evaluate a sensor-
A total of 17 healthy adult horses, all in work, were recruited to the study. Breeds involved included draught cross, Irish Sport Horse and Warmblood.
Horses were fitted with sensors on the head (accelerometer), pelvis (accelerometer) and right forelimb (gyroscope). They were trotted twice in a straight line for at least 25 metres to establish baseline recordings.
The sensors measured vertical pelvic movement asymmetry (PMA) for both right and left hind limb strides and the average difference in maximum (PDMax) and minimum (PDMin) pelvic height between right and left hind limb strides. Perfectly symmetrical pelvic movement would result in a value for PDMax of 0 mm.
A flexion test was performed by the clinician lifting a randomly selected hind limb by the metatarsus until it was parallel to the ground, keeping the tarsus maximally flexed for 60 seconds. Once released, the horse was trotted for a minimum of 10 strides. Response to flexion was assessed as negative or positive by an experienced observer.
Changes in PMA, PDMax and PDMin before and after flexion were calculated for each test. The results were compared with the observer's assessment of the response.
The researchers found that positive flexion tests resulted in a significant increase in PMA and PDMax. Flexion had no significant effect on PDMin.
The results show that the changes in pelvic movement associated with a positive flexion test can be objectively measured using a wireless inertial sensor-
John Marshall, lecturer in equine surgery at the University of Glasgow, who led the study, concluded: “A positive response to flexion resulted in significant changes to objective measurements of pelvic symmetry, supporting the use of inertial sensor systems to objectively assess response to flexion tests.”
Using this method, it is possible to determine diagnostic cut-
Professor Jim Moore, North American Editor of the EVJ, continued: “The introduction of an objective approach to documenting lameness examination will not only help vets and trainers to investigate equine lameness more accurately. It will also serve as an unbiased method of communicating lameness examination findings among vets, trainers, farriers and other professionals.”
For more details see:
Use of a wireless, inertial sensor-
Marshall JF, Lund DG and Voute LC
Equine Veterinary Journal (2012) 44, S43, pages 8–11,
Flexor testing, using the sensor-
Measuring response to flexion tests