A method for fatigue testing of equine McIII subchondral bone under a simulated fast workout training programme

Area of Science:

• Equine biomechanics
• Orthopedic research
• Veterinary science

Background:

• Standard bone fatigue testing uses single loads, unlike the varied conditions horses experience.
• In vivo, Thoroughbred racehorses face a spectrum of loads and frequencies during training and racing.
• Subchondral bone in the equine third metacarpal (McIII) is particularly vulnerable.

Purpose of the Study:

• To develop and test a novel fatigue testing method for equine McIII subchondral bone.
• To simulate the loading conditions experienced by racehorses during fast workouts.
• To better understand the development of subchondral bone injuries in equine athletes.

Main Methods:

• In vitro biomechanical experimental study using equine McIII subchondral bone specimens (n=12).
• A novel fatigue loading protocol was created, mimicking a sequence of gaits in a typical fast workout.
• Specimens were subjected to repeated loading loops until failure.

Main Results:

• The mean time to failure was 76,393 seconds, equivalent to approximately 18.3 fast workouts.
• Ten out of twelve specimens completed at least one full workout loop.
• All specimens failed during the simulated gallop phase of the loading protocol.

Conclusions:

• The developed protocol more accurately reflects in vivo fatigue loading conditions for equine McIII subchondral bone.
• The highest speeds, specifically during gallop, are crucial in the pathogenesis of subchondral bone injury.
• Limitations include shorter resting times and unconfined testing compared to in vivo conditions.