Surface strains around the midshaft of the third metacarpal bone during turning.
BACKGROUND
Bone strains quantify skeletal effects of specific exercise and hence assist in designing training programmes to avoid bone injury.


OBJECTIVE
To test whether compressive strains increase on the lateral surface of the inside third metacarpal bone (McIII) and the medial surface of the outside McIII in a turn.


METHODS
Rosette strain gauges on dorsal, medial and lateral surfaces of the midshaft of the left McIII in 2 Thoroughbred geldings were recorded simultaneously during turning at the walk on a bitumen surface.


RESULTS
Medial surface: Compression peaks were larger in the outside limb. Tension peaks were larger in the inside limb and in a tighter turn. On the lateral surface compression and tension peaks were larger on the inside limb, which showed the largest recorded strains (compression of -1400 microstrains). Dorsal compression strains were larger on the outside limb and on a larger circle. Tensile strains were similar in both directions and larger on a larger circle.


CONCLUSIONS
Compressive strains increased on the lateral surface of the inside McIII and medial surface of the outside McIII in a turn.


CONCLUSIONS
Slow-speed turning exercise may be sufficient to maintain bone mechanical characteristics in the inside limb lateral McIII cortex. Further work is needed to confirm these findings and to determine whether faster gaits and/or tighter turns are sufficient to cause bone modelling levels of strain in the medial and lateral McIII cortex.
Davies
H M S
HM
Department of Veterinary Science, University of Melbourne, Melbourne, Victoria 3010, Australia.
Merritt
J S
JS
D000818:Animals; D001696:Biomechanical Phenomena; D002350:Carpus, Animal / Q000502:physiology; D006736:Horses / Q000502:physiology*; D008023:Ligaments, Articular / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D008297:Male; D008663:Metacarpus / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D013314:Stress, Mechanical