Effects of 6 degree elevation of the heels on 3D kinematics of the distal portion of the forelimb in the walking horse.
Authors: Chateau H, Degueurce C, Denoix J M
Journal: Equine veterinary journal
Summary
Whilst farriers have long used heel elevation to modify landing mechanics and reduce strain on the digital apparatus, the actual three-dimensional movements of the interphalangeal joints during locomotion remained poorly characterised due to limitations of surface-marker technology. Chateau and colleagues implanted ultrasonic transducers in four horses to directly measure how a 6-degree heel wedge altered motion of the proximal interphalangeal joint (PIPJ), distal interphalangeal joint (DIPJ), and metacarpophalangeal joint (MPJ) during the stance phase of walk, using sophisticated joint coordinate system analysis to isolate true rotational movements. Heel elevation significantly increased flexion at both the PIPJ and DIPJ whilst extending the MPJ by approximately 0.8 degrees, yet paradoxically reduced extension of the lower joints at heel-off, with minimal changes observed in frontal or transverse planes of movement. These findings resolve longstanding confusion in the literature regarding heel wedges' effects on the MPJ by demonstrating that changes at this joint are intrinsically linked to substantial alterations in PIPJ mechanics—a relationship previous skin-marker studies had overlooked. For practitioners, this work confirms that heel elevation primarily modifies sagittal plane kinematics and supports its use as a targeted intervention for conditions affecting the digital joints, though the reduced extension phase may have implications for long-term loading patterns that warrant further investigation.
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Practical Takeaways
- •6-degree heel wedges alter digital joint mechanics in ways that previous skin-marker studies may have missed, particularly the substantial effect on the proximal interphalangeal joint
- •Farriers should recognize that heel elevation primarily affects sagittal plane motion of all three digital joints, with increased flexion during weight-bearing and decreased extension at breakover
- •The previously controversial findings about heel wedges and the metacarpophalangeal joint may be explained by the significant but overlooked involvement of the proximal interphalangeal joint
Key Findings
- •Heel wedges significantly increased maximal flexion of the proximal and distal interphalangeal joints during stance phase
- •Heel wedges increased maximal extension of the metacarpophalangeal joint by mean 0.8 ± 0.3 degrees
- •Extension of the proximal and distal interphalangeal joints was decreased at heel-off with wedges
- •Few extrasagittal plane effects observed; changes were primarily in the sagittal plane