Effect of lateral heel wedges on sagittal and transverse plane kinematics of trotting Shetland ponies and the influence of feeding and training regimes.
Authors: Back W, Remmen J L M A, Knaap J, de Koning J J
Journal: Equine veterinary journal
Summary
# Editorial Summary Lateral heel wedges are widely used empirically to manage patellar fixation and bone spavin, yet their biomechanical effects remain poorly understood. Back and colleagues employed three-dimensional kinematic analysis at 300 Hz on 24 Shetland ponies assigned to different feeding and training protocols, measuring hindlimb motion before and after applying 5-degree lateral heel wedges during treadmill trotting. The wedges produced substantial transverse plane changes: the stifle joint adducted by 1.8 degrees, the tarsal joint abducted by 2.9 degrees, and the fetlock joint abducted by 4.7 degrees, whilst sagittal plane changes manifested as reduced forelimb protraction and hindlimb flexion. Most strikingly, restricted feeding dramatically exacerbated these effects—ponies on limited rations showed stifle adduction changes nearly 5-fold greater than the acute wedge effect, coupled with patellar luxation scores twice as severe (1.8 versus 0.9), highlighting that nutritional management fundamentally influences hindlimb stability independent of mechanical interventions. Whilst wedges may mechanically relieve medial patellar ligament tension and reduce medial tarsal joint pressure in the short term, the substantial additional stress imposed on the fetlock joint—combined with the overwhelming protective benefit of adequate body condition—suggests that practitioners should prioritise nutrition and conditioning before or alongside wedge therapy, and recognise that chronic application requires further investigation to establish genuine clinical benefit beyond acute kinematic changes.
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Practical Takeaways
- •Lateral heel wedges do reduce medial patellar ligament tension and medial tarsal joint pressure acutely, supporting empirical use for patella fixation and bone spavin, but increased fetlock stress requires careful monitoring
- •Body condition management appears more biomechanically critical than heel wedges alone—maintaining adequate weight provides substantially greater stabilizing effect on hindlimb lateral stability than the wedge intervention
- •Feeding strategy significantly influences hindlimb kinematics independent of the wedge effect; ensure adequate nutrition in treated animals rather than relying on wedges as a standalone corrective measure
Key Findings
- •Lateral heel wedges caused significant transversal plane changes: stifle joint adduction increased 1.8°, tarsal joint abduction 2.9°, and fetlock joint abduction 4.7° (P < 0.05)
- •Restricted feeding resulted in stifle joint adduction 85° larger and tarsal joint abduction 5.6° larger than ad libitum feeding, with patella luxation scores 2x worse (1.8 vs 0.9)
- •Wedges produced less pronounced sagittal plane changes than feeding restrictions, with reduced forelimb protraction and hindlimb flexion during trotting
- •Poor body condition had approximately 5x greater effect on stifle and tarsal joint transversal plane movement compared to the acute wedge effect