Effect of lateral heel wedges on sagittal and transverse plane kinematics of trotting Shetland ponies and the influence of feeding and training regimes

Abstract

SummaryReasons for performing study: Lateral heel wedges are used to treat horses and ponies with patella fixation or bone spavin. However, these therapies are purely empirically based and lack scientific evidence. Objectives: Lateral heel wedges would change joint motion in the sagittal, but mainly in the transversal planes, in healthy horses. This effect would be increased by restricted feeding and decreased by extra training. M e t h o d s :A g roup of 24 Shetland ponies age 3 years was used, as foals had been assigned to restricted and ad libitum (ad lib) feeding, and low and high level training groups of 6 animals each. An experienced judge evaluated passive patella luxation in the square standing pony, using a score of 0 (normal) to 4 (stationary patella luxation). The motion of the markers, glued to the skin covering skeletal landmarks on the left foreand hindlimbs, was recorded 3 dimensionally at a frequency of 300 Hz using a modified CODA-3 apparatus while trotting on a treadmill at a speed of 3.0 m/sec, before and directly after 5 °l ateral heel wedges had been applied to the hindlimbs. A f t e r data analysis, the kinematic variables in the sagittal and transversal plane, under these 3 conditions (wedge, feeding, training), were compared statistically using a multivariate repeated measures analysis, general linear model (P<0.05). R e s u l t s : In the sagittal plane, an acute change in hind hoof conformation resulted in a less animated trot with a less p rotracted forelimb and less hindlimb flexion. This is s i m i l a r, although less pronounced, to the decrease in limb flexion re p o rted previously as a result of restricted feeding. M o re specifically, lateral heel wedges resulted in significant changes in the transversal plane angles of all joints in the hindlimb. The stifle joint became maximally 1.8° more adducted just before the end of the stance phase, while the tarsal joint was 2.9° and fetlock joint 4.7° more abducted (P<0.05). In the restricted feeding group, stifle joint adduction was 8.5° and tarsal joint abduction 5.6° larger than in the ad libitum feeding group (P<0.05). The patella luxation score was also significantly higher in this gro u p (1.8) compared to ponies fed ad libitum ( 0 . 9 ) . Conclusions:The acute effects of lateral heel wedges on the equine locomotor system in the transversal plane movement relieve tension from the medial patellar ligament and decrease pressure on the medial side of the tarsal joint. However, the fetlock joint experiences considerably more out of plane stress. Poor body condition resulted in a 2x worse patella luxation score, while the effect on stifle and tarsal joint movement in the transversal plane was almost 5x and 2x larger, respectively, than a lateral wedge. Potential relevance: The clinical importance of general body condition for maintaining lateral stability in the equine hindlimbs is established, but future research may prove that wedges are beneficial to treat patella fixation and bone spavin in the long term.

Heel effects on joint contact force components in the equine digit: a sensitivity analysis

“…Indeed, both Chateau et al (2006) and Peham et al (2006) showed that the use of heel wedges modifies the angle variation of the coffin, pastern and the fetlock joints. Additionally, Back et al (2003) demonstrated some indirect effects on forelimb kinematics of wedges applied to the hindlimb. However, it has also previously been shown that some acute effects of the application of wedges would become nonsignificant over a longer period of post test recordings (Firth et al 1988).…”

“…(2006) showed that the use of heel wedges modifies the angle variation of the coffin, pastern and the fetlock joints. Additionally, Back et al . (2003) demonstrated some indirect effects on forelimb kinematics of wedges applied to the hindlimb.…”

Toe modifications in hind feet shoes optimise hoof‐unrollment in soundWarmblood horses at trot

“…Among the latter are shoes and shoeing techniques. The effects of shoeing have been investigated in a number of studies but the main focus is almost always on the front feet and less often on the hind feet .…”

Unipodal stance influences radiographic evaluation of foot balance in horses

“…Analysis after application of lateral or medial hoof wedges showed interphalangeal joint space narrowing on the wedged side, results confirmed by a study on foot balance and intra‐articular pressure showing silicone moving to the non‐wedged side after DIPJ injection . Research on the treatment of proximal patella fixation and bone spavin demonstrated an increased adduction of the stifle, tarsus, and fetlock at the end of the stance phase as an effect of lateral hoof wedges . One could thus say that the unipodal stance mimics an adduction of the limb, as the distal limb moves closer to the median plane of the body, and therefore provokes a lateral DIPJ reduction.…”