Effects of 6° elevation of the heels on 3D kinematics of the distal portion of the forelimb in the walking horse

Effects of sand, asphalt and 3-degree hind toe or heel elevation on horse kinematics

BACKGROUND

Although the effects of both the surfaces and plantar angles on equine locomotion have been widely discussed, limited scientific data are available.

METHODS

Our objectives were to determine the effects of two surfaces (asphalt and sand) and of 3-degree hind toe or heel elevation on horse kinematics in an experimental study. Six saddle horses were shod with a reference shoeing (REF), characterized by a fore aluminium (REF F) and hind steel racehorse (REF H) shoeing. Two dimensional kinematic videos compared horse's kinematic parameters when walking and trotting on asphalt and sand. On asphalt, REF was also compared with REF F and a modified REF H with additional 3-degree hind-toe or -heel wedges.

RESULTS

On asphalt versus sand, horses had, at the trot, a shorter stride duration and forelimb maximal retraction, and at walk and trot, a greater fetlock, carpus, elbow and tarsus extension, a greater fore and hind limbs maximal protraction and a shorter hind limbs maximal retraction. Increasing the plantar angle decreased the tarsus and hind fetlock extension, in contrast to fore-limb, on asphalt during the stance phase.

CONCLUSIONS

These findings could be useful to adapt rehabilitation programs related to fore and hind limb pathologies, at slow gaits.

Influence of Speed, Ground Surface and Shoeing Condition on Hoof Breakover Duration in Galloping Thoroughbred Racehorses

Simple Summary

In the stride cycle of a horse, there is a period of time when the hoof pushes off from the ground surface and rotates through an angle of approximately 90 degrees before it is lifted off. This time period is known as hoof breakover. Using slow-motion video footage, this study measured breakover duration in retired Thoroughbred racehorses galloping at a range of speeds on two surfaces (artificial and turf) in four shoeing conditions (aluminium, barefoot, GluShu and steel). Hooves from different limbs were assessed separately in this asymmetric gait. Increasing speed was correlated with decreasing breakover duration, and this trend was more enhanced in the hindlimbs than in the forelimbs at high gallop speeds. Breakover duration was faster on the artificial surface compared to the turf surface for all limbs, under the ground conditions studied. The first limb to contact the ground surface after the suspension phase (the ‘non-leading’ hindlimb), was additionally influenced by shoeing condition and an interaction that occurred between shoeing condition and speed. Determining parameters that alter breakover duration will be important for lowering the risk of musculo-skeletal injuries, optimising gait quality and improving performance in galloping racehorses during both training and racing.

Abstract

Understanding the effect of horseshoe–surface combinations on hoof kinematics at gallop is relevant for optimising performance and minimising injury in racehorse–jockey dyads. This intervention study assessed hoof breakover duration in Thoroughbred ex-racehorses from the British Racing School galloping on turf and artificial tracks in four shoeing conditions: aluminium, barefoot, aluminium–rubber composite (GluShu) and steel. Shoe–surface combinations were tested in a randomized order and horse–jockey pairings (n = 14) remained constant. High-speed video cameras (Sony DSC-RX100M5) filmed the hoof-ground interactions at 1000 frames per second. The time taken for a hoof marker wand fixed to the lateral hoof wall to rotate through an angle of 90 degrees during 384 breakover events was quantified using Tracker software. Data were collected for leading and non-leading forelimbs and hindlimbs, at gallop speeds ranging from 23–56 km h⁻¹. Linear mixed-models assessed whether speed, surface, shoeing condition and any interaction between these parameters (fixed factors) significantly affected breakover duration. Day and horse–jockey pair were included as random factors and speed was included as a covariate. The significance threshold was set at p < 0.05. For all limbs, breakover times decreased as gallop speed increased (p < 0.0005), although a greater relative reduction in breakover duration for hindlimbs was apparent beyond approximately 45 km h⁻¹. Breakover duration was longer on turf compared to the artificial surface (p ≤ 0.04). In the non-leading hindlimb only, breakover duration was affected by shoeing condition (p = 0.025) and an interaction between shoeing condition and speed (p = 0.023). This work demonstrates that speed, ground surface and shoeing condition are important factors influencing the galloping gait of the Thoroughbred racehorse.

Influence of trimming, hoof angle and shoeing on breakover duration in sound horses examined with hoof-mounted inertial sensors

OBJECTIVE

Aim of the current in vivo, observational study was to investigate the effect of trimming, heel elevation and different types of shoeing on breakover duration (BreakD) with a novel, hoof-mounted inertial measurement unit (IMU) sensor system.

METHODS

Ten sound, crossbred horses were examined barefoot before and after trimming fitted with an IMU sensor at the dorsal hoof wall. Additionally, application of 5° heel wedges, plain steel shoes, rolled-toe shoes and palmarly-placed quarter-clip shoes was tested. Horses were guided in a straight line on firm ground. Obtained data were speed corrected prior to calculations testing the influence of different manipulations for their significance on BreakD.

RESULTS

Trimming had no significant influence on BreakD. Heel elevation caused a significant decrease of BreakD in walk and trot. Shoeing with a plain steel shoe resulted in a significant increase in BreakD in walk. This could be rescinded by creating a rolled toe or placing the shoe palmarly.

CONCLUSION

Obtained results emphasize the use of heel wedges or rolled-toe and palmarly-placed shoes to ease breakover in the context of therapeutic shoeing. Hoof-mounted IMU sensors with high resolution seem to be a practical and valuable approach to accurately examine BreakD and factors influencing this parameter.

Immediate effects of an artificial change in hoof angulation on the dorsal metacarpophalangeal joint angle and cross-sectional areas of both flexor tendons

Corrective shoeing is used to change hoof angulation with the intention to influence the angulation of the digital joints to reduce strain on associated tendons. The objective of this study is to examine how gradual changes in hoof angulation affect the dorsal metacarpophalangeal joint (DMPJ) angulation and cross-sectional areas (CSAs) of the deep digital flexor tendon (DDFT) and superficial digital flexor tendon (SDFT) concerning the individual toe conformation. Forelimbs of 30 horses were examined barefoot and equipped with 5°, 10° and 20° toe wedges (TWs) and heel wedges (HWs). Phalangeal angulation and lengths were measured in lateromedial radiographs of the digit. CSAs of both flexor tendons was calculated in sonographic images. Significant effects on the DMPJ and CSA of the DDFT/SDFT were measured with 10° and 20° HWs or 20° TWs. Both flexor tendons showed increasing CSA after heel elevation. Significant interindividual variations occurred. Phalangeal angulation and length influenced the responsivity of the parameters to a changed hoof angulation. Significant impact of corrective shoeing on the DMPJ and flexor tendons is related to a distinct change in hoof orientation and varies with individual toe conformation. Similar response of the DDFT and SDFT to raised and lowered hoof orientation needs further investigation for a more specific application of therapeutic shoeing.

Functional locomotor consequences of uneven forefeet for trot symmetry in individual riding horses

Left-right symmetrical distal limb conformation can be an important prerequisite for a successful performance, and it is often hypothesized that asymmetric or uneven feet are important enhancing factors for the development of lameness. On a population level, it has been demonstrated that uneven footed horses are retiring earlier from elite level competition, but the biomechanical consequences are not yet known. The objectives of this study were to compare the functional locomotor asymmetries of horses with uneven to those with even feet. Hoof kinetics and distal limb kinematics were collected from horses (n = 34) at trot. Dorsal hoof wall angle was used to classify horses as even or uneven (<1.5 and >1.5° difference between forefeet respectively) and individual feet as flat (<50°), medium (between 50° and 55°) or upright (>55°). Functional kinetic parameters were compared between even and uneven forefeet using MANOVA followed by ANOVA. The relative influences of differences in hoof angle between the forefeet and of absolute hoof angle on functional parameters were analysed using multiple regression analysis (P<0.05). In horses with uneven feet, the side with the flatter foot showed a significantly larger maximal horizontal braking and vertical ground reaction force, a larger vertical fetlock displacement and a suppler fetlock spring. The foot with a steeper hoof angle was linearly correlated with an earlier braking-propulsion transition. The conformational differences between both forefeet were more important for loading characteristics than the individual foot conformation of each individual horse. The differences in vertical force and braking force between uneven forefeet could imply either an asymmetrical loading pattern without a pathological component or a subclinical lameness as a result of a pathological development in the steeper foot.

Descrição do movimento da articulação metacarpofalangiana de equinos pela metodologia baseada em videogrametria

Caracterizou-se, mediante análise cinemática tridimensional baseada na videogrametria, o ângulo dorsal da articulação metacarpofalangiana de equinos em sete equinos da raça Puro Sangue Árabe. A análise tridimensional do movimento foi realizada em esteira rolante. O programa Dvideo foi utilizado para a obtenção das coordenadas tridimensionais do sistema de calibração e dos marcadores reflexivos posicionados na extremidade proximal do terceiro osso metacárpico, articulação metacarpofalangiana e extremidade distal da primeira falange. A articulação metacarpofalangiana apresentou extensão máxima durante o momento de apoio, no qual a face lateral do terceiro osso metacarpiano se apresentava de forma perpendicular ao solo. Foram observados dois picos de flexão durante a fase de elevação. Concluiu-se que a instrumentação utilizada para a análise cinemática tridimensional permitiu a investigação quantitativa da variação angular do movimento de extensão e flexão da articulação metacarpofalangiana de equinos por meio de imagens digitalizadas.

Raising heels of hind hooves changes the equine coffin, fetlock and hock joint angle: a kinematic evaluation on the treadmill at walk and trot

REASONS FOR PERFORMING STUDY

Raised heels are commonly recommended for various equine orthopaedic conditions. However, the simultaneous effect of raised heels on the different joint angles of the equine hindlimb throughout the motion cycle has not been previously evaluated.

OBJECTIVE

To document the simultaneous effect of raised heels on the joint angles of the equine hindlimb coffin, fetlock and hock joints.

METHODS

Eight sound, adult, Warmblood horses were evaluated barefoot and with a heel wedge of 8 or 16 degrees, walking and trotting on a horizontal treadmill. Markers placed on the dorsal and cranial aspect of the hindlimb were traced using a 3D high speed video system and joint angles calculated.

RESULTS

The effects of raising the hindlimb heels by 8 or 16 degrees on the angles of the hindlimb during the stance phase are a reduction of the plantar combined coffin joint and pastern joint angle, a reduction of maximum extension in the fetlock joint, and an increase in maximum hock flexion. The relation between angles did not change significantly during the course of the stance phase in the three measurement situations, with only small differences in time of occurrence of each joint angle maxima and minima.

CONCLUSIONS

Raising the heels of hind hooves increases flexion of the coffin and hock joints during the stance phases of walk and trot, and a doubling of the angle of the raised heels also doubles the effect on the joint angles investigated. Raised heels reduce the maximum extension of the fetlock joint during the the stance phase at walk and trot.

POTENTIAL RELEVANCE

This study provides evidence for the therapeutic use of raised shoes with heels in horses with pain on maximum hock extension, e.g. spavin.

Effects of egg-bar shoes on the 3-dimensional kinematics of the distal forelimb in horses walking on a sand track

REASONS FOR PERFORMING STUDY

Understanding of the biomechanical effects of egg-bar shoes remains incomplete because kinematic studies are usually performed on hard tracks and with skin markers that do not measure the actual 3-dimensional (3D) movements of the 3 digital joints.

OBJECTIVE

To quantify the effects of egg-bar shoes on the 3D kinematics of the distal forelimb in horses walking on a sand track.

METHODS

Four healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while the horses were walking on a sand track. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with egg-bar shoes were compared to those obtained with standard shoes. Mean differences were expressed in a 0.95 confidence interval.

RESULTS

With egg-bar shoes, the initial sinking of the heels into the ground during landing was reduced and the heels were raised by up to 5.1 degrees (3.5-6.7 degrees) compared to standard shoes at mid-stance. Concurrently, maximal flexion of the distal (DIPJ) and proximal (PIPJ) interphalangeal joints was increased by up to 3.2 degrees (2.2-4.2 degrees) and 1.8 degrees (1.1-2.5 degrees), respectively, at the beginning of the stance phase. At heel-off, extension of the DIPJ was reduced by 3.8 degrees (2.6-5.0 degrees). In extrasagittal planes of movement, egg-bar shoes prevented sinking of the medial quarter into the ground which led to a slight decrease of DIPJ medial rotation and lateromotion.

CONCLUSIONS

Egg-bar shoes prevent the heels and, to a lesser extent, the medial side of the hoof from sinking into the ground on a sand track. They contribute to a decrease of DIPJ maximal extension at heel-off and to hoof stabilisation in the transversal plane.

POTENTIAL RELEVANCE

Such quantitative results support the clinical indications of egg-bar shoes.

Three-dimensional kinematics of the distal forelimb in horses trotting on a treadmill and effects of elevation of heel and toe

REASONS FOR PERFORMING STUDY

Comprehensive understanding of the 3-dimensional (3D) kinematics of the distal forelimb and precise knowledge of alterations induced by dorsopalmar foot imbalance remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints.

OBJECTIVE

To quantify the effects of 6 degree heel or toe wedges on the 3D movements of the 4 distal segments of the forelimb in horses trotting on a treadmill.

METHODS

Three healthy horses were equipped with ultrasonic markers fixed surgically to the 4 distal segments of the left forelimb. The 3D movements of these segments were recorded while horses were trotting on a treadmill. Rotations of the digital joints were calculated by use of a joint coordinate system. Data obtained with 6 degree heel or toe wedges were compared to those obtained with flat standard shoes.

RESULTS

Use of heel wedges significantly increased maximal flexion and decreased maximal extension of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints. Inverse effects (except for PIPJ maximal extension) were observed with the toe wedges. In both cases, neither flexion-extension of the metacarpophalangeal joint nor extrasagittal motions of the digital joints were statistically different between conditions.

CONCLUSIONS

At a slow trot on a treadmill, heel and toe wedges affect the sagittal plane kinematics of the interphalangeal joints.

POTENTIAL RELEVANCE

Better understanding of the actual effects of toe and heel wedges on the 3D kinematics of the 3 digital joints may help to improve clinical use of sagittal alteration of hoof balance in the treatment of distal forelimb injuries.

Effect of toe and heel elevation on calculated tendon strains in the horse and the influence of the proximal interphalangeal joint

The sagittal alteration of hoof balance is a common intervention in horses, with corrective shoeing being one of the most frequently applied methods of managing tendonitis. However, the effect of toe or heel elevation on tendon strains is poorly understood. This study aimed to examine the effect of toe and heel wedges on the superficial digital flexor tendon, deep digital flexor tendon, and the third interosseous muscle or suspensory ligament strains using in vivo data and an accurate subject-specific model. Kinematic data were recorded using invasive markers at the walk and trot. Computerized tomography was then used to create a subject-specific model of an equine distal forelimb and strains were calculated for the superficial digital flexor tendon, the deep digital flexor tendon accessory ligament and the suspensory ligament for seven trials each of normal shoes, and toe and heel elevation. As the proximal interphalangeal joint is often ignored in strain calculations, its influence on the strain calculations was also tested. The deep ligament showed the same results for walk and trot with the heel wedge decreasing peak strain and the toe wedge increasing it. The opposite results were seen in the suspensory ligament and the superficial digital flexor tendon with the heel wedge increasing peak strain and the toe wedge decreasing it. The proximal interphalangeal joint was shown to be influential on the strains calculated with normal shoes and the calculated effect of the wedges. Our results imply that corrective shoeing appears to decrease strain in the tendon being targeted; the possibility of increases in strain in other structures should also be considered.