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Topic:Biomechanics
Biomechanics in horses refers to the study of the mechanical principles that govern movement and physical function in equine species. This field encompasses the analysis of gait, locomotion, and the forces exerted by and upon the horse's musculoskeletal system. Biomechanical studies often involve the use of motion capture technology, force plates, and computer modeling to assess how horses move and how various factors, such as conformation, training, and health status, influence their performance and soundness. Research in equine biomechanics contributes to understanding injury prevention, rehabilitation, and performance optimization. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanics of movement, the impact of external and internal forces, and the applications of biomechanical analysis in equine care and management.
Kinematic analysis of the locomotion symmetry of sound horses at a slow trot. This study of the locomotion symmetry was undertaken to provide standard symmetry indices of a group of sound horses at the trot. Using a 3D data collection system, the kinematics of the limb joints of 13 clinically nonlame horses were recorded while trotting in the standard conditions of the clinical lameness examination. A kinematic symmetry indice based on an inter-correlation method was defined and applied to the vertical displacement-time and joint angle-time diagrams of the left and right joints of the horses. For each horse, the mean symmetry indice of each joint was calculated using va...
Comparison of the temporal kinematics of the canter pirouette and collected canter. The objectives were to compare the temporal characteristics of canter pirouette strides with collected canter strides in elite dressage horses, and to determine whether the stride kinematics of the canter pirouettes fulfilled the requirements specified in the Federation Equestre Internationale Rules for Dressage Events. Eleven horses were videotaped (60 fields/s) during the individual medal competition at the 1992 Olympic Games. Temporal variables were extracted from the videotapes using standard methods. Two strides were analysed on each of the left and right leads and these were pooled to gi...
Joint moments and power in equine gait: a preliminary study. A method is described for the estimation of joint moments of force and power in the equine forelimb using S-VHS video and force platform data. Video and force data were collected for 5 walking trials in a sound Dutch Warmblood horse. The sagittal plane positional and angular data were combined with the vertical and cranio-caudal ground reaction forces to calculate net joint moments of force in the sagittal plane across the carpal, fetlock and coffin joints during the stance phase of the forelimb. The mechanical power was calculated as the product of the netjoint moment and the joint's angular ...
The distribution of material properties in the equine third metacarpal bone serves to enhance sagittal bending. The distribution of material properties within the equine third metacarpal bone (MC3), and its possible effect on the mechanics of the structure, was quantitatively evaluated using single-load-to-failure compressive materials testing of specimens from ten horses. Bone samples from six regions within five proximodistal levels of MC3 were milled into right cylinders and compressed at a strain rate of 0.01 s-1. Diaphyseal MC3 bone material was stiffer, stronger, deformed less to yield and failure, and absorbed more energy to yield, than metaphyseal cortical bone material. Lateral and medial MC3 c...
Effect of maturation and aging on the histomorphometric and biochemical characteristics of equine superficial digital flexor tendon. To assess tendon morphology and non-reducible crosslink concentration, and associations of these findings with horse age and previously reported mechanical and ultrasonographic findings. Methods: Superficial digital flexor tendon samples were obtained from 23 horses aged 2 to 23 years. The tendons had undergone ultrasonography and were submitted to biomechanical testing in the physiologic range prior to sample acquisition. Methods: Samples were sectioned in a transverse plane; then dorsal, palmar, central, lateral, and medial regions were evaluated for fascicle cross-sectional area (CSA), sept...
An in vitro biomechanical investigation of the mechanical properties of dynamic compression plated osteotomized adult equine tibiae. To determine the monotonic mechanical properties of osteotomized adult equine tibiae stabilized with two dynamic compression plates (DCP) and to compare the mechanical properties with those of intact tibiae and in vivo loads. Methods: The compressive, bending, and torsional mechanical properties of plated and intact tibiae were assessed in vitro. Methods: Twelve pairs of adult equine tibiae. Methods: Tibiae were loaded in axial compression, craniocaudal 3-point bending, or torsion in external rotation in a single cycle to failure. Mechanical properties were determined from load-displacement da...
Comparison of collagen fibril populations in the superficial digital flexor tendons of exercised and nonexercised thoroughbreds. This study was undertaken to test the hypothesis that collagen fibrils, the submicroscopic units of strength in tendon, would hypertrophy in response to a specific defined training programme. Fibril diameters were measured in central and peripheral regions of superficial digital flexor tendon (SDFT) samples from five 18-month-old horses which underwent a subsequent 18 month training programme and 6 age- and sex-matched controls. Central region fibrils from the trained horses had a mass-average diameter (MAD) of 105.3 nm, which was significantly lower (P < 0.01) than that of 131.7 nm for the...
Effects of anesthesia of the palmar digital nerves on kinematic gait analysis in horses with and without navicular disease. To determine the effect of local anesthesia of the palmar digital nerves on forelimb kinematics in Quarter Horses with and without navicular disease. Methods: 12 adult Quarter Horses; 5 clinically normal (sound) and 7 with navicular disease. Methods: Kinematic measurements were made on adult horses trotting on a treadmill, before and after palmar digital nerve block (PDNB). Twenty-three displacement, joint angle, and temporal gait measurements of the right forelimb and head were made for 5 strides in each horse. Initial (before local anesthesia) right forelimb measurements were obtained after ...
Artifactual nonlinearity due to wear grooves and friction in four-point bending experiments of cortical bone. Experiments and analyses were performed to determine the cause of a nonlinear force-deflection response observed in four-point flexural fatigue of beams of cortical bone machined from the mid-diaphysis of the equine third metacarpus. Observable grooves which formed on the beam surface at supports and load noses were found to be the primary cause of the nonlinearity. An additional geometric nonlinearity at large deflections revealed by finite element modeling may be minimized by using the smallest diameter supports and load noses recommended in ASTM 790. However, frictional constraint of the be...
Pregnancy-associated changes in material properties of the third metacarpal cortical bone in mares. To investigate the effect of late gestation, age, and parity on material properties of third metacarpal (MCIII) cortical bone in mares. Methods: 8 healthy mares (treatment group) that died or were euthanatized within 24 hours after parturition because of foaling complications and 6 age-matched, healthy, nonpregnant mares (control group). Methods: After random assignment for mechanical testing and microradiography, the dorsal half of transverse mid-diaphyseal sections of each MCIII bone was divided into lateral, dorsal, and medial regions. Cylinders of bone from each of the 3 regions were teste...
Residual strength of equine bone is not reduced by intense fatigue loading: implications for stress fracture. Fatigue or stress fractures are an important clinical problem in humans as well as racehorses. An important question in this context is, when a bone experiences fatigue damage during extreme use, how much is it weakened compared to its original state? Since there are very limited data on this question and stress fractures are common in racehorses, we sought to determine the effect of fatigue loading on the monotonic strength of equine cortical bone. Beams were machined from the dorsal, medial and lateral cortices of the third metacarpal bones of six thoroughbred racehorses. Beams from left and...
Age-related differences in collagen crimp patterns in the superficial digital flexor tendon core region of untrained horses. To measure collagen fibril crimp angles and lengths as well as collagen fibril mass-average diameters in central and peripheral regions of the superficial digital flexor tendon of wild horses, to ascertain any age-related changes in either region in the absence of imposed galloping exercise. Methods: Measurements from a random cull of wild horses. Methods: Superficial digital flexor tendon samples were taken from 23 wild horses ranging in age from two to ten years. Methods: Horses were divided into 'young' (< 5 years, n = 10), 'middle-aged' (5 to < 10 years, n = 9) and 'ol...
Architecture and the division of labor in the extensor carpi radialis muscle of horses. The extensor carpi radialis muscle of the horse is deceptive at first appearance. It has a fusiform shape similar to other forearm extensor muscles. The fiber arrangement also appears long and relatively parallel. However, it may contain two or more compartments that correlate with differing functional roles. Histochemical and immunocytochemical analysis of proximal and distal regions of the muscle (n = 9) demonstrate that the proximal portion of the muscle is composed of a mean of 13% type I, presumed slow twitch, and 61% type IIb, presumed fast twitch fibers. In contrast, the distal compartm...
Exercise intolerance in endurance horses. Endurance competition requires synchronism and development of metabolic and musculoskeletal systems. An understanding of the existence of performance-limiting factors may permit the detection of exercise intolerance that could lead to performance failure, fatigue, and exhaustion. New concepts for assessment of fitness have increased the understanding of individual capacities and deficiencies and the interaction of the different systems involved in exercise.
Collagen fiber organization is related to mechanical properties and remodeling in equine bone. A comparison of two methods. We studied birefringence as an indicator of collagen fiber orientation in the diaphysis of the equine third metacarpal bone. We had previously shown that tissue from the lateral cortex of this bone is stronger monotonically, but less fatigue resistant, than tissue from the medial and dorsal regions. To learn whether collagen fiber orientation might play a role in this regional specialization, we tested three hypotheses using the same specimens: (1) collagen fiber orientation is regionally dependent; (2) remodeling changes collagen fiber orientation; (3) longitudinal collagen fibers correlate p...
The effect of exercise on diaphragmatic activation in horses. Horses chronically-instrumented with costal diaphragmatic electromyographic electrodes were studied during exercise while unencumbered by a breathing mask. Exercise-associated changes in esophageal (Pes), gastric (Pga) and transdiaphragmatic (Pdi) pressures were measured and related to diaphragmatic electromyographic activity (CS EMG) and to left forelimb impact. In all breaths examined, CS EMG always coincided with decrements in Pes. For all exercise trials, linear increases in CS EMG, Pga and Pdi and linear decreases in Pes, as a function of exercise intensity, always occurred. During all ga...
In vitro fatigue behavior of the equine third metacarpus: remodeling and microcrack damage analysis. We studied remodeling and microcrack damage in specimens of Thoroughbred racehorse third metacarpal bone that had been subjected to monotonic or fatigue failure. We asked three questions. What effects does mechanical loading have on histologically observable microcrack damage? Are there regional variations in remodeling of the equine cannon bone, and do these variations correlate with mechanical properties? To what extent are remodeling and microcrack damage age-dependent? Machined beams from the medial, lateral, and dorsal cortices were loaded to fracture in four-point bending monotonically, ...
In vitro determination of equine third metacarpal bone unloading, using a full limb cast and a walking cast. To improve fracture treatment, in vitro experiments were performed to study the influence of a full limb cast and a walking cast on the loading regimen of bones in the distal portion of the equine forelimb. Methods: 6 forelimbs of 6 Shetland ponies. Methods: Loading of the third metacarpal bone was considered a representative measure for distal limb loading. Electrical resistance rosette strain gauges were attached to the dorsal, palmar, medial, and lateral surfaces of the midshaft of this bone in 6 forelimbs of 6 Shetland ponies. The limbs were tested in a pneumatic loading device to a maxima...
The effect of hole diameter on the torsional mechanical properties of the equine third metacarpal bone. The torsional monotonic structural material properties of equine metacarpi with or without, either a 5/16 inch or 3/8 inch diameter bicortical lateromedial middiaphyseal hole were assessed to determine the effect of a hole on metacarpal strength. Torsional stiffness was not significantly effected by the presence of a bicortical hole, whereas yield and failure angles, torques and energies of metacarpi with a hole were 51% to 97% of those of intact bones. Significant differences were not apparent for yield and failure mechanical properties between metacarpi with a 5/16 inch diameter hole and met...
Evidence of structural and material adaptation to specific strain features in cortical bone. Functionally induced strains provide epigenetic signaling for bone modeling and remodeling activities. Strain gauge documentation of the equine third metacarpal reveals a neutral axis passing through the craniolateral cortex, resulting in a narrow band of cortex loaded predominantly in tension, with the remainder of the cortex experiencing a wide range of compression strain magnitudes that are maximal in the caudomedial cortex. This predictable strain pattern provides a model for examining the hypothesis that strain mode, magnitude, and strain energy density are potential correlates of compact...
Prerace venous blood acid-base values in standardbred horses. The administration of sodium bicarbonate (NaHCO3) or 'milk shakes' to Standardbred horses before racing is widespread. This study analysed nonrace day (CTL) and prerace venous acid-base values from Standardbred horses racing in Pennsylvania (PA) and New Jersey (NJ). Mean +/- s.d. CTL bicarbonate (HCO3) and base excess (BE) values, for a group of horses stabled during the 1993 racing season at Pocono Downs, Pennsylvania, were 28.6 +/- 1.9 and 2.6 +/- 1.7 mmol/l, respectively. In the same population of horses, mean +/- s.d. values for prerace HCO3- and BE values were 33.1 +/- 2.8 and 7.0 +/- 2.3...
Segmental variations of in vitro mechanical properties in equine superficial digital flexor tendons. To determine the local variations of mechanical properties of the equine superficial digital flexor tendon (SDFT). Methods: 10 SDFT of adult horses, selected for absence of abnormality. Methods: Needles (with a dark marker at both ends) pinned perpendicularly through each tendon to delimit 7 segments. Each tendon was tested in traction until rupture; test was filmed, using an 8-mm video camera. For each image, the coordinates of the center of mass of each marker and the corresponding force were registered. The third-degree polynomial that best fits the stress-strain curve thus obtained was cal...
Instrumentation and techniques in equine fracture fixation. In recent years fracture fixation in the horse has changed significantly. New devices, mainly adapted from the human field, have been successfully introduced into large animal surgery. Examples of such implants include the DCS/DHS implant system, the self-tapping screw, the cannulated screw, and the pinless external fixator. However, new devices have also been developed exclusively for equine fracture management, including the interlocking intramedullary nail and the external skeletal fixation device. With these devices the surgeon has more options for repairing fractures in horses. Neverthele...
Instrumentation and techniques in locomotion and lameness. The success of a clinical gait laboratory depends on choosing the right equipment, installing it correctly, running calibration checks, and having skilled technical and professional personnel. For kinematic analysis, videographic or optoelectronic systems are the method of choice, with 2-D data being adequate for the majority of equine evaluations. A force plate provides a precise description of the 3-D ground reaction force; transmission of the force through the body tissues is measured using strain gauges attached to the bones and tendons. Accelerometers bonded to the hoof wall provide infor...
A method of signal processing in motion analysis of the trotting horse. The aim of this paper is to present a method of signal processing necessary for motion analysis in the trotting horse. Motion analysis is widely used to assess lameness in horses. By definition, lameness in trot is present if the movements during the stance phases of both fore or hind limbs differ. The motion of the horse is recorded using a system for motion analysis (Selcom, 1983, SELSPOT II User Manual, Pad Nr. 6710) and the vertical motion of the head during both stance phases is compared. The symmetry is analyzed comparing the values of the Fourier coefficients. Additional head movements ...
Osteonal structure in the equine third metacarpus. In studying the flexural fatigue properties of the equine third metacarpal (cannon) bone, we previously found that the dorsal region was weaker monotonically, but more fatigue resistant, than the lateral region. Fatigue resistance was associated with fracture surfaces which demonstrated that secondary osteons had "pulled out" of the surrounding matrix; this never happened in lateral specimens. We therefore became interested in the osteonal structure of this bone, and began to study its birefringence patterns in circularly polarized light. We found that the predominant type of secondary osteon ...
The modulus of elasticity of equine hoof wall: implications for the mechanical function of the hoof. During normal weight-bearing and locomotion, the equine hoof wall deforms in a consistent pattern; the proximal dorsal wall rotates caudo-ventrally about the distal dorsal border and there is latero-medial flaring posteriorly. The aim of this study is to examine whether there are regional differences in the modulus of elasticity of hoof wall material and whether such differences correlate with the pattern of deformation which occurs in vivo. The modulus of elasticity of equine hoof wall was determined in tension and compression for samples from six forefeet. Samples were tested at the mid-poin...
Kinematics of the distal hindlimb during stance phase in the fast trotting standardbred. Fast trotting Standardbred horses were filmed along a straight on an oval dirt track. Five consecutive stance phases were analysed to describe the planar kinematics of the distal hindlimb. The rapid changes in the geometry of the distal hindlimb that occur during the early stance phase were studied. The hoof segment was initially braked vertically and moved in the direction of the horse. The hoof moved forward on the track surface for more than 20% of the stance time (ST). Two specific deviations in the otherwise smooth course of the fetlock joint angle appeared at 16 and 29% of ST. Tarsal ang...
In vitro evaluation of four methods of attaching transfixation pins into a fiberglass cast for use in horses. To compare the axial stability provided by 4 methods of attaching transfixation pins into a fiberglass cast. Methods: Axial stability of 4 methods of transfixation pin attachment to a fiberglass cast cylinder was determined in vitro. Methods of attachment included simple incorporation of the pins into the cast, placement of a washer and nut on the pin and incorporation into the cast, extension of pins beyond the cast and attachment to a steel halo, and washers within the cast and attachment to a steel halo. Methods: A model was designed to simulate a transfixation cast applied to the equine me...
