Biomedical subjects

H M Clayton

Publications and source records attributed to H M Clayton.

At least 19 recordsLinked to original sources

PubMed2006

Effect of standing tarsal angle on joint kinematics and kinetics.

REASONS FOR PERFORMING STUDY: The tarsal joint is a frequent site of lameness, but little objective information is available regarding the effects of tarsal conformation on joint movements or forces. OBJECTIVE: To compare tarsal kinematics and kinetics in horses with large, intermediate and small tarsal angles. METHODS: Sagittal plane standing angle of the right tarsal joint was measured in 16 horses as they stood squarely with the hind hooves vertically beneath the hip joint. Tarsal angles were classified as small (< 155.5 degrees), intermediate (155.5-165.5 degrees) or large (> 165.5 degrees). Reflective markers, attached over the centres of joint rotation, were tracked during stance as the horses trotted across a force plate at a standardised speed. Joint angles and ground reaction forces were combined with morphometric data to calculate net joint moments and net joint powers across the tarsus using inverse dynamics. RESULTS: In all horses, the tarsus flexed during the impact phase and extended in late stance. Tarsal angles were stratified according to standing tarsal angle throughout stance. Horses with large standing angles showed less flexion and less energy absorption at the tarsus during the impact phase than those with intermediate or small angles and generated less vertical impulse than horses with small standing angles. Net extensor moment at the tarsus during stance was lower for horses with large standing angles. CONCLUSIONS: In horses with large tarsal angles, less concussion was absorbed during the impact phase, which may be a factor in the development of degenerative joint disease; and the smaller vertical impulse and extensor moment later in stance may limit propulsive ability. However, the smaller net joint moment may reduce the risk of plantar ligament desmitis. CLINICAL SIGNIFICANCE: The effects of conformation on kinematics and kinetics of the tarsal joint may influence both performance and soundness.

Analysis of Variance↗

PubMed2004

Verification of skin-based markers for 3-dimensional kinematic analysis of the equine tarsal joint.

REASONS FOR PERFORMING STUDY: Kinematic studies are usually based on tracking markers attached to the skin. However, complex joints, such as the tarsal joint, function in 3-dimensions (3D), and have therefore necessitated application of the invasive bone pin technique, limiting kinematic studies to the research laboratory. This study investigates the feasibility of using skin-based markers for 3D analysis of tarsal joint motion. HYPOTHESIS: Three-dimensional motions of the tarsal joint can be measured with an acceptable degree of accuracy using skin markers. METHODS: Retroreflective markers were attached over the tibial and metatarsal segments. Markers were tracked automatically at trot. Three-dimensional skin correction algorithms were used for correction of skin displacement, and 3D motions derived from the corrected (CSD) and uncorrected (USD) skin displacement were compared with data from a previous study in which those motions were described using bone-fixed markers (BFM) by correlation, root mean square errors (RMS) and shape agreement (SA) of the curves. RESULTS: The RMS of BFM and CSD were smaller than those of BFM and USD for all motions. The correlation coefficients of BFM and CSD were higher than those of BFM and USD. SA was good or fair for all motions except internal/external rotation and medial/lateral translation. CONCLUSIONS AND POTENTIAL RELEVANCE: With appropriate correction for skin movement relative to skeletal landmarks, skin markers can identify tarsal 3D motions for flexion/extension, abduction/adduction, cranial/caudal translation, and proximal/distal translation, allowing analysis and comparison of information between horses during swing and stance phases.

Algorithms↗

PubMed2004

Three-dimensional carpal kinematics of trotting horses.

REASONS FOR PERFORMING STUDY: Descriptions of 3D kinematics assist in understanding joint function and dysfunction, and are an essential step toward 3D inverse dynamic analysis. OBJECTIVES: To measure 3D carpal joint motion during trotting. METHODS: Three-dimensional trajectories of bone-fixed markers on the radius and third metacarpus of the right forelimb of 3 healthy horses were recorded at 120 Hz using a 6-camera analysis system. Joint kinematics were calculated in terms of helical angles between the 2 segments using a spatial attitude method. RESULTS: All horses showed carpal extension and internal rotation of the metacarpus relative to the radius as the carpus assumed the close-packed position. In late stance, the carpus began a cycle of flexion that continued through midswing, accompanied by a small cycle of internal rotation. The direction of abduction/adduction varied between horses. The predominant rotational movement was flexion/extension, which showed a range of motion of 15 +/- 6 degrees in stance and 76 +/- 13 degrees in swing. CONCLUSIONS: Carpal motions were generally similar between horses with the exception of abduction/adduction. POTENTIAL RELEVANCE: Knowledge of carpal joint motion should assist in understanding the pathogenesis of carpal injuries. However, it seems probable that real differences exist between individuals; therefore, further investigations of the effect of conformation on carpal motion should be performed in a much larger population of horses.

Animals↗

PubMed2004

Energetic and kinematic consequences of weighting the distal limb.

REASON FOR PERFORMING STUDY: It is well known that adding a load to a horse's back increases its energetic costs of locomotion, but the magnitude of increase obtained by loading the most distal portion of limb has not been measured. OBJECTIVES: To measure oxygen consumption in horses with mass added to the back and hooves. Because such mass distribution alters inertial parameters of the limbs, kinematic measurements were made to quantify the magnitude of change in limb movement. METHODS: Steady-state oxygen consumption was measured in 6 horses with a load of 2.4 kg. The load was either carried on the back or distributed equally between the 4 limbs. Modified bell boots kept the mass at the level of P3. Horses trotted on a treadmill at speeds ranging from 2 to 5 m/sec (in 0.5 m/sec increments). High-speed (250 Hz) digital images were recorded in a sagittal plane and the positions of retroreflective markers located on standard positions on the limbs were digitised for kinematic analysis. RESULTS: Loading of the distal limbs produced a 6.7% increase in metabolic rate, an order of magnitude higher than when the mass was added over the back. Although the stride period was 2% longer in horses with loads on the distal limbs, time of contact and duty factor were not different. Distal limb loading increased the range of motion in hind- but not forelimbs. CONCLUSIONS: The costs of swinging the limbs in the horse are considerable and the addition of weights to the distal limb can have a profound effect on not only the energetics of locomotion but also the kinematics, at least in the hindlimb. POTENTIAL RELEVANCE: The use of weighted shoes, intended to increase animation of the gait, increases the metabolic effort of performance horses a disproportionate amount. The additional mass also increases the joint range of motion and, potentially, the likelihood of injury.

Animals↗

PubMed2004

Three-dimensional kinematic analysis of horses with induced tarsal synovitis.

REASONS FOR PERFORMING STUDY: Techniques for 3D analysis have recently been developed. This study applied 3D kinematic analysis to describe the effects of lameness in the distal intertarsal (DIT) and tarsometatarsal (TMT) joints; complex joints such as this may show measurable amounts of movement outside the sagittal plane that may change in response to pathological conditions. HYPOTHESIS: Three-dimensional motions of the tarsal joint change after the induction of synovitis at the DIT and TMT joints. METHODS: Twelve retroreflective markers, attached on the skin over the right limb, were used to develop 3D coordinate systems for tibial and metatarsal segments. Data were collected at trot from 4 horses on 2 occasions, before (sound condition) and after (lame condition) induction of synovitis of the DIT and TMT joints. Ranges of 3D motions of the metatarsal segment relative to the tibial segment were compared between sound and lame conditions using t tests. RESULTS: There were significant decreases (P<0.05) in tarsal joint flexion and cranial translation of the metatarsus relative to the tibia during stance, and in proximal translation of the metatarsus during swing. CONCLUSIONS AND POTENTIAL RELEVANCE: In the lame condition, reduced cranial translation at the DIT and TMT joints may lead to a reduction in the motion of the articular cartilage surfaces relative to each other, which may have adverse effects on cartilage nutrition and function. Further studies of tarsal 3D kinematics in horses with bone spavin could allow quantification of the biomechanical effects of the special shoes used for conservative treatment.

Animals↗

PubMed2004

Three-dimensional analysis of patterns of skin displacement over the equine radius.

REASONS FOR PERFORMING STUDY: Surface markers are usually used to track bone movement. However, skin movement related to the bone has a large effect on the analysis of skeletal kinematics. A 2-dimensional (2D) skin displacement correction model has been successfully developed, but no 3D skin displacement model exists. OBJECTIVES: To develop a 3-dimensional (3D) skin displacement model for the equine radial segment during trot. METHODS: The 3D trajectories of 6 skin-based markers and a bone-fixed triad were captured at trot in 4 horses. Skin displacements in the bone-based coordinate system were calculated using a singular-value decomposition method. The truncated Fourier series models were developed for the skin displacements using a generalised cross-validatory spline. RESULTS: Mean + /- s.d. of peak skin displacement of the 3 markers on the proximal radius as percentage of radial length was 10.7 +/- 0.5, 4.6 +/- 1.5 and 14.5 +/- 2.9% in x, y and z direction, respectively. For the 3 markers on the distal radius, the equivalent displacements were 4.7 +/- 0.6, 1.7 +/- 0.8 and 7.3 +/- 18% in x, y and z direction, respectively. CONCLUSIONS: The 3D skin displacement model for correction of skin marker motion over the equine radius relative to the bone can be established using a truncated Fourier series, which has previously been used successfully to develop 2D models. POTENTIAL RELEVANCE: This method of determining 3D skin displacement correction needs to be extended to the entire fore- and hindlimbs to provide a more sensitive measure of kinematic analysis. Accurate descriptions of the 3D motions of the limb segments and interactions between adjacent segments at the joints are necessary for understanding of the mechanics of different gaits and the gait aberrations that manifest as lameness.

Animals↗

PubMed2004

Effects of athletic taping of the fetlock on distal limb mechanics.

REASONS FOR PERFORMING STUDY: Athletic taping is used frequently by human athletes to stabilise, maintain or strengthen soft tissue structures, but empirical evidence supporting any changes in equine kinematics is lacking. OBJECTIVES: To assess the effects of athletic taping of the fetlock applied by an experienced athletic trainer on forelimb mechanics in healthy horses. HYPOTHESES: That athletic taping of the distal forelimb reduces 1) hyperextension of the fetlock joint during stance, 2) flexion of the fetlock joint during swing and 3) ground reaction forces during stance. METHODS: Ground reaction force and kinematic data were obtained for 6 healthy horses trotting at 3 m/sec for 4 sequential conditions (baseline, untaped; pre-exercise, taped; post exercise, taped post 30 mins trotting exercise; transfer, 4 h after tape removal). Data were analysed using 2-way mixed ANOVAs (condition; joint). RESULTS: A statistically significant interaction was identified for the fetlock during the swing phase (mean +/- s.d. peak flexion at baseline 157 +/- 4 degrees, reduced with taping to 172 +/- 4 degrees; P<0.05) compared with no differences across conditions for the other joints. Peak vertical force reduced significantly (P<0.05) with taping. CONCLUSIONS: Athletic taping of the fetlock does not alter the kinematics of the forelimb during stance, but does limit flexion of the fetlock during the swing phase. The decreased peak vertical force may be due to an increased proprioceptive effect. POTENTIAL RELEVANCE: Reduced peak vertical forces may be of benefit in preventing or reducing injury. Further investigation remains necessary before it can be concluded that taping should be applied for tendinous or ligamentous rehabilitation in equine patients.

Analysis of Variance↗

PubMed2004

Mepivacaine local anaesthetic duration in equine palmar digital nerve blocks.

REASONS FOR PERFORMING STUDY: Perineural analgesics are used for lameness diagnosis but the duration of effect, knowledge of which would provide valuable information when performing subsequent blocks, is unknown. OBJECTIVE: To evaluate the duration of a palmar digital nerve block using force plate measurements. METHODS: Ten horses diagnosed with unilateral navicular syndrome were trotted at range of 3 +/- 0.15 m/sec over a force plate to record ground reaction forces for 5 trials of each forelimb. Data were recorded before nerve block, and then at 15 mins, 1, 2 and 24 h post nerve block. RESULTS: Before nerve block, peak vertical force (mean +/- s.e.) was significantly higher in the contralateral forelimb (CL = 5345 +/- 188 N) than in the lame forelimb (L = 4256 +/- 204 N; P<0.05). At 15 mins post nerve block there was no significant difference between the 2 forelimbs (CL = 5140 +/- 184 N; L = 5126 +/- 129 N), and this remained the case for 1 h. By 2 h, the mean score for the lame leg had decreased (L = 4642 +/- 182 N) but was still greater than preblock. By 24 h, vertical forces had returned to preblock values. CONCLUSIONS: The palmar digital nerve block was fully effective between 15 mins and 1 h. The analgesic effect began to subside between 1 and 2 h but sufficient analgesia persisted to affect gait characteristics beyond 2 h. POTENTIAL RELEVANCE: When using a palmar digital nerve block, it is important to perform lameness evaluations between 15 mins and 1 h to be sure of effective nerve blockade.

Anesthetics, Local↗

PubMed2004

Ground reaction forces and limb function in tölting Icelandic horses.

REASONS FOR PERFORMING STUDY: Gaited horses employ 4-beat stepping (singlefoot) gaits that extend into speeds typical of trots. Ground reaction force (GRF) patterns of these specialised gaits have not been reported; therefore, appraisal of these gaits using nongaited horse kinetics may lead to clinical misjudgements. HYPOTHESIS: GRFs of tölting Icelandic horses will be comparable in profile and magnitude with those of trotting horses. METHODS: Forelimb and hindlimb GRFs were obtained for 10 Icelandic horses ridden at a tölt. These data were evaluated across 3 speed ranges: <2, 2.5-5 and >5 m/sec. RESULTS: Virtually all vertical force tracings were single-peaked. Forelimbs typically had greater peak vertical forces and impulses compared with hindlimbs. Support duration and forelimb vertical impulse were correlated negatively with speed, whereas peak vertical, braking and propulsive forces and hindlimb braking and propulsive impulses were correlated positively with speed. CONCLUSIONS: GRF profiles of tölting Icelandic horses are more similar to profiles of trots than walks, suggesting that tölts follow bouncing mechanics. POTENTIAL RELEVANCE: Greater overlap of limb support in 4-beat gaits (even at high speeds) is associated with lower peak vertical force magnitudes of tölts compared with those reported for trots at comparable speeds, which may help limit the occurrence of overloading injuries in Icelandic horses.

Animals↗

PubMed2002

Effects of weight carrying, exercise and a myo-anabolic supplement on growth and muscle.

Weight training is commonly used by human athletes to increase strength and fitness. This study was performed to examine the effect of weight-carrying and nutritional supplementation on muscle development and growth in young horses. This study examined the effect of weight-carrying and nutritional supplementation on muscle development and growth. Seventeen horses were divided into 3 groups: controls exercised in a free-flow exerciser, a weight group that performed the same exercise, carrying progressively increasing weight up to 45 kg, and a weight-supplement group, that also received a myo-anabolic supplement. Horses were accustomed to handling for 30 days then baseline measurements of weight, body condition score, wither height, hip height, forearm and gaskin circumferences, and cross-sectional area of the longissimus dorsi were taken. Horses were stalled for 108 days then conditioned for 78 days. At the end of conditioning, all measurements were taken again. Supplemented weight-carrying horses increased their lean body tissue, as indicated by greater bodyweight (P<0.05) combined with decreased body condition score (P<0.01). Greater increases in wither height (P = 0.09) and hip height (P<0.01) were seen in weight-carrying horses, probably the result of increased muscle tone. Supplemented weight-carrying horses increased forearm (P<0.01) and gaskin circumferences (P<0.05). It is believed that weight-carrying, when combined with additional dietary protein, enabled greater muscle anabolism. Additional research into the potential additive effect of resistance training and diet are warrented.

Animal Nutritional Physiological Phenomena↗

PubMed2002

Influence of trotting and supplemental weight on metacarpal bone development.

The use of weight-training to alter bone strength has not been investigated in horses. Recognising that bone responds to loading, we studied the effect of carrying weight on bone development during training. Seventeen horses were divided into 3 groups: controls exercised counterclockwise in a free-flow exerciser; the weight group performed the same exercise carrying progressively increasing weight up to 45 kg and the weight supplement group also received a myo-anabolic supplement. Radiographic equivalence measure of bone mineral content of zones of the third metacarpi (MCIII) was determined on 4 occasions: baseline (Day 108), pre-conditioning following 108 days stall confinement (Day 0), mid-conditioning (Day 39) and end-conditioning (Day 78). Stall confinement resulted in loss of mineral in lateral and medial cortices of both MCIII. During conditioning, weight-carrying increased mineral deposition in lateral and medial cortices of MCIII of the left (inside) leg compared with controls. In the right leg, controls had lower mineral content of the lateral cortex at Day 39 than weight-carrying horses but no differences between treatments were recorded at Day 78. Markers of bone metabolism did not change from baseline to pre-conditioning, but increased from Day 0 to 39 and 78 for all groups. This study demonstrates the benefits to bone mineral deposition in the third metacarpi of carrying weight when trained at low speeds and re-emphasises the potential for bone loss when not given sufficient exercise.

Animals↗

PubMed2002

Three-dimensional kinematics of the tarsal joint at the trot.

The tarsal joint is a common site of injury for many sport horses. Understanding the biomechanics of this complex joint begins with developing a clear picture of the kinematics during normal locomotion. This study describes the 3D kinematics of the tarsal joint by measuring the motion of the tibia and third metatarsus in 4 sound Quarter Horses with targets attached directly to the bones via steel pins. The objective was to determine if the tarsus had significant motion outside the tarsocrural joint. Two Steinmann pins were inserted into the lateral side of the right hindlimb and marker triads were fixed to the end of each pin. 3D motion of the bones was recorded as each subject trotted in hand. Three rotations were expressed using an attitude vector based on the finite helical angle method. Three translations were calculated as the motion of the tibia relative to the third metatarsus. Angular and translation data were mostly coupled with flexion angle. Internal/external rotation during stance and translations during swing showed evidence of noncoupled motion. Although the majority of tarsal motion occurs in the tarsocrural joint, there is evidence that translations and rotations occur in other locations within the tarsal joint and that some of these are related to the tarsal joint 'snapping' phenomenon. This research provides a set of reference 3D kinematics which will aid in the study of the aetiology and mechanical effects of tarsal joint lameness.

Animals↗

PubMed2002

Effect of walking velocity on forelimb kinematics and kinetics.

A database of biomechanical variables obtained from normal horses walking at a range of velocities is needed for comparison with the variables obtained from lame horses in which velocity cannot be predetermined. The objective was to investigate velocity-dependent changes in selected kinematic variables, ground reaction forces (GRF) and net joint energies in the forelimb and to develop statistical equations to calculate expected values of these variables for horses walking at different velocities. Five sound horses walked at a range of velocities (0.82 to 1.91 m/s) over a force plate. Kinematic data were recorded simultaneously for 51 trials. Kinematic, GRF and energetic variables were determined using standard methods. Correlation and simple regression analyses between velocity and measured variables were performed. An increase in walking velocity was correlated with an increase in stride length and decreases in stride and stance duration. Vertical, braking and propulsive impulses decreased as a consequence of the large reduction in stance duration, even though peak vertical, braking and propulsive GRFs increased. There was no significant increase in energy generation at any of the forelimb joints, indicating that muscle activity was not the source of the increase in GRFs. Changes in the longitudinal GRFs appeared to be influenced by velocity-dependent increases in head and neck oscillations. The equations obtained in this study can be used to calculate the expected normal variables from a range of walking velocities and to detect deviations from normal values in lame horses.

Animals↗

PubMed2002

Hindlimb net joint energies during swing phase as a function of trotting velocity.

Net joint powers and energies have been described in walking horses during the swing phase of the stride in the fore- and hindlimb (Clayton et al. 2001). During trotting, swing phase net joint powers have been described in the forelimb but not in the hindlimb. The effects of velocity on power profiles and energy patterns are important in relation to locomotor energetics. The objective of this study was to evaluate velocity-dependent changes in hindlimb net energy profiles of the swing phase during trotting. Inverse dynamic analysis was used to calculate net joint energies at the hindlimb joints of 6 horses trotting overground at velocities ranging from 2.27-5.17 m/s. At all velocities, there was net energy generation at the hip and tarsus and net energy absorption at the stifle, fetlock and coffin joints. Velocity-dependent bursts of energy generation at the hip actively protracted the limb in early swing and initiated retraction in late swing. Synchronous with the bursts of energy generation at the hip were velocity-dependent bursts of energy absorption across the stifle that acted to control flexion in early swing and extension in late swing. The distal limb was raised and lowered by velocity-dependent bursts of energy generation that flexed the tarsus in early swing and extended it in late swing. The energy bursts in early swing increased linearly with velocity, whereas the energy bursts in late swing increased as a function of the square or cube of velocity. The results contribute to understanding the mechanisms used to accelerate and decelerate the limbs more rapidly as velocity increases, which is an important consideration in racing and sporting performance.

Animals↗

PubMed2001

Effect of walking velocity on hindlimb kinetics during stance in normal horses.

The objectives of this study were to measure the effect of walking velocity on net joint moments and joint powers in the hindlimb during stance and to use the data to predict these variables at different walking velocities. Videographic and force data were collected synchronously from 5 sound horses walking over a force plate at a range of velocities. Force and kinematic data from 56 trials were combined using an inverse dynamic solution to determine net joint moments and joint powers. Analysis by simple regression and correlation (P < 0.05, r2 > or = 0.30, r > 0.50) showed that, in early stance, there were significant velocity-dependent increases in the peak magnitudes of the following variables: extensor moment and positive power at the hip, flexor moment and positive power at the stifle, extensor moment, negative and positive power at the tarsus, and flexor moment and negative power at the fetlock. In late stance, there were significant velocity-dependent increases in the peak magnitudes of the following variables: flexor moment at the hip, negative power at the stifle and flexor moment and positive power at the tarsus. As velocity increased, the hip showed an increase in energy generation, whereas the tarsus showed increases in both energy generation and absorption. It is concluded that an increase in walking velocity is associated with increases in peak magnitudes of the net joint moments and joint powers in the hindlimb; and that energy generation at the hip makes the largest contribution to the increase in velocity.

Animals↗

PubMed2001

Sensitivity of forelimb swing phase inverse dynamics to inertial parameter errors.

Estimations of segmental inertial parameters are required for true inverse dynamics calculations during the swing phase of locomotion. This study attempts to quantify the effect of inertial parameter errors on inverse dynamic solutions. Swing phase forelimb net joint moments and powers at the trot (mean +/- s.d 3.03 +/- 0.16 m/s) were calculated with sagittal plane kinematic data from 5 Dutch Warmbloods using inertial parameters based on published regression equations for the breed. Significant peaks in the net moment and power curves for each forelimb joint were identified and measured. Net joint moments and powers were then recalculated after varying the segment mass, location of the segment centre of mass and the mass moment of inertia separately for each of the limb segments. Peak values for the net joint moments and joint powers were determined after each variation, and the percent change in peak value per percent change in inertial parameter was calculated. Segment mass was the most influential parameter, followed by location of the centre of mass. Changes in the mass moment of inertia showed little effect on peak values. The most influential single inertial parameter was the mass of the hoof segment with a mean +/- s.d effect 0.74 +/- 0.22 and 0.69 +/- 0.18 percent peak change per percent parameter change on net joint moments and powers, respectively, across all joints. The results demonstrate the need for an accurate approximation of segment masses during the swing phase, especially the hoof, and the need to account for any additional masses in the model, such as shoes.

Animals↗

PubMed2001

Determination of hoof mass and centre of mass from morphological measurements.

Determination of net joint moments and powers requires accurate measurements of mass and centre of mass (COM) for the limb segments. The objective of this research was to develop regression equations for calculating mass and COM of the hoof segment that are applicable over a wide range of hoof morphologies. Ninety-one hooves (mean +/- s.d. 0.99 +/- 0.50 kg) were weighed and the 3-dimensional COM determined using a mass balance technique. Ten morphological variables were measured and used as independent variables in linear regressions with dependent variables of mass and centre of mass. The regression equation for mass was dependent upon coronet circumference, lateral height, solar length, solar width, heel height, toe height and base circumference (r2 = 0.978). Mediolateral COM was dependent only on solar length (r2 = 0.874). Dorsopalmar COM depended only upon solar length (r2 = 0.792) and vertical COM was defined only by lateral height (r2 = 0.377). Midlateral COM, measured at the midhoof wall along the tubules, was found to depend on coronet circumference, lateral height, toe length and toe height (r2 = 0.414). The large sample size and the inclusion of a variety of hoof masses and morphologies allow these results to be generalised to a wide range of the equine population. It was concluded that the mass and COM of the hoof segment can be estimated to a high degree of accuracy based on easily obtained morphological measurements.

Animals↗

PubMed2001

Arthrocentesis of the temporomandibular joint in adult horses.

OBJECTIVE: To develop a method for arthrocentesis of the temporomandibular joint in adult horses. ANIMALS: 7 equine cadaver heads and 6 clinically normal adult horses. PROCEDURE: Fluoroscopy, contrast radiography, and computed tomography were used on cadaver specimens to locate the temporomandibular joint, identify externally palpable landmarks for joint access, guide needle placement into the joint, and illustrate regional anatomy. The arthrocentesis technique was performed on 6 live healthy adult horses to determine efficacy and safety of this procedure. RESULTS: Externally palpable structures were identified as landmarks for temporomandibular arthrocentesis, including the lateral border of the condylar process of the mandible, the zygomatic process of the temporal bone, and the lateral pericapsular fat pad. Arthrocentesis was successful in all 6 joints in the live horses, and no complications developed. CONCLUSIONS AND CLINICAL RELEVANCE: The technique identified will improve the ability to examine and treat the temporomandibular joint in horses.

Animals↗