Average Joint Angles Research Articles

Stroke walking and balance characteristics via principal component analysis

Balance impairment is associated gait dysfunction with several quantitative spatiotemporal gait parameters in patients with stroke. However, the link between balance impairments and joint kinematics during walking remains unclear. Clinical assessments and gait measurements using motion analysis system was conducted in 44 stroke patients. This study utilised principal component analysis to identify key joint kinematics characteristics of patients with stroke during walking using average joint angles of pelvis and bilateral lower limbs in every gait-cycle percentile related to balance impairments. Reconstructed kinematics showed the differences in joint kinematics in both paretic and nonparetic lower limbs that can be distinguished by balance impairment, particularly in the sagittal planes during swing phase. The impaired balance group exhibited greater joint variability in both the paretic and nonparetic limbs in the sagittal plane during entire gait phase and during terminal swing phase respectively compared with those with high balance scores. This study provides a more comprehensive understanding of stroke hemiparesis gait patterns and suggests considering both nonparetic and paretic limb function, as well as bilateral coordination in clinical practice. Principal component analysis can be a useful assessment tool to distinguish differences in balance impairment and dynamic symmetry during gait in patients with stroke.

Markerless motion capture provides repeatable gait outcomes in patients with knee osteoarthritis

Motion analysis has seen minimal adoption for orthopaedic clinical assessments. Markerless motion capture solutions, namely Theia3D, address limitations of previous methods and provide gait outcomes that are robust to clothing choice and repeatable in healthy adults. Repeatability in orthopaedic populations has not been investigated and is important for clinical utility and adoption. The purpose of this study was to evaluate the repeatability of Theia3D for gait analysis in a knee osteoarthritis population. Ten orthopaedic patients with knee osteoarthritis underwent gait analysis on three visits, with an average of 8 days between. Participants were recorded during one-minute overground walking trials at self-selected typical and fast speeds by 8 synchronized video cameras. Video data were processed using Theia3D. Intraclass correlations were used to examine the repeatability of temporal distance metrics as well as segment lengths of the underlying kinematic model. Inter-trial and inter-session variability of lower extremity joint angles were estimated for each point of the gait cycle. Intraclass correlations were greater than 0.98 for all temporal distance metrics for both speeds. Lower body segment lengths had intraclass correlations above 0.90. Participant average joint angle waveforms displayed consistent patterns between visits. The average inter-trial and inter-session variability in joint angles across speeds were 1.17 and 1.45 degrees, respectively. The variability in joint angles between visits was less than typically reported for marker-based methods. Gait outcomes measured with Theia3D were highly repeatable in patients with knee osteoarthritis providing further validation for its use in clinical assessment and longitudinal studies.

Geometric Co-Ordinate Feature Point Estimation (Gfpe): A Novel Approach to Analyse Of Kinematic Characteristics of Yoga Asanas Based on Anybody Simulation Software

The kinematic characteristics of yoga asanas is crucial for comprehending the biomechanical demands and benefits associated with these postures. Utilizing AnyBody simulation software, researchers delve into the intricate movements and alignments involved in various yoga poses. Through advanced biomechanical modeling, AnyBody allows for the analysis of joint angles, muscle activations, and forces exerted on the body during asana practice. This paper presented an analysis of the kinematic characteristics of yoga asanas using AnyBody Simulation in conjunction with Geometric Co-ordinate Feature Point Estimation (GFPE). By integrating advanced biomechanical modelling capabilities of AnyBody with GFPE’s precision in identifying geometric features, this study aims to elucidate the intricate movements and alignments inherent in various yoga poses. Through comprehensive simulations, joint angles, muscle activations, and forces exerted on the body during asana practice are meticulously analyzed. The examination of body posture with GFPE in the downward-facing dog pose, the average joint angles of the shoulder, elbow, and wrist were found to be 130°, 150°, and 160°, respectively. Additionally, muscle activation levels were measured, with the triceps brachii exhibiting an average activation of 70% of maximum voluntary contraction during the pose.

FGDA-GS: Fast guided decision attack based on gradient signs for skeletal action recognition

The black-box adversarial attacks for skeletal action recognition currently construct high-quality adversarial examples by sacrificing queries and perturbation imperceptibility. To overcome the above drawbacks, we propose a novel fast guided decision attack based on gradient signs for skeletal action recognition (FGDA-GS) scheme. Firstly, to reduce the queries, we guide the adversary to attack along the gradient direction obtained by sampling in a custom Gaussian distribution and design a gradient direction estimation method based on successful history information queries, which can quickly determine the updated direction of the effective perturbation without a large query. Secondly, to ensure the imperceptibility of the adversarial examples, we design a manifold projection function matching the first-order derivatives based on joint position constraints, joint angle constraints, and bone-length constraints to generate complete and natural skeletal adversarial examples that are invisible to the human eye. Finally, comprehensive experimental results demonstrate that FGDA-GS can generate strong-natured, highly effective adversarial examples with significantly reduced query. Specifically, FGDA-GS achieves a 100% attack success rate on different datasets and models with reduced queries by hundreds to thousands and reduced time by more than half. Particularly in the untargeted attack setting, compared to BASAR, FGDA-GS outperforms in terms of average joint position deviation, average joint acceleration deviation, average joint angle acceleration deviation, and average bone-length deviation percentage for the ST-GCN model on the NTU dataset, with percentage reductions of 91.13%, 91.81%, 80.60%, and 81.08%, respectively. We also conducted experiments on defense methods to validate our proposed scheme's effectiveness further.

Ergonomic risk assessment during massage among physiotherapists: Introduction of generic postures notion.

Musculoskeletal disorders are prevalent among physiotherapists. They perform many repetitive tasks in awkward postures that require a high muscle load. This issue was often addressed through subjective analysis (questionnaire) but rarely using postural evaluation combined with an ergonomic assessment. The aim of this article was to decompose draining lymphatic massage performed by physiotherapists in generic postures (GP) to quickly assess the musculoskeletal disorder risk. Based on numeric video recorded in frontal and sagittal planes, 3360 postures were defined from 20-minutes lymphatic drainage massage performed by 7 physiotherapists over a period of 6 months. A hierarchical cluster analysis was applied to define the GP. Seven GP were identified, which were described by their average joint angles, variability and relative frequency. GP6, GP4 and GP2 had the highest frequencies (17.6%, 16.9% and 16.8% respectively). Trunk and neck were essentially flexed (neck: 17.0±10.0° for GP1; trunk: 20.4±8.7° for GP4). Shoulder flexion and abduction ranged from 15° (GP7) to 60° (GP4). Mean and variability of RULA score completed the analysis. The highest scores were computed for GP2 and GP3 (respectively 5.5±1.3 and 5.8±1.2, p < 0.05). GP4 had the lowest (4.0±1.1, p < 0.05). The results suggest that massages have to be monitored. Attention should be paid to the postures used to prevent the occurrence of MSDs. The massages could be described as a combination of generic posture for a rapid ergonomic assessment.

The Effect of Metacarpal Shortening on Finger Strength and Joint Motion: A Cadaveric Biomechanical Study

Discrepancies exist between previous biomechanical and clinical studies when determining acceptable metacarpal shortening after metacarpal fractures. This study aimed to determine the amount of acceptable shortening after a metacarpal fracture before finger motion and strength is compromised. We defrosted ten fresh-frozen cadaveric hands. A screw-driven external fixator was placed to stabilize the metacarpal, then a 15.0-mm section of the index metacarpal was excised and replaced with a three dimensional-printed, custom-designed polyethylene insert. The hand was then mounted on a custom testing rig, and the index finger was flexed using the flexor digitorum profundus tendon. Joint angles and fingertip force were recorded as the finger was flexed. Incrementally smaller inserts were placed, and testing was repeated. The average joint angles of the intact condition for the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints were (54 [SD = 13], 79 [SD = 21], and 73 [SD = 10]), respectively. There were no statistically significant changes to any joint angle with any amount of shortening. The maximal fingertip contact pressures were 41 N (17), 31 N (12), 24 N (14), 19 N, (11), and 14 N (8) for the 15 mm, 12.5 mm, 10 mm, 7.5 mm, and 5 mm inserts, respectively. All changes in fingertip force by insert size were statistically significant. Metacarpal shortening does not affect flexion range of motion regardless of the amount of shortening, but it significantly affects finger strength. The loss of strength after shortening was approximately 6.5% per mm of shortening for the fractured metacarpal. When viewed in the context of the hand as a whole and the contribution of the index finger to grip being only 23.5%, it is unlikely that any shortening will significantly affect the average patient regarding grip strength. However, for a patient who requires fine motor strength, any amount of shortening may affect their finger function and needs to be addressed.

Shape-model scaled gait models can neglect segment markers without consequential change to inverse kinematics results

Inverse Kinematics (IK) is an optimisation to estimate joint angles from motion capture data, where marker trajectories and weighting strategies determine the outcome. Skin-mounted markers are subject to Soft Tissue Artefact (STA), particularly thigh markers. Our first aim was to test the effect of neglecting thigh markers on IK results across different markersets. Our second aim was to investigate inter-markerset differences using varying weighting strategies. Twenty participants participated in a treadmill walking motion capture session. Inverse kinematic analysis was performed using three markersets, termed Contemporary (segment clusters), NoThigh (Contemporary without thigh markers), and Traditional (modified Helen Hayes). Seven weighting schemes were used with varying magnitudes with each markerset. Joint angles (comprising tri-planar hip angles, and sagittal knee and ankle angles) were compared across all three conditions. NoThigh and Traditional generated joint angle results that differed from the Contemporary markerset by a median of 1.2° and 1.5°, respectively. Non-sagittal hip angles differed the most. Most average joint angle differences were smaller than previously-estimated STA error. NoThigh generated less difference from Contemporary than Traditional for the hip and knee joints. Intuitively, weighting strategies that heavily favour shared markers resulted in IK results with closer inter-markerset agreement. Thigh markers can be neglected without introducing more error than STA, and different markersets (with validation) can be compared against each other when using strategic weighting. This creates new research pathways for collaboration and data re-use, as well as freeing researchers (and participants) of their attachment to thigh markers.

Identification of generic drilling task phases and height effect: Coupling of kinematic and kinetic data

BackgroundThe prevention of work-related musculoskeletal disorders (MSDs) is an important issue for the health of operators, especially when the workload is heavy, such as in drilling activities. Research questionThis study aimed to propose an objective identification and description of the different phases that comprise a drilling task as well as a biomechanical and ergonomic evaluation of the subjects' overall posture during its effective part. MethodsFourteen healthy subjects performed three successive drillings at two different heights, 130 (H130) and 170 cm (H170) from the ground, of a 3 mm thick steel plate. Kinematic and kinetic data were simultaneously acquired using a Qualisys motion capture system and a force platform. The speed profiles of each body segments and the evolution of the force exerted were analysed to identify the different phases. Then, the average joint angles of the whole body were calculated during the drilling phase for the two heights considered and compared. Finally, the measured postures were qualified through the Rapid Upper Limb Assessment (RULA) score in order to assess the risk of developing MSDs for each condition. ResultsThe drilling task could be divided into five phases whatever the condition: transport, aiming, repositioning, drilling, and return. The increase in height has doubled the duration of the drilling phase while reducing the force exerted by about 30 %. Similarly, height variation significantly influenced the subjects' posture, mainly in the head, trunk and upper limbs, and the RULA scores obtained for conditions H130 and H170 were 6 and 7 respectively. SignificanceThe results indicate, on the one hand, the relevance of coupling kinematic and kinetic data in order to analyse the drilling task and, on the other hand, that operators are exposed to considerable risk of developing MSDs, even at intermediate heights, which increase as the height increases.

Exploring the Contribution of Proprioceptive Reflexes to Balance Control in Perturbed Standing

Humans control balance using different feedback loops involving the vestibular system, the visual system, and proprioception. In this article, we focus on proprioception and explore the contribution of reflexes based on force and length feedback to standing balance. In particular, we address the questions of how much proprioception alone could explain balance control, and whether one modality, force or length feedback, is more important than the other. A sagittal plane neuro-musculoskeletal model was developed with six degrees of freedom and nine muscles in each leg. A controller was designed using proprioceptive reflexes and a dead zone. No feedback control was applied inside the dead zone. Reflexes were active once the center of mass moved outside the dead zone. Controller parameters were found by solving an optimization problem, where effort was minimized while the neuro-musculoskeletal model should remain standing upright on a perturbed platform. The ground was perturbed with random square pulses in the sagittal plane with different amplitudes and durations. The optimization was solved for three controllers: using force and length feedback (base model), using only force feedback, and using only length feedback. Simulations were compared to human data from previous work, where an experiment with the same perturbation signal was performed. The optimized controller yielded a similar posture, since average joint angles were within 5 degrees of the experimental average joint angles. The joint angles of the base model, the length only model, and the force only model correlated weakly (ankle) to moderately with the experimental joint angles. The ankle moment correlated weakly to moderately with the experimental ankle moment, while the hip and knee moment were only weakly correlated, or not at all. The time series of the joint angles showed that the length feedback model was better able to explain the experimental joint angles than the force feedback model. Changes in time delay affected the correlation of the joint angles and joint moments. The objective of effort minimization yielded lower joint moments than in the experiment, suggesting that other objectives are also important in balance control, which cause an increase in effort and thus larger joint moments.

Estimation of Full-Body Poses Using Only Five Inertial Sensors: An Eager or Lazy Learning Approach?

Human movement analysis has become easier with the wide availability of motion capture systems. Inertial sensing has made it possible to capture human motion without external infrastructure, therefore allowing measurements in any environment. As high-quality motion capture data is available in large quantities, this creates possibilities to further simplify hardware setups, by use of data-driven methods to decrease the number of body-worn sensors. In this work, we contribute to this field by analyzing the capabilities of using either artificial neural networks (eager learning) or nearest neighbor search (lazy learning) for such a problem. Sparse orientation features, resulting from sensor fusion of only five inertial measurement units with magnetometers, are mapped to full-body poses. Both eager and lazy learning algorithms are shown to be capable of constructing this mapping. The full-body output poses are visually plausible with an average joint position error of approximately 7 cm, and average joint angle error of 7. Additionally, the effects of magnetic disturbances typical in orientation tracking on the estimation of full-body poses was also investigated, where nearest neighbor search showed better performance for such disturbances.

Mannequin system for the self-training of nurses in the changing of clothes

Purpose – For self-training of nursing students, this paper developed a mannequin to simulate and measure the movement of a patient’s arms while nurses changed the patient’s clothes on a bed. In addition, using the mannequin the purpose of this paper is to determine the difference in the handling of a patient’s arms between nursing teachers and students. Design/methodology/approach – The target patient was an old man with complete paralysis. Three-degrees-of-freedom (DOF) shoulder joints and one-DOF elbow joints were applied to the mannequin. The angles of all joints were measured using a potentiometer, and those angles were transmitted to a computer via Bluetooth. Findings – In a preliminary experiment, the two nursing teachers confirmed that the mannequin arms simulated the motion of the arms of a paralyzed patient. In the experiment, two teachers and six students changed the clothes of the mannequin. The average joint angle of the left elbow and the moving frequency of the left elbow, right shoulder adduction/abduction and right shoulder internal/external rotation were lower in the case of teachers dressing the mannequin than when students were dressing it. Originality/value – The proposed system can simulate a completely paralyzed patient that nursing students would normally be almost unable to train with. Additionally, the proposed approach can reveal differences between skilled and non-skilled people in the treatment of a patient’s body.

Handing Over Objects to Human in a Friendly and Comfortable Manner

In this paper, a robotic motion planning scheme is proposed to generate hand-over motions in a friendly and comfortable manner. Two sub-problems are studied: The determination of the final target position (where the robot should hand over the object to) and the generation of human-like motion in the hand-over process (how the robot should hand over the object to the position). First, experiments of different subjects are conducted to explore the common characteristics in the optimal hand-over positions. The result shows that their joint angles are similar at the optimal hand-over position. Therefore, the optimal hand-over position can be determined by forward kinematics based on the measured average joint angles. Then, two methods are proposed to plan the human-like hand-over motions in an obstacle-free environment and in an obstacle-present environment, respectively. A series of experimental comparisons is conducted to prove the validity of the methods. A robotic arm is controlled to hand over a cube to humans in human-like way and nonhuman-like way. The subjects are asked to grade the hand-over motion of the robotic arm on a scale of 1 to 5. The results show that the hand-over motions planned by the methods proposed in this paper can make people feel safer and more comfortable.

Tibiofemoral Alignment: Contributing Factors to Noncontact Anterior Cruciate Ligament Injury

The mechanisms of noncontact anterior cruciate ligament injury remain undefined. The purpose of this study was to identify the tibiofemoral alignment in the lateral compartment of the knee for three variations of a one-limb landing in noncontact sports activities: the safe, provocative, and exaggerated provocative positions. These positions were chosen on the basis of a previous study that measured the average joint angles of the limb at the point of ground contact for athletes who landed without injury (safe) and those who sustained an anterior cruciate ligament injury (provocative). It was hypothesized that, in the provocative positions, altered tibiofemoral alignment predisposes the knee to possible subluxation, potentially leading to an anterior cruciate ligament injury. Magnetic resonance images were acquired for a single knee in twenty-five noninjured athletes for the three landing positions. The angle between the posterior tibial slope and the femur along with three distances (from the tibiofemoral point of contact to [1] the femoral sulcus point, [2] the posterior tibial point, and [3] the most anterior point of the circular posterior aspect of the condyle) were measured for each acquisition. The tibial slope relative to the femur was directed significantly more inferior to superior in the provocative and exaggerated positions than in the safe landing position. Similarly, as the limb transitioned from the safe to the provocative positions, the tibiofemoral joint contact point was significantly closer to the femoral sulcus point and to the most anterior point of the circular posterior portion of the lateral femoral condyle. As the limb moves toward the provocative landing position, the anatomical alignment based on slope and contact characteristics places the knee at possible risk for noncontact anterior cruciate ligament injury. An enhanced understanding of the mechanism of anterior cruciate ligament injury may lead to improved preventative strategies.

Tibiofemoral joint contact forces and knee kinematics during squatting

Axial tibiofemoral joint contact forces were non-invasively determined for two high range of motion (high flexion) squatting activities. An electromagnetic motion tracking system and a non-conductive force platform were used to collect kinematic and kinetic data. An innovative scaling method was used to model subject-specific muscle group moment arms. One subject attained a peak axial tibiofemoral joint contact force of 49.7 N/kg during squatting at 149.9° knee flexion. Average joint angles and average axial joint contact forces were calculated for each of the activities in order to facilitate a comparison with stair climbing data. Compared to stair climbing, the maximum average joint contact forces during the squatting activities occurred at significantly higher flexion angles ( p < 0.05.) The relative simplicity of the method makes it useful for application to large subject groups from diverse regions. The results of this study can be applied to the diagnosis and treatment of pathologies, and to the development of high range of motion (ROM) knee replacements.

Description of joint movements in human and non-human primate locomotion using Fourier analysis

To describe and help interpret joint movements in various forms of primate locomotion, we explored the use of Fourier analysis to represent changing joint angles as a series of sine and cosine curves added together to approximate the raw angular data. Results are presented for four joints (shoulder, elbow, hip and knee) with emphasis on the shoulder, and for five types of locomotion (catarhine primate quadrupedal walking, human hands-and-feet creeping and hands-and-knees creeping, and human walking and running). Fourier analysis facilitates functional interpretation of the angles of all four joints, by providing average joint angles and an indication of the number of peaks and troughs in the angular data. The description of limb movements also afforded us the opportunity to compare human and other catarhine joint angles, and we interpret the Fourier results in terms of locomotor posture and type. In addition, the shoulder data are useful for determination of some aspects of interlimb coordination. Non-human primates walking quadrupedally and humans creeping on hands and knees generally evince diagonal couplets interlimb coordination, in which the hand on one side strikes the substrate at about the same time as the contralateral foot or knee. Furthermore, human walking and running seem to follow a similar pattern, as indicated by Fourier analysis. From our data it is concluded that human bipedal gaits are qualitatively similar to diagonal couplets gaits in other primates, but quite different from the lateral couplets gaits used by many non-primate mammals. A number of other benefits of Fourier analysis in primate locomotion studies are also discussed. These include the ability to make statistical comparisons among various types of limb movements in a wide variety of species, a simple archival technique for limb movement data, and a greater understanding of the variability of locomotor movements.

The Utility of Diagnosing Lumbar Rotational Instability from Twist CT Scans

The twist CT has been advocated as a useful diagnostic tool for determining lumbar segment instability. According to this test, facet joints showing wide separation on lumbar spine rotation are believed to be pathological. However, no reports have presented the reliability of measuring facet joint separation from clinical twist CT films, nor tested for an association between tendency to separate and anatomical joint orientation. Forty-five patients, referred for mechanical low back pain, were scanned first in neutral, then right and left trunk twisted positions. Images were video-digitized onto computer for quantitative measurement of facet joint morphology. The induced facet joint separation was contrasted with the neutral scan joint approximation and any difference was expressed in millimeters. The coefficient of variability (c.v.) of defining right and left transverse plane facet joint orien-tation, and of joint separation, from repeated assessment in ten images was acceptable (c.v. = 2% and 3.5%, respectively). The average joint angle increased from L2–3 to L5–S1 and the mean facet joint separation of 2.6 mm was greatest at the L4–5 level. Forty-three percent of all segments showed little additional separation (<0.2 mm) when in a rotated posture. In the remainder, a slight relationship existed between facet geometry and separation; joints with wider angles were associated with greater separation than those with a more sagittal configuration (r=0.36, p<0.01). No conclusive trend was recorded in this patient series for facet joints to separate when the subject adopted an end-range rotated posture. A mild association between physiological separation of facet joints and their morphological angle was determined. This trend alone should not afford confidence in attributing such separation as having pathological significance.

THE UTILITY OF DIAGNOSING LUMBAR ROTATIONAL INSTABILITY FROM TWIST CT SCANS

The twist CT has been advocated as a useful diagnostic tool for determining lumbar segment instability. According to this test, facet joints showing wide separation on lumbar spine rotation are believed to be pathological. However, no reports have presented the reliability of measuring facet joint separation from clinical twist CT films, nor tested for an association between tendency to separate and anatomical joint orientation. Forty-five patients, referred for mechanical low back pain, were scanned first in neutral, then right and left trunk twisted positions. Images were video-digitized onto computer for quantitative measurement of facet joint morphology. The induced facet joint separation was contrasted with the neutral scan joint approximation and any difference was expressed in millimeters. The coefficient of variability (c.v.) of defining right and left transverse plane facet joint orien-tation, and of joint separation, from repeated assessment in ten images was acceptable (c.v. = 2% and 3.5%, respectively). The average joint angle increased from L2–3 to L5–S1 and the mean facet joint separation of 2.6 mm was greatest at the L4–5 level. Forty-three percent of all segments showed little additional separation (&lt;0.2 mm ) when in a rotated posture. In the remainder, a slight relationship existed between facet geometry and separation; joints with wider angles were associated with greater separation than those with a more sagittal configuration (r=0.36, p&lt;0.01). No conclusive trend was recorded in this patient series for facet joints to separate when the subject adopted an end-range rotated posture. A mild association between physiological separation of facet joints and their morphological angle was determined. This trend alone should not afford confidence in attributing such separation as having pathological significance.

Effects of muscle kinematics on surface EMG amplitude and frequency during fatiguing dynamic contractions.

Fifteen male subjects performed a repetitive elbow flexion/extension task with a 7-kg mass until exhaustion. Average joint angle, angular velocity, and biceps brachii surface electromyographic (EMG) amplitude (aEMG) and mean power frequency (MPF) were calculated with each consecutive 250-ms segment of data during the entire trial. Data were separated into concentric or eccentric phases and into seven 20 degree-ranges from 0 to 140 degrees of elbow flexion. A regression analysis was used to estimate the rested and fatigued aEMG and MPF values. aEMG values were expressed as a percentage of amplitudes from maximum voluntary contractions (MVC). Under rested dynamic conditions, the average concentric aEMG amplitude was 10% MVC higher than average eccentric values. Rested MPF values were similar for concentric and eccentric phases, although values increased approximately 20 Hz from the most extended to flexed joint angles. Fatigue resulted in an average increase in concentric and eccentric aEMG of 35 and 10% MVC, respectively. The largest concentric aEMG increases (up to 58% MVC) were observed at higher joint velocities, whereas eccentric increases appeared to be related to decreases in velocity. Fatigue had a similar effect on MPF during both concentric and eccentric phases. Larger MPF decreases were observed at shorter muscle lengths such that values within each angle range were very similar by the end of the trial. It was hypothesized that this finding may reflect a biological minimum in conduction velocity before propagation failure occurs.

Defining normal three-dimensional kinematics of the lower forelimb in horses

Summary Although the equine metacarpophalangeal joint is frequently damaged, there is a scarcity of data concerning the three-dimensional kinematics of this joint. Thus, the purpose of this study was to define normal three-dimensional kinematics of the distal forelimb. Six mature Thoroughbreds were adapted to a high-speed treadmill and filmed at awalk (2.0 m/s), trot (4.0 m/s), and left-lead canter (7.0 m/s). An autodigitizing videographic system was used to collect and analyze the three-dimensional kinematic data. Retroreflective markers were placed on the left forelimb at approximate centers of rotation of the carpal and metacarpophalangeal joints and at midpoints of the radius, third metacarpal bone, and hoof. The measures made during the experiment included the angle the fetlock and hoof made with the ground in three dimensions (the XZ, YZ, and XY planes), range of motion of the fetlock joint, limb acceleration and velocity, stride length, and stride frequency. The average joint angles in the XZ plane at impact were 134.6°, 140.6°, and 151.7°, and at lift-offwere 69.6°, 81.2°, and 88.9° for the walk, trot, and canter, respectively. In the YZ plane, average impact angles were 99.2°, 97.2°, and 100.3°, and lift-off angles were 96.4°, 96.6°, and 95.5° for the walk, trot and canter, respectively. In the XY plane, average impact angles were 136.4°, 130.3°, and 136.3°, and lift-off angles were 163.2°, 168.4°, and 173.6° for the walk, trot and canter, respectively. Total range of motion of the fetlock joint was 50.3° at the walk, 52.1° at the trot, and 56.0° at the canter. Average acceleration values of the fetlock joint determined at peakprotraction were -90.3, -121.9, and -201.6 and at the end of retraction were 112.0, 126.1, and 238.7 m/s 2 for the walk, trot, and canter, respectively. The average stride frequencies for the walk, trot and canter were 0.98, 1.44, and 1.88 Hz, respectively. The average stride lengths for the walk, trot and canter were 2.21, 2.72, and 3.79 m, respectively. These data will be used to build a base on normal three-dimensional kinematic patterns of the distal forelimb of the horse moving at the walk, trot, and canter on a high-speed treadmill.