Is a standalone inertial measurement unit accurate and precise enough for quantification of movement symmetry in the horse?

Quantification of spinal ataxia in dogs with thoracolumbar spinal cord injury

The clinical sign of ataxia is related to several neurological diseases and is seen in conjunction with paresis in dogs with spinal cord injury (SCI). Endeavours to objectify canine spinal ataxia in SCI remain limited. The aim of this clinical study was to determine and quantify differences between gait characteristics of ataxic dogs with thoracolumbar myelopathy and healthy control dogs using a computer-and treadmill-based gait analysis system. Five dogs with spinal ataxia and six healthy dogs underwent video-and computer-assisted gait analysis while walking on a four-ground reaction force plate treadmill system (maximum speed of 0.7 m/s). Spatio-temporal and kinetic gait characteristics regarding the dogs' locomotion were analysed with a focus on the individual coefficient of variation (CV), as a potential measure for quantification of the level of ataxia. Ataxic dogs with thoracolumbar SCI showed no effect on symmetry indices but higher variability in spatio-temporal and kinetic gait parameters mainly in the pelvic, but also in the thoracic limbs. Double support phase of the individual limb was prolonged in SCI dogs at the cost of the single support and swing phase. Reduced peaks of ground reaction forces (GRF) could potentially be explained by reduction of muscle strength, as a strategy of avoiding falling by taking enthusiastic steps, or by alteration of the rhythmogenic spinal circuits between the pelvic and thoracic limb pattern generators.

Inertial Sensor Technologies-Their Role in Equine Gait Analysis, a Review

Objective gait analysis provides valuable information about the locomotion characteristics of sound and lame horses. Due to their high accuracy and sensitivity, inertial measurement units (IMUs) have gained popularity over objective measurement techniques such as force plates and optical motion capture (OMC) systems. IMUs are wearable sensors that measure acceleration forces and angular velocities, providing the possibility of a non-invasive and continuous monitoring of horse gait during walk, trot, or canter during field conditions. The present narrative review aimed to describe the inertial sensor technologies and summarize their role in equine gait analysis. The literature was searched using general terms related to inertial sensors and their applicability, gait analysis methods, and lameness evaluation. The efficacy and performance of IMU-based methods for the assessment of normal gait, detection of lameness, analysis of horse-rider interaction, as well as the influence of sedative drugs, are discussed and compared with force plate and OMC techniques. The collected evidence indicated that IMU-based sensor systems can monitor and quantify horse locomotion with high accuracy and precision, having comparable or superior performance to objective measurement techniques. IMUs are reliable tools for the evaluation of horse-rider interactions. The observed efficacy and performance of IMU systems in equine gait analysis warrant further research in this population, with special focus on the potential implementation of novel techniques described and validated in humans.

Quantification of phenobarbital-induced ataxia in dogs with idiopathic epilepsy

Ataxia is a clinical sign seen in several neurological diseases and has been reported as an adverse effect of anti-seizure medication such as phenobarbital (PB). Efforts to objectify canine ataxia in order to provide appropriate treatment or monitor adverse effects of drugs remain limited. Automated quantitative gait analysis can be useful for the acquisition of objective data for the evaluation and monitoring of ataxia in dogs. The aim of this prospective clinical study was to examine the gait characteristics of dogs with PB induced ataxia and compare them with healthy dogs using a computer- and treadmill-based gait analysis system. Six healthy dogs and five dogs with idiopathic epilepsy (IE) with PB-induced ataxia underwent video- and computer-assisted gait analysis during slow walking (maximum speed of 0.7 m/s) on a treadmill with four ground reaction force plates (one plate per limb). Kinetic and spatio-temporal gait parameters of dogs' locomotion were analyzed, including individually calculated coefficients of variation. Dogs with IE treated with PB showed higher variability in spatio-temporal but not in kinetic gait parameters. Double support phase of gait cycles was increased on the cost of single support and swing phases. Body weight standardized ground reaction forces in vertical, craniocaudal, and mediolateral direction were severely affected by ataxia. Compensatory mechanisms in locomotion of dogs with PB-induced ataxia included spatio-temporal and kinetic gait characteristics, most likely in order to compensate imbalance caused by limb incoordination.

Research trends in equine movement analysis, future opportunities and potential barriers in the digital age: A scoping review from 1978 to 2018

BACKGROUND

Since Muybridge's 'horse in motion', researchers in the equine movement analysis field continue to improve objective analysis and performance monitoring while ensuring representative data capture. However, subjective evaluation remains the primary method of equine gait analysis in the applied setting, despite evidence highlighting the unreliability of this approach.

OBJECTIVES

To map research trends, limitations and opportunities across the diverse equine gait analysis literature.

STUDY DESIGN

Joanna Briggs Institute and Cochrane systematic scoping review.

METHODS

Search terms were chosen based on the 'PICO' framework and included keywords such as: Equine, Gait, Kinematics and Analysis. Studies were excluded based on predetermined criteria by two independent researchers. Data were extracted from 510 articles from 1978 to 2018.

RESULTS

Insights derived from movement analysis appear to be driven by tool availability. Observational research (42.9%) was the most popular study design. Use of wearable technology as a primary research tool is established within the field, accounting for 13.5% of studies. Analysis of limitations identified 17.8% of studies citing challenges to the transferability of research results. Restricted sample size appears to be an underlying contributor to many of the limitations identified. In terms of research opportunities, advances in intervention studies were called for (10.4% of studies) in the following three areas; clinical, rehabilitative exercise and performance/training.

MAIN LIMITATIONS

This review was confined to research in the English language.

CONCLUSIONS

Standardised research reporting may alleviate sample size issues by facilitating data pooling, database creation and meta-analyses. Large holistic data collections and application frameworks based on wearable technologies are not reflected in the current equine gait analysis literature and thus represent an interesting opportunity for this field. Progress and lessons learned from the human field of movement analysis can be useful in supporting this potential development.

EquiMoves: A Wireless Networked Inertial Measurement System for Objective Examination of Horse Gait

In this paper, we describe and validate the EquiMoves system, which aims to support equine veterinarians in assessing lameness and gait performance in horses. The system works by capturing horse motion from up to eight synchronized wireless inertial measurement units. It can be used in various equine gait modes, and analyzes both upper-body and limb movements. The validation against an optical motion capture system is based on a Bland-Altman analysis that illustrates the agreement between the two systems. The sagittal kinematic results (protraction, retraction, and sagittal range of motion) show limits of agreement of ± 2.3 degrees and an absolute bias of 0.3 degrees in the worst case. The coronal kinematic results (adduction, abduction, and coronal range of motion) show limits of agreement of - 8.8 and 8.1 degrees, and an absolute bias of 0.4 degrees in the worst case. The worse coronal kinematic results are most likely caused by the optical system setup (depth perception difficulty and suboptimal marker placement). The upper-body symmetry results show no significant bias in the agreement between the two systems; in most cases, the agreement is within ±5 mm. On a trial-level basis, the limits of agreement for withers and sacrum are within ±2 mm, meaning that the system can properly quantify motion asymmetry. Overall, the bias for all symmetry-related results is less than 1 mm, which is important for reproducibility and further comparison to other systems.

GaitKeeper: A System for Measuring Canine Gait

It is understood gait has the potential to be used as a window into neurodegenerative disorders, identify markers of subclinical pathology, inform diagnostic algorithms of disease progression and measure the efficacy of interventions. Dogs’ gaits are frequently assessed in a veterinary setting to detect signs of lameness. Despite this, a reliable, affordable and objective method to assess lameness in dogs is lacking. Most described canine lameness assessments are subjective, unvalidated and at high risk of bias. This means reliable, early detection of canine gait abnormalities is challenging, which may have detrimental implications for dogs’ welfare. In this paper, we draw from approaches and technologies used in human movement science and describe a system for objectively measuring temporal gait characteristics in dogs (step-time, swing-time, stance-time). Asymmetries and variabilities in these characteristics are of known clinical significance when assessing lameness but presently may only be assessed on coarse scales or under highly instrumented environments. The system consists an inertial measurement unit, containing a 3-axis accelerometer and gyroscope coupled with a standardized walking course. The measurement unit is attached to each leg of the dog under assessment before it is walked around the course. The data by the measurement unit is then processed to identify steps and subsequently, micro-gait characteristics. This method has been tested on a cohort of 19 healthy dogs of various breeds ranging in height from 34.2 cm to 84.9 cm. We report the system as capable of making precise step delineations with detections of initial and final contact times of foot-to-floor to a mean precision of 0.011 s and 0.048 s, respectively. Results are based on analysis of 12,678 foot falls and we report a sensitivity, positive predictive value and F-score of 0.81, 0.83 and 0.82 respectively. To investigate the effect of gait on system performance, the approach was tested in both walking and trotting with no significant performance deviation with 7249 steps reported for a walking gait and 4977 for a trotting gait. The number of steps reported for each leg were approximately equal and this consistency was true in both walking and trotting gaits. In the walking gait 1965, 1790, 1726 and 1768 steps were reported for the front left, front right, hind left and hind right legs respectively. 1361, 1250, 1176 and 1190 steps were reported for each of the four legs in the trotting gait. The proposed system is a pragmatic and precise solution for obtaining objective measurements of canine gait. With further development, it promises potential for a wide range of applications in both research and clinical practice.

Identifying optimal parameters for quantification of changes in pelvic movement symmetry as a response to diagnostic analgesia in the hindlimbs of horses

REASONS FOR PERFORMING STUDY

Subjective evaluation of the response to diagnostic analgesia of hindlimb lameness is influenced by expectation bias. Quantification of pelvic movement with inertial measurement units is possible, but it is unclear which measure of movement symmetry best reflects the changes seen after diagnostic analgesia.

OBJECTIVES

To test our hypothesis that objective measures closely relating to those used for subjective visual lameness scoring (quantifying the difference between sacral upward or downward movement or between movement amplitudes of the left and right tubera coxae) would show the largest and most consistent response.

STUDY DESIGN

Retrospective analysis of subjective and objective clinical lameness data.

METHODS

Thirteen horses with hindlimb lameness underwent visual lameness scoring and independent gait assessment with inertial measurement units. Established objective measures were calculated and changes before/after diagnostic analgesia regressed against the change in lameness grade. Slopes of regression lines were calculated and confidence intervals assessed.

RESULTS

All objective parameters showed variation between horses and across lameness grades. The following 3 measures documented a consistent increase in symmetry for each grade of change in lameness score: difference between sacral displacement minima; upward movement difference; and range of motion difference between the tubera coxae.

CONCLUSIONS

Several pelvic parameters are suitable for objective quantification of changes after diagnostic analgesia in hindlimb-lame horses. A change of 9-13% per lameness grade can be expected. Upward movement of the tubera coxae is the most sensitive objective measure for quantifying a response to diagnostic analgesia. However, when assessed visually, this measure requires simultaneous focusing on pelvic and limb movements. Other parameters that show a similar response might be more easily perceived, requiring only assessment of tubera coxae range of motion or downward displacement of the sacrum without simultaneous focus on limb movement.