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SummaryComputer aided kinematic and synchronized force plate gait analysis were used to characterize joint movement in 14 large mixed breed dogs at a trot. A curvilinear relationship of joint angle to time was described, for three forelimb and three hindlimb joints. Two peaks of maximum extension, one preceding the onset and at the end of stance phase were observed for the femorotibial, tarsus and cubital joints. The carpus, scapulohumeral and coxofemoral joint exhibited one peak of maximum extension. The variance in joint angle measurement was calculated for repeated trials for a given dog and for differences between dogs using a 2-factor repeated measures ANOVA. The mean variance for all joints except the carpal joint for trial repetition was 12.6 (degrees)2 (range, 2.6-23.9) and for differences between dogs 6.2 (degrees)2 (range, 1.0-11.3). The carpal joint exhibited greater variation with a mean variance, attributable to trial repetition, of 42.5 (degrees)2 (range, 39.4-44.3) and a variance between dogs of 52.4 (degrees)2 (range, 18.5-89.4).The results obtained would suggest that computer assisted kinematics is an accurate means of assessing joint angle movement in large mixed breed dogs with a low level of variance attributable to trial repetition and to differences between dogs, with the exception of the carpal joint. The sample of mixed breed dogs in this study is similar to dogs that would be seen in a clinical sample population. Our results suggest that computer assisted kinematics could be an important tool in providing objective information on gait, in clinical and research studies, using mixed breed dogs.This study describes the trot in 14 large mixed breed dogs using computer aided kinematic and force plate gait analysis techniques. Variances in fore and hindlimb joint angle measurements were deter-mined, for a given dog, by repeated trials and for differences between dogs. The measured variances were low in all joints except the corpus, despite diverse dog conformation in the study.

Patients with osteoarthritis (OA) primarily seek treatment due to pain and disability, yet the primary endpoints for rodent OA models tend to be histological measures of joint destruction. The discrepancy between clinical and preclinical evaluations is problematic, given that radiographic evidence of OA in humans does not always correlate to the severity of patient-reported symptoms. Recent advances in behavioral analyses have provided new methods to evaluate disease sequelae in rodents. Of particular relevance to rodent OA models are methods to assess rodent gait. While obvious differences exist between quadrupedal and bipedal gait sequences, the gait abnormalities seen in humans and in rodent OA models reflect similar compensatory behaviors that protect an injured limb from loading. The purpose of this review is to describe these compensations and current methods used to assess rodent gait characteristics, while detailing important considerations for the selection of gait analysis methods in rodent OA models.

Gait analysis is a useful tool to understand behavioral changes in preclinical arthritis models. While observational scoring and spatiotemporal gait parameters are the most widely performed gait analyses in rodents, commercially available systems can now provide quantitative assessments of spatiotemporal patterns. However, inconsistencies remain between testing platforms, and laboratories often select different gait pattern descriptors to report in the literature. Rodent gait can also be described through kinetic and kinematic analyses, but systems to analyze rodent kinetics and kinematics are typically custom made and often require sensitive, custom equipment. While the use of rodent gait analysis rapidly expands, it is important to remember that, while rodent gait analysis is a relatively modern behavioral assay, the study of quadrupedal gait is not new. Nearly all gait parameters are correlated, and a collection of gait parameters is needed to understand a compensatory gait pattern used by the animal. As such, a change in a single gait parameter is unlikely to tell the full biomechanical story; and to effectively use gait analysis, one must consider how multiple different parameters contribute to an altered gait pattern. The goal of this article is to review rodent gait analysis techniques and provide recommendations on how to use these technologies in rodent arthritis models, including discussions on the strengths and limitations of observational scoring, spatiotemporal, kinetic, and kinematic measures. Recognizing rodent gait analysis is an evolving tool, we also provide technical recommendations we hope will improve the utility of these analyses in the future.

IntroductionOsteoarthritis (OA) results in pain and disability; however, preclinical OA models often focus on joint-level changes. Gait analysis is one method used to evaluate both preclinical OA models and OA patients. The objective of this study is to describe spatiotemporal and ground reaction force changes in a rat medial meniscus transection (MMT) model of knee OA and to compare these gait measures with assays of weight bearing and tactile allodynia.MethodsSixteen rats were used in the study. The medial collateral ligament (MCL) was transected in twelve Lewis rats (male, 200 to 250 g); in six rats, the medial meniscus was transected, and the remaining six rats served as sham controls. The remaining four rats served as naïve controls. Gait, weight-bearing as measured by an incapacitance meter, and tactile allodynia were assessed on postoperative days 9 to 24. On day 28, knee joints were collected for histology. Cytokine concentrations in the serum were assessed with a 10-plex cytokine panel.ResultsWeight bearing was not affected by sham or MMT surgery; however, the MMT group had decreased mechanical paw-withdrawal thresholds in the operated limb relative to the contralateral limb (P = 0.017). The gait of the MMT group became increasingly asymmetric from postoperative days 9 to 24 (P = 0.020); moreover, MMT animals tended to spend more time on their contralateral limb than their operated limb while walking (P < 0.1). Ground reaction forces confirmed temporal shifts in symmetry and stance time, as the MMT group had lower vertical and propulsive ground reaction forces in their operated limb relative to the contralateral limb, naïve, and sham controls (P < 0.05). Levels of interleukin 6 in the MMT group tended to be higher than naïve controls (P = 0.072). Histology confirmed increased cartilage damage in the MMT group, consistent with OA initiation. Post hoc analysis revealed that gait symmetry, stance time imbalance, peak propulsive force, and serum interleukin 6 concentrations had significant correlations to the severity of cartilage lesion formation.ConclusionThese data indicate significant gait compensations were present in the MMT group relative to medial collateral ligament (MCL) injury (sham) alone and naïve controls. Moreover, these data suggest that gait compensations are likely driven by meniscal instability and/or cartilage damage, and not by MCL injury alone.