Water height modifies forelimb kinematics of horses during water treadmill exercise

Although equine water treadmills (WTs) are increasingly being used for the rehabilitation of equine athletes, the immediate- and short-term effects of this type of exercise on limb movement in the WT and overground are unknown. Therefore, the objective of this study was to evaluate the effects of WT exercise on equine forelimb kinematics on land and under various WT conditions before and after a prolonged period of WT conditioning. External markers were used to collect 2D kinematic data (joint extension, flexion, range of motion (ROM), elevation; stride mechanics) at 120 frames/s. Thirteen mixed breed, English performance horses were filmed under three test conditions: (1) horses walked on sand; (2) horses walked on a WT (water heights: dry, carpus, stifle); (3) horses walked on sand immediately following a WT session. Walking speeds during testing varied between horses, ranging from 1.3-1.5 m/s, but were held constant for each individual horse for all tests on both days. Testing occurred on days 1 and 10, with horses being trained on the WT for days 2 through 8 (28 min/day). Comparisons were made using linear mixed effects models. Carpal ROM and elbow ROM were greater when horses were walked in water, compared to without water (dry treadmill) and overground (P<0.0001 for all). This increased ROM was achieved primarily via an increase in joint flexion. With the addition of water, stride length increased and stride frequency decreased, accompanied by an increased percentage duration of swing phase. No effects of conditioning on gait mechanics were observed overground. Therefore, WT exercise may be meaningful for physical rehabilitation through increased joint flexion and ROM observed.

Analysis of change in gait in the ovine stifle: normal, injured, and anterior cruciate ligament reconstructed

Background

Many patients who undergo anterior cruciate ligament (ACL) reconstructive surgery develop post-traumatic osteoarthritis (PTOA). ACL reconstructive surgery may not fully restore pre-injury joint biomechanics, thereby resulting in further joint damage and contributing to the development of PTOA. In an ovine model of idealized ACL reconstruction (ACL-R), it has been shown that signs of PTOA develop within surgical joints by 20 weeks post-surgery. The aim of the present study was to investigate whether altered kinematics contribute to early PTOA development within ACL-R joints of the ovine injury model by comparing the gait of these surgical animals to the gait of a stable normal control group, and an unstable injury group in which the ACL and medial collateral ligament (MCL) had been transected.

Methods

Fifteen skeletally mature female sheep were allocated evenly into 3 treatment groups: normal control, ACL-R, and ACL/MCL Tx (each group n = 5). Each animal’s gait was recorded at baseline, 4 weeks post injury, and 20 weeks post injury. Principal component analysis (PCA) was used to identify the kinematic patterns that may be discriminant between treatment groups. Results from previous studies were referenced to present the amount of gross PTOA-like changes that occurred in the joints.

Results

ACL-R and ACL/MCL transected (Tx) animals developed a similar amount of early PTOA-like changes within the surgical joints, but differed significantly in the amount of kinematic change present at 20 weeks post-surgery. We showed that the stifle joint kinematics of ACL/MCL Tx differed significantly from those of CTRL and the majority of ACL-R animals, while no significant differences in joint kinematic changes were found between ACL-R and CTRL animals.

Conclusions

These results suggest that the early PTOA-like changes reported in the ACL-R model cannot be attributed exclusively to post-surgical kinematic changes, and therefore biologic components in the post-injury environment must be contributing significantly to PTOA development.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1576-3) contains supplementary material, which is available to authorized users.