The effects of rehabilitation interventions on hind limb kinematics in a rat model of osteoarthritis

Abstract

Osteoarthritis (OA) is a joint disorder and the knee is the most common large joint affected by it, causing many clinical symptoms in elderly populations. Knee OA has effects on gait patterns, such as a varus rotation at the knee, and these effects can change depending on the severity of the disease. Testing rehabilitation interventions for knee OA can provide an understanding of possible preventative measures. Animal models such as the rat medial meniscal tear (MMT) model have been used in testing interventions. Two interventions, exercise and immobilization, were applied to the MMT injury model. A custom biplanar high-speed video radiography system was chosen to measure the kinematics of the experimental rats and quantify the effects of the interventions. Prior to use, workflows needed to be developed for this system. Additionally, the system needed to be validated and an appropriate analysis technique for the knee OA study needed to be chosen. Through extensive testing, an XMALab workflow reliant on manual recognition of joint centers and an Autoscoper workflow using 3D models of subject-specific bones were developed. The system’s accuracy and precision values were measured using phantoms of known length, yielding a system accuracy of 0.087 mm and precision of 0.073 mm. Qualitative and quantitative differences between the two workflows were compared and the Autoscoper workflow was chosen for the knee OA study for its ability to measure more angles. 14 rats were organized into four experimental groups: a non-intervention, an exercise intervention, an immobilization intervention, and a sham surgery group. The kinematic and spatiotemporal parameters were measured at three gait cycle events. Hip abduction results indicate the non-intervention group developed mild OA, while hip abduction and knee varus rotation results indicate the exercise intervention group developed advanced OA. The immobilization group results were indistinguishable from atrophic changes.