This chapter focuses on the prospects for the use of motion sensors in assessing joint motion and load-related parameters, particularly during walking, in patients with Osteoarthritis (OA), especially knee OA. Many of the issues that remain challenging in the application of motion sensors for OA also apply to the use of such sensors in other musculoskeletal and neurological conditions. Impact forces associated with the initial contact of the foot with the ground at the beginning of stance have also been of interest in OA, although they are not part of routine gait assessments. In addition to the load-related movement parameters that have been of interest in OA such as the knee adduction moment and impact forces, patients with OA also demonstrate some changes in knee joint kinematics, i.e., the position and angular orientation of the knee joint during gait. Impact forces in OA have been investigated with accelerometers.