Introduction

Joint diseases are an umbrella term used to describe several diagnostic categories of which rheumatoid arthritis (RA) and osteoarthritis (OA) are among the most common. Approximately 0.5–1% of the population of North America is diagnosed with RA and the prevalence worldwide is slightly lower . RA and OA are major causes of work disability, diminished function and loss of independence. Physical therapy is among the first line of treatment options in OA and RA, yet, there is no agreement about which physical therapy training programmes are most effective and how these interventions impact the biomechanics of affected joints . Medical treatments target pain and inflammation to improve joint function. However, severe pain associated with structural joint changes may require surgical interventions such as osteotomies, arthrodesis or joint replacement . In 2003, 202,500 primary total hip replacements (THRs) and 402,100 primary total knee replacements (TKRs) were performed in the United States . The worldwide prevalence of total hip and knee replacements has escalated dramatically in persons with OA while surgery is decreasing in RA due to the implementation of biologic therapies . The costs of medical therapy, conservative treatment and associated indirect costs such as disability combine to produce high societal costs .

While pathophysiology differs between these two diseases, both result in musculoskeletal impairments, reduced aerobic capacity, pain, limitations in function and, in some cases, joint deformity. This could lead to alterations in gait such as reduced walking speed . This chapter describes gait analysis, with an emphasis on three-dimensional (3D) gait analysis with respect to joint rotations (kinematics) and joint reactions (kinetics). This chapter also reviews common gait deviations in adults with RA and OA and describes changes in gait following surgical and non-surgical interventions.