Quantitative functional assessment of walking in the patient with severe hip osteoarthritis

Introduction Osteoarthritis (OA) is the most common degenerative joint disorder, accounting for significant disability and health care expenditure. The gait of patients with hip OA is affected by pain, stiffness and lameness, reducing the joint mobility, this gradually decreasing autonomy and quality of life. Quantifiable outcome measures are necessary to assess the benefits of treatment on gait in patient with severe hip OA. Analysis of gait impairment is better approached by the study of mechanical and energetic measurements considered to be summary indicators of the gait mechanism [1]. By studying these variables it is possible to gain further insight into mechanisms responsible for abnormal gait and whether or not the normal walking mechanism is preserved in OA patients. The aim of this study was to show the interest of a functional assessment of walking and more precisely on the mechanical muscular work and energy cost during gait in patients with severe hip osteoarthritis. Material and Methods Walking of thirty OA patients was assessed by a three-dimensional (3D) motion system (Elite, BTSbioengineering, Italy), including simultaneous mechanical and energetic measurements. Data were recorded on a force measuring motor-driven treadmill (Mercury LTmed, HP Cosmos, Germany). The external muscular work was computed from 3D force signal recorded by strain gauges [2]. The internal work was computed from kinematic data [2]. The metabolic cost of walking was determined by the subject’s oxygen consumption measured with an ergospirometer (Medisoft, Belgium). Results Patients showed an increase of external mechanical work associated to altered pendulum mechanism as compared to healthy subjects. However, the overall energy cost was normal. Discussion and Conclusion Biomechanical analysis of gait provides objective evidence of the altered mechanism of locomotion in patients with severe hip osteoarthritis. These measurements may be relevant to assess impairment in ambulatory patients and may be also useful in clinical research to improve knowledge of the effect of treatment