Age-related differences in sagittal-plane knee function at heel-strike of walking are increased in osteoarthritic patients

Objective: To compare age-related patterns of gait with patterns associated with knee osteoarthritis (OA), the following hypotheses were tested: (H1) The sagittal-plane knee function during walking is different between younger and older asymptomatic subjects; (H2) The age-related differences in H1 are increased in patients with knee OA. Design: Walking trials were collected for 110 participants (1.70 +/- 0.09 m, 80 +/- 14 kg). There were 29 younger asymptomatic subjects (29 +/- 4 years) and 81 older participants (59 +/- 9 years), that included 27 asymptomatic subjects and 28 and 26 patients with moderate and severe medial knee OA. Discrete variables characterizing sagittal-plane knee function were compared among the four groups using ANOVAs. Results: During the heel-strike portion of the gait cycle at preferred walking speed, the knee was less extended and the Shank less inclined in the three older groups compared to the younger asymptomatic group. There were similar differences between the severe OA group and the older asymptomatic and moderate OA groups. Both OA groups also had the femur less posterior relative to the tibia and smaller extension moment than the younger group. During terminal stance, the severe OA group had the knee less extended and smaller knee extension moment than the younger asymptomatic and older moderate OA groups. Conclusions: The differences in knee function, particularly those during heel-strike which were associated with both age and disease severity, could form a basis for looking at mechanical risk factors for initiation and progression of knee OA on a prospective basis. (C) 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.