This study investigated the tibiofemoral joint (TFJ) forces and supporting muscle forces displayed by knee osteoarthritis (OA) patients during stair ascent, and if these forces were influenced by the presence of pain. Fifteen knee OA patients partitioned into two groups based on pain experienced during stair ascent trails using a Visual Analogue Scale (VAS) (OA-pain = 10; OA-no pain = 5) and 14 healthy aged-matched controls took part in this study. Kinematic and kinetic data were collected during three stair ascent trials, which provided the inputs for the musculoskeletal model FreeBody. TFJ contact forces and muscles forces were predicted by the model at early, mid-and late stance. These variables were compared between groups using a one-way analysis of variance. The results show the OA-pain (P < .05; d = 2.4) and OA-no pain (P < .05; d = 1.1) groups displayed reduced medial TFJ contact forces and altered muscle forces in comparison to healthy controls during early stance. This suggests pain and the anticipation of pain results in knee OA patients deliberately offloading the front limb during stair ascent, which alters supporting muscle forces. This study provides valuable information on knee OA mechanics during stair ascent for clinicians developing rehabilitation programs. K E Y W O R D S muscle forces, musculoskeletal model, osteoarthritis, stair ascent, tibiofemoral joint forces 1 INTRODUCTION Stair ascent is a challenging everyday activity for those who suffer with knee osteoarthritis (OA). Many studies have reported stair ascent being one of the main activities which elicits knee pain for those with knee OA, 1,2 greatly affecting quality of life. 3 The increased susceptibility of knee pain during stair ascent likely comes from weight-bearing at higher knee flexion angles. 4 Because of this, knee OA patients have been reported to compensate while walking upstairs to offload the OA knee as a strategy to avoid pain. 5 Asay et al 4 reported that during stair ascent those with knee OA increased trunk flexion angle during the weight-acceptance phase of stance to reduce the quadriceps moment in comparison to healthy controls. Further, Meireles et al 6 found that, in comparison to healthy controls, knee OA patients altered their stair ascent This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

No abstract

No abstract