Whole-body angular momentum during stair ascent and descent in individuals with and without knee osteoarthritis

Abstract

Given the higher fall risk and the fatal sequelae of falls on stairs, it is worthwhile to investigate the mechanism of dynamic balance control in individuals with knee osteoarthritis during stair negotiation. Whole-body angular momentum (<jats:inline-formula><jats:tex-math>$$\:\overrightarrow{H}$$</jats:tex-math></jats:inline-formula>) is widely used as a surrogate to reflect dynamic balance and failure to constrain <jats:inline-formula><jats:tex-math>$$\:\overrightarrow{H}$$</jats:tex-math></jats:inline-formula> may increase the fall risk. This study aimed to compare the range of <jats:inline-formula><jats:tex-math>$$\:\overrightarrow{H}$$</jats:tex-math></jats:inline-formula> between people with and without knee osteoarthritis during stair ascent and descent. Seven participants with symptomatic knee osteoarthritis and eight asymptomatic controls were instructed to ascend and descend an instrumented staircase at a fixed cadence. Kinematic and kinetic data were collected and range of <jats:inline-formula><jats:tex-math>$$\:\overrightarrow{H}$$</jats:tex-math></jats:inline-formula> in sagittal, frontal, and transverse planes were computed. The knee osteoarthritis group exhibited greater <jats:inline-formula><jats:tex-math>$$\:\overrightarrow{H}$$</jats:tex-math></jats:inline-formula> in the sagittal plane during both stair ascent (<jats:italic>P</jats:italic> = 0.005, Cohen’s d = 1.7) and descent (<jats:italic>P</jats:italic> = 0.020, Cohen’s d = 1.3) as well as in the transverse plane during stair descent (<jats:italic>P</jats:italic> = 0.015, Cohen’s d = 1.3), than the control group. These observations may be explained by greater hip flexion (<jats:italic>P</jats:italic> < 0.05, Cohen’s d > 1.12<jats:italic>)</jats:italic> and reduced knee flexion moment (<jats:italic>P</jats:italic> < 0.001, Cohen’s d<-2.77) during stair ascent and descent, and decreased foot progression angle (<jats:italic>P</jats:italic> = 0.038, Cohen’s d=-1.2) during stair descent, in individuals with knee osteoarthritis. No significant difference in frontal plane <jats:inline-formula><jats:tex-math>$$\:\overrightarrow{H}$$</jats:tex-math></jats:inline-formula> was found between the two groups (<jats:italic>P</jats:italic> > 0.05). Individuals with knee osteoarthritis exhibited greater whole-body angular momentum during stair negotiation when compared to asymptomatic controls. Our findings may provide mechanistic rationale for a greater fall risk among people with knee osteoarthritis.