Differences in gait parameters between healthy subjects and persons with moderate and severe knee osteoarthritis: a result of altered walking speed?

BACKGROUND: While knee osteoarthritis has been shown to affect a multitude of kinematic, kinetic and temporo-spatial gait parameters, few investigations have examined the effect of increasing levels of radiographic osteoarthritis severity on these gait parameters. Fewer still have investigated the effect of walking speed on gait variables in persons with knee osteoarthritis. The objective of this study was to investigate the influence of walking speed on biomechanical variables associated with joint loading in persons with varying severities of medial compartment knee osteoarthritis.

METHODS: Twenty-one persons with moderate osteoarthritis (Kellgren-Lawrence score 2-3) and 13 persons with severe osteoarthritis (Kellgren-Lawrence score of 4) participated. Twenty-two persons without knee pain or radiographic evidence of arthritis comprised a healthy control group. Sagittal plane kinetics, knee adduction moment, sagittal plane knee excursion, ground reaction forces and knee joint reaction forces were calculated from three-dimensional motion analysis at 1.0m/s, self-selected and fastest tolerable walking speeds. Differences were analyzed using multivariate analysis of variance and multivariate analysis of covariance with speed as a covariate.

FINDINGS: Persons with knee osteoarthritis showed significantly lower knee and ankle joint moments, ground reaction forces, knee reaction force and knee excursion when walking at freely chosen speeds. When differences in walking speed were accounted for in the analysis, the only difference found at all conditions was decreased knee joint excursion.

INTERPRETATION: Compared to a healthy control group, persons with knee OA demonstrate differences in joint kinetics and kinematics. Except for knee excursion, these differences in gait parameters appear to be a result of slower freely chosen walking speeds rather than a result of disease progression.