Asymmetry of gait initiation in patients with unilateral knee arthritis.

Abstract

To identify how patients with knee arthritis modify their equilibrium and movement control strategies during gait initiation. Observational study. University hospital movement analysis laboratory. Twelve patients with unilateral knee arthritis and 12 healthy control subjects. Durations of the phases of gait initiation (ie, postural, monopodal, and double-support phases), center-of-pressure displacements, ground reaction forces, pelvic velocity, step length, and knee range of motion were measured using a movement analysis system and force plates. Gait initiation was slower in patients than in controls no matter which leg was the supporting one. In patients, the durations of the postural and the monopodal phases were modified in an asymmetrical way according to the leg used as the supporting one. The postural phase was lengthened and the monopodal phase was shortened when the affected leg was the supporting one. Opposite effects were observed when the sound leg was supporting. Step length, knee range of motion, and maximal pelvic velocity were reduced in patients whatever the side of the supporting leg. Gait initiation is an asymmetrical process in unilateral knee arthritis patients, who develop adaptive posturomotor strategies that shorten the monopodal phase on the affected leg.