Impact of step width on trunk motion and gait adaptation in elderly women with knee osteoarthritis.

Background: Step width during walking can provide important information about aging and pathology. Although knee osteoarthritis (OA) is a common disease in elderly women, little is known about how different step widths influence gait parameters in patients with knee OA.

Objective: To address this, we investigated the differences between narrower and wider step width on the center of mass (CoM) and gait biomechanics of elderly women with knee OA.

Methods: Gait and CoM data were measured using a three-dimensional motion capture system and anthropometric data were acquired via standing full-limb radiography. Thirty elderly women with knee OA were divided into two groups depending on the average step width value (0.16 m). Specifically, the narrower step width group included those with a below average step width (n= 15) and the wider step width group included those with an above average step width (n= 15). The differences between the two groups were analyzed using an independentt-test.

Results: Walking speed, step length, knee and ankle sagittal excursion, and medial-lateral CoM range were significantly greater in the narrower group. In contrast, the medial-lateral CoM velocity, medial-lateral ground reaction force (GRF), and foot progression angle were significantly higher in wider group. The external knee adduction moment, vertical GRF, and vertical CoM did not differ between the groups.

Conclusions: Our data indicate that step width in women with knee OA is associated with trunk motion and gait patterns. People with a narrower step might improve their gait function by increasing trunk frontal control to maintain gait stability. In contrast, in those with a wider step, greater toe out angle and shorter step length might be a compensatory adaptation to reduce knee loading.