The effect of bilateral knee osteoarthritis on gait symmetry during walking on different heights of staircases.

Knee osteoarthritis (KOA) can lead to asymmetric gait, which is one of many potential risk factors for falls. Particularly, those working in industrial environments are often required to navigate stairs, yet there is limited understanding of how KOA impacts gait symmetry during stair negotiation. The goal of this study was to find out how negotiating stairs affects the balance of walking in people with bilateral KOA by measuring ground reaction forces (GRFs). Fifteen patients with bilateral KOA and fifteen healthy controls were recruited for the study. Participants were instructed to perform level-ground walking, as well as ascending and descending stairs at two different heights (180 mm and 210 mm). GRF symmetry was assessed using the symmetric index, cross-correlation (Xcorr), mean square error, root mean square error, maximum error, and mutual information (MI) methods. A significant interaction between the effect of staircase height and the effect of KOA was found in Xcorr in the anterior-posterior (AP, p < 0.001), medial-lateral (ML, p = 0.044) directions, and MI (AP, p < 0.001). Xcorr and MI were significantly smaller in KOA than in controls while ascending and descending the 210 mm staircase, indicating a significantly asymmetric gait in AP direction when descending or ascending stairs. However, no significant interactions were found when using other measures. The conclusions were that 1) reducing the height of the staircase may help KOA patients achieve better symmetry and lower the risk of falls in the industrial environment, and 2) the XCorr was suggested to measure the gait symmetry.