Gait after unilateral total knee arthroplasty: frontal plane analysis.

After unilateral total knee arthroplasty (TKA), osteoarthritis (OA) in the non-operated knee often progresses. The altered gait mechanics exhibited by patients after TKA increase the loading on the non-operated knee and predispose it to disease progression. Therefore, our objective was to examine the potentially detrimental changes in frontal plane kinetics and kinematics during walking in patients who underwent unilateral TKA. Thirty-one subjects 6 months after TKA, 24 subjects 1 year after unilateral TKA, and 20 control subjects were recruited. All subjects underwent 3D gait analysis. In the TKA groups, the non-operated knee had a higher adduction angle and higher dynamic loading, knee adduction moment and impulse, compared to the operated knee. This increased loading may be an underlying reason for OA progression in the non-operated knee. Measures of loading in the control knee did not differ from that of the non-operated knee in the TKA group, but the TKA group walked with shorter step length. While the non-operated knee loading was not different from controls, there may be greater risk of cumulative loading in the non-operated knee of the TKA group given the shorter step length.