Difference in knee rotation between total and unicompartmental knee arthroplasties during stair climbing.

Abstract

PURPOSE: The purpose of this study was to compare knee kinematics during stair

walking in patients with simultaneous total knee arthroplasty (TKA) and

unicompartmental knee arthroplasties (UKA). It was hypothesized that UKA would

reproduce more normalized knee kinematics than TKA during stair ascent and

descent. METHODS: Six patients who received UKA in one knee and TKA in the other

knee were included in the study. For this study, a four-step staircase was

assembled with two force platforms being positioned at the centre of the second

and third steps. Each patient was attached with 16 reflective markers at both

lower extremities and was asked to perform five roundtrip trials of stair

climbing. Kinematic parameters including stance duration, knee angle, vertical

ground reaction force (GRF), joint reaction force, and moments were obtained and

analysed using a10-camera motion system (VICON, Oxford, UK). Nonparametric

Friedman test was used to compare the results between two arthroplasty methods

and between stair ascent and descent. RESULTS: Compared to TKA, UKA knees

exhibited significantly greater degree of rotation in transverse planes (5.0

degrees during ascent and 6.0 degrees during descent on average), but showed no

difference in terms of the other parameters. When comparing the results during

stair ascent with descent, overall greater knee angle, vertical GRF, joint

reaction force, and moment were observed during stair descent. CONCLUSIONS: Both

UKA and TKA knees have shown overall similar knee kinematics, though UKA knee may

allow greater degree of rotation freedom, which resembles normal knee kinematics

during stair walking.