Asymmetry in sit-to-stand movement in patients following transtibial amputation and healthy individuals.

The aim of this study was to analyse the asymmetry of sit-to-stand (STS) movement in a group of subjects following unilateral transtibial amputation (STTA) and a group of healthy subjects (HSs). Experimental measurements investigated standing-up pattern from two seat heights and at three different speeds. Body motion was measured using an optical measuring system with active markers. Floor and seat reaction forces and moments were measured by two force plates and an integrated force-moment sensor. Analysis of ankle, knee, hip and trunk inclination angles shows that STTA perform STS movement with different initial foot placement than HS, resulting in different lower extremity loadings and larger trunk inclination. Asymmetry was defined as the difference between left and right extremity parameters averaged throughout STS movement. A root-mean-square error was used to assess the asymmetry in ground reaction forces and in ankle, knee and hip angles and moments. The influence of different seat heights and velocities on asymmetry was tested using one-way ANOVA. The asymmetry of STTA and HS was affected neither in kinematic nor in kinetic parameters. Performing STS at higher speeds was found to result in decreased trunk flexion. The asymmetry assessment, as determined in this study, can be used in rehabilitation for improving STS strategies or as an evaluation tool for estimating the progress of the rehabilitation process.