Effect of slope in an immersive virtual environment on segmental asymmetry in people with femoral amputation and a microprocessor knee

Abstract

Purpose The continued development of microprocessor-based knee prostheses has improved the independence of people with a femoral amputation in many environments. This study aimed to describe the effect of slopes on kinematic joint variables and segmental asymmetry. Methods Ten individuals with transfemoral amputation fitted with microprocessor-controlled knees performed 5 sessions of treadmill walking at their preferred speed in an immersive virtual environment in 5 incline conditions (Level, 3° and 6° Uphill, and 3° and 6° Downhill). The Human Body Model was used to quantify kinematic joint variables from motion capture system data. The perimeter-to-area method was used to determine the symmetry ratio of the trajectory of the leg segments in the sagittal plane Results There was a significant effect of the Uphill conditions on step length and width on the intact side and on all kinematic joint variables on both sides, although the changes differed according to the phase of the gait cycle. The segmental symmetry index was significantly modified in all slope conditions compared with Level. Conclusions Kinematic joint variables are affected by slopes; the effect was greater for the Uphill than Downhill conditions compared with the Level condition. The perimeter-to-area symmetry ratio differed from the Level condition for all slope conditions. These results indicate that, although microprocessor knees improve the autonomy of prosthesis users, work is required to improve their capacity of adaptation to varied terrain to reduce kinematic asymmetry.