Biomechanical Analysis of Stepping Up and Down a One-Step Stair

Introduction
This thesis aims to develop an analysis routine for the tasks of stepping up and down a one-step stair, which can be used in addition to level gait analysis. Furthermore, data from the one-step stair and data from level gait are compared. Materials and Methods Retrospective data collected of 17 healthy adult subjects was used. In addition to level gait, they performed the three tasks stepping up and stepping down a one-step stair with the landing leg as leading leg and stepping down with the non-landing leg as leading leg. Data consisting of kinematics, kinetics and surface electromyography was recorded using a motion capture system and evaluated using MATLAB R2020a. Descriptive statistics were used to visualize data as curves and t-tests (α-level 0.05) were applied for the evaluation of statistical significance.
Results
Maximum knee flexion of the trailing leg during step descent was significantly higher, achieving 97° / 100° (non-landing leg as leading leg / landing leg as leading leg), compared to the leading leg (60° / 62°) and to level gait (59°). Step descent required significantly greater power absorption by the leading leg ankle (-8.66 W/kg / -8.36 W/kg) compared to the trailing leg ankle (-1.82 W/kg / -1.13 W/kg) and level gait (-1.74 W/kg). Meanwhile, step ascent showed significantly higher maximum knee and hip flexion for the leading leg (100° and 83°) compared to the trailing leg (58° and 34°) and to level gait (59° and 33°). Step ascent resulted in significantly higher maximum power generation by the trailing leg ankle (5.42 W/kg) compared to the leading leg ankle (0.27 W/kg) and compared to level gait (3.93 W/kg). In contrast, the maximum power generation by the leading leg’s knee during step ascent (2.43 W/kg) was significantly higher compared to the trailing leg’s knee (0.78 W/kg) and compared to the knee during level gait (1.17 W/kg). The maximum power generation by the hip was significantly higher during level gait (2.05 W/kg) and for the leading leg during step ascent (1.88 W/kg) compared to the trailing leg during step ascent (0.47 W/kg).
Discussion
For stepping down, mostly the knee of the trailing leg was challenged in terms of range of motion. Furthermore, the maximum power that needed to be absorbed by the leading leg ankle was almost five times the maximum value during level walking. Stepping up required wider ranges of motion of the knee and hip of the leading leg, compared to the trailing leg and level gait. Moreover, the power that needed to be generated by the trailing leg ankle was 38 % higher than the power generated during level gait.
Conclusion
The findings suggest that evaluations of the one-step stair tasks are a beneficial addition to the pre-existing level gait analysis routine. They require wider ranges of motion, higher internal moment generation, power absorption and power generation ability compared to level gait. Therefore, the one-step stair tasks highlight the individual patient’s abilities and possible issues become more evident.