Knee biomechanics of alternate stair ambulation patterns.

PURPOSE This study compared the kinematics and kinetics of the knee joint during traditional step-over-step (SOS) and compensatory step-by-step lead-leg (SBSL) and trail-leg (SBST) stair ambulation patterns. METHODS Seventeen (M:9) healthy adults completed five trials of ascent and descent using three different stepping patterns: 1) SBSL, 2) SBST, and 3) SOS. Kinematics and kinetics were collected with an optoelectronic motion-tracking system and a force plate embedded into a four-step staircase. An inverse-dynamics link-segment model (QGAIT system) was used to calculate the net joint kinetics. RESULTS During stair ascent, different peak anteroposterior (AP) forces were observed across all three stepping patterns (SOS > SBSL > SBST, P < 0.05). During ascent, the flexion moments of SOS (0.96 N x m x kg(-1)) and SBSL (0.97 N x m x kg(-1)) patterns were similar and much larger than the SBST moments (0.14 N x m x kg(-1)). In the descent conditions, the initial AP peak force for SOS was larger than that of SBSL and SBST. However, the second peak force for SOS (4.92 N x kg(-1)) and SBST (4.68 N x kg(-1)) were larger than SBSL (1.57 N x kg(-1)). During descent, the initial peak flexion moment for the SOS pattern was larger than SBSL and SBST, whereas during the second peak, SOS (1.05 N x m x kg(-1)) and SBST (1.11 N x m x kg(-)) were no different and larger than SBSL (0.18 N x m x kg(-1)). CONCLUSION Overall, SBSL during ascent and SBST during descent had the highest loads. These results increase our understanding of alternative stepping patterns and have important clinical (reduction of loading on injured/diseased leg) and rehabilitation implications.