Comparing different data collection and analysis techniques for quantifying healthy knee joint function during stair ascent and descent.

There is currently no standard data collection or analysis method for the assessment of stair gait using motion analysis. This makes the comparison of results from different studies difficult. It is important to gain an appreciation of the discrepancies in kinematic and kinetic information generated by employing different computational approaches, as these differences may be critical in cases where methodologies were to change over a long-term study. This study explores the effect of using different methodologies for the assessment of non-pathological knee function of ten subjects during stair ascent and descent. Two methods of computing knee kinematics were compared: (a) using in-house software and a pointer method of anatomical calibration and (b) using commercial software, Visual3D (C-motion, Inc.) and skin-mounted markers. Significant differences were found between the two methods when calculating a frontal plane range of motion (p < 0.05). Three methods of computing knee moments were compared. Knee moments computed using the inverse dynamic analysis (IDA) approach of Visual3D (C-motion, Inc.) were significantly different (p < 0.05) to those calculated using in-house IDA software that ignores the foot and ankle and to those computed using a vector cross-product approach. This study highlights the implications of comparing data generated from different collection and analysis methods.