Osteoarthritis (OA) is a chronic joint disease, the most common musculoskeletal complaint worldwide, and is associated with significant health and welfare costs. Previous research indicates that co-activation of muscles may lead to the onset of knee OA. Therefore, investigation of muscle recruitment patterns and neuromuscular efficiency in healthy individuals compared to patients with knee OA in simple closed chain exercises using electromyography (EMG), motion analysis system and force plates may lead to a better understanding of how knee OA develops (6). The present studies chosen were in the frontal plane while performing lateral step up and step down tasks for a 4 inch and 8 inch step height. In the stepping tasks it was discovered that there is a greater magnitude EMG and ground reaction force (GRF) for 8 inch rather than a 4 inch step. Additionally, a higher activation of gluteus medius, gluteus maximus and quadriceps muscles (rectus femoris , vastus lateralis , vastus medius) was revealed in both the stepping tasks.

Listed In: Biomechanics, Orthopedic Research, Physical Therapy

Despite its use in biomechanics research, there exists no standardized method for implementing a residual analysis to define the optimum cutoff frequency (OCF) of low-pass digital filters. Given the potential for this processing to have an impact on results, an objective routine is necessary for consistent data treatment between investigations and laboratories. Therefore, the goal of this study was to formalize an objective routine to implement a residual analysis, and examine whether it could be applied to kinetic signals. METHODS - Part I: The following parameters were hypothesized to effect the OCF determined through residual analysis: (i) linearity criterion magnitude, (ii) frequency axis resolution and (iii) range of cutoff frequencies included in the analysis. Part II: Two existing datasets were used to evaluate the objective routine that was developed. For each study, four dependent measures were calculated from ground reaction force data, including: (i) peak force, (ii) time to peak force, (iii) rate of force development and (iv) impulse. To examine the influence of using a digital Butterworth filter with OCF, each measure was compared to both the raw signal and a commonly applied cutoff frequency of 20 Hz. RESULTS - The objective routine developed was found to be most sensitive to the range of frequencies included in the analysis. In Part II, both the F-20 and OCF filtering conditions had minimal impact on all force-time dependent measures, except for rate of force development. IMPLICATIONS - Residual analysis may not be appropriate for selecting an OCF when filtering kinetic signals.
Listed In: Biomechanical Engineering, Biomechanics, Gait, Orthopedic Research, Sports Science