Assessment of waveform similarity in electromyographical clinical gait data: the linear fit method

The assessment of waveform similarity is a crucial issue in gait analysis for the comparison of electromyography (EMG) and kinematic patterns with reference data. A typical scenario is in fact the comparison of a patient’s EMG pattern with a relevant physiological pattern. Many methods have been proposed for a quantitative comparison of the two patterns, suggesting the absence of a gold standard. A recently proposed method for comparing kinematic patterns is the linear fit method (LFM). This study aims at testing the applicability of this method on data of EMG. The validity of LFM was tested in terms of appropriateness, sensitivity, specificity, and reliability, by comparing 20 EMG pathological gait patterns (obtained by a group of patients with Parkinson’s Disease) and 20 EMG physiological gait patterns (obtained by healthy subjects). When gastrocnemious and tibialis anterior EMG activity was analyzed, the appropriateness of LFM in discriminating pathological patterns resulted of 97.5%, with a sensitivity of 95% and a specificity of 100%. The reliability was good for 2 out of 3 parameters in each group of subjects. The LFM resulted a simple method suitable for analysing the waveform similarity in gait EMG clinical analysis.