Quantitative evaluation indices for hemiplegic gait characteristics based on power spectrum density for time history signals measured by accelerometers attached to the lumbar part

Abstract

The purpose of this study is to propose the quantitative evaluation indices for the hemiplegic gait characteristics by accelerometers attached to the right and left lumbar part. Subjects are 16 patients with hemiplegia, 8 males and 8 females whose ages are from 46 to 83 years. Twenty-six healthy adults also participated as a control group. An FFT analysis for both hemiplegic gait and healthy normal walking test results is carried out paying attention to the component with frequency of 0.5fw (half frequency component of the gait cycle fw) . Based on these analytical results, it is revealed that the component with frequency of 0.5fw in the fore and after direction is obviously prominent for the hemiplegic gait compared with measured values of healthy normal gait. The parameter PR is defined as the power spectrum ratio of 0.5fw to fw component. The relationship between gait stage (GS) and PR is investigated for both subjects of hemiplegic patients and healthy adults. Dynamic load factor (DLF) corresponding to the vertical walking force and lateral displacement of the waist are also calculated using power spectrum density for time history signals measured by the accelerometers. This led to the conclusion that the parameter PR in the fore and after direction, DLF in the vertical direction and lateral displacement of the waist are the useful evaluation indices for the hemiplegic gait analysis from the viewpoint of rehabilitation medicine.

Keywords

• hemiplegic gait
• quantitative evaluation index
• accelerometer
• fft analysis
• rehabilitation medicine