- J S Petrofsky: Department of Physical Therapy, Loma Linda University, School of Allied Health, California, USA. jerry-petrofsky@sahp.llu.edu
A microprocessor-based gait analysis system is described that uses two electromyogram (EMG) amplifiers, two foot switches and an audio feedback device to allow the retraining of one type of improper gait, where the hip abductors (gluteus medius muscles) are weak on one side of the body, causing the opposite hip to drop during the swing phase of gait (Trendelenburg gait). As the abnormality is strictly on one side of the body in most people, the circuitry is minimised, as gait can be analysed by only comparing muscle activity in the affected gluteus medius muscle with that in the unaffected gluteus medius muscle, through the EMG. Two foot contact switches are used to help assess timing of the step cycle. If gait is different on the two sides of the body, an audio cue directs the patient to correct the abnormality by increasing activity on the affected side. The device is tested on five patients. Trendelenburg gait is reduced by an average of 29 degrees through the use of the device. The average stride length at the beginning of the study is 0.32 +/- 0.3 m. By the end of the study, the stride length is increased to 0.45 +/- 0.2 m for the entire group of five subjects. The speed of gait has increased from 1.6 +/- 0.4 kmh(-1) to 3.1 +/- 0.5km h(-1).