A new design of cervical traction modality with closed loop traction weight control based on electromyographic (EMG) biofeedback was developed. It consists of the development of a high signal-to-noise ratio EMG scanner, on-line self-adjusted traction weight controller, computer interface hardware, and closed loop biofeedback control software. Six healthy, young adults received conventional cervical traction to establish basic information of cervical EMG activities. Twenty-four patients with cervical radiculopathy were randomly divided into two groups for clinical assessment by conventional and new EMG biofeedback traction modality.
The average electromyographic activity in healthy subjects ranged from 2.41 to 3.49 μV, whereas EMG activity in patients with neck pain ranged from 4.75 to 6.97 μV. There was a significant decrease of EMG activity during the whole traction phase, especially at pull phase in healthy subjects, but it was not as significant in patients with cervical radiculopathy. There was no significant change of myoelectric activity in the paraspinal muscles at vertebral levels C1-2, C3-4, and C5-6.
Comparison of the average EMG activity of the paraspinal C-5 muscle in different phases of cervical traction showed a more significant decrease of EMG activity during the pull phase of traction as well as after traction in the high muscle tension group (with EMG activity above 5 μV), especially with the biofeedback traction modality. The raised traction force from start to optimum was shortened from 4 to 2 wk to achieve the same effective outcome by biofeedback as conventional traction modality.