Novel method to measure active myofascial trigger point stiffness using ultrasound imaging.

INTRODUCTION

Myofascial trigger points (MTrPs) are one of the most common and important causes of musculoskeletal pain. Ultrasound is a useful modality in examining musculoskeletal disorders. By applying compressive stress and observing changes in ultrasound images, the elastic modulus (Young's modulus) can be calculated. Our objective was to develop a novel method to distinguish MTrPs from normal tissues.

METHODS

A total of 29 subjects with MTrP in the sternocleidomastoid muscle were assessed. A force gauge was attached to a transducer to obtain stress levels. To obtain strain, images were recorded in both with stress and without stress states. By dividing the stress level by the measured strain, the elastic modulus was determined.

RESULTS

Elastic modulus in MTrPs and the normal part of the muscle were measured to be 13379.57 ± 1069.75Pa and 7078.24 ± 482.92Pa, respectively (P = 0.001). This indicated that MTrPs were stiffer than normal parts of the muscle.

CONCLUSION

This study presents a new method for the quantitative measurement of the elastic modulus of MTrP, thereby distinguishing MTrPs from normal adjacent muscular tissue, with more simplicity and lower cost, compared to other ultrasound methods.