Muscle Knots (Myofascial Trigger Points)

Myofascial trigger points, more commonly known as muscle knots, are stiff, localized spots of exquisite tenderness in a palpable taut band of skeletal muscle. Acute trauma and repetitive microtrauma have been proposed as etiologic factors.

Myofascial trigger points can be classified as active or latent. Active myofascial trigger points are spontaneously painful, tender to palpation, and may be associated with stiffness and restricted range of motion. Latent myofascial trigger points, on the other hand, are not spontaneously painful, but are tender to palpation, and may also be associated with stiffness and restricted range of motion.

Ultrasound findings have been described as ovoid hypoechoic lesions within muscle. Active myofascial trigger points have higher peak systolic velocities and retrograde diastolic flow compared to latent myofascial trigger points on Color Doppler.

References

• Sikdar S, Shah JP, Gebreab T, Yen RH, Gilliams E, Danoff J, Gerber LH. Novel applications of ultrasound technology to visualize and characterize myofascial trigger points and surrounding soft tissue. Arch Phys Med Rehabil. 2009 Nov;90(11):1829-38.