Myofascial Trigger Point (MTrP) Size and Elasticity Properties Can Be Used to Differentiate Active and Latent MTrPs in Lower Back Skeletal Muscle

Myofascial Trigger Points (MTrPs) are localized contraction knots that develop after muscle overuse or an acute trauma. Significant work has been done to understand, diagnose, and treat MTrPs in order to improve patients suffering from their effects. However, effective non-invasive diagnostic tools are still a missing gap in both understanding and treating MTrPs. Effective treatments for patients suffering from MTrP mediated pain require a means to measure MTrP properties quantitatively and diagnostically both prior to and during intervention. Further, quantitative measurements of MTrPs are often limited by the availability of equipment and training. Here we develop ultrasound (US) based diagnostic metrics that clinicians can use during patient diagnosis and treatment. We highlight the advantages and limitations of previous US-based approaches that utilize elasticity theory. We show how US-based measurements can distinguish Active from Latent MTrPs. We demonstrate that Active MTrPs tend to be smaller, stiffer, and deeper in the muscle tissue. We provide evidence that more than one MTrP within a single US-image field increases the stiffness of neighboring MTrPs. Finally, we highlight a combination of metrics (depth, thickness, and stiffness) that can be used to assess individual MTrPs in combination with standard clinical assessments.