Matt Clark
February 15, 2023

How Can the Pact Sense Measures Muscle Knots:

The Pact Sense classifies the mechanical properties of any soft tissue measured at five different depths. The measurement taken at multiple depths increases the sensitivity of the device to accurately distinguish between different points in the same tissue regions (see Muscle Characterization Using System Identification) . Therefore, in the case of knots, we can utilize the Pact Sense to determine the stark differences in the mechanical properties of knotted tissue and healthy, pliable tissue. 

The Pact Sense classifies soft tissue using five different parameters; stiffness, damping, stiffness slope, damping slope, & inertia (see Scanner Parameters Overview). In the case of a knot, it is hypothesized that the stiffness & damping measured will be higher at the knot site, while surrounding tissue will show lower stiffness & damping values. To test this hypothesis we designed a 2-part mini study. First, we conducted a control experiment to determine the Pact Sense’s capabilities to distinguish a “knot” from its surrounding material. That was followed by an assessment of a real patient with a verified muscle knot located on their right upper trapezius muscle.

Case Study: Upper Right Trapezius Muscle Knot

A patient diagnosed with a muscle knot in their upper right trapezius muscle was asked to come into the Pact HQ to assess the mechanical properties of their knot and surrounding tissue of the trap muscle. The site of the knot was identified using the Butterfly IQ+ Ultrasound device and marked on the skin surface with a body marker. Then, two additional marks were placed 20 mm below the site of the knot and 20 mm above the site of the knot. Two sets of Pact Sense measurements were collected on each test point, while the patient laid in the prone position. The purpose of these measurements were to identify real, applicable differences in mechanical properties of a knot and its surrounding tissue.

Figure 1. A) Ultrasound cross section of the site 20 mm below the muscle knot. B) The site of the muscle knot identified under ultrasound, indicated by thickened fascial tissue. C) Ultrasound cross section of the site 20 mm above the muscle knot.

Pact Sense Results:

Following measurements on the patient, there were clear differences in damping slope, damping, & inertia detected by the Pact Sense on the site of the knot. The mean damping slope below the knot was 1930 Ns/m2 and 2614 Ns/m2 above the knot, while the mean damping slope directly over the knot was 6712 Ns/m2. Furthermore, the mean damping below the knot was 8.2 Ns/m and 9.4 Ns/m above the knot, while the mean damping over the knot was 11.4 Ns/m. Finally, the average inertia below the knot was 0.023 kg and 0.021 kg above the knot, while the mean inertia directly over the knot was 0.016 kg. Therefore, damping and damping slope were found to be elevated over the site of the muscle knot and inertia decreased on the site of the knot.

Figure 2. Damping Slope, Damping, & Mass below the knot, above the knot, and directly over the knot

What does this mean: 

In practical applications of the Pact Sense, the device shows great sensitivity to the difference in mechanical properties of a knot from its surrounding tissue. Significant differences in this individual's damping slope, damping, and inertia can be leveraged to track the knot’s change over time as it is treated. With the goal to have more uniform damping slope, damping, and inertia across the muscle tissue, this individual has a clear understanding to decrease damping slope and damping, while raising inertia. Specific recoveries and treatments can be monitored to show the effectiveness of returning the knotted tissue to a healthy state.

Since the Pact Sense can clearly distinguish knotted tissue from a muscle region, it opens the possibility of the Pact Sense as a diagnostic tool for muscle knots. Additionally, the feature of continuous scanning can be implemented to “sweep” a muscle group to identify the position of a knot, as well as give specific information about the entire muscle. 

One thing to note is that for different knots, the changes to mechanical properties may be different. For this individual’s case, it was damping slope, damping, and inertia that showed clear differences. For other cases, it may be stiffness slope and stiffness showing a more distinguishable difference. Under that circumstance, recovery and treatment may look different. Therefore, it is important to look at all the Pact Sense parameters when identifying and monitoring a muscle knot.

How can I use this knowledge for monitoring my own tissue health: 

Muscle knots are a common occurrence and understood to be small pea-like knotted tissue that can be felt as much stiffer than healthy tissue. Once a knot is identified, the Pact Sense can objectively tell you how stiff that knot is and how damped the site is, meaning how resistant it is to movement. With the goal to improve stiffness and damping values of that knot to the values of surrounding healthy tissue to increase pliability and health, Pact Sense measurements can be taken before and after recovery, stretching, and various treatment techniques to monitor their effectiveness in treating the knot. As you examine the changes in stiffness and damping over time, you can see if the treatment is effective or if another technique should be tried. Additionally, as continuous scanning is developed, the Pact Sense will be able to diagnose the muscle knot directly while continuing to monitor its changes over time. Offering another application to provide an objective diagnosis and monitoring system of muscle knots.

  1. Jafri MS. Mechanisms of Myofascial Pain. Int Sch Res Notices. 2014;2014:523924. doi: 10.1155/2014/523924. PMID: 25574501; PMCID: PMC4285362.