Disclosures: William Berrigan, MD: No financial relationships or conflicts of interest

Objective: The purpose of the of this study was to determine how hip and knee positioning impacts Shear Wave Elastography (SWE) values as a measure of muscle stiffness within the semimembranosus (SM) and semitendinosus (ST).

Design: This was a cross-sectional experiment in which subjects participated in one two-hour visit. Setting : The study took place at the National Institutes of Health inside the Functional and Applied Biomechanics Laboratory. Participants : Ten healthy subjects ages 8-58 years (6males, 4 females) participated.

Interventions: SWE shear modulus values were obtained over the mid-substance of the SM and ST muscle bellies in four separate positions: seated with the knee flexed and extended, and lying prone with the knee flexed and extended.

Main Outcome Measures: Our main outcome measure was shear modulus values, measured in kPa, of the SM and ST.

Results: Higher shear modulus values and greater variability were found when participants were seated compared to prone (hip placed at 90° compared to 0°). In addition, higher values were also found when the knee was extended compared to flexed when the hip was placed at 90° but not at 0°. Conclusions: These results demonstrate that joint and muscle position, particularly when assessing the hamstrings, largely impacts resulting SWE values. Therefore, joint and muscle position need to be systematically controlled for and reported when establishing normative ranges for SWE values across specific age groups. This will enable physicians to more precisely determine whether patients’ SWE values indicate clinically meaningful differences in comparison to normative data.

Level of Evidence: Level IV

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/hip-position-influences-shear-wave-elastography-measurements-of-the-hamstring-muscles-in-healthy-subjects/