Stiffness of the infraspinatus and the teres minor muscles during shoulder external rotation: An in-vitro and in-vivo shear wave elastography study

Takuma Yuri, Jose H. Trevino, Taku Hatta, Yoshiro Kiyoshige, Philip M. Jacobs, Hugo Giambini

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Background: A better understanding of the morphological and functional differences in the anatomical sub-regions of the rotator cuff muscles is critical so that appropriate surgical and rehabilitation methodologies can be implemented in patients with shoulder-related injuries. The purpose of the current study was to develop a comprehensive imaging protocol using shear-wave elastography for the infraspinatus and teres minor muscles, and investigate differences in elastic properties of three distinct infraspinatus muscle sub-regions and of the teres minor muscle. Methods: First, we developed a protocol for probe positioning for both muscles using three cadaveric shoulders. Second, we evaluated in-vivo elastic properties [passive and active stiffness (kPa)] and excursion (mm) outcomes from these muscles during shoulder external rotation. Findings: Elastic properties were significantly different among the infraspinatus muscle sub-regions and teres minor muscle. Passive stiffness decreased with increasing rotation angles except for the middle sub-region of the infraspinatus muscle which showed a decreased up to mid-range followed by an increment towards the end-range. Overall, active stiffness of the infraspinatus muscle and teres minor muscle decreased with increasing rotation angles, while that of the middle sub-region increased up to mid-range, and decreased at the end-range. Interpretation: Distinct characteristics of the infraspinatus and teres minor muscles, and more importantly, of the individual sub-regions within the infraspinatus muscle call for an in-depth analysis of their morphological and functional differences. Special attention should be put into these sub-regions when performing surgical and rehabilitation procedures for patients with shoulder-related injuries.

Original languageEnglish (US)
Article number105328
JournalClinical Biomechanics
Volume85
DOIs
StatePublished - May 2021

Keywords

  • Excursion
  • Infraspinatus
  • Shear-wave elastography
  • Sub-regions
  • Teres minor

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine

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