AUTHOR=Kositsky Adam , Barrett Rod S. , du Moulin William , Diamond Laura E. , Saxby David J. 

TITLE=Semitendinosus muscle morphology in relation to surface electrode placement in anterior cruciate ligament reconstructed and contralateral legs

JOURNAL=Frontiers in Sports and Active Living

VOLUME=Volume 4 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2022.959966

DOI=10.3389/fspor.2022.959966

ISSN=2624-9367

ABSTRACT=The semitendinosus tendon is commonly harvested as graft tissue for anterior cruciate ligament reconstruction (ACLR). Although the semitendinosus tendon can regenerate following harvesting, ACLR results in substantial reductions in semitendinosus muscle size and length, potentially complicating electrode placement for electromyography. The purpose of this study was to assess whether the most commonly used electrode placement (recommended by the “surface EMG for non-invasive assessment of muscles” (SENIAM) project) is appropriate for measuring semitendinosus electromyograms after ACLR. In nine participants (unilateral ACLR with semitendinosus graft), B-mode ultrasonography was used to bilaterally determine (i) muscle-tendon junction position and semitendinosus tendon regeneration (ACLR leg only), and (ii) semitendinosus anatomical cross-sectional area (ACSA) at the SENIAM recommended electrode placement site at rest and during isometric maximal voluntary contractions (MVC) at two knee joint angles. Depending on contraction state and joint angle, semitendinosus muscle had retracted past the recommended placement site in 33-78% of ACLR legs, but not in any contralateral legs. Semitendinosus ACSA was smaller at rest and MVC in the ACLR leg and decreased from rest to MVC and with the increase in knee flexion angle in both legs, likely due to sliding of the muscle under the skin. These results suggest SENIAM guidelines are likely unsuitable for recording surface electromyograms from the semitendinosus muscle after tendon harvesting for ACLR as the muscle of interest may not be within the electrode detection volume.