An exploratory study of the use of ultrasound in the measurement of anterior tibial translation under gastrocnemius muscle stimulation

Abstract

Gastrocnemius’ role as an agonist or antagonist of the anterior cruciate ligament (ACL) is not 27 well understood. This study explored the use of ultrasound imaging to investigate how 28 gastrocnemius stimulation levels influenced anterior tibial translation. The gastrocnemii of 10 29 participants were stimulated to four different levels using electrical muscle stimulation. The 30 quadriceps were co-activated at a fixed level. Anterior tibial translation was determined using 31 ultrasound imaging. Intraclass correlation coefficient [ICC (2,1)] was used to assess the intra-32 rater reliability over two sessions. Intra-rater reliability was good at rest and under most 33 muscle stimulation levels (ICC = 0.84 to 0.92), and moderate with the lowest (ICC = 0.71) 34 and highest stimulation (ICC = 0.61). While anterior tibial translation was not significantly 35 different across simulation levels, ultrasound imaging recorded the anterior movement of the 36 tibia as the gastrocnemius was activated, thus supporting gastrocnemius’ role as an antagonist 37 of the ACL.