Mechanotendography: description and evaluation of a new method for investigating the physiological mechanical oscillations of tendons using a piezo-based measurement system

The mechanotendography (MTG) analyzes mechanical oscillations of tendons during muscular actions. It can be assessed as equivalent to mechanomyography just applied for tendons. Since this method is unknown, the aim of this investigation was to evaluate the technical reliability of a piezo-based measurement system used for MTG. The reliability measurements were performed using audio files played by a subwoofer. The thereby generated mechanical pressure waves were recorded by a piezoelectric sensor based measurement system. The piezo sensor was fixed onto the subwoofer’s coverage. An audio of 40 Hz-sine oscillations and, to stay close to human applications, four different formerly in vivo recorded MTG-signals from Achilles and triceps brachii tendon were converted into audio files and were used as test signals. Five trials with each audio were performed. One audio was used for repetition trials on another day. The correlation of the recorded signals were estimated by the Spearman correlation coefficient (MCC), the intraclass-correlation-coefficient (ICC(3,1)), Cronbach’s alpha (CA) and by mean distances (MD) between the signals. They were compared between repetition and random matched signals. The repetition trials show high correlations (MCC: 0.86 ± 0.13, ICC: 0.89 ± 0.12, CA: 0.98 ± 0.03), low MD (0.03 ± 0.03V) and differ significantly from the random matched signals (MCC: 0.15 ± 0.10, ICC: 0.17 ± 0.09, CA: 0.37 ± 0.16, MD: 0.19 ± 0.01V) ( p = 0.001 – 0.043). This speaks for an excellent reliability of the piezo-based measurement system in a technical setting. Since research showed that the skin above superficial tendons oscillates adequately, we estimate this tool as valid for the application in musculoskeletal systems. It might provide further insight into the functional behavior of tendons during muscular activity.