Recommendation for stiffness measurement on gastrocnemii and Achilles tendon at rest and in loaded conditions
Authors: Nguyen Anh Phong ,   Université catholique de Louvain, Faculté des Sciences de la motricité, Place Pierre de Coubertin 1, 1348 Louvain-La-Neuve, Belgium, Verdebout Julien , Fontaine Antoine , Mahaudens Philippe , Detrembleur Christine ,   Université catholiquede Louvain, Institut de Recherche Expérimentale et Clinique, Neuromusculoskeletal lab, avenue mounier 53, 1200 Brussels, Belgium,   Université catholique de Louvain, Faculté des Sciences de la motricité, Place Pierre de Coubertin 1, 1348 Louvain-La-Neuve, Belgium,   Université catholique de Louvain, Faculté des Sciences de la motricité, Place Pierre de Coubertin 1, 1348 Louvain-La-Neuve, Belgium,   Université catholique de Louvain, Faculté des Sciences de la motricité, Place Pierre de Coubertin 1, 1348 Louvain-La-Neuve, Belgium,   Université catholiquede Louvain, Institut de Recherche Expérimentale et Clinique, Neuromusculoskeletal lab, avenue mounier 53, 1200 Brussels, Belgium,   Cliniques universitairesSaint-Luc, Service d’orthopédie et de traumatologie de l’appareil locomoteur, Avenue Hippocrate 10, B-1200 Brussels, Belgium,   Cliniques universitairesSaint-Luc, Service de médecine physique et réadaptation, Avenue Hippocrate 10, B-1200 Brussels, Belgium,   Université catholique de Louvain, Faculté des Sciences de la motricité, Place Pierre de Coubertin 1, 1348 Louvain-La-Neuve, Belgium,   Université catholiquede Louvain, Institut de Recherche Expérimentale et Clinique, Neuromusculoskeletal lab, avenue mounier 53, 1200 Brussels, Belgium
Published: July 2024

Background: It is challenging to offer both clinically accessible and reproductible musculotendinous stiffness assessment in patient. This is particularly challenging in the ankle plantar flexor such as the gastrocnemii and the Achilles tendon as they are important in both walking and running. Design: cross-sectional studies Objectives: to determine the most reliable and clinically relevant stiffness point of measurement for gastrocnemii and Achilles tendon Methods: The stiffness were calculated using MyotonPro device on both legs in healthy individuals. Four points of measurement were taken in the Achilles tendon and six on the gastrocnemii. In addition, the measurements were taken in two conditions, at rest, i.e., in lying condition and loaded, i.e., standing. All participants were measured during sessions with one week apart to report intra- and inter- reliability. Results: The result reported moderate to excellent intraclass correlation coefficient in the lying condition with Intraclass coefficient between 0.735 and 0.933 depending on the location. However, in standing condition, result reported poor to good measurement for the Achilles tendon (between 0.000 and 0.636) and excellent reliability for the gastrocnemii (between 0.902 and 0.986). Conclusion: Researcher and clinician should take caution when assessing the Achilles tendon stiffness. The Achilles tendon should be assessed at least 6 cm above the bone insertion as is procure the most reliable point of measurement and the only point that could be reassess between days.