Substantiating the Use of Tendotonometry for the Assessment of Achilles and Patellar Tendon Stiffness: A Systematic Review

Objective:To systematically describe the next relevant aspects of tendotonometry in (1) its validity and reliability, (2) differences between populations, (3) the effect of interventions, and (4) differences between healthy and symptomatic Achilles tendon (AT) and patellar tendon (PT).Data Sources:Three online databases (PubMed, Embase, and EBSCOhost) were systematically searched on the 10th of October 2023. All scientific literature concerning the use of tendotonometry in assessing tendon stiffness was collected. Articles were eligible if tendotonometry with a myotonometer digital palpation device was used to assess PT or AT stiffness in adults.Main results:Thirty-four studies were included, which were categorized into studies regarding the (1a) reliability and (1b) validity of tendotonometry, (2) differences in stiffness between populations, (3) changes in stiffness due to interventions, (4) stiffness of healthy compared with injured tendons, and (5) other observational studies. The inter-rater and intrarater reliability of tendotonometry appeared to be good in assessing AT and PT stiffness, with only moderate evidence for the AT and inconclusive evidence for the PT. There is high certainty evidence that tendotonometry can detect differences in AT and PT stiffness after training interventions. Inconsistent results were found for the adequacy of tendotonometry to detect differences in AT and PT stiffness between populations.Conclusions:This review shows a potential role for tendotonometry in measuring tendon stiffness. However, more research is needed for validating the use of tendotonometry in AT and PT and its exact clinical interpretation.