Intra-Rater and Inter-Rater Reliability Analysis of Muscle-Tone Evaluation Using a Myotonometer for Children with Developmental Disabilities

Assessing muscle tone is an essential component of the diagnosis, prognosis, and treatment planning of developmental disabilities (DD) in children and is of great help in developing clinical diagnosis patterns. The purpose of this study was to investigate intra-rater and inter-rater reliability using the myotonometer, which is an assessment tool to measure muscle tone in children with DD. This study included 26 children diagnosed with DD. Two physical therapists measured the children’s muscle tone using a myotonometer. For all the muscles measured, reliability was determined using the intra-class correlation coefficient (ICC), the standard measurement error (SEM), and the minimal detectable change (MDC). The intra-rater reliability for all muscles was excellent (ICC = 0.75~0.78), except for the biceps brachii (ICC = 0.68). The inter-rater reliability was also excellent for all muscles (ICC = 0.75~0.95), and the SEM and MDC showed small measurement errors. Therefore, the intra-rater and inter-rater reliability of measurements by the myotonometer was found to be good or excellent. This suggests that the myotonometer is a tool that can objectively assess muscle tone, and it can be utilized in clinical practice to quickly and conveniently measure muscle tone in children with DD.