Intra- and Inter-rater Reliabilities of Measurements of Fascial Displacement and Muscle Stiffness by Using Ultrasound Images

Abstract

[Purpose] We examined the intra- and inter-rater reliabilities of measurements of fascial displacement and muscle stiffness made by ultrasound imaging. [Subjects and Methods] We imaged the lower limbs of 10 healthy individuals (20 limbs) with no medical history of orthopedic disease. The moving distances of the superficial and deep layers of the fascia in the lateral head of the gastrocnemius during passive dorsal flexion, and muscle stiffness with the ankle joint in the neutral position were measured by ultrasound, and the measurements were repeated after four days. [Results] For all measurements, the intraclass correlation coefficients were “almost perfect (0.81∼1.00)”, and there were no fixed or proportional biases in the intra- and inter-rater reliabilities. For the intra-rater reliability, the 95% confidence intervals for the minimum detectable change (MDC₉₅) in the superficial and deep layers were 0.24 mm and 0.34 mm, respectively, and 5.94 for the muscle stiffness. With regard to inter-rater reliability, MDC₉₅ of the superficial and deep layers was 0.08 mm and 0.10 mm, respectively, and 1.54 for muscle stiffness. [Conclusion] Both the intra- and inter-rater reliabilities of this measure method were high after four days.