Observation of Achilles Tendon Collagen Fiber Reorientation in Elderly Persons

Abstract

[Purpose] To quantitatively evaluate the Achilles tendon collagen fiber orientation of elderly people by measuring the luminance variation coefficient in ultrasound images of active and passive motion tasks of the ankle joints. [Participants and Methods] The subjects were 20 healthy adults aged 60 years or older. Two exercise tasks, one passive movement of the ankle joint and the other active movement of the ankle joint, were performed and measured by ultrasound echo. The luminance average value and the luminance variation coefficient were calculated from the luminance histogram. [Results] The luminance average value increased, and the luminance variation coefficient decreased. The change rate of the luminance variation coefficient was large in the final dorsiflexion position in the passive movement task and in the 0–30% maximal voluntary contraction interval in the active movement task. [Conclusion] The results suggest that collagen fibers in the Achilles tendon of elderly people may be reoriented during active and passive ankle joint movements.