Age-related structural-mechanical property changes in human peroneus longus muscle

Background: Functional impairment of the muscle-tendon unit is one of the most remarkable effects of aging. The function of the peroneus longus muscle is to stabilise the foot and ankle joint. A deterioration of the structural and mechanical properties of this muscle can potentially lead to foot problems in older adults. This study aimed to investigate the effects of age on structural, histological, and mechanical features in peroneus longus muscle samples taken from embalmed cadavers of two different age groups; young adult (30–60 years) and old adult (over 60 years). Materials and methods: The mechanical property was analysed through the results of cross-sectional area, tensile, tensile stress, and modulus of elasticity. The arran- gement of the collagen in the perimysium and tendon was examined by scanning electron microscopy. Fatty infiltration within the musculotendinous junction was evaluated by Masson’ trichrome stained muscle sections. Results: This study thus provides evidence that there are indeed age-induced mechanical property changes in the peroneus longus muscle, which include reductions in the tensile force, tensile stress, and modulus of elasticity, and is related to the malformation of collagen fibrils and the massive fat accumulation in the musculotendinous junction. Conclusions: These alterations may further result in a reduction of muscle strength and quality in an older person.