The purpose of the study was to examine the acute effect of static stretching exercise on the resting stiffness of gastrocnemius muscle belly. Ten healthy young adults performed standing wall stretching in dorsiflexion for 1 min at a time and repeated five times. Before and after stretching, the shear modulus was measured in medial and lateral heads of the resting gastrocnemius muscle with ultrasound shear-wave elastography. After the stretching, dorsiflexion range of motion (ROM) of the ankle joint increased (P < 0.01) by 3.9° and returned in 20 min. Immediately after stretching, shear modulus decreased (P < 0.01) by 14%, compared with before stretching across muscle heads. The decrease in shear modulus returned in 20 min after stretching. In the comparison group of 10 additional subjects, the standing intervention without stretching had no influence on these measures. There was a negative correlation between dorsiflexion ROM and shear modulus in either head before and after stretching. The results demonstrate the transient decreases in the stiffness of the resting gastrocnemius muscle belly and indicate that joint flexibility is greater in individuals with lower resting stiffness of the muscle belly.
Three-dimensional (3D) behavior of the talocrural joint is primarily determined by the articular surface morphology of the talar trochlea and tibiofibular mortise. However, morphological features of the anterior and posterior regions of the talar trochlea remain unclear. The objectives of this study were to evaluate anterior and posterior radii of the medial and lateral talar trochlea and to estimate subject-specific kinematics of the talocrural joint. Fifty dry tali were scanned using computed tomography to create 3D bone models. Radii of curvature of the anterior and posterior region at both the medial and lateral trochlea were calculated. Orientations of the dorsiflexion and plantarflexion axis passing through the centers of the circles fitted to the anterior region of the medial and lateral trochlea and through the centers of the circles fitted to the posterior region of the medial and lateral trochlea were evaluated, respectively. The anterior radius of the medial trochlea was significantly smaller than that of the lateral trochlea by a mean of 7.8 mm (P < 0.001). The posterior radius of the medial trochlea was larger than that of lateral trochlea in 30 samples (60%) and vice versa in 20 samples (40%). Unilateral asymmetric shape of anterior trochlea would induce external rotation of the talus during ankle dorsiflexion, whereas bilateral asymmetric shape of posterior trochlea would induce opposite axial rotations among subjects during ankle plantarflexion, which would help the physical therapists to restore talocrural joint motions to ideal state for patients with ankle injuries. Clin. Anat. 29:1066-1074, 2016. © 2016 Wiley Periodicals, Inc.
The shape of the calcaneus determines the mechanical interaction of the foot with the ground during the heel‐strike in human walking. Detailed knowledge of the pattern of sexual dimorphism of the human calcaneus could help to clarify the pathogenetic mechanism of foot and knee disorders, which are more prevalent in females. Therefore, the aim of this study was to characterize and visualize the three‐dimensional shape variations of the calcaneus in relation to sex and age using geometric morphometrics. Computed tomography images of 56 feet without subtalar injuries or disorders were used in this study. Thirty‐seven anatomical landmarks were identified on the bone model of the calcaneus to calculate principal components (PCs) of shape variations among specimens. The PC scores were compared between males and females, and their correlations with age were also analyzed. The female calcaneus was longer in length and shorter in height than that of males. The medial process of the calcaneal tuberosity in females was more inferiorly projected and the tuberosity was shifted more laterally. Also, the calcaneus was wider and the sustentaculum tali thickened with aging. Female structural features of the calcaneus alter the kinematics of the foot during walking and could be a structural factor in foot and knee disorders. This study contributes to a comprehensive understanding of shape variations in the human calcaneus. Clin. Anat., 33:751–758, 2020. © 2019 Wiley Periodicals, Inc.
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