Displacement Of Myotendinous Junction Research Articles

Automatic Myotendinous Junction Tracking in Ultrasound Images with Phase-Based Segmentation.

Displacement of the myotendinous junction (MTJ) obtained by ultrasound imaging is crucial to quantify the interactive length changes of muscles and tendons for understanding the mechanics and pathological conditions of the muscle-tendon unit during motion. However, the lack of a reliable automatic measurement method restricts its application in human motion analysis. This paper presents an automated measurement of MTJ displacement using prior knowledge on tendinous tissues and MTJ, precluding the influence of nontendinous components on the estimation of MTJ displacement. It is based on the perception of tendinous features from musculoskeletal ultrasound images using Radon transform and thresholding methods, with information about the symmetric measures obtained from phase congruency. The displacement of MTJ is achieved by tracking manually marked points on tendinous tissues with the Lucas-Kanade optical flow algorithm applied over the segmented MTJ region. The performance of this method was evaluated on ultrasound images of the gastrocnemius obtained from 10 healthy subjects (26.0 ± 2.9 years of age). Waveform similarity between the manual and automatic measurements was assessed by calculating the overall similarity with the coefficient of multiple correlation (CMC). In vivo experiments demonstrated that MTJ tracking with the proposed method (CMC = 0.97 ± 0.02) was more consistent with the manual measurements than existing optical flow tracking methods (CMC = 0.79 ± 0.11). This study demonstrated that the proposed method was robust to the interference of nontendinous components, resulting in a more reliable measurement of MTJ displacement, which may facilitate further research and applications related to the architectural change of muscles and tendons.

Shear elastic modulus is a reproducible index reflecting the passive mechanical properties of medial gastrocnemius muscle belly.

BackgroundPassive mechanical properties are important in muscle function because they are related to the muscle extensibility. Recently, the assessment of muscle shear elastic modulus using shear-wave elastographic (SWE) imaging was developed. However, reliability and validity of shear elastic modulus measurements during passive stretching remain undefined.PurposeTo investigate the reproducibility and validity of the shear elastic modulus measured by SWE imaging during passive stretching.Material and MethodsTen healthy men volunteered for this study. The shear elastic modulus of medial gastrocnemius (MG) muscle belly was measured using ultrasonic SWE imaging during passive dorsiflexion. To assess the intra-session and inter-day reliabilities, the protocol was performed twice by the same investigator with a 5-min rest period between measurement sessions and twice on two different days by the same investigator with a 1–2-week interval between the two sessions. To assess the inter-investigator reliability, the protocol was performed on the same day by two investigators with a 5-min rest between measurement sessions. In addition, B-mode ultrasonography was used to determine the displacement of myotendinous junction (MTJ) of MG during passive ankle dorsiflexion.ResultsThe intra-session, inter-day, and inter-investigator reliabilities of the method was confirmed on the basis of acceptably low coefficient of variations and substantially high intraclass correlation coefficients. In addition, a significant correlation was found between MTJ displacement and shear elastic modulus.ConclusionThese results suggested that shear elastic modulus measured using SWE imaging is a reproducible index reflecting the passive mechanical properties.

Gender differences in the passive stiffness of the human gastrocnemius muscle during stretch

The aim of this study was to determine whether muscle stiffness measured in vivo was different between males and females. Distal displacement of the gastrocnemius medialis myotendinous junction was measured directly using ultrasonography during passive dorsiflexion in eight males and eight females (age range 19-28 years). Plantarflexion torque and myotendinous junction displacement were measured at 5° intervals, where 0° was with the foot at right angles to the tibia. Stiffness of the gastrocnemius medialis muscle was calculated between 0° and 25° of dorsiflexion, and defined as passive plantarflexion torque/distal displacement of the myotendinous junction (N m cm(-1)). Relative muscle stiffness was also calculated as distal displacement relative to resting muscle length, and as passive torque relative to plantarflexion maximal voluntary contraction torque. No significant gender difference was observed in passive dorsiflexion torque, or in passive torque/maximal voluntary torque throughout the range of motion. Distal displacement of the gastrocnemius myotendinous junction was 26% more in females than in males (P < 0.05). Myotendinous junction displacement was 5.0 ± 1.4% of resting gastrocnemius medialis length in females, and 3.9 ± 0.6% in males. Over 25° of passive dorsiflexion, gastrocnemius medialis muscle stiffness was greater in males than in females by 44% (P < 0.05). In conclusion, based on the in vivo assessment of myotendinous junction displacement, passive gastrocnemius medialis muscle stiffness is greater in males than in females.