Obst Steven J, Renault Jean-Baptiste, Newsham-West Richard, Barrett Rod S
School of Rehabilitation Sciences and Centre for Musculoskeletal Research, Griffith Health Institute, Griffith University, Queensland, Australia;
J Appl Physiol (1985). 2014 Feb 15;116(4):376-84. doi: 10.1152/japplphysiol.01249.2013. Epub 2013 Dec 26.
Freehand three-dimensional ultrasound (3DUS) was used to investigate longitudinal and biaxial transverse deformation and rotation of the free Achilles tendon in vivo during a voluntary submaximal isometric muscle contraction. Participants (n = 8) were scanned at rest and during a 70% maximal voluntary isometric contraction (MVIC) of the plantarflexors. Ultrasound images were manually digitized to render a 3D reconstruction of the free Achilles tendon for the computation of tendon length, volume, cross-sectional area (CSA), mediolateral diameter (MLD), anteroposterior diameter (APD), and transverse rotation. Tendon longitudinal and transverse (CSA, APD, and MLD) deformation and strain at 70% MVIC were calculated relative to the resting condition. There was a significant main effect of contraction on tendon length and mean CSA, MLD, and APD (P < 0.05), but no effect on tendon volume (P = 0.70). Group mean transverse strains for CSA, MLD, and APD averaged over the length of the tendon were -5.5%, -8.7% and 8.7%, respectively. Peak CSA, MLD, and APD transverse strains all occurred between 40% and 60% of tendon length. Transverse rotation of the free tendon was negligible at rest but increased under load, becoming externally rotated relative to the calcaneal insertion. The relationship between longitudinal and transverse strains of the free Achilles tendon during muscle-induced elongation may be indicative of interfascicle reorganization. The finding that transverse rotation and strain peaked in midportion of the free Achilles tendon may have important implications for tendon injury mechanisms and estimation of tendon stress in vivo.
在自愿进行次最大等长肌肉收缩过程中，使用徒手三维超声（3DUS）研究体内游离跟腱的纵向和双轴横向变形及旋转情况。对8名参与者在静息状态下以及在跖屈肌进行70%最大自愿等长收缩（MVIC）期间进行扫描。超声图像经手动数字化处理，以重建游离跟腱的三维模型，用于计算肌腱长度、体积、横截面积（CSA）、内外侧直径（MLD）、前后直径（APD）以及横向旋转。相对于静息状态，计算70% MVIC时肌腱的纵向和横向（CSA、APD和MLD）变形及应变。收缩对肌腱长度、平均CSA、MLD和APD有显著的主效应（P < 0.05），但对肌腱体积无影响（P = 0.70）。沿肌腱长度平均的CSA、MLD和APD的组平均横向应变分别为-5.5%、-8.7%和8.7%。CSA、MLD和APD的峰值横向应变均出现在肌腱长度的40%至60%之间。游离肌腱在静息时的横向旋转可忽略不计，但在负荷下增加，相对于跟骨附着点向外旋转。肌肉诱导伸长过程中游离跟腱的纵向和横向应变之间的关系可能表明肌束间的重新组织。游离跟腱中部横向旋转和应变达到峰值这一发现可能对肌腱损伤机制及体内肌腱应力估计具有重要意义。
