Finni Taija, Khair Raad, Franz Jason R, Sukanen Maria, Cronin Neil, Cone Stephanie
Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä, Jyväskylä, Finland.
Joint Department of Biomedical Engineering, University of North Carolina Chapel Hill and North Carolina State University, Chapel Hill, North Carolina, USA.
Scand J Med Sci Sports. 2025 Apr;35(4):e70042. doi: 10.1111/sms.70042.
The Achilles tendon (AT) comprises three subtendons whose relative locations, and respective lines of action, vary individually. This study was aimed to demonstrate the efficacy of a novel method, combining Ultrasound and electrical STIMulation (USTIM), to identify the in vivo location of individual subtendons in cross-sections of the AT. We individually stimulated the triceps surae muscle heads and imaged localized tissue movement on a transverse plane 1 cm proximal to the calcaneus using B-mode ultrasonography. Movement induced by muscle stimulation was presumed to arise from movement in the respective subtendon. Frame-by-frame changes in grayscale values were analyzed to detect localized tissue movement, establishing the three subtendon locations. From 12 successfully assessed legs, we found test-retest reliability to be excellent (ICC = 0.93, N = 3), and intra- and inter-rater reliability to be good for the subtendon centroid locations (ICC > 0.77, N = 12). Reliability for identifying the subtendon area was good for test-retest (ICC = 0.77) and intra-rater assessments (ICC > 0.70) but moderate between raters (ICC = 0.53). Subtendon centroid locations assessed using USTIM showed a strong association (N = 2; r= 0.80, p < 0.001) with those identified via the high-field MRI method established by Cone et al. Fitting with prior literature, the majority of (83%) tendons were identified as low twist type I. The novel USTIM method can identify in vivo locations of the three subtendons within a cross-section of AT with moderate to excellent reliability. This method could be used to unravel the intricacies of structure-function relationships in the AT, with potential clinical benefits for treatment of patients with AT injuries.
跟腱（AT）由三条子腱组成，它们的相对位置和各自的作用线各不相同。本研究旨在证明一种结合超声和电刺激（USTIM）的新方法在确定跟腱横切面中各子腱体内位置方面的有效性。我们分别刺激腓肠肌三头，并用B型超声成像跟骨近端1厘米处横断面上的局部组织运动。肌肉刺激引起的运动被认为是由相应子腱的运动引起的。通过分析灰度值的逐帧变化来检测局部组织运动，从而确定三条子腱的位置。在12条成功评估的腿中，我们发现重测信度极佳（ICC = 0.93，N = 3），子腱质心位置的评分者内和评分者间信度良好（ICC > 0.77，N = 12）。子腱面积识别的重测信度良好（ICC = 0.77），评分者内评估也良好（ICC > 0.70），但评分者间信度中等（ICC = 0.53）。使用USTIM评估的子腱质心位置与Cone等人建立的高场MRI方法确定的位置显示出很强的相关性（N = 2；r = 0.80，p < 0.001）。与先前文献相符，大多数（83%）肌腱被确定为低扭转I型。这种新的USTIM方法能够以中等至极佳的信度识别跟腱横切面内三条子腱的体内位置。该方法可用于揭示跟腱结构-功能关系的复杂性，对跟腱损伤患者的治疗可能具有临床益处。
