基于振动的弹性成像方案在精英运动员中评估跟腱刚度的可靠性，适用于多个关节角度
2026年6月16日
该方案描述了一种标准化的便携式超声方法，用于量化精英运动员在多个踝关节角度下跟腱的功能刚度谱，从而在不同负荷条件下可靠且可重复地评估腱的机械行为。
我们采用一种新型弹性成像方案，评估多个关节角度下的跟腱刚度，旨在表征各类运动精英运动员的生物力学适应。与现有方法不同，我们的基于振动的弹性成像能够可靠地评估肌腱的连续刚度，以及在整个运动范围内的变化。首先，从国家级体育队伍招募参与者，包括年龄在18至26岁的职业男运动员，涵盖多个体育项目。
通过让参与者踢球来确定主导腿。准备设备：配备9L3至8.5兆赫线性阵列探头的M5软组织弹性计和机械激励模块。准备额外的设备，包括跟腱靴、超声凝胶和检查床。
打开主电源，确认系统状态指示灯亮起。然后，打开平板界面，通过选择指定的应用图标启动超声系统软件，确认系统进入主超声操作界面，实时显示B模式成像。将B模式参数设置为7.5兆赫频率，四条采集线，5毫米深度范围，300毫秒采集时间。
接着，指示参与者脱鞋，然后将受试者俯卧在检查沙发上，脚踝完全伸出沙发边缘约五厘米。触诊以定位跟骨结节的上端。在该标志点附近标记0.5厘米处，用皮肤标记来确定初始测量点。
在换能器表面均匀涂抹预热的耦合凝胶。轻轻将探针对准测量点，并将目标点对准探针前侧下方。现在把超声系统切换到弹性成像模式。
将参考线定位为获得深度范围从肌腱筋膜下方开始。调整目标区域以覆盖腱厚，同时避免接触皮肤、皮下组织和Kager脂肪垫。在采集前，确保换能器平面在大于75度时几乎垂直于皮肤表面，以确认成像质量。
确认换能器与皮肤的距离大约是五毫米。确认没有明显气泡，筋膜和肌腱纤维是否清晰可见。一旦激发装置开启，系统即可自动计算剪切模量，并显示有效数据的均值和标准差值。
采集过程中保持参与者和操作员姿势一致，以获得至少10个有效的连续数据点。收集到足够多的数据点后，按下冻结功能停止数据采集。检查数据集中的异常值，并使用系统编辑功能去除异常数据点。
在放松、零度中性、20度足底屈曲、40度足底屈曲、20度背屈和40度背屈条件下，依次对双侧跟腱进行测量。每个脚踝角度至少重复测量三次。仅在连续数据点的标准差低于平均值10%时，才验证每次测量，符合设备内部验证标准的要求。
保存B模式图像和机械成像图以作文档记录。完成放松状态测量后，将参与者的脚放入可调节踝关节测试靴中，确保鞋跟完全贴合靴底后跟杯。使用附带固定前脚掌、中足和小腿，防止测试时脚跟抬起或横向移动。
松开靴铰链机构上的双侧锁定旋钮。通过将结构标记与量角刻度对齐，手动引导脚踝到目标角度。将锁定旋钮拧紧，以固定在目标角度的踝关节。
锁定角度后立即进行超声测量，以防止粘弹性腱松弛。之后，指示参与者脱下踝靴。清洁并消毒所有器械和超声探头。
通过高质量B模式图像，具有清晰连续的肌腱纤维结构，且在预定关注区域内呈现稳定均匀弹性图，成功测量。不同接头角度的平均变异系数范围为0.14至0.25。所有评估的关节角的类间相关系数值范围为0.871至0.974。
在放松状态下观察到最高的可靠性，在中性零度位置观察到最低的可靠性。所有参与者的跟腱硬度从足底屈曲到背屈呈非线性增长。广义混合模型显示关节角度显著主效应，而侧卧和运动型则无主效应。
角度与运动的相互作用显著，表明了特定踝关节角度下的运动硬度差异。该方案非侵入性测量跟腱的功能刚度谱，捕捉其在动态角度上的非线性机械行为。动态采集过程中的关键挑战是保持恒定的接触压力和垂直方向，以避免运动伪影。
未来的研究可以绘制肌腱行为图，监测肌腱操作的康复情况，评估训练适应，并预测动态运动表现。
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Overview
This study introduces and validates a portable, standardized protocol for quantifying the functional stiffness spectrum of the Achilles tendon across multiple ankle joint angles. By employing a force–ultrasound fusion system, the method enables continuous mechanical profiling of the tendon, offering improved assessment over traditional single-value or laboratory-bound techniques. The protocol demonstrates high repeatability and reliability, making it suitable for diverse applications in athlete monitoring and injury risk assessment.
Key Study Components
Area of Science
- Sports medicine
- Biomechanics
- Musculoskeletal imaging
Background
- The Achilles tendon’s mechanical properties are crucial for athletic performance and injury prevention.
- In vivo assessment of tendon stiffness is challenging due to limitations of current methods.
- Conventional ultrasonography with dynamometry is expensive and limited to laboratory settings and single joint positions.
- Existing elastography techniques often lack functional relevance or are constrained by methodological assumptions.
Purpose of Study
- To present and validate a portable protocol for quantifying the Achilles tendon’s stiffness spectrum across multiple ankle joint angles.
- To shift assessment from a static stiffness value to a continuous mechanical profile reflecting nonlinear tendon behavior.
- To enable practical, repeatable tendon assessment in laboratory, clinical, and field settings.
Methods Used
- Application of mechanically induced low-frequency vibrations to the Achilles tendon.
- Ultrasound-based motion tracking to estimate the shear elastic modulus of superficial tendon tissue.
- Force–ultrasound fusion system for synchronized measurement.
- Measurements performed bilaterally in elite male athletes at predefined ankle joint positions (relaxed, plantarflexed, neutral, dorsiflexed).
Main Results
- The protocol showed good intra-trial repeatability and excellent intra-session reproducibility across all joint angles.
- Coefficients of variation were within acceptable limits for soft-tissue elastography.
- Intraclass correlation coefficients indicated high measurement reliability.
- Achilles tendon stiffness increased non-linearly with dorsiflexion, demonstrating angle-dependent mechanical behavior.
- No significant effect of side dominance was observed, but sport-specific differences appeared at selected joint angles.
Conclusions
- The protocol provides a practical and repeatable approach for characterizing Achilles tendon mechanical behavior under functionally relevant loading.
- Its portability and standardized workflow support use in laboratory, clinical, and field environments.
- The method is valuable for athlete monitoring, injury risk assessment, and longitudinal evaluation of tendon adaptation.
Frequently Asked Questions
Executive Industry Relevance
Quantitative assessment of tendon mechanical properties is critical for translational musculoskeletal research and preclinical model development. This portable vibration-based elastography protocol enables standardized, reproducible measurement of Achilles tendon stiffness across multiple joint angles, supporting predictive confidence in biomechanical target validation. Its reliability and functional relevance position it as a valuable tool for risk-adjusted advancement in sports medicine and musculoskeletal R&D portfolios.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables interrogation of tendon mechanical behavior under physiologically relevant loading conditions.
- Supports functional target validation by quantifying nonlinear stiffness profiles across joint angles.
- Facilitates biological de-risking for musculoskeletal intervention strategies.
Screening & Assay Development
- Provides a standardized, repeatable workflow for tendon stiffness quantification.
- Delivers quantitative outputs suitable for assay reproducibility and cross-study comparison.
- Prepares validated biomechanical systems for downstream screening or intervention studies.
Translational & Preclinical Research
- Aligns tendon mechanical profiling with disease-relevant and athlete-specific translational models.
- Enables longitudinal evaluation of tendon adaptation and intervention effects.
- Supports risk-adjusted decisions for advancing candidate therapies targeting tendon health.
Pipeline & Workflow Integration
This protocol integrates into the discovery-to-preclinical continuum for musculoskeletal research, bridging early biomechanical hypothesis testing with translational model validation.
- Discovery Biology: Quantifies tendon mechanical response to loading, clarifying functional pathways and de-risking targets.
- Screening: Standardizes measurement of tendon stiffness for reproducible, quantitative assay outputs.
- Analytics: Provides continuous mechanical profiles and statistical reliability metrics for robust condition comparison.
- Translational Research: Enables alignment of preclinical models with athlete-relevant mechanical endpoints.
- Enterprise Reuse: Offers a portable, standardized capability for repeated use across laboratory, clinical, and field settings.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in tendon research.
- Operational Value: Delivers standardized, reproducible, and scalable tendon assessment workflows.
- Strategic Value: Improves go/no-go decisions and capital efficiency by enabling reliable mechanical phenotyping.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of musculoskeletal R&D assets.
Implementation Considerations
- Requires expertise in ultrasound imaging and biomechanical data interpretation.
- Needs access to force–ultrasound fusion instrumentation and vibration induction hardware.
- Demands cross-team standardization for protocol reproducibility and data comparability.
- Adaptable to various joint angles and subject populations within validated operational limits.
- Practical limitations include dependency on operator training and instrumentation availability.
