实时超声测量用于等长收缩条件下修复跟腱应变的研究

In-vivo Strain Measurement for Surgically Repaired Achilles Tendon under Isometric Contraction Using Real-time Ultrasound Imaging

跟腱（Achilles tendon,AT）在人体运动中承受了巨大的应力,它的力学特性,尤其是撕裂后的力学特性,引起了大量的研究兴趣。在康复治疗中,运动的类型和强度是防止修复的肌腱受到再损伤的关键。治疗师通常根据肿胀、炎症反应等临床症状来定性评估病人的康复训练适当与否。本研究采用了7.5MHz的线阵型超声探头,对等长收缩下修复跟腱的应变进行了测量。实验中6名进行了跟腱修复手术的男性受试者的年龄介于28~51岁之间,撕裂距离跟腱附着点2-7cm。手术后12.8±1.3个星期进行测量,以受试者的健康脚为对照组。研究还对三位健康男性受试者惯用脚和非惯用脚跟腱弹性特征的差异进行了测试。超声图像取自沿肌腱方向的撕裂处,采用Cybex 6000同时在体采集等长收缩条件下跟腱的超声图像以及腓肠肌-比目鱼肌产生的扭矩。定制的踝足矫形器可用于超声成像平面与肌腱位置的校准,以便由超声图像提取肌腱特定部位的应变信息。实验利用成像技术对离体猪肌腱的测量,证明了超声测量的有效性。我们发现跟腱撕裂修复位置的应变较对侧健康腿小14.8%±12.6%,两者存在显著差异（p=0.017）。今后可进一步研究沿肌腱方向上应变的分布以及康复过程中分布的变化。本研究将有助于跟腱修复手术后病人训练计划的制定和优化。

Achilles tendon is subjected to great stress during human locomotion,and hence its mechanical properties are of great interests especially after rupture.During rehabilitation,the type and intensity of exercise are important and crucial to prevent further damage to the repaired tendon.Therapists usually base on clinical symptoms such as swelling,signs of inflammation to determine whether the given exercise is appropriate or not.In this study,ultrasound imaging with a 7.5 MHz linear-array probe was used to study the strains of the repaired Achilles tendon during isometric contractions.Six male subjects with age ranging from 28 to 51 years old were recruited and their level of rupture was 2 to 7 cm from the insertion of Achilles tendon.They were tested 12.8±1.3 weeks after operation.Their healthy legs were used as control.In addition,three healthy male subjects were recruited to test the differences of the tendon strain between the dominant and non-dominant legs.Ultrasound images were obtained along the Achilles tendon at the level of rupture site in-vivo under isometric contraction using Cybex 6000,which also recorded the torque of gastrocnemius-soleus complex simultaneously.Ankle-foot-orthosis（AFO） custom-made for each foot was used to secure the consistent alignment between the ultrasound imaging plane and the tendon.The strain of the selected part of the tendon during the contraction was extracted from the ultrasound images.The ultrasound measurement was validated using an in vitro experiment with porcine Achilles tendons together with an optical imaging technique.We found that the strain at the repaired site after rupture was 14.8% ± 12.6%,which was significantly（p = 0.017） smaller than that of the tendon at the contralateral healthy side,which was 23.7%±12.7%.Future studies can focus on the strain distribution along the tendon and how the distribution changes during the healing process.This research may provide information for therapists to select optimized exercise plan for patients during their rehabilitation process after the repair of Achilles tendon.