Background:Massive irreparable rotator cuff tears (MIRCTs) are among the most challenging shoulder conditions to treat surgically. Supraspinatus tendon reconstruction (STR) is a recently introduced technique for MIRCTs based on fascia lata-muscle interface healing, which completely differs from the classic bridging technique with fascia lata-tendon interface healing. However, histological and biomechanical comparisons of the fascia-muscle and fascia-tendon interfaces have not been performed.Purpose:To investigate the histological and biomechanical healing of the fascia-bone interface and fascia-muscle interface after chronic MIRCTs in a rat model using different surgical methods.Study Design:Controlled laboratory study.Methods:The authors established a chronic MIRCT model in the right shoulder of rats and then repaired it using the STR or bridging repair technique. Evaluations were performed at 2, 4, 8, and 12 weeks, including histological, imaging, biomechanical, and functional analyses.Results:Both techniques resulted in good fascia-bone interface healing based on the histological results. The STR group had significantly more cartilage formation at 8 and 12 weeks and higher Modified Tendon Maturity Score after 12 weeks at the fascia-bone interface compared with the bridging repair group and formed the typical 4-layered structure. Collagen fibers in the fascia-muscle and fascia-tendon interfaces exhibited normal muscle-tendon interface characteristics at 12 weeks. However, the STR group had more improvement in fatty infiltration compared with the bridging repair group. The ultimate failure load and stiffness did not differ between the STR and bridging repair groups 4 weeks postoperatively in both the fascia-bone interface and supraspinatus muscle-fascia-bone integrity. Movement distance and grasp time were significantly longer in the STR group than in the bridging repair group at 12 weeks and attached the level in the normal control groups.Conclusion:These results suggest that the fascia-muscle interface from the STR technique is histologically and functionally better than the fascia-tendon interface. Moreover, this study provides a theoretical basis for the clinical use of the STR technique.Clinical Relevance:The fascia-muscle interface and fascia-tendon interface were the key points of the STR and bridging techniques, respectively. The fascia-muscle interface is histologically and functionally superior to the bridging technique, and the STR technique might be a better choice for the treatment of MIRCTs.

中文翻译：

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大鼠模型中冈上肌腱重建与桥接技术：组织学、生物力学和功能结果


背景：大规模不可修复的肩袖撕裂（MIRCT）是手术治疗最具挑战性的肩部疾病之一。冈上肌腱重建（STR）是最近推出的一种基于阔筋膜-肌肉界面愈合的MIRCT技术，与经典的阔筋膜-肌腱界面愈合桥接技术完全不同。然而，尚未对筋膜-肌肉和筋膜-肌腱界面进行组织学和生物力学比较。目的：使用不同的方法研究大鼠模型慢性MIRCT后筋膜-骨界面和筋膜-肌肉界面的组织学和生物力学愈合情况。研究设计：对照实验室研究。方法：作者在大鼠右肩建立慢性MIRCT模型，然后使用STR或桥接修复技术对其进行修复。在第 2、4、8 和 12 周时进行评估，包括组织学、成像、生物力学和功能分析。结果：根据组织学结果，两种技术均实现了良好的筋膜-骨界面愈合。与桥接修复组相比，STR组在第8周和第12周时有明显更多的软骨形成，并且在12周后筋膜-骨界面处的改良肌腱成熟度评分更高，并形成了典型的四层结构。 12周时，筋膜-肌肉和筋膜-肌腱界面中的胶原纤维表现出正常的肌肉-肌腱界面特征。然而，与桥接修复组相比，STR 组在脂肪浸润方面有更多改善。术后 4 周，STR 组和桥接修复组的筋膜-骨界面和冈上肌-筋膜-骨完整性的最终失效载荷和刚度没有差异。 12周时STR组的运动距离和抓握时间明显长于桥接修复组，并与正常对照组持平。结论：这些结果表明STR技术的筋膜-肌肉界面在组织学和功能上是良好的。比筋膜-肌腱界面更好。本研究为STR技术的临床应用提供了理论依据。 临床意义：筋膜-肌肉界面和筋膜-肌腱界面分别是STR技术和桥接技术的关键点。筋膜-肌肉界面在组织学和功能上优于桥接技术，STR技术可能是治疗MIRCT的更好选择。