Background:

Various patches have been used to bridge massive rotator cuff tears (MRCTs) by reconnecting the cuff tendons to the humeral head, but the outcomes continue to be suboptimal. Notably, the graft-bone junction is a vulnerable site for failure, which requires optimization in patch design and techniques to enhance initial and postoperative fixation strength at the graft-bone interface.

Hypothesis:

The plug-type patch (Plug-Pat) through intratunnel fixation would optimize mechanical characteristics in initial graft-to-bone fixation and subsequently improve postoperative biomechanical and histological properties in graft-to-bone healing when compared with the routine rectangular patch (Rect-Pat).

Study Design:

Controlled laboratory study.

Methods:

A total of 60 mature male New Zealand White rabbits underwent acute rotator cuff defects to create chronic models with MRCTs. The fascia lata autograft was then harvested to prepare a Plug-Pat, which was distally rooted in the bone tunnel and proximally sutured to native tendons in a horizontal mattress fashion to reconnect the humeral head and cuff tendons. The control group was repaired with a routine Rect-Pat that was secured onto the bone surface for graft-bone fixation. After surgery, the cuff-graft-bone complexes of rabbits in both groups were harvested immediately (0 weeks) for time-zero initial fixation strength and refreshed contact area assessment, and at 6 or 12 weeks for postoperative biomechanical and histological evaluation.

Results:

The Plug-Pat significantly enhanced initial fixation strength in comparison with the Rect -Pat (mean ± SD; failure load, 36.79 ± 4.53 N vs 24.15 ± 2.76 N; P < .001) and decreased failure at the graft-bone interface of the construct at 0 weeks, with a significantly increased refreshed bone bed contact area (52.63 ± 2.97 mm² vs 18.28 ± 1.60 mm²; P < .001) between the graft and bone. At 6 and 12 weeks postoperatively, the Plug-Pat similarly resulted in greater failure load (43.15 ± 4.53 N vs 33.74 ± 2.58 N at 6 weeks; P = .001; 76.65 ± 5.04 N vs 58.17 ± 5.06 N at 12 weeks; P < .001) and stiffness (10.77 ± 2.67 N/mm vs 8.43 ± 0.86 N/mm at 6 weeks; P = .066; 16.98 ± 2.47 N/mm vs 13.21 ± 1.66 N/mm at 12 weeks; P = .011), with less specimen failure at the graft-bone interface than the Rect-Pat. In histological analyses, the Plug-Pat had a higher postoperative graft-bone integration score than the Rect-Pat, showing a more mature intratunnel healing interface with fibrocartilage tidemark formation, improved collagen properties, and more oriented cells when compared with those at the surface healing interface in the Rect-Pat.

Conclusion:

The Plug-Pat enhanced initial fixation strength and enlarged the refreshed contact area for graft-bone connection at time zero and subsequently improved postoperative biomechanical properties and graft-bone integration at the graft-bone healing interface when compared with the Rect-Pat.

Clinical Relevance:

The Plug-Pat using intratunnel fixation may be a promising strategy for patch design to optimize its initial and postoperative graft-bone connection for bridging reconstruction of MRCTs.

中文翻译：

---

插头型补片在慢性兔模型中桥接大量肩袖撕裂的移植物与骨整合中具有即时和术后优势

背景：

通过将袖带肌腱重新连接到肱骨头，已使用各种贴片来弥合大量肩袖撕裂 (MRCT)，但结果仍然不是最佳的。值得注意的是，移植骨连接处是一个易发生故障的部位，需要优化补片设计和技术，以增强移植骨界面处的初始和术后固定强度。

假设：

与常规矩形补片（Rect-拍）。

学习规划：

受控实验室研究。

方法：

共有 60 只成熟的雄性新西兰白兔接受了急性肩袖缺损，以创建具有 MRCT 的慢性模型。然后收获自体阔筋膜以制备 Plug-Pat，其远端植根于骨隧道中，近端以水平床垫方式与天然肌腱缝合，以重新连接肱骨头和袖带肌腱。对照组采用常规 Rect-Pat 修复，固定在骨表面用于移植骨固定。术后立即（0周）采集两组兔的袖带-移植物-骨复合体进行零时间初始固定强度和更新接触面积评估，并在6或12周进行术后生物力学和组织学评估。

结果：

与 Rect -Pat 相比，Plug-Pat 显着增强了初始固定强度（平均值 ± SD；失效载荷，36.79 ± 4.53 N 对比 24.15 ± 2.76 N；P < .001）并减少了移植物-骨界面处的失效在 0 周时构建，移植物和骨之间的更新骨床接触面积显着增加（52.63 ± 2.97 mm ² vs 18.28 ± 1.60 mm ²；P < .001）。在术后 6 周和 12 周，Plug-Pat 同样导致更大的失败负荷（43.15 ± 4.53 N vs 33.74 ± 2.58 N，6 周；P = .001；76.65 ± 5.04 N vs 58.17 ± 5.06 N，12 周；P < .001) 和刚度 (10.77 ± 2.67 N/mm vs 8.43 ± 0.86 N/mm 6 周；P= .066; 16.98 ± 2.47 N/mm 对比 13.21 ± 1.66 N/mm 在 12 周；P = .011)，与 Rect-Pat 相比，移植骨界面处的样本失败更少。在组织学分析中，Plug-Pat 的术后移植骨整合评分高于 Rect-Pat，与表面的相比，显示出更成熟的隧道内愈合界面，纤维软骨潮标形成，改善的胶原蛋白特性和更多定向细胞Rect-Pat 中的愈合界面。

结论：

与 Rect-Pat 相比，Plug-Pat 增强了初始固定强度并扩大了在零时间时移植骨连接的更新接触面积，随后改善了移植骨愈合界面处的术后生物力学特性和移植骨整合。

临床相关性：

使用隧道内固定的 Plug-Pat 可能是一种有前途的补片设计策略，以优化其初始和术后移植骨连接，用于 MRCT 的桥接重建。