Orthopaedic Biomechanics Laboratory, Congress Medical Foundation, Pasadena, CA, USA; Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
Orthopaedic Biomechanics Laboratory, Congress Medical Foundation, Pasadena, CA, USA; Department of Orthopedic Surgery, Osaka Medical College, Takatsuki, Osaka, Japan.
J Shoulder Elbow Surg. 2021 Jul;30(7):1477-1486. doi: 10.1016/j.jse.2020.10.034. Epub 2020 Dec 2.
Ulnar collateral ligament (UCL) repair with single-strand suture augmentation has been introduced as a viable surgical option for throwers with acute UCL tears. For the original single-strand suture augmentation construct, revision UCL reconstructions can be challenging owing to the bone loss at the site of anchor insertion in the center of the sublime tubercle. This biomechanical study assessed a small-diameter (1.5-mm) ulnar bone tunnel technique for double-strand suture-augmented UCL repair that may be more easily converted to salvage UCL reconstruction if necessary, as well as a salvage UCL reconstruction with a docking technique after a failed primary suture-augmented UCL repair.
In 7 fresh-frozen cadaveric upper extremities (mean age, 66.3 years), a custom shoulder testing system was used to simulate the late cocking phase of throwing. The elbow valgus opening angle was evaluated using a MicroScribe 3DLX device for sequentially increasing valgus torque (from 0.75 to 7.5 Nm in 0.75-Nm increments) at 90° of flexion. Valgus angular stiffness (in newton-meters per degree) was defined as the correlation of sequentially increasing valgus torque with the valgus opening angle through simple linear regression (slope of valgus torque - valgus opening angle curve). Four conditions were tested: intact elbow, distal UCL avulsion, primary UCL repair with double-strand suture augmentation using small-diameter bone tunnels, and subsequent docking UCL reconstruction in the same specimen. Load-to-failure tests were performed for primary UCL repair with double-strand suture augmentation and subsequent docking UCL reconstruction.
With increasing elbow valgus torque, the valgus opening angle increased linearly in each condition (R ≥ 0.98, P < .001). Distal UCL avulsion resulted in significantly decreased angular stiffness compared with the intact UCL (P < .001). Both UCL repair with double-strand suture augmentation and subsequent UCL reconstruction showed significantly increased angular stiffness values compared with distal UCL avulsion (P < .001 and P < .001, respectively). On load-to-failure testing, there was no significant difference in stiffness, yield torque, and ultimate torque between the primary suture-augmented UCL repair and the subsequent UCL reconstruction (P = .11, P = .77, and P = .38, respectively). In all specimens undergoing the small-diameter ulnar bone tunnel technique for double-strand suture-augmented UCL repair, failure occurred by retear of the repaired ligament without causing an ulnar bone bridge fracture.
Primary UCL repair with double-strand suture augmentation using small-diameter bone tunnels was able to restore valgus stability. When failure occurs, this technique retains enough cortical bone to permit subsequent docking UCL reconstruction.
对于急性 UCL 撕裂的投掷者，采用单股缝线增强的尺侧副韧带 (UCL) 修复已被引入作为一种可行的手术选择。对于最初的单股缝线增强结构，由于在 sublime 结节中心的锚钉插入部位的骨质丢失， revision UCL 重建可能具有挑战性。这项生物力学研究评估了一种小直径（1.5 毫米）尺骨骨隧道技术，用于双股缝线增强 UCL 修复，如果需要，该技术可能更容易转换为 salvage UCL 重建，并且在初次缝线增强 UCL 修复失败后，采用 docking 技术进行 salvage UCL 重建。
在 7 个新鲜冷冻的上肢尸体标本（平均年龄 66.3 岁）中，使用定制的肩部测试系统模拟投掷的晚期扣球阶段。使用 MicroScribe 3DLX 设备评估肘外翻开口角度，在 90°屈曲下，逐渐增加外翻扭矩（以 0.75Nm 递增至 7.5Nm）。外翻角刚度（牛顿米/度）定义为通过简单线性回归（外翻扭矩-外翻开口角度曲线的斜率），逐渐增加外翻扭矩与外翻开口角度之间的相关性。测试了 4 种情况：完整的肘部、远端 UCL 撕脱、使用小直径骨隧道的初次 UCL 修复的双股缝线增强、以及同一标本中的后续 docking UCL 重建。对初次 UCL 修复的双股缝线增强和后续的 docking UCL 重建进行了失效负载测试。
随着肘外翻扭矩的增加，每种情况下的外翻开口角度都呈线性增加（R ≥ 0.98，P<.001）。远端 UCL 撕脱与完整的 UCL 相比，角刚度明显降低（P<.001）。UCL 修复的双股缝线增强和随后的 UCL 重建与远端 UCL 撕脱相比，角刚度值明显增加（P<.001 和 P<.001）。在失效负载测试中，初次缝线增强 UCL 修复和随后的 UCL 重建之间的刚度、屈服扭矩和最终扭矩没有显著差异（P=0.11、P=0.77 和 P=0.38）。在所有接受小直径尺骨骨隧道技术进行双股缝线增强 UCL 修复的标本中，修复韧带的再次撕裂而不是尺骨骨桥骨折导致失效。
使用小直径骨隧道的初次 UCL 修复的双股缝线增强能够恢复外翻稳定性。当失效发生时，该技术保留了足够的皮质骨，允许随后进行 docking UCL 重建。
