Kevin Baker, Beaumont Research Institute, 3811 W 13 Mile Rd, Suite 404, Royal Oak, MI 48073.
Am J Sports Med. 2013 Oct;41(10):2278-87. doi: 10.1177/0363546513498999. Epub 2013 Aug 12.
Ulnar collateral ligament (UCL) reconstruction aims to restore valgus stability, and numerous techniques have been described in the literature. HYPOTHESIS/ PURPOSE: To biomechanically compare the GraftLink (GL) technique with traditional bone tunnels used in the docking (DO) technique. It is hypothesized that the GL method will offer a stiffer, less lax construct compared with the DO.
Controlled laboratory study.
Native and reconstructed states were tested in 7 matched pairs of cadaveric arms. To test kinematics, a 1.5-N·m valgus torque was applied and the resultant displacement at 15° to 90° of flexion was measured. Dissipated energy and the torque at the peak of the 10th cycle of preconditioning were analyzed during kinematic tests. Failure testing was performed by internal rotation of the humerus at 4.5 deg/s in 70° of flexion. Ulnotrochlear joint (UTJ) gapping was quantified during failure tests by use of video tracking.
Kinematics testing revealed no differences between the native state and the reconstructed state in either the DO or the GL group at any flexion angle. Stiffness was lower in the reconstructed specimens in both the DO (39.92 N·m/rad) and GL (50.74 N·m/rad) groups compared with their matched native states (DO Native, 71.41 N·m/rad, P = .005; GL Native, 86.36 N·m/rad, P = .002). There was no difference in stiffness between DO and GL. Reconstructed specimens in the GL group had lower torque at failure compared with native specimens (17.404 N·m vs 24.63 N·m, P = .038), but there was no difference in the DO group at failure. There was no difference in torque at failure between DO and GL. The DO exhibited higher angular displacement at failure compared with the native state (34.21° vs 21.79°, P = .010) and compared with the GL when normalized (1.58-fold vs 1.19-fold, P = .039). Compared with their native states, both DO and GL had significantly higher UTJ gapping at 3 N·m and at failure. The DO had significantly higher normalized UTJ gapping than the GL at 3 N·m (P = .037) and at failure (P = .043).
The DO and GL both restored joint kinematics under low loading conditions. Although less stiff, the GL exhibited lower joint gapping and laxity than did the DO.
Understanding the biomechanics of UCL reconstruction has significant implications for postoperative management as it relates to early rehabilitation. Biomechanically inferior constructs could risk graft failure or early loosening during rehabilitation, and comparing the biomechanics of new techniques to established, widely used procedures such as the docking technique can provide important information about the immediate postoperative performance.
尺侧副韧带（UCL）重建旨在恢复外翻稳定性，文献中已经描述了许多技术。假说/目的：对 GraftLink（GL）技术与传统的对接（DO）技术中的骨隧道进行生物力学比较。假设 GL 方法将提供比 DO 更坚固、更不易松弛的结构。
对照实验室研究。
在 7 对匹配的 cadaveric 手臂中对自然状态和重建状态进行了测试。为了测试运动学，施加了 1.5-N·m 的外翻扭矩，并测量了在 15°到 90°屈曲时的相应位移。在运动学测试过程中分析了耗散能量和预条件化第 10 个循环的峰值扭矩。失效测试通过在 70°屈曲时以 4.5 度/秒的速度对内旋转肱骨进行。在失效测试过程中，使用视频跟踪量化了尺侧滑车关节（UTJ）张开度。
在任何屈曲角度下，DO 或 GL 组的自然状态和重建状态的运动学测试均无差异。与各自的自然状态相比，DO（39.92 N·m/rad）和 GL（50.74 N·m/rad）组的重建标本的刚度均较低（DO Native，71.41 N·m/rad，P =.005；GL Native，86.36 N·m/rad，P =.002）。DO 和 GL 之间的刚度没有差异。GL 组的重建标本的失效扭矩低于自然标本（17.404 N·m 与 24.63 N·m，P =.038），但 DO 组在失效时没有差异。DO 和 GL 之间的失效扭矩没有差异。与自然状态相比，DO 在失效时的角度位移更高（34.21°与 21.79°，P =.010），与 GL 相比归一化后更高（1.58 倍与 1.19 倍，P =.039）。与自然状态相比，DO 和 GL 在 3 N·m 和失效时的 UTJ 张开度均显著增加。与 GL 相比，DO 在 3 N·m（P =.037）和失效时（P =.043）的标准化 UTJ 张开度更高。
DO 和 GL 都在低负荷条件下恢复了关节运动学。尽管 GL 不那么僵硬，但与 DO 相比，它的关节间隙和松弛度更低。
了解 UCL 重建的生物力学具有重要意义，因为它与术后管理有关，与早期康复有关。生物力学上较差的结构可能会导致在康复期间移植物失败或早期松动，并且将新技术的生物力学与广泛使用的技术（如对接技术）进行比较，可以提供有关术后性能的重要信息。
