Patel Neel K, Chan Calvin, Murphy Conor I, Debski Richard E, Musahl Volker, Hogan MaCalus V
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
Orthopaedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
Orthop J Sports Med. 2020 Sep 9;8(9):2325967120946744. doi: 10.1177/2325967120946744. eCollection 2020 Sep.
Disruption of the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), and interosseous membrane (IOM) is a predictive measure of residual symptoms after an ankle injury. Controversy remains regarding the ideal fixation technique for early return to sport, which requires restoration of tibiofibular kinematics with early weightbearing.
To quantify tibiofibular kinematics after syndesmotic fixation with different tricortical screw and suture button constructs during simulated weightbearing.
Controlled laboratory study.
A 6 degrees of freedom robotic testing system was used to test 9 fresh-frozen human cadaveric specimens (mean age, 65.1 ± 17.3 years). A 200-N compressive load was applied to the ankle, while a 5-N·m external rotation and a 5-N·m inversion moment were applied independently to the ankle at 0° of flexion, 15° and 30° of plantarflexion, and 10° of dorsiflexion. Fibular medial-lateral translation, anterior-posterior translation, and internal-external rotation relative to the tibia were tracked by use of an optical tracking system in the following states: (1) intact ankle; (2) AITFL, PITFL, and IOM transected ankle; (3) single-screw fixation; (4) double-screw fixation; (5) hybrid fixation; (6) single suture button fixation; and (7) divergent suture button fixation. Repeated-measures analysis of variance with Bonferroni correction was performed for statistical analysis.
In response to the external rotation moment and axial compression, single tricortical screw fixation resulted in significantly higher lateral translation of the fibula compared with that of the intact ankle at 10° of dorsiflexion ( < .05). Suture button fixation resulted in significantly higher posterior translation of the fibula at 0° of flexion and 10° of dorsiflexion, whereas divergent suture button fixation resulted in higher posterior translation at only 0° of flexion ( < .05). In response to the inversion moment and axial compression, single tricortical screw and hybrid fixation significantly decreased lateral translation in plantarflexion, whereas double tricortical screw fixation and hybrid fixation significantly decreased external rotation of the fibula compared with that of the intact ankle at 15° of plantarflexion ( < .05).
Based on the data in this study, hybrid fixation with 1 suture button and 1 tricortical screw may most appropriately restore tibiofibular kinematics for early weightbearing. However, overconstraint of motion during inversion may occur, which has unknown clinical significance.
Surgeons may consider this data when deciding on the best algorithm for syndesmosis repair and postoperative rehabilitation.
下胫腓前韧带（AITFL）、下胫腓后韧带（PITFL）和骨间膜（IOM）的断裂是踝关节损伤后残余症状的一项预测指标。对于早期恢复运动的理想固定技术仍存在争议，这需要在早期负重的情况下恢复胫腓关节的运动学。
量化在模拟负重过程中，使用不同的三皮质螺钉和缝线纽扣结构进行下胫腓联合固定后的胫腓关节运动学。
对照实验室研究。
使用一个6自由度机器人测试系统对9个新鲜冷冻的人体尸体标本（平均年龄65.1±17.3岁）进行测试。对踝关节施加200N的压缩载荷，同时在踝关节处于0°屈曲、15°和30°跖屈以及10°背屈时，分别独立施加5N·m的外旋和5N·m的内翻力矩。在以下状态下，使用光学跟踪系统追踪腓骨相对于胫骨的内外侧平移、前后平移以及内外旋转：（1）完整踝关节；（2）AITFL、PITFL和IOM横断的踝关节；（3）单螺钉固定；（4）双螺钉固定；（5）混合固定；（6）单缝线纽扣固定；（7）发散缝线纽扣固定。采用带有Bonferroni校正的重复测量方差分析进行统计分析。
在应对外旋力矩和轴向压缩时，在背屈10°时，单皮质螺钉固定导致腓骨的外侧平移显著高于完整踝关节（P<0.05）。缝线纽扣固定在屈曲0°和背屈10°时导致腓骨的后向平移显著更高，而发散缝线纽扣固定仅在屈曲0°时导致更高的后向平移（P<0.05）。在应对内翻力矩和轴向压缩时，单皮质螺钉和混合固定在跖屈时显著减少了外侧平移，而双皮质螺钉固定和混合固定在跖屈15°时导致腓骨的外旋相较于完整踝关节显著减少（P<0.05）。
基于本研究的数据，1个缝线纽扣和1个三皮质螺钉的混合固定可能最适合在早期负重时恢复胫腓关节的运动学。然而，内翻时可能会出现运动过度受限的情况，其临床意义尚不清楚。
外科医生在决定下胫腓联合修复和术后康复的最佳方案时可考虑这些数据。
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