Background Studies on ankle syndesmosis have focused on anterior inferior tibiofibular ligament (AITFL) and interosseous membrane injuries; however, the characteristics of posterior inferior tibiofibular ligament (PITFL) ruptures remain unclear. Purpose/Hypothesis This study evaluated the biomechanical characteristics of syndesmotic instability caused by PITFL injury and compared various treatment methods. We hypothesized that PITFL injury would lead to syndesmotic internal rotational instability and that the stability would be restored with suture tape (ST) PITFL augmentation. Study Design Controlled laboratory study. Methods Ten uninjured fresh-frozen cadaveric leg specimens were tested via forces applied to the external and internal rotation of the ankle joint. The fibular rotational angle (FRA) related to the tibia, anterior tibiofibular diastasis (aTFD), and posterior tibiofibular diastasis (pTFD) were measured using a magnetic tracking system. Six models were created: (1) intact, (2) AITFL injury; (3) AITFL + PITFL injury; (4) suture button (SB) fixation; (5) SB + anterior ST (aST) fixation; and (6) SB + aST + posterior ST fixation. The FRA, aTFD, and pTFD were statistically compared between the intact ankle and each injury or fixation model. Results In the intact state, the changes in FRA and aTFD were 1.09° and 0.33 mm when external rotation force was applied and were 0.57° and 0.41 mm when internal rotation force was applied. In the AITFL injury model, the changes in FRA and aTFD were 2.38° and 1.51 mm when external rotation force was applied, which were significantly greater versus intact (P = .032 and .008, respectively). In the AITFL + PITFL injury model, the changes in FRA and pTFD were 2.12° and 1.02 mm when internal rotation force was applied, which were significantly greater versus intact (P = .007 and .003, respectively). In the SB fixation model, the change in FRA was 2.98° when external rotation force was applied, which was significantly higher compared with intact (P < .001). There were no significant differences between the SB + aST fixation model and the intact state on any measurement. Conclusion PITFL injury significantly increased syndesmotic instability when internal rotation force was applied. SB + aST fixation was effective in restoring syndesmotic stability. Clinical Relevance These results suggest that SB + aST fixation is sufficient for treating severe syndesmotic injury with PITFL rupture.

中文翻译：

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胫腓后韧带断裂联合损伤治疗方法的比较：尸体生物力学研究。

背景 踝关节联合的研究主要集中在前下胫腓韧带（AITFL）和骨间膜损伤。然而，后下胫腓韧带（PITFL）断裂的特征仍不清楚。目的/假设 本研究评估了由 PITFL 损伤引起的联合不稳定性的生物力学特征，并比较了各种治疗方法。我们假设 PITFL 损伤会导致联合内部旋转不稳定，并且通过缝合带 (ST) PITFL 增强可以恢复稳定性。研究设计 受控实验室研究。方法通过施加于踝关节外旋和内旋的力对10个未受伤的新鲜冷冻尸体腿标本进行测试。与胫骨相关的腓骨旋转角（FRA），使用磁跟踪系统测量前胫腓分离（aTFD）和后胫腓分离（pTFD）。创建了六个模型：(1) 完整的，(2) AITFL 损伤；(3) AITFL+PITFL 损伤；(4)缝合纽扣(SB)固定；（5）SB+前ST（aST）固定；(6) SB + aST + 后 ST 固定。FRA、aTFD 和 pTFD 在完整踝关节和每个损伤或固定模型之间进行了统计比较。结果在完好状态下，外旋时FRA和aTFD的变化分别为1.09°和0.33 mm，内旋时分别为0.57°和0.41 mm。在 AITFL 损伤模型中，当施加外旋转力时，FRA 和 aTFD 的变化分别为 2.38° 和 1.51 mm，与完整相比明显更大（分别为 P = 0.032 和 0.008）。在 AITFL + PITFL 损伤模型中，当施加内旋力时，FRA 和 pTFD 的变化分别为 2.12° 和 1.02 mm，与完整相比明显更大（分别为 P = .007 和 0.003）。在SB固定模型中，外旋力作用下FRA的变化为2.98°，明显高于完整模型（P < .001）。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。施加内旋转力时为 02 毫米，与完整相比显着更大（分别为 P = 0.007 和 0.003）。在SB固定模型中，外旋力作用下FRA的变化为2.98°，明显高于完整模型（P < .001）。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。施加内旋转力时为 02 毫米，与完整相比显着更大（分别为 P = 0.007 和 0.003）。在SB固定模型中，外旋力作用下FRA的变化为2.98°，明显高于完整模型（P < .001）。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。在SB固定模型中，外旋力作用下FRA的变化为2.98°，明显高于完整模型（P < .001）。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。在SB固定模型中，外旋力作用下FRA的变化为2.98°，明显高于完整模型（P < .001）。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。在任何测量中，SB + aST 固定模型和完整状态之间没有显着差异。结论 PITFL 损伤在施加内旋力时显着增加了联合不稳定性。SB + aST 固定可有效恢复联合稳定性。临床相关性 这些结果表明，SB + aST 固定足以治疗伴有 PITFL 破裂的严重联合损伤。