Department of Research and Innovation, Møre and Romsdal Hospital Trust, Ålesund, Norway.
Department of Orthopaedic Surgery, Møre and Romsdal Hospital Trust, Ålesund, Norway.
Foot Ankle Int. 2023 Sep;44(9):895-904. doi: 10.1177/10711007231180212. Epub 2023 Jul 21.
Conventionally, transsyndesmotic fibula fractures with concomitant signs of deltoid ligament injury have been considered unstable and thus treated operatively. Recent studies have indicated that partial deltoid ligament rupture is common and may allow for nonoperative treatment of stress-unstable ankles if normal tibiotalar alignment is obtained in the weightbearing position. Biomechanical support for this principle is scarce. The purpose of this study was to evaluate the biomechanical effects of gradually increasing deltoid ligament injury in transsyndesmotic fibula fractures.
Fifteen cadaveric ankle specimens were tested using an industrial robot. All specimens were tested in 4 states: native, SER2, SER4a, and SER4b models. Ankle stability was measured in lateral translation, valgus, and internal and external rotation stress in 3 talocrural joint positions: 20 degrees plantarflexion, neutral, and 10 degrees dorsiflexion. Talar shift and talar valgus tilt in the talocrural joint was measured using fluoroscopy.
In most tests, SER2 and SER4a models resulted in a small instability increase compared to native joints and thus were deemed stable according to our predefined margins. However, SER4a models were unstable when tested in the plantarflexed position and for external rotation in all positions. In contrast, SER4b models had large-magnitude instability in all directions and all tested positions and were thus deemed unstable.
This study demonstrated substantial increases in instability between the SER4a and SER4b states. This controlled cadaveric simulation suggests a significant ankle-stabilizing role of the deep posterior deltoid after oblique transsyndesmotic fibular fracture and transection of the superficial and anterior deep deltoid ligaments.
The study provides new insights into how the heterogenicity of deltoid ligament injuries can affect the natural stability of the ankle after Weber B fractures. These findings may be useful in developing more targeted and better treatment strategies.
传统上，伴有三角韧带损伤迹象的 Syndesmotic 腓骨骨折被认为是不稳定的，因此需要手术治疗。最近的研究表明，部分三角韧带断裂很常见，如果在负重位获得正常的胫距对线，可以对不稳定的踝关节进行非手术治疗。支持这一原则的生物力学证据很少。本研究旨在评估 Syndesmotic 腓骨骨折中三角韧带损伤逐渐增加的生物力学影响。
使用工业机器人测试了 15 个尸体踝关节标本。所有标本均在 4 种状态下进行测试：原始、SER2、SER4a 和 SER4b 模型。在 3 个距下关节位置（20 度跖屈、中立和 10 度背屈）下，测量踝关节在侧向平移、外翻和内、外旋转应力下的稳定性。使用透视法测量距下关节中的距骨移位和距骨外翻倾斜。
在大多数测试中，与原始关节相比，SER2 和 SER4a 模型仅导致较小的不稳定性增加，因此根据我们预先定义的范围被认为是稳定的。然而，SER4a 模型在跖屈位和所有位置的外旋测试中不稳定。相比之下，SER4b 模型在所有方向和所有测试位置都具有较大的不稳定性，因此被认为是不稳定的。
本研究表明，SER4a 和 SER4b 状态之间的不稳定性有显著增加。这项对照尸体模拟研究表明，在斜形 Syndesmotic 腓骨骨折和浅层及前深层三角韧带切断后，深层后三角韧带对踝关节有显著的稳定作用。
该研究提供了新的见解，了解三角韧带损伤的异质性如何影响 Weber B 骨折后踝关节的自然稳定性。这些发现可能有助于制定更有针对性和更好的治疗策略。
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