Department of Orthopaedics, The Gold Coast University Hospital, Gold Coast, QLD, Australia.
Department of Orthopaedics, The Gold Coast University Hospital, Gold Coast, QLD, Australia.
J Shoulder Elbow Surg. 2019 Apr;28(4):e111-e116. doi: 10.1016/j.jse.2018.10.008. Epub 2019 Jan 24.
Fixation of a 3-part radial head fracture with cannulated compression screws will show equivalent stiffness to a locking plate under axial load. Debate exists regarding the management of Mason type III fractures, with many believing that open reduction and internal fixation provides advantages over other options. By virtue of their subarticular placement, screw fixation is less likely to cause impingement compared with plate fixation, which can result in loss of rotation and requirement for hardware removal. Insufficient fixation stability can lead to nonunions, necrosis of the radial head, pain, and instability. We tested the mechanical stability of fixation of simulated radial head fractures using headless compression screws compared with standard plate construct.
Standardized test constructs were created with repeatable osteotomy cuts and hardware placement on each Synbone model (Synbone AG, Malans, Switzerland). We presectioned 22 proximal radius Synbone models to simulate a 3-part radial head fracture. The models were fixed using a radial head locking plate or headless compression screws in a tripod construct. The constructs were potted into a compression test jig using 2-part epoxy resin. Compression testing was performed using a 30-kN Instron Universal machine (Instron, Norwood, MA, USA). The compression tool was spherical, representing the surface of the capitellum.
There was no significant difference between the stiffness of the Synbone constructs under axial load.
There was no significant difference between fixation stiffness of a 3-part radial head fracture with headless compression screws in a tripod structure vs. a locking plate in Synbone. Further study is required to allow clinical application.
经皮空心加压螺钉固定三部分桡骨头骨折在轴向负荷下的刚度与锁定钢板相当。对于 Mason Ⅲ型骨折的处理存在争议，许多人认为切开复位内固定优于其他选择。由于螺钉固定的位置靠近关节面，与钢板固定相比，发生撞击的可能性较小，而钢板固定可能导致旋转丧失和需要取出内固定物。固定稳定性不足可导致骨折不愈合、桡骨头坏死、疼痛和不稳定。我们比较了无头加压螺钉与标准钢板固定结构固定模拟桡骨头骨折的机械稳定性。
在每个 Synbone 模型（Synbone AG，Malans，瑞士）上，使用可重复的截骨和硬件放置来创建标准化的测试结构。我们预先切割了 22 个 Synbone 近端桡骨模型，以模拟三部分桡骨头骨折。模型采用桡骨头锁定钢板或无头加压螺钉以三脚架结构固定。使用 2 部分环氧树脂将构建体浇注到压缩测试夹具中。使用 30 kN 的 Instron 万能试验机（Instron，Norwood，MA，USA）进行压缩测试。压缩工具为球形，代表头状骨的表面。
在轴向负荷下，Synbone 结构的刚度没有显著差异。
在 Synbone 中，三部分桡骨头骨折的无头加压螺钉固定在三脚架结构中的固定刚度与锁定钢板无显著差异。需要进一步的研究才能允许临床应用。
