Bennett Chase, Behn Anthony, Daoud Adam, Nork Sean, Sangeorzan Bruce, Dikos Gregory, Bishop Julius
*Department of Orthopaedic Surgery, Stanford University Medical Center, Redwood City, CA; †Department of Orthopaedic Surgery, Harborview Medical Center, Seattle, WA; and ‡OrthoIndy at St.Vincent Indianapolis, Indianapolis, IN.
J Orthop Trauma. 2016 Dec;30(12):664-669. doi: 10.1097/BOT.0000000000000699.
The preferred method of fixation for posterior malleolus fractures remains controversial, and practices vary widely among surgeons. The purpose of this study was to compare anterior-to-posterior (AP) lag screws with posterior buttress plating for fixation of posterior malleolus fractures in a human cadaveric model.
Posterior malleolus fractures involving 30% of the distal tibial articular surface were created in 7 pairs of fresh frozen cadaveric ankles. One specimen in each pair was randomly assigned to fixation with either 2 AP lag screws or a one-third tubular buttress plate without supplemental lag screws. Each specimen was then subjected to cyclic loading from 0% to 50% of body weight for 5000 cycles followed by loading to failure. Outcome measures included permanent axial displacement during each test cycle (axial displacement at no load), peak axial displacement during each test cycle (axial displacement at 50% body weight), load at 1-mm axial displacement, ultimate load, and axial displacement at ultimate load.
The buttress plate group showed significantly less peak axial displacement at all time points during cyclic loading. Permanent axial displacement was significantly less in the buttress plate group beginning at cycle 200. There were no significant differences between the 2 groups during load-to-failure testing.
Posterior malleolus fractures treated with posterior buttress plating showed significantly less displacement during cyclical loading compared with fractures fixed with AP lag screws. Surgeons should consider these findings when selecting a fixation strategy for these common fractures. Further research is warranted to investigate the clinical implications of these biomechanical findings.
后踝骨折的首选固定方法仍存在争议，外科医生的做法差异很大。本研究的目的是在人体尸体模型中比较前后位（AP）拉力螺钉与后支撑钢板固定后踝骨折的效果。
在7对新鲜冷冻的尸体踝关节上制造累及胫骨远端关节面30%的后踝骨折。每对中的一个标本随机分配用2枚AP拉力螺钉或一块三分之一管状支撑钢板进行固定，不使用辅助拉力螺钉。然后对每个标本施加相当于体重0%至50%的循环载荷，持续5000个循环，随后加载至破坏。结果测量指标包括每个测试循环中的永久轴向位移（无载荷时的轴向位移）、每个测试循环中的峰值轴向位移（体重50%时的轴向位移）、轴向位移1毫米时的载荷、极限载荷以及极限载荷时的轴向位移。
支撑钢板组在循环加载过程中所有时间点的峰值轴向位移均显著较小。从第200个循环开始，支撑钢板组的永久轴向位移显著较小。在破坏载荷测试中，两组之间无显著差异。
与用AP拉力螺钉固定的骨折相比，采用后支撑钢板治疗的后踝骨折在循环加载过程中的位移显著较小。外科医生在为这些常见骨折选择固定策略时应考虑这些发现。有必要进行进一步研究以探讨这些生物力学发现的临床意义。
