Stewart Rebecca, Kieser David C, Scholze Mario, Hammer Niels, Stone Brad, Hooper Gary
Department of Orthopaedic Surgery and MSM, Christchurch Hospital, Christchurch, New Zealand.
Anatomy-Biomechanics Laboratory, Department of Anatomy, University of Otago, Dunedin, New Zealand.
ANZ J Surg. 2018 Oct;88(10):1051-1055. doi: 10.1111/ans.14822. Epub 2018 Aug 23.
Vertical shear fractures are unstable and potentially life-threatening injuries that require urgent reduction and stabilization. The aim of this study was to compare the biomechanical efficacy of three different external fixation pin configurations for vertical shear pelvic fractures in a cadaveric model. We hypothesized that a modified external fixation pin configuration with a crestal (CR) pin in the stable hemipelvis and bilateral supra-acetabular (SA) pins provides the greatest overall stability to axial loading.
The force to failure within a standard standing axial load (maximum 650 N) was tested on 10 human cadaveric pelvises with vertical shear fractures. Three pin configurations were compared including iliac crest (IC), SA and a modified SA frame with a third CR pin on the stable hemipelvis. Both displacement at the posterior pelvis at 650 N and force to failure of >25 mm displacement was recorded.
The mean force to failure was highest with CR (499 N), then IC (350 N) and then SA (265 N) pin configurations, being statistically non-significant (P = 0.165). The minimum force to failure followed a similar trend with 296, 68 and 43 N for CR, IC and SA, respectively. About 1/4 CR, 1/4 IC and 2/9 SA pins sustained 650 N or more without failure.
It was shown that this new design may reliably withstand a seated physiological load of 250 N. However, none of the three pin configurations tested can reliably withstand a standing load of 650 N. Further experiments are needed to quantify these findings under physiological loading.
垂直剪切骨折不稳定且可能危及生命，需要紧急复位和固定。本研究的目的是在尸体模型中比较三种不同外固定针配置用于垂直剪切型骨盆骨折的生物力学效果。我们假设在稳定半骨盆使用嵴部（CR）针和双侧髋臼上（SA）针的改良外固定针配置能为轴向载荷提供最大的整体稳定性。
对10例垂直剪切骨折的人体尸体骨盆进行标准站立轴向载荷（最大650 N）下的破坏载荷测试。比较了三种针配置，包括髂嵴（IC）、SA以及在稳定半骨盆带有第三根CR针的改良SA框架。记录了650 N时骨盆后部的位移以及位移>25 mm时的破坏载荷。
CR针配置的平均破坏载荷最高（499 N），其次是IC（350 N），然后是SA（265 N）针配置，差异无统计学意义（P = 0.165）。最小破坏载荷也呈类似趋势，CR、IC和SA分别为296、68和43 N。约1/4的CR针、1/4的IC针和2/9的SA针能承受650 N或更高载荷而不发生破坏。
结果表明这种新设计可能可靠地承受250 N的坐姿生理载荷。然而，所测试的三种针配置均不能可靠地承受650 N的站立载荷。需要进一步实验在生理载荷下量化这些结果。
