Daly Charles A, Boden Allison L, Hutton William C, Gottschalk Michael B
Emory University, Atlanta, GA, USA.
Emory Orthopaedics & Spine Center, Atlanta, GA, USA.
Hand (N Y). 2019 Nov;14(6):760-764. doi: 10.1177/1558944718769385. Epub 2018 Apr 4.
Current techniques for fixation of proximal pole scaphoid fractures utilize antegrade fixation via a dorsal approach endangering the delicate vascular supply of the dorsal scaphoid. Volar and dorsal approaches demonstrate equivalent clinical outcomes in scaphoid wrist fractures, but no study has evaluated the biomechanical strength for fractures of the proximal pole. This study compares biomechanical strength of antegrade and retrograde fixation for fractures of the proximal pole of the scaphoid. A simulated proximal pole scaphoid fracture was produced in 22 matched cadaveric scaphoids, which were then assigned randomly to either antegrade or retrograde fixation with a cannulated headless compression screw. Cyclic loading and load to failure testing were performed and screw length, number of cycles, and maximum load sustained were recorded. There were no significant differences in average screw length (25.5 mm vs 25.6 mm, = .934), average number of cyclic loading cycles (3738 vs 3847, = .552), average load to failure (348 N vs 371 N, = .357), and number of catastrophic failures observed between the antegrade and retrograde fixation groups (3 in each). Practical equivalence between the 2 groups was calculated and the 2 groups were demonstrated to be practically equivalent (upper threshold = .010). For this model of proximal pole scaphoid wrist fractures, antegrade and retrograde screw configuration have been proven to be equivalent in terms of biomechanical strength. With further clinical study, we hope surgeons will be able to make their decision for fixation technique based on approaches to bone grafting, concern for tenuous blood supply, and surgeon preference without fear of poor biomechanical properties.
目前用于固定舟骨近端骨折的技术采用经背侧入路的顺行固定，这会危及舟骨背侧 delicate 的血管供应。掌侧和背侧入路在舟骨腕部骨折中显示出相当的临床疗效，但尚无研究评估近端骨折的生物力学强度。本研究比较了舟骨近端骨折顺行和逆行固定的生物力学强度。在 22 对匹配的尸体舟骨上制作模拟舟骨近端骨折，然后随机分配用无头空心加压螺钉进行顺行或逆行固定。进行循环加载和破坏载荷测试，并记录螺钉长度、循环次数和承受的最大载荷。顺行和逆行固定组之间在平均螺钉长度（25.5 mm 对 25.6 mm，P = 0.934）、平均循环加载次数（3738 对 3847，P = 0.552）、平均破坏载荷（348 N 对 371 N，P = 0.357）以及观察到的灾难性失败数量（每组 3 例）方面均无显著差异。计算了两组之间的实际等效性，结果表明两组实际等效（上限阈值 = 0.010）。对于这种舟骨近端腕部骨折模型，已证明顺行和逆行螺钉配置在生物力学强度方面是等效的。通过进一步的临床研究，我们希望外科医生能够根据植骨方法、对脆弱血供的担忧以及外科医生的偏好来决定固定技术，而不必担心生物力学性能不佳。
