Johnson Joey P, Borenstein Todd R, Waryasz Gregory R, Klinge Stephen A, McClure Philip K, Chambers Alison B, Hayda Roman A, Born Christopher T
*Department of Orthopaedic Surgery, Warren Alpert Medical School, Brown University, Providence, RI; †Division of Orthopaedic Trauma, Department of Orthopaedic Surgery, Warren Alpert Medical School, Brown University, Providence, RI; ‡Department of Orthopedic Sports Medicine, University of Connecticut Department of Orthopedics, Farmington, CT; and §Department of Pediatric Orthopedics, Texas Scottish Rite Hospital, Dallas, TX.
J Orthop Trauma. 2017 Jul;31(7):363-368. doi: 10.1097/BOT.0000000000000836.
To compare the static and dynamic mechanical properties of a modified crossed cannulated screw (CS) configuration, the inverted triangle (IT) cannulated screw configuration, and a compression hip screw (CHS) with derotation screw in Pauwels type III femoral neck fractures.
Thirty synthetic femora were divided into 3 groups, and vertical femoral neck osteotomies were made. Ten osteotomized femora were fixed with a CS configuration, 10 were fixed with 3 parallel screws in an IT configuration, and the remaining 10 osteotomized femora were fixed with a CHS construct. All groups were tested using a cyclic (up to 15,000 load cycles) axial loading protocol, and survivors were statically loaded to failure. Cycles to failure, load to failure, and stiffness were calculated. The Kaplan-Meier method was used to estimate survival functions and were compared among fixation methods. The relationship between construct structural properties (maximum load and stiffness) and treatment were assessed using general linear modeling.
All CHS fixation constructs survived the 15,000 cycle loading protocol. They endured longer (P = 0.034) than the CS fixation constructs (mean failure 13,332 cycles), but were not different from IT fixation constructs (mean failure 13,592 cycles). Maximum loads to failure for CS (3870 N) and IT (3756 N) fixation constructs were not different, but were less (P < 0.0001) than the maximum loads to failure for the CHS fixation constructs (5654 N). These findings parallel the results of the axial stiffness measurements: CS fixation constructs (663.01 N/mm) were not stiffer than IT fixation constructs (620.0 N/mm), but were less (P = 0.0005) than the axial stiffness of the CHS fixation constructs (1241.86 N/mm).
The biomechanical performance of the CHS fixation method was superior to both the CS fixation method and the IT fixation method using a synthetic femoral model and this test protocol. Biomechanical performance of the latter 2 groups was indistinguishable. We recommend the use of CHS with the derotational screw construct for Pauwels III femoral neck fractures whenever possible.
比较改良交叉空心钉（CS）构型、倒三角（IT）空心钉构型以及带防旋螺钉的加压髋螺钉（CHS）在 Pauwels III 型股骨颈骨折中的静态和动态力学性能。
将 30 根合成股骨分为 3 组，并制作垂直股骨颈截骨模型。10 根截骨后的股骨采用 CS 构型固定，10 根采用 IT 构型的 3 根平行螺钉固定，其余 10 根截骨后的股骨采用 CHS 结构固定。所有组均采用循环（高达 15000 次加载循环）轴向加载方案进行测试，对幸存者进行静态加载直至失效。计算失效循环次数、失效载荷和刚度。采用 Kaplan-Meier 方法估计生存函数，并在不同固定方法之间进行比较。使用一般线性模型评估结构性能（最大载荷和刚度）与治疗方法之间的关系。
所有 CHS 固定结构均在 15000 次循环加载方案中存活。它们的耐受时间比 CS 固定结构更长（P = 0.034）（平均失效 13332 次循环），但与 IT 固定结构无差异（平均失效 13592 次循环）。CS（3870 N）和 IT（3756 N）固定结构的最大失效载荷无差异，但低于 CHS 固定结构的最大失效载荷（5654 N）（P < 0.0001）。这些结果与轴向刚度测量结果一致：CS 固定结构（663.01 N/mm）的刚度不高于 IT 固定结构（620.0 N/mm），但低于 CHS 固定结构的轴向刚度（1241.86 N/mm）（P = 0.0005）。
在使用合成股骨模型和该测试方案时，CHS 固定方法的生物力学性能优于 CS 固定方法和 IT 固定方法。后两组的生物力学性能无明显差异。我们建议尽可能对 Pauwels III 型股骨颈骨折使用带防旋螺钉结构的 CHS。
