螺钉垂直度对舟状骨腰部骨折加压的影响。
Effect of Screw Perpendicularity on Compression in Scaphoid Waist Fractures.
作者信息
Swanstrom Morgan M, Morse Kyle W, Lipman Joseph D, Hearns Krystle A, Carlson Michelle G
机构信息
Division of Hand and Upper Extremity Surgery, Hospital for Special Surgery, New York, New York.
Department of Biomechanics, Hospital for Special Surgery, New York, New York.
出版信息
J Wrist Surg. 2017 Aug;6(3):178-182. doi: 10.1055/s-0036-1596059. Epub 2016 Dec 1.
Central and perpendicular (PERP) screw orientations have each been described for scaphoid fracture fixation. It is unclear, however, which orientation produces greater compression. This study compares compression in scaphoid waist fractures with screw fixation in both PERP and pole-to-pole (PTP) configurations. PERP orientation was hypothesized to produce greater compression than PTP orientation. Ten preoperative computed tomography scans of scaphoid waist fractures were classified by fracture type and orientation in the coronal and sagittal planes. Three-dimensional models of each scaphoid and fracture plane were created. Simulated Acutrak 2 (Acumed, Hillsboro, OR) screws were placed into the models in both PERP and PTP orientations. Engagement length and screw angle relative to the fracture were measured. Compression strength was calculated from the shear area, average density, and angle acuity. The PTP angle between screw and fracture ranged from 36 to 84 degrees. By definition, the PERP screw-to-fracture angle was 90 degrees. Perpendicularity of the PTP screw to the fracture was positively correlated to compression strength. PERP screws had greater compression than PTP screws when the PTP screw-to-fracture angle was < 80 degrees (106 vs. 80 N), but there was no difference in compression when the PTP screw-to-fracture angle was > 80 degrees, approximating the PERP screw. Increasing screw perpendicularity resulted in higher compression when the screw-to-fracture angle of the PTP screw was < 80 degrees. Maximum compression was obtained with a screw PERP to the fracture. The increased compression gained from PERP screw placement offsets the decreased engagement length. These results provide guidelines for optimal screw placement in scaphoid waist fractures.
舟骨骨折固定术已分别描述了中心和垂直(PERP)螺钉方向。然而,尚不清楚哪种方向能产生更大的压缩力。 本研究比较了舟骨腰部骨折采用PERP和极对极(PTP)两种构型螺钉固定时的压缩情况。假设PERP方向比PTP方向能产生更大的压缩力。 对10例舟骨腰部骨折的术前计算机断层扫描,根据骨折类型以及在冠状面和矢状面的方向进行分类。创建了每个舟骨和骨折平面的三维模型。将模拟的Acutrak 2(Acumed,俄勒冈州希尔斯伯勒)螺钉以PERP和PTP两种方向置入模型中。测量了螺钉相对于骨折的啮合长度和角度。根据剪切面积、平均密度和角度锐度计算压缩强度。
螺钉与骨折之间的PTP角度范围为36至84度。根据定义,PERP螺钉与骨折的角度为90度。PTP螺钉与骨折的垂直度与压缩强度呈正相关。当PTP螺钉与骨折的角度<80度时,PERP螺钉的压缩力大于PTP螺钉(106对80 N),但当PTP螺钉与骨折的角度>80度时,压缩力无差异,接近PERP螺钉。
当PTP螺钉与骨折的角度<80度时,螺钉垂直度增加会导致更高的压缩力。螺钉垂直于骨折时可获得最大压缩力。PERP螺钉置入增加的压缩力抵消了啮合长度的减少。
这些结果为舟骨腰部骨折的最佳螺钉置入提供了指导。