Martin Dennis P, Park Andrew G, Jamison David, Jones Christopher M, Ilyas Asif M
The Rothman Institute, Department of Orthopedic Surgery, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA.
The Rothman Institute, Department of Orthopedic Surgery, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA.
J Hand Surg Am. 2019 Dec;44(12):1093.e1-1093.e8. doi: 10.1016/j.jhsa.2019.02.003. Epub 2019 Mar 18.
This biomechanical study compared the stability of volar locking plates (VLPs) and locking fragment-specific (LFS) dorsal and radial styloid plates for the fixation of dorsal (AO 23-B2) and radial styloid (AO 23-B1) shear fractures of the distal radius, respectively.
Two groups of 6 composite radii were fixed with a VLP or an LFS dorsal plate over a simulated dorsal shear fracture. Two additional groups of 6 radii received the same VLP or an LFS radial plate to fix a radial styloid fracture. Each plated radius was tested under cyclic axial compression by a servohydraulic testing machine that recorded axial displacement per cycle. Construct stiffness was calculated from the slope of the force-displacement curve.
In the dorsal shear fracture model, the dorsal LFS plate exhibited less displacement than the VLP (0.32 ± 0.04 vs 0.43 ± 0.07 mm, respectively) and showed greater average stiffness (645 ± 64 vs 433 ± 88 N/mm, respectively). Plate type was responsible for 53.1% of the variation in displacement and 68.6% of the variation in stiffness. In the radial styloid fracture model, variations due to number of cycles elapsed and plate type were similar for displacement and stiffness in both groups. The average stiffness during cyclical nondestructive testing was 566 ± 45 and 573 ± 60 N/mm for VLP and LFS radial plating groups, respectively.
For AO 23-B2 (dorsal rim) fractures, the dorsal LFS plates exhibited significantly less displacement and greater stiffness in axial loading than VLPs. For AO 23-B1 (radial styloid) fractures, the VLP displayed similar displacement and stiffness to the radial LFS plates.
All constructs tested could be expected to withstand axial compressive forces typical of early postoperative rehabilitation.
本生物力学研究比较了掌侧锁定钢板（VLP）与锁定碎骨块专用（LFS）背侧及桡骨茎突钢板分别用于固定桡骨远端背侧（AO 23 - B2）和桡骨茎突（AO 23 - B1）剪切骨折的稳定性。
两组各6个合成桡骨标本，通过模拟背侧剪切骨折分别用VLP或LFS背侧钢板固定。另外两组各6个桡骨标本用相同的VLP或LFS桡骨钢板固定桡骨茎突骨折。每个固定钢板的桡骨标本通过伺服液压试验机进行循环轴向压缩测试，记录每个循环的轴向位移。根据力 - 位移曲线的斜率计算结构刚度。
在背侧剪切骨折模型中，背侧LFS钢板的位移小于VLP（分别为0.32±0.04 vs 0.43±0.07 mm），且平均刚度更大（分别为645±64 vs 433±88 N/mm）。钢板类型导致位移变化的53.1%，刚度变化的68.6%。在桡骨茎突骨折模型中，两组位移和刚度因循环次数和钢板类型引起的变化相似。VLP和LFS桡骨钢板固定组在循环无损测试期间的平均刚度分别为566±45和573±60 N/mm。
对于AO 23 - B2（背侧边缘）骨折，背侧LFS钢板在轴向加载时的位移明显小于VLP，且刚度更大。对于AO 23 - B1（桡骨茎突）骨折，VLP与桡侧LFS钢板的位移和刚度相似。
所有测试的固定结构预计都能承受术后早期康复典型的轴向压缩力。
