Hong Thomas S, Lee Daniel J, Jahani Babak, Broz Kaitlyn S, Aboytes Donald A, Tang Simon, DeMartini Stephen, Brogan David M
Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, MO.
Institute of Materials Science and Engineering, Washington University in St. Louis, St. Louis, MO; Departments of Biomedical Engineering and Mechanical Engineering, Washington University in St. Louis, St. Louis, MO.
J Hand Surg Am. 2024 Dec;49(12):1186-1195. doi: 10.1016/j.jhsa.2024.07.019. Epub 2024 Sep 11.
The purpose of this study was to compare the effect of varying screw lengths on load to failure and retention of the dorsal ulnar corner fragment after fixation of comminuted intra-articular distal radius fractures in a cadaveric model.
Twenty-four fresh frozen cadaveric forearms were subjected to a standardized distal radius osteotomy to mimic an intra-articular fracture pattern. Dual X-ray absorptiometry scans were performed to ensure minimal variability in bone density. All fractures were fixed with a volar locking plate and distal locking screws. Three different lengths of distal locking screws were used in each group of eight specimens to simulate the clinical decision of different distal screw lengths. The screw lengths tested were bicortical, 100% of the width of the bone but unicortical, and 75% of the width of the bone and unicortical. All specimens were preconditioned with cyclic axial loading and then axially loaded using matching acrylic resin molds to clinical failure and fragment displacement as detected by a motion analysis system. Retention or loss of the dorsal ulnar corner fragment during loading was recorded as a binary variable.
Between the three groups, there were no statistically significant differences in precycling stiffness, postcycling stiffness, load at 2 mm displacement of the dorsal ulnar corner, or force at failure. The group with 75% length screws had a significantly higher loss of reduction of the dorsal ulnar corner (86%) compared with the other groups (0%).
Varying screw lengths did not affect the stiffness or overall loads to failure of axially loaded specimens. However, the 75% length screws did not reliably secure the dorsal ulnar corner fragments. Although this did not significantly affect the overall load to failure of the construct, displacement of this fragment may have implications for rotation of the forearm through the distal radioulnar joint.
Surgeons should consider the utilization of full-length unicortical locking screws to ensure adequate fixation of the dorsal ulnar corner.
本研究的目的是在尸体模型中比较不同长度螺钉对粉碎性关节内桡骨远端骨折固定后尺骨背侧角骨折块的破坏载荷和保留情况的影响。
对24个新鲜冷冻的尸体前臂进行标准化的桡骨远端截骨术，以模拟关节内骨折模式。进行双能X线吸收测定扫描，以确保骨密度的变异性最小。所有骨折均用掌侧锁定钢板和远端锁定螺钉固定。在每组8个标本中使用三种不同长度的远端锁定螺钉，以模拟不同远端螺钉长度的临床决策。测试的螺钉长度为双皮质的、骨宽度的100%但为单皮质的，以及骨宽度的75%且为单皮质的。所有标本均先进行循环轴向加载预处理，然后使用匹配的丙烯酸树脂模具进行轴向加载，直至临床失败，并通过运动分析系统检测骨折块移位。加载过程中尺骨背侧角骨折块的保留或丢失记录为二元变量。
在三组之间，预循环刚度、循环后刚度、尺骨背侧角位移2 mm时的载荷或破坏时的力均无统计学显著差异。与其他组（0%）相比，螺钉长度为75%的组尺骨背侧角的复位丢失率显著更高（86%）。
不同长度的螺钉不影响轴向加载标本的刚度或整体破坏载荷。然而，长度为75%的螺钉不能可靠地固定尺骨背侧角骨折块。虽然这并未显著影响结构的整体破坏载荷，但该骨折块的移位可能会影响前臂通过桡尺远侧关节的旋转。
外科医生应考虑使用全长单皮质锁定螺钉，以确保尺骨背侧角的充分固定。
