Nazzal Ehab M, Mattar Luke T, Newell Benjamin W, Coutinho Dominic V, Kaufmann Robert A, Baratz Mark E, Debski Richard E
Orthopedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA; University of Pittsburgh Medical Center Department of Orthopedic Surgery, Pittsburgh, PA.
Orthopedic Robotics Laboratory, University of Pittsburgh, Pittsburgh, PA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA.
J Hand Surg Am. 2025 Feb;50(2):239.e1-239.e8. doi: 10.1016/j.jhsa.2023.06.022. Epub 2023 Aug 8.
The objective of this study was to determine the structural properties of the cadaver bone-screw interface for cementless intramedullary screw fixation in the context of total elbow arthroplasty.
The intramedullary canals of seven humerus and seven ulna specimens from fresh-frozen cadavers were drilled using custom drill bits until the inner cortex was reached and then hand tapped for the corresponding thread size. Titanium screws were advanced into the tapped holes until securely seated. The bones were potted and then mounted on a uniaxial material testing machine. A tensile load was applied, and end-of-test elongation, failure load, energy absorbed, and stiffness were determined. End-of-test load and elongation were defined as the elongation and load experienced by the structure at 3,000 N or failure. Each specimen was inspected for evidence of pullout, loosening, or visible fractures.
The end-of-test load and elongation for the humerus specimens were 2721 ± 738 N and 3.0 ± 0.9 mm, respectively. The ulna specimens reached 92% of the humerus specimens' end-of-test load at 2,514 ± 678 N and 120% of their end-of-test elongation (3.6 ± 0.6 mm). The stiffness of the humerus specimens was 1,077 ± 336 N/mm, which was 1.3 times greater than the stiffness of the ulna specimens (790 ± 211 N/mm). Lastly, the energy absorbed by the humerus samples was 3.6 ± 1.6 J, which was 92% of the energy absorbed by the ulna samples at 3.9 ± 1.1 J. One humerus and three ulnas failed before the end-of-test load of 3,000 N. Two failures were caused by screw pullout and two by bone fracture.
Our findings demonstrate that intramedullary screw fixation is successful in withstanding forces that are greater than required for osseointegration.
Uncemented fixation may be beneficial in elbow arthroplasty.
本研究的目的是确定在全肘关节置换术中，用于非骨水泥髓内螺钉固定的尸体骨-螺钉界面的结构特性。
使用定制钻头在来自新鲜冷冻尸体的七个肱骨和七个尺骨标本的髓腔内钻孔，直至到达内侧皮质，然后用手攻丝至相应的螺纹尺寸。将钛螺钉拧入攻丝孔中，直至牢固就位。将骨头装入盆中，然后安装在单轴材料试验机上。施加拉伸载荷，并测定试验结束时的伸长量、破坏载荷、吸收能量和刚度。试验结束时的载荷和伸长量定义为结构在3000 N或破坏时所经历的伸长量和载荷。检查每个标本是否有拔出、松动或可见骨折的迹象。
肱骨标本的试验结束时载荷和伸长量分别为2721±738 N和3.0±0.9 mm。尺骨标本在2514±678 N时达到肱骨标本试验结束时载荷的92%，试验结束时伸长量达到其120%（3.6±0.6 mm）。肱骨标本的刚度为1077±336 N/mm，是尺骨标本刚度（790±211 N/mm）的1.3倍。最后，肱骨样本吸收的能量为3.6±1.6 J，是尺骨样本吸收能量（3.9±1.1 J）的92%。一个肱骨和三个尺骨在3000 N的试验结束载荷之前发生破坏。两次破坏是由螺钉拔出引起的，两次是由骨折引起的。
我们的研究结果表明，髓内螺钉固定能够成功承受大于骨整合所需的力。
非骨水泥固定在肘关节置换术中可能有益。
