Department of Orthopaedic Surgery, Louisiana State University Health Science Center, Shreveport, LA, United States.
Department of Radiology, Louisiana State University Health Science Center, Shreveport, LA, United States.
Orthop Traumatol Surg Res. 2020 Nov;106(7):1405-1412. doi: 10.1016/j.otsr.2019.12.025. Epub 2020 Mar 31.
Temporary external fixation has been widely utilized in the stabilization of plateau fractures while waiting for an optimization of the soft tissue conditions before subsequent permanent internal fixation. Simultaneously, MRI is beneficial in the assessment of concomitant damage to ligaments and menisci so that these injuries could be promptly identified, and surgical planning executed at the time of definitive fixation of the bony injury. Increasing numbers of side-bars and pins have been previously suggested to increase frame rigidity, but at the same time, several studies have indicated the presence of MRI artifacts which may obscure key anatomical structures, even when MRI-compatible fixation devices are used. This study aims to identify, among six potential configurations, the construct that maximizes stability while most minimizing the number of MRI artifacts generated among different configurations commonly used.
There is one or more configurations among the others that maximize stability while preserving a clinically acceptable level of MRI quality.
Six constructs were recreated on cadaveric specimens and identified by the disposition of the bars: H, Anterior, Flash, Hashtag, Rhomboid, and Diamond. Stage one evaluated the amount of artifact produced during MRI on instrumented cadaveric legs, as well as the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) at five specific regions of interest. Stage two assessed the amount of compressional and torsional stiffness of the configurations on bone surrogate models.
Image artifacts were not detected within the knee joint for all considered constructs. In terms of SNR The H, Anterior, Hashtag, and Diamond configurations were not significantly different from their control (p>0.366) while the others were significantly different (p<0.03). The values of CNR found for the H and Hashtag configurations were not significantly different from their controls (p>0.07) while the remaining configurations were significantly different (p<0.03). In compression, the H and Diamond configurations had similar stiffness (p=0.468) of 35.78N/mm and 31.44N/mm, respectively, and were stiffer than the other configurations. In torsion, the constructs have shown different stiffness (p<0.001) with a minimum value of 0.66 Nm/deg for the Rhomboid configuration, which was significantly less stiff than the Anterior configuration (1.20 Nm/deg [p<0.001]). There was no difference between the Diamond and H configurations (p=0.177) or between them and the Hashtag configuration (p=0.215).
An external fixator construct directly bridging the femur and tibia without interconnections is the most stable and produces MRI scans without image artifacts that would interfere with diagnostic quality.
V, basic science study, diagnostic imaging and mechanical testing.
在等待软组织状况优化后再进行后续的永久性内固定之前，临时外固定已被广泛用于治疗高原骨折。同时，MRI 有助于评估韧带和半月板的伴随损伤，以便及时发现这些损伤，并在骨损伤的确定性固定时进行手术规划。以前曾有人建议增加侧杆和销钉的数量来增加框架的刚性，但同时，多项研究表明，即使使用 MRI 兼容的固定装置，也会产生 MRI 伪影，从而掩盖关键的解剖结构。本研究旨在从六种潜在配置中确定一种或多种可最大限度地提高稳定性的配置，同时最大限度地减少不同常用配置产生的 MRI 伪影数量。
在其他配置中，有一种或多种配置可以在保持可接受的 MRI 质量水平的同时最大限度地提高稳定性。
在尸体标本上重新创建了六种构建，并通过杆的布置来识别：H 型、前侧型、Flash 型、Hashtag 型、菱形型和钻石型。第一阶段评估了在仪器化的尸体腿上进行 MRI 时产生的伪影量，以及五个特定感兴趣区域的信噪比 (SNR) 和对比噪声比 (CNR)。第二阶段评估了在骨骼替代模型上配置的压缩和扭转刚度。
在所有考虑的构建中，关节内均未检测到图像伪影。就 SNR 而言，H、前侧、Hashtag 和钻石配置与对照无显著差异（p>0.366），而其他配置则有显著差异（p<0.03）。H 和 Hashtag 配置的 CNR 值与对照无显著差异（p>0.07），而其余配置则有显著差异（p<0.03）。在压缩时，H 和 Diamond 配置具有相似的刚度（p=0.468），分别为 35.78N/mm 和 31.44N/mm，并且比其他配置更硬。在扭转时，构建具有不同的刚度（p<0.001），菱形配置的最小值为 0.66 Nm/deg，明显小于前侧配置（1.20 Nm/deg [p<0.001]）。菱形和前侧配置（p=0.177）或菱形和 Hashtag 配置（p=0.215）之间没有差异。
直接在股骨和胫骨之间桥接而没有任何连接的外固定器构建是最稳定的，并且产生的 MRI 扫描没有会干扰诊断质量的图像伪影。
V，基础科学研究，诊断成像和力学测试。
