Pérez David, Martel Oscar, Yánez Alejandro, Cano José R, Cuadrado Alberto, Torrent Gara, López Luis
Thoracic Surgery Section, Hospital Universitario Insular de Gran Canaria, Las Palmas, Spain.
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Las Palmas, Spain.
Interact Cardiovasc Thorac Surg. 2020 Jan 1;30(1):11-17. doi: 10.1093/icvts/ivz217.
Although the Nuss procedure for pectus excavatum is still associated with a non-negligible risk of postoperative bar displacement, the potential effects of the length and shape of the bar on its corrective ability and stability have not been sufficiently studied. The aim of this study was to determine how the modelling of the pectus bar affects its stability and whether an alternative configuration of the implant can improve clinical success.
Simulated implantation of bars with different shapes and sizes in a computational model was carried out. A 250 N sternal force was applied to the bars, and the resulting forces and moments on the fixation points were identified. Afterwards, a clinical trial was carried out in a group of patients with pectus excavatum, some of whom received long inverted U-shaped bars and some of whom received implants designed from the computational results.
When U-shaped bars were tested, the sternal force generated unbalanced horizontal reaction forces (16 vs 61 N) and large reaction moments at the ends of the bar, conferring the tendency to slide and to rotate, respectively. No lateral or rotational destabilizing forces occurred in the case of a flat bar. Cosmetic outcomes, postoperative times and hospital stays were similar in both clinical groups. However, 2 cases (2/15) of bar flipping occurred in patients who received the conventional bar.
The shape of the bar is a determinant of its stability. A flat, shorter pectus bar provides adequate correction of the deformity with less tendency for bar displacement in the repair of pectus excavatum.
尽管漏斗胸的努斯手术仍伴有不可忽视的术后钢板移位风险，但钢板的长度和形状对其矫正能力及稳定性的潜在影响尚未得到充分研究。本研究旨在确定漏斗胸钢板的塑形如何影响其稳定性，以及植入物的替代构型是否能提高临床成功率。
在计算模型中模拟植入不同形状和尺寸的钢板。对钢板施加250N的胸骨力，并确定固定点处产生的力和力矩。之后，对一组漏斗胸患者进行了临床试验，其中一些患者接受了长倒U形钢板，另一些患者接受了根据计算结果设计的植入物。
测试U形钢板时，胸骨力产生了不平衡的水平反作用力（16对61N），并在钢板两端产生了较大的反作用力矩，分别导致了滑动和旋转的趋势。对于平板状钢板，未出现侧向或旋转失稳力。两个临床组的美容效果、术后时间和住院时间相似。然而，接受传统钢板的患者中发生了2例（2/15）钢板翻转。
钢板的形状是其稳定性的决定因素。扁平、较短的漏斗胸钢板在漏斗胸修复中能提供足够的畸形矫正，且钢板移位的趋势较小。
