Msallem Bilal, Maintz Michaela, Halbeisen Florian S, Meyer Simon, Sigron Guido R, Sharma Neha, Cao Shuaishuai, Thieringer Florian M
Clinic of Oral and Cranio-Maxillofacial Surgery, University Hospital Basel, CH-4031 Basel, Switzerland.
Medical Additive Manufacturing Research Group (Swiss MAM), Department of Biomedical Engineering, University of Basel, CH-4123 Allschwil, Switzerland.
Materials (Basel). 2022 Mar 7;15(5):1970. doi: 10.3390/ma15051970.
Cranioplasty with freehand-molded polymethylmethacrylate implants is based on decades of experience and is still frequently used in clinical practice. However, data confirming the fracture toughness and standard biomechanical tests are rare. This study aimed to determine the amount of force that could be applied to virtually planned, template-molded, patient-specific implants (n = 10) with an implant thickness of 3 mm, used in the treatment of a temporoparietal skull defect (91.87 cm2), until the implant cracks and finally breaks. Furthermore, the influence of the weight and porosity of the implant on its force resistance was investigated. The primary outcome showed that a high force was required to break the implant (mean and standard deviation 1484.6 ± 167.7 N), and this was very strongly correlated with implant weight (Pearson’s correlation coefficient 0.97; p < 0.001). Secondary outcomes were force application at the implant’s first, second, and third crack. Only a moderate correlation could be found between fracture force and the volume of porosities (Pearson’s correlation coefficient 0.59; p = 0.073). The present study demonstrates that an implant thickness of 3 mm for a temporoparietal skull defect can withstand sufficient force to protect the brain. Greater implant weight and, thus, higher material content increases thickness, resulting in more resistance. Porosities that occur during the described workflow do not seem to reduce resistance. Therefore, precise knowledge of the fracture force of polymethylmethacrylate cranial implants provides insight into brain injury prevention and serves as a reference for the virtual design process.
使用徒手塑形的聚甲基丙烯酸甲酯植入物进行颅骨成形术基于数十年的经验，目前仍在临床实践中频繁使用。然而，证实其断裂韧性和标准生物力学测试的数据却很少见。本研究旨在确定可施加于虚拟规划、模板塑形、针对个体患者定制的植入物（n = 10）上的力的大小，这些植入物厚度为3 mm，用于治疗颞顶颅骨缺损（91.87 cm²），直至植入物出现裂纹并最终断裂。此外，还研究了植入物的重量和孔隙率对其抗受力的影响。主要结果表明，植入物断裂需要很大的力（平均值和标准差为1484.6 ± 167.7 N），并且这与植入物重量密切相关（皮尔逊相关系数为0.97；p < 0.001）。次要结果是植入物首次、第二次和第三次出现裂纹时所施加的力。在断裂力与孔隙体积之间仅发现中等程度的相关性（皮尔逊相关系数为0.59；p = 0.073）。本研究表明，用于颞顶颅骨缺损的3 mm厚植入物能够承受足够的力来保护大脑。更大的植入物重量，即更高的材料含量会增加厚度，从而产生更大的抵抗力。在所描述的制作流程中出现的孔隙似乎不会降低抵抗力。因此精确了解聚甲基丙烯酸甲酯颅骨植入物的断裂力有助于预防脑损伤，并为虚拟设计过程提供参考。
