Fused Filament Fabrication of Porous PEEK and PEKK Spinal Cages: Which 3D Printing Conditions Control Static and Fatigue Strength?

非技术摘要：当一个人抱怨背痛时，这表明他们可能正在经历脊柱疼痛和不适，通常归因于椎间盘突出。椎间盘突出是由于突然的身体活动导致脊柱中的椎间盘样结构隆起或滑出原位，导致附近神经受压。为了修复椎间盘突出和减轻背痛，脊柱植入物用于促进两个椎骨之间的融合。然而，为了使这种植入物在体内有效地发挥作用，它们必须具有强度和使附近的骨骼和组织生长到植入物中的能力。实现这种生物固定可作为成功愈合的指标，同时确保脊柱的适当支撑。在这项研究中，研究人员将利用一种特殊的增材制造方法，称为熔丝制造（FFF）。该技术涉及熔融聚合物的逐层沉积以构建完整的结构。根据其在医疗器械中的历史用途，本研究将使用两种聚合物，聚醚醚酮（PEEK）和聚醚酮酮（PEKK）。由于实现坚固结构的重要性，研究人员将通过系统地改变关键参数来优化制造过程，这些参数有可能增强由PEEK和PEKK聚合物制成的植入物结构的强度。使用FFF打印技术制造此类植入物的能力不仅有助于降低制造成本，带来更实惠的医疗保健，而且还提高了患者的整体生活质量。技术摘要：本研究项目的目的是建立由熔融纤维制造（FFF）聚醚醚酮（PEEK）和聚醚酮酮（PEKK）制成的腰椎融合器的结构和力学性能之间的相关性。该项目最终旨在促进专门用于治疗顽固性背痛的增材制造（AM）椎间融合器（IBFD）的知识进步。有助于实现总体目标的研究目标包括优化腰椎融合器的FFF过程和评估打印融合器的性能。最佳构建参数（速度和温度）将通过涉及microCT、光学显微镜、量热法、机械测试和扫描电子显微镜（SEM）的综合材料表征过程确定。然后将使用已确定的优化构建参数打印实心和多孔腰椎融合器。根据ASTM F2077（椎间融合器的试验方法），在各种载荷条件下评估打印的融合器的耐久性，以建立结构-性能关系。将使用有限元分析（FEA）和蒙特卡罗模拟评价脊柱融合器的迭代性能。这些发现有可能有助于开发在手术干预中使用的一致和可靠的AM脊柱融合器，降低器械失效风险，并改善患者结局。AM的使用可以提高医疗设备的可及性，因为它具有成本效益且易于生产，最终有助于实现负担得起的医疗保健。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical Abstract:When an individual complains of back pain, it is an indication that they may be experiencing soreness and discomfort in their spine, typically attributed to herniated discs. Herniated discs occur when the cushion-like structures in the spine bulge or slip out of place due to ruptures caused by sudden physical activities, resulting in the compression of nearby nerves. To repair herniated discs and reduce back pain, spinal implants are used to facilitate fusion between two vertebrae. However, for such implants to function effectively within the body, it is crucial for them to possess both strength and the ability to have nearby bone and tissue grow into the implant. Achieving this biological fixation serves as an indicator of successful healing while ensuring proper support of the spine. In this study, the researchers will utilize a specific additive manufacturing method called Fused Filament Fabrication (FFF). The technique involves the layer-by-layer deposition of melted polymer to construct a complete structure. Two polymers, polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) will be used in this study based on their historic use in medical devices. Due to the significance of achieving a strong structure, the researchers will optimize the manufacturing process by systematically varying key parameters that have the potential to enhance the strength of the implant structures fabricated from PEEK and PEKK polymers. The ability to create such an implant using FFF printing technology not only contributes to a reduction in manufacturing costs, leading to more affordable healthcare, but also enhances the overall quality of life for patients.Technical Abstract:The purpose of this research project is to establish the correlation between the structural and mechanical properties of lumber spine cages made from Fused Filament Fabricated (FFF) polyetheretherketone (PEEK) and polyetherketoneketone (PEKK). The project ultimately seeks to contribute to the progression of knowledge of additively manufactured (AM) Intervertebral Body Fusion Devices (IBFDs) specifically used in treating intractable back pain. The research objectives that would help in achieving the overall goal include optimization of the FFF process for lumbar spine cages and assessing the performance of the printed cages. The optimal build parameters (speed and temperature) will be determined by a comprehensive material characterization process involving microCT, optical microscopy, calorimetry, mechanical testing, and Scanning Electron Microscopy (SEM). The established optimized build parameters will then be used to print both solid and porous lumbar spine cages. The printed cages would be assessed for durability under various loading conditions per ASTM F2077 (Test Methods for Intervertebral Body Fusion Devices) to establish the structure-properties relationship. Finite Element Analysis (FEA) and Monte Carlo simulations would be used to evaluate the iterative performance of the spine cages. The findings have the potential to contribute to the development of consistent and reliable AM spine cages utilized in surgical interventions, reducing the risk of device failure, and improving patient outcomes. The use of AM can increase accessibility to medical devices due to cost-effective and easily produced medical devices and ultimately contribute to affordable healthcare.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.