Wang Lizhen, Huang Huiwen, Yuan Hao, Yao Yan, Park Jeong Hun, Liu Jinglong, Geng Xuezheng, Zhang Kuo, Hollister Scott J, Fan Yubo
Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, School of Engineering Medicine, Beihang University, No. 37 Xueyuan Road, Haidian District, Beijing 100083, China.
Wallace H. Coulter Department of Biomedical Engineering and Center for 3D Medical Fabrication, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, GA 30332, USA.
Acta Biomater. 2023 Oct 15;170:185-201. doi: 10.1016/j.actbio.2023.08.040. Epub 2023 Aug 25.
The incidence of screw loosening, migration, and pullout caused by the insufficient screw-bone fixation stability is relatively high in clinical practice. To solve this issue, the auxetic unit-based porous bone screw (AS) has been put forward in our previous work. Its favorable auxetic effect can improve the primary screw-bone fixation stability after implantation. However, porous structure affected the fatigue behavior and in vivo longevity of bone screw. In this study, in vitro fatigue behaviors and in vivo osseointegration performance of the re-entrant unit-based titanium auxetic bone screw were studied. The tensile-tensile fatigue behaviors of AS and nonauxetic bone screw (NS) with the same porosity (51%) were compared via fatigue experiments, fracture analysis, and numerical simulation. The in vivo osseointegration of AS and NS were compared via animal experiment and biomechanical analysis. Additionally, the effects of in vivo dynamic tensile loading on the osseointegration of AS and NS were investigated and analyzed. The fatigue strength of AS was approximately 43% lower while its osseointegration performance was better than NS. Under in vivo dynamic tensile loading, the osseointegration of AS and NS both improved significantly, with the maximum increase of approximately 15%. Preferrable osseointegration of AS might compensate for the shortage of fatigue resistance, ensuring its long-term stability in vivo. Adequate auxetic effect and long-term stability of the AS was supposed to provide enough screw-bone fixation stability to overcome the shortages of the solid bone screw, developing the success of surgery and showing significant clinical application prospects in orthopedic surgery. STATEMENT OF SIGNIFICANCE: This research investigated the high-cycle fatigue behavior of re-entrant unit-based auxetic bone screw under tensile-tensile cyclic loading and its osseointegration performance, which has not been focused on in existing studies. The fatigue strength of auxetic bone screw was lower while the osseointegration was better than non-auxetic bone screw, especially under in vivo tensile loading. Favorable osseointegration of auxetic bone screw might compensate for the shortage of fatigue resistance, ensuring its long-term stability and longevity in vivo. This suggested that with adequate auxetic effect and long-term stability, the auxetic bone screw had significant application prospects in orthopedic surgery. Findings of this study will provide a theoretical guidance for design optimization and clinical application of the auxetic bone screw.
在临床实践中，由于螺钉与骨的固定稳定性不足而导致的螺钉松动、移位和拔出的发生率相对较高。为了解决这个问题，我们在之前的工作中提出了基于负泊松比单元的多孔骨螺钉（AS）。其良好的负泊松比效应可以提高植入后螺钉与骨的初始固定稳定性。然而，多孔结构影响了骨螺钉的疲劳行为和体内使用寿命。在本研究中，对基于凹进单元的钛负泊松比骨螺钉的体外疲劳行为和体内骨整合性能进行了研究。通过疲劳实验、断口分析和数值模拟，比较了孔隙率相同（51%）的AS和非负泊松比骨螺钉（NS）的拉伸-拉伸疲劳行为。通过动物实验和生物力学分析，比较了AS和NS的体内骨整合情况。此外，还研究并分析了体内动态拉伸载荷对AS和NS骨整合的影响。AS的疲劳强度约低43%，但其骨整合性能优于NS。在体内动态拉伸载荷作用下，AS和NS的骨整合均显著改善，最大增幅约为15%。AS较好的骨整合可能弥补其抗疲劳性的不足，确保其在体内的长期稳定性。AS足够的负泊松比效应和长期稳定性应该能够提供足够的螺钉与骨的固定稳定性，以克服实心骨螺钉的不足，提高手术成功率，并在骨科手术中显示出显著的临床应用前景。重要意义声明：本研究调查了基于凹进单元的负泊松比骨螺钉在拉伸-拉伸循环载荷下的高周疲劳行为及其骨整合性能，这是现有研究中尚未关注的。负泊松比骨螺钉的疲劳强度较低，而骨整合性能优于非负泊松比骨螺钉，尤其是在体内拉伸载荷下。负泊松比骨螺钉良好的骨整合可能弥补其抗疲劳性的不足，确保其在体内的长期稳定性和使用寿命。这表明，具有足够的负泊松比效应和长期稳定性，负泊松比骨螺钉在骨科手术中具有显著的应用前景。本研究结果将为负泊松比骨螺钉的设计优化和临床应用提供理论指导。
