Department of Materials Science and Engineering, The Ohio State University, 140 W 19th Ave., Columbus, OH, 43210, USA.
Department of Plastic and Reconstructive Surgery, Ohio State Plastic Surgery, 915 Olentangy River Road, Columbus, OH, 43212, USA.
Biomed Eng Online. 2024 Oct 26;23(1):105. doi: 10.1186/s12938-024-01289-x.
Manually bent, standard-of-care, Ti-6Al-4V, mandibular graft fixation devices are associated with a significant post-operative failure rate. These failures require the patient to endure stressful and expensive re-operation. The approach recommended in this report demonstrates the optimization of graft fixation device mechanical properties via "stiffness-matching" by varying the fixation device's location, shape, and material composition through simulation of the device's post-operative performance. This provides information during pre-operative planning that may avoid future device failure. Optimized performance may combine translation of all loading into compression of the bone graft with the adjacent bone segments and elimination or minimization of post-healing interruption of normal stress-strain (loading) trajectories.
This study reports a sheep mandibular graft model where four animals received virtually optimized, experimental nickel-titanium (NiTi) fixation plates fabricated using laser beam powder bed fusion (LPBF) additive manufacturing (AM). The last animal, our control, received a standard-of-care, manually bent, Ti-6Al-4V (aka Ti64) fixation plate. A 17.5-mm mandibular graft healed completely in all four animals receiving the experimental device. Experimental NiTi-implanted sheep experienced mandibular bone healing and restoration. The Ti64 plate, in the control animal, fractured and dislocated shortly after being implanted.
The use of stiffness-matched implants, by means of plate material (NiTi) and geometry (porosity) enhanced bone healing and promoted better load transfer to the healed bone when compared to the bulk Ti64 found in the fixation plate that the Control animal received. The design technique and screw orientation and depth planning improved throughout the study leading to more rapid healing. The large animal model reported here provides data useful for a follow-on clinical trial.
手动弯曲的、标准护理的 Ti-6Al-4V 下颌骨移植物固定装置与较高的术后失败率相关。这些失败需要患者承受紧张和昂贵的再次手术。本报告中推荐的方法通过改变固定装置的位置、形状和材料组成来模拟装置的术后性能，从而通过“刚度匹配”来优化移植物固定装置的机械性能。这提供了术前规划时可能避免未来装置失效的信息。优化的性能可能将所有负载转化为骨移植物与相邻骨段的压缩，并消除或最小化愈合后正常应力-应变（负载）轨迹的中断。
本研究报告了一个绵羊下颌骨移植物模型，其中四只动物接受了虚拟优化的、使用激光束粉末床熔合（LPBF）增材制造（AM）制造的实验性镍钛（NiTi）固定板。最后一只动物，即我们的对照动物，接受了标准护理的手动弯曲的 Ti-6Al-4V（又名 Ti64）固定板。在接受实验装置的四只动物中，所有四只动物的 17.5mm 下颌骨移植物完全愈合。接受实验性 NiTi 植入的绵羊经历了下颌骨愈合和修复。在对照动物中，Ti64 板在植入后不久就断裂和脱位。
与对照动物接受的固定板中的块状 Ti64 相比，通过使用刚度匹配的植入物（通过板材料（NiTi）和几何形状（多孔性））增强了骨愈合，并促进了更好的负载传递到愈合的骨，从而使用了刚度匹配的植入物。设计技术以及螺钉方向和深度规划在整个研究过程中得到了改进，从而促进了更快的愈合。本报告中报道的大型动物模型提供了有用的后续临床试验数据。
