目的:对于具有足够软组织的未经照射的患者,使用患者特定的笼子植入物进行下颌骨重建是一种有希望的替代血管化游离皮瓣重建的方法。或临床状况不利于显微外科重建的患者。这项研究旨在评估3D打印患者特定的笼子植入物的生物力学性能,该植入物在尸体和回顾性病例系列研究中采用半自动工作流程设计。
方法:我们使用先前开发的设计工作流程为两个人类尸体下颌骨设计了笼子植入物。通过有限元分析(FEA)和准静态生物力学测试评估植入物的生物力学性能。使用数字图像相关(DIC)测量全场应变,并通过比较骨骼内最大主应变的分布来验证FE模型。病例系列的回顾性研究涉及三名患者,每个人都接受了类似设计的笼子植入物治疗。在下颌联合和骨不连的情况下,使用实验验证的FEA评估了这些植入物的生物力学性能。
结果:在两个尸体下颌骨的准静态测试中,在对侧骨折之前未观察到植入物或螺钉失效。FEA和DIC应变等值线图显示出强线性相关(r=0.92)和低标准误差(SE=29.32με),计算模型产生的应变值较高,为2.7倍。作用在案例系列植入物上的总应力远低于增材制造(AM)商业纯钛的屈服强度,在高度剧烈的咀嚼条件下模拟时。与非粘合移植物相比,模拟移植物和残余下颌骨之间的完全结合可使植入物内的局部峰值应力显着降低(72.7±1.5%)。
结论:这项研究表明,开发的半自动工作流程适用于设计患者特定的笼式植入物,在苛刻的咀嚼条件下具有令人满意的机械功能。提出的工作流程可以帮助临床工程师创建重建系统和简化手术前计划。然而,仍需要更多的研究来评估骨移植物插入的成骨潜力。
Mandibular reconstruction using patient-specific cage implants is a promising alternative to the vascularized free flap reconstruction for nonirradiated patients with adequate soft tissues, or for patients whose clinical condition is not conducive to microsurgical reconstruction. This study aimed to assess the biomechanical performance of 3D printed patient-specific cage implants designed with a semi-automated workflow in a combined cadaveric and retrospective
case series study.
We designed cage implants for two human cadaveric mandibles using our previously developed design workflow. The biomechanical performance of the implants was assessed with the finite element analysis (FEA) and quasi-static biomechanical testing. Digital image correlation (DIC) was used to measure the full-field strains and validate the FE models by comparing the distribution of maximum principal strains within the bone. The retrospective study of a
case series involved three patients, each of whom was treated with a cage implant of similar design. The biomechanical performance of these implants was evaluated using the experimentally validated FEA under the scenarios of both mandibular union and nonunion.
No implant or screw failure was observed prior to contralateral bone fracture during the quasi-static testing of both cadaveric mandibles. The FEA and DIC strain contour plots indicated a strong linear correlation (r = 0.92) and a low standard error (SE=29.32με), with computational models yielding higher strain values by a factor of 2.7. The overall stresses acting on the
case series\' implants stayed well below the yield strength of additively manufactured (AM) commercially pure titanium, when simulated under highly strenuous chewing conditions. Simulating a full union between the graft and remnant mandible yielded a substantial reduction (72.7±1.5%) in local peak stresses within the implants as compared to a non-bonded graft.
This study shows the suitability of the developed semi-automated workflow in designing patient-specific cage implants with satisfactory mechanical functioning under demanding chewing conditions. The proposed workflow can aid clinical engineers in creating reconstruction systems and streamlining pre-surgical planning. Nevertheless, more research is still needed to evaluate the osteogenic potential of bone graft insertions.