Devasconcellos P, Balla V K, Bose S, Fugazzi R, Dernell W S, Bandyopadhyay A
W. M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920, USA.
Vet Comp Orthop Traumatol. 2012;25(4):286-96. doi: 10.3415/VCOT-11-03-0043. Epub 2012 May 11.
To design, manufacture and analyze custom implants with functional gradation in macrostructure for attachment of amputation prostheses.
The external shape of the implant was designed by extracting geometrical data of canine cadavers from computed tomography (CT) scans to suit the bone cavity. Three generations of implant designs were developed and were optimized with the help of fit/fill and mechanical performance of implant-cadaver bone assembly using CT analysis and compression testing, respectively. A final optimized, custom Ti6Al4V alloy amputation implant, with approximately 25% porosity in the proximal region and approximately zero percent porosity in the distal region, was fabricated using Laser Engineered Net Shaping (LENS™)--a laser based additive manufacturing technology.
The proposed design changes in the second generation designs, in terms of refining thresholds, increased the average fill of the bone cavity from 58% to 83%. Addition of a flange between the stem and the head in the second generation designs resulted in more than a seven-fold increase in the compressive load carrying capacity of the assembly. Application of LENS™ in the fabrication of present custom fit Ti6Al4V alloy implants enabled incorporation of 20 to 30% porosity in the proximal region and one to two percent residual porosity in the distal portion of the implant.
Patient specific prostheses having direct connection to the skeletal structure can potentially aid in problems related to load transfer and proprioception in amputees. Furthermore, application of LENS™ in the fabrication of custom implants can be faster to incorporate site specific porosity and gradients for improving long-term stability.
设计、制造并分析具有宏观结构功能梯度的定制植入物，用于截肢假体的附着。
通过计算机断层扫描（CT）扫描提取犬类尸体的几何数据来设计植入物的外部形状，以适应骨腔。开发了三代植入物设计，并分别使用CT分析和压缩测试，借助植入物 - 尸体骨组件的拟合/填充和机械性能进行优化。使用激光工程净成形（LENS™）——一种基于激光的增材制造技术，制造了最终优化的定制Ti6Al4V合金截肢植入物，其近端区域孔隙率约为25%，远端区域孔隙率约为零。
第二代设计中提出的设计更改，在细化阈值方面，使骨腔的平均填充率从58%提高到了83%。第二代设计在柄和头部之间添加凸缘后，组件的抗压承载能力增加了七倍多。在制造当前定制的Ti6Al4V合金植入物中应用LENS™，使得植入物近端区域能够纳入20%至30%的孔隙率，远端部分的残余孔隙率为1%至2%。
与骨骼结构直接相连的患者特异性假体可能有助于解决截肢者与负荷传递和本体感觉相关的问题。此外，在定制植入物制造中应用LENS™可以更快地纳入特定部位的孔隙率和梯度，以提高长期稳定性。
