Design and 3D-printing of titanium bone implants: brief review of approach and clinical cases

Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3D-printing, direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only net-shape geometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables new applications of the technology in important fields, such as production of medical implants. The 3D-printing of medical implants is an extremely rapidly developing application. The success of this development lies in the fact that patient-specific implants can promote patient recovery, as often it is the only alternative to amputation. The production of AM implants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerous challenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technological and design chain of bio-medical bone implant production from the computed tomography that is performed by the surgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processing procedures and certification. The current work presents examples that were produced by joint work of Polygon Medical Engineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3D-modelling specifically for the implants production. TechMed were in charge of the optimization of models and they manufactured the implants by Electron-Beam Melting (EBM®), using an Arcam EBM® A2X machine.

Clinical and radiographic evaluations of titanium trabecular metal components manufactured by 3D printing for primary total hip arthroplasty: a 5-year follow-up / 中华创伤骨科杂志

Objective To explore the mid-term efficacy of porous titanium trabecular metal ( TTM ) components manufactured by 3D printing for primary total hip arthroplasty ( THA ). Methods Enrolled for this prospective clinical trial were 19 patients ( 20 hips ) who were to receive primary THA from May 2012 to June 2013 at Department of Orthopaedics and Traumatology, Puai Hospital. Of them, 9 patients ( 10 hips) used 3D printing porous TTM for acetabular prosthesis in primary THA while the other 10 patients ( 10 hips ) used Pinnacle acetabular prosthesis. At 5 years after operation, clinical and radiographic evaluations were conducted to assess acetabular component stability, osseointegration in the acetabulum-bone interface, and osteolysis incidence. Harris scores were used to assess the hip functions. Results The follow-up duration for all the patients averaged 5 years. By the Harris scores, 8 cases were excellent and 2 good in the TTM group while 9 excellent and one good in the Pinnacle group. The Harris scores were significantly improved from preoperative 48.2+5.5 to 92.8+3.1 at 5 years after operation in the TTM group and significantly from 46.5 ± 8.7 to 94.6 ± 2.9 in the Pinnacle group ( P ＜0.05 ). There were no significant differences regarding the preoperative Harris scores and those 5 years after operation between the 2 groups ( P ＞ 0.05 ) . Radio-graphic evaluation showed stable acetabular components, fine osseointegration, and no implant loosening or osteolysis. Two hips in the TTM group had a postoperative radiolucent line which disappeared 6 months later. The 5-year survival rate of the acetabular components was 100% for both groups, taking prosthetic loosening or revision as the end point. Conclusion The 3D printing TTM has shown excellent mid-term efficacy but its long-term efficacy needs further follow-up study.

Structural and mechanical characterization of custom design cranial implant created using additive manufacturing

Background: Reconstruction of customized cranial implants with a mesh structure using computer-assisted design and additive manufacturing improves the implant design, surgical planning, defect evaluation, implant-tissue interaction and surgeon's accuracy. The objective of this study is to design, develop and fabricate cranial implant with mechanical properties closer to that of bone and drastically decreases the implant failure and to improve the esthetic outcome in cranial surgery with precision fitting for a better quality of life. A customized cranial mesh implant is designed digitally, based on the Digital Imaging and Communication in Medicine files and fabricated using state of the Art-Electron Beam Melting an Additive Manufacturing technology. The EBM produced titanium implant was evaluated based on their mechanical strength and structural characterization. Results: The result shows, the produced mesh implants have a high permeability of bone ingrowth with its reduced weight and modulus of elasticity closer to that the natural bone thus reducing the stress shielding effect. Scanning electron microscope and micro-computed tomography (CT) scanning confirms, that the produced cranial implant has a highly regular pattern of the porous structure with interconnected channels without any internal defect and voids. Conclusions: The study reveals that the use of mesh implants in cranial reconstruction satisfies the need of lighter implants with an adequate mechanical strength, thus restoring better functionality and esthetic outcomes for the patients.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology,so as to guide the development of 3D-prinited porous titanium orthopedic implants.Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure.The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM),and universal material testing machine was used to conduct compressive test on the scaffolds.Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface.The relative error of strut size produced by SLM and EMB was 20.9％-35.8％ and-9.1％-46.8％,respectively.The scaffold with strut width of 0.2 mm could not be produced by EBM.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa,respectively.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa,respectively.Conclusions The manufacturing precision of SLM is higher than that of EBM.Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds.In the same process,with the increase of porosity,both the compressive strength and elastic modulus decrease.When the porosities are similar,the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology,so as to guide the development of 3D-prinited porous titanium orthopedic implants.Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure.The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM),and universal material testing machine was used to conduct compressive test on the scaffolds.Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface.The relative error of strut size produced by SLM and EMB was 20.9％-35.8％ and-9.1％-46.8％,respectively.The scaffold with strut width of 0.2 mm could not be produced by EBM.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa,respectively.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa,respectively.Conclusions The manufacturing precision of SLM is higher than that of EBM.Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds.In the same process,with the increase of porosity,both the compressive strength and elastic modulus decrease.When the porosities are similar,the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology, so as to guide the development of 3D-prinited porous titanium orthopedic implants. Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure. The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM), and universal material testing machine was used to conduct compressive test on the scaffolds. Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface. The relative error of strut size produced by SLM and EMB was 20.9%-35.8% and －9.1%-46.8%, respectively. The scaffold with strut width of 0.2 mm could not be produced by EBM. The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa, respectively. The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa, respectively. Conclusions The manufacturing precision of SLM is higher than that of EBM. Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds. In the same process, with the increase of porosity, both the compressive strength and elastic modulus decrease. When the porosities are similar, the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology,so as to guide the development of 3D-prinited porous titanium orthopedic implants.Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure.The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM),and universal material testing machine was used to conduct compressive test on the scaffolds.Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface.The relative error of strut size produced by SLM and EMB was 20.9％-35.8％ and-9.1％-46.8％,respectively.The scaffold with strut width of 0.2 mm could not be produced by EBM.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa,respectively.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa,respectively.Conclusions The manufacturing precision of SLM is higher than that of EBM.Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds.In the same process,with the increase of porosity,both the compressive strength and elastic modulus decrease.When the porosities are similar,the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Evaluation of the fit of pure titanium crown 3D-printed by electron beam melting (EBM)technology / 实用口腔医学杂志

Objective:To study the fit of pure titanium single crown fabricated by electron beam melting(EBM).Methods:Pure titanium crowns were fabricated by EBM,selective laser melting(SLM),CAD/CAM(R +K and DMG)and conventional lost wax technique(LW)respectively(n =5).Marginal and internal gap was copied by light-body silicone and measured using a digital mi-croscope .The data of marginal gap(MG)and internal gap(IG)were statisticaly analysed by ANOVA and SPSS statistical package version 17.0.Results:The MG and IG(μm)of pure titanium crowns in EBM group were 38.42 ±6.72 and 105.54 ±33.18,in SLMgroup 38.63 ±6.82 and 114.63 ±52.18,in DMG CAD/CAMgroup 26.18 ±4.36 and 102.18 ±40.81,in R +K CAD/CAM group 26.98 ±4.44 and 102.24 ±25.30,in LW group were 42.61 ±5.73 and 102.98 ±45.67,respectively.The marginal fit of the EBMgroup was significantly smaller than 120 μm of the generally accepted clinical standards.In the 2 CAD/CAM groups the MG was smaller than that of other 3 groups(P 0.05).Conclu-sion:The marginal fit of titanium single crown fabricated by EBMis similar to that by SLM,better than that of LW and inferior than that of CAD/CAM.The internal fit of the crowns made by the 5 systems is similar.

Bone inductive potential of electron beam melting rapid prototyping technology in the repair of orthopedic implants / 中国组织工程研究

BACKGROUND:Electron beam melting rapid prototyping technology, has the characteristic of shaping precisely and complexly, is a new type of rapid prototyping technology using metal powder. Now, it has shown unique advantages in the fields of aerospace, automotive and medical implant equipments. OBJECTIVE: To explore the properties of the product, the customization ability of orthopedic implants through electron beam melting rapid prototyping, especial y the ability of inducing bone ingrowth. METHODS:We retrieved PubMed Database, China Journal Ful-text Database, and China National Knowledge Infrastructure, as wel as Dongfang Daily, World Science, and Chinese Journal of Orthopaedics by hand, and assembly documents in Chinese and English. Retrieval time was up to September 2013. Inclusion criteria: ① articles concerning electron beam melting rapid prototyping technology; ② articles addressing surgical implants. A total of 50 articles were included. RESULTS AND CONCLUSION:Electron beam melting state Ti6Al4V orthopedic implant has a good comprehensive performance, since the three-dimensional porous structure via electron beam melting rapid prototyping, which has a characteristic of customization, can induce bone ingrowth.