To register for the Medical Implant Scanning and Manufacturing Workshop, held on Monday, May 11, please visit the RAPID Show pages.

Finite Element Analysis and Rapid Prototyping to Enhance the Patient-Specific Implant Fabrication 

Patient specific orthopedic implant manufacturing is a challenging one for the doctors' community. In this work, a three dimensional (3D) Finite Element model of the left tibia bone of an adult male was developed from Computed tomography (CT) scan. With the help of image processing software Materialise's Interactive Medical Image Control System (MIMICS), the exact geometry of the bone is reconstructed through the process of segmentation and region growing by defining the threshold value and converted into a Computer Aided Design (CAD) Initial Graphics Exchange Specification (IGES) format. It is used to create solid CAD model using CATIA by Non-Uniform Rational B-Spline (NURBS) functions and to design the patient specific implants. The model is imported into Hypermesh software to repair, reconstruct and mesh. The meshed model is imported into Finite Element Analysis (FEA) software. Fracture is simulated using element removal techniques and the implant is fitted. Finite Element Analysis (FEA) is carried out to validate the implant design by correlating the mechanical behavior of the model through assigning the suitable material property, loading and boundary conditions before and after fracture. The model is fabricated using the Rapid Prototyping (RP) technique. The RP model fabricated can be used for design verification and as a functional implant. Patient specific implant design by integrating the FEA and RP minimizes the implant failure and enhance the confident level of the surgical team. 

Devika Ramesh, Research Scholar, Anna University
Arumaikkannu Ganesan, Assistant Professor, Department of Manufacturing Engineering, Anna University, India 


Custom Implant Development using Rapid Manufacturing - MedCAD 

This presentation will present 6 cases we have created implants for. The ages of patients range from 9 years old to 50 and involve custom reconstructive and plastic surgery implant examples. It will also compare the current non-digital and digital. Our process has also involved surgical planning for complex cases. The implants are made from rapid prototypes and RP guides and splints were used in some cases, which enable the surgeon to have a physical model to use in the operating room for measurement.

Nancy Hairston, President, VanDuzen Inc.


Application of Laser Engineered Net Shaping for the Acquisition of Porous and Fully Dense Structures 

The advances in capability of replacing or upgrading human anatomical parts have boosted the production of medical prototypes. RP in biomedical sciences is making progress, enabling the manufacturing of porous scaffolds, implants, dental implants, orthopedic prosthesis, teaching aids and models for surgery planning. One of the developing areas of RP application is the field of tissue engineering where it is now possible to study the micro fluidics of the human body system by fabricating porous structures with interconnecting channels. This research gives insight into the application of Laser Engineered Net Shaping (LENS) for acquisition of porous structures. 

This presentation discusses a research study on the influence of process parameters to obtain porous and/or fully dense structures using Laser Engineered Net Shaping (LENS). Laser power, scan speed, hatch/raster spacing and powder feed rate are considered to be the most influential parameters on the structure and mechanical characteristics of materials processed using LENS. Therefore, these parameters have been varied to obtain vital information about the possibilities that the LENS system offers. Influence of process parameters on the structure of the porous structure, its density, as well as its columnar grain growth will be analyzed. It has been verified that laser power and powder feed rate have the largest influence on the hardness of porous samples, while raster spacing in combination with powder feed rate dictate the level of pore connectivity. 

Tamara Novakov, Teaching/Research Assistant, Purdue University
Mark Jackson, Assistant Professor, Purdue University 


Comparison of Direct Metal Fabrication Technologies for Production of Medical Implants 

Several direct metal fabrication technologies are available on the market for production of medical implants. Each technology has its own pros and cons and it is sometimes difficult to decide which technology to use or invest in. These technologies are often considered to be competitors but that is not always the case. Laser based systems tend to be more accurate than electron beam based systems and provide smaller features and finer surfaces. However, the cost is usually higher and the build time longer which can prohibit fabrication of larger implants. This presentation looks at a number of case studies were both electron beam and laser beam systems have been used to fabricate custom implants out of titanium. Build time, surface quality, feature size, and cost are discussed. The presentation gives an overview of the technologies and can help potential users to choose the system that fit their needs the best. 

Ola Harrysson, Associate Professor, NC State University 


 

1:00 p.m. - 5:30 p.m.
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In Vitro and In Vivo Test on Specimens Made by SLM and EBM Preliminary results will be presented for specimens manufactured by e-beam or SLM. The technologies allow production of 3D Ti6Al4V parts with osteo-integration surface in nearly one step. To assess their osteo-integration potential, in vitro and in vivo tests were done. The materials used were Ti6Al4V samples manufactured by e-beam or SLM. The method used was an in vitro test that investigated friction coefficient of samples against cortical bone.

A second study looked at humane mesenchymal cells behavior onto and into the structures. An in vivo test on e-beam samples was done in femoral condyles of goats. The samples were post-treated and cleaned to minimize particle loosening and maximize biocompatibility. Histological analyses were done 6 weeks after surgery. An in vivo test on SLM samples (cleaned and post-treated) was done in sheep mandibles. Histological analyses were done 8 weeks after surgery.
The results of the in vitro tests were friction coefficients for e-beam topographies resulted about 0.6. From literature, for an HAP coating it was 0.3. In vivo tests on e-beam samples showed good bone to implant contact like control specimens (titanium plasma sprayed). Bone in growth was noted (1,5 mm). In vivo tests on SLM samples showed enhanced osteo-conductivity, bone remodeling and surface colonization. The conclusion drawn was that surfaces obtained using RM, if properly designed and carefully post treated, obtain results comparable with consolidated solutions.

Emanuele Magalini, Dott. – R&D Technician, Eurocoating


Volume Productions of Implants With RM 

Various rapid prototyping technologies have been around for quite some time now, also for metallic materials. The emphasis in the past has been to build prototypes but the goal has also been to find high volume production of parts where the unique opportunities of this technology are utilized. Such applications have been harder to find.
This presentation provides an insight into a case where EBM is used in production of CE-approved Acetabular Cups in Ti6Al4V with integrated, designed network structures. It is a case where EBM is being used to build a part with a unique design using a production method which provides clear benefits over traditional methods.
A new way to manufacture orthopedic implants with integrated, designed network structures enables the creation of optimal surface environments for improved osseointegration, eliminating the need to add a porous coating of titanium beads or hydroxyapatite to the implant's surface. 

With this method the implant manufacturer and surgeons can together design an implant with the optimal network structure (topography, geometry, size of network cells) in a CAD program. 

The computer then cuts this 3-dimensional CAD model into very thin 2-dimensional slices, which are transferred to a machine for Rapid Manufacturing, where the implants are manufactured by melting thin layers of metal powder. 

The process takes place in vacuum, which makes it especially well suited to manufacture parts in reactive materials with a high affinity for oxygen, such as titanium. 

Two European orthopedic implant manufacturers are currently using this technology for series production of CE-certified acetabular cups with integrated network structures. 

The technology is also used to create light-weight CMF implants, consisting almost entirely of network structures. 

Andy Christensen, Medical Modeling 


Direct Digital Manufacturing: Scan-Based Implant Modeling Technologies in a Digital Vertically Integrated Manufacturing Environment
 
Melotte introduces Direct Digital Manufacturing technologies in a broad range of high-end industries. As an engineering company we've add Layered Manufacturing to our portfolio in 2004 and we immediately decided to do a vertical integration with the ultimate goal to deliver complex parts (tolerances below 5µm) within the principles of one-day machining. Today, Melotte produces medical implants based on CT scan data (cranio Facial) in titanium, complex hybrid products for the nuclear, petrochemical & high-end OEM business and we deliver products to the art & jewelry business. With our blog, The World of Layered Manufacturing in Metals we reach interested RM users worldwide. 

Mario Fleurinck, General Manager, Melotte
Hildi Willems, Marketing & Communication Manager, Melotte 


Jumping Through Hoops and Over Hurdles - Addressing the Issues of Rapid Manufacturing for the Medical Industry 

This paper looks at the time, effort and ongoing costs of supplying high quality medical devices to surgeons and the medical industry. The Direct Metal Laser Sintering (DMLS) process generates additional issues for the medical industry over and above those of other sectors. It requires biocompatibility and mechanical testing of these new materials, proving they are comparable with currently accepted materials. With the procedures required for the long term traceability of processes and materials used in production.

The acceptance and compliance process starts with the material and machine suppliers and ends with a certified product to the clinician. Each step of the production chain requires its own procedure and processes making the manufacture and traceability of any product a real challenge.

As the first Rapid Manufacturing company using DMLS in Europe to achieve ISO 13485 certification, we are well positioned to address these issues. 

Sexy Technology, tough to implement when speaking about the emerging technologies, Direct Metal Laser Sintering, Electron Beam Melting, etc. Speakers talk about the sexy process, speed of build, surface finish, part density and the complex shapes built. What they don't tell you about is the infrastructure required when manufacturing products acceptable to OEM's, especially those within the medical sector. Whether it's an implant or an instrument, a whole new ethos is required in production. Even materials and manufacturing processes used for instruments require certifying and auditing by the OEM's and external bodies such as the FDA and ISO. 

Litigation — who is responsible for the final part? The responsibility for the final product needs addressing. Should the product fail for any reason, the person responsible to the end customer should be identifiable. The scale of the change causes implementation delay when the medical industry changes a product's material or introduces a new process; it is carried out in a controlled and structured way using strict procedures. In order to use DMLS manufactured parts they will have to change both their process and material at the same time. The result is that the technology could take a long time to introduce; OEM's are standing back, waiting to see what happens. None wants to be the first, but all want to take advantage of the excellent benefits it offers. We must find a way to engage such parties so that they can lead the change rather than observe it. 

Philip Kilburn, Medical Markets Manager, 3T RPD Limited
In Vitro and In Vivo Test on Specimens Made by SLM and EBM


PANEL DISCUSSION: Panel Discussion With the Experts

Interactive forum for discussion, ideas and solutions to all of your implant questions and needs, answered by industry leaders including the following machine manufacturers: 3D Systems, EOS and ARCAM.