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Case study: Trabecular Metal Cage 2017-05-19T11:11:43+00:00

Case study: Trabecular Metal Cage

Intervertebral cages of porous titanium or trabacular metal is an attractive alternative for cages made out of PEEK. Titanium has superior properties with respect to bone in growth compared to PEEK. Furthermore, it is possible to generate designs that has similar stiffness properties as bone. A new method to generate porous titanium cages is using an additive layer manufacturing process. This is a relative new technique which has just left the experimental stage could be used in batch manufacturing.

The goal of this project was to design, engineer and CE mark a new cage line by using an additive layer manufacturing process. We have completed this project, using our 5 step approach.

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Stage 1: Explore

Because the manufacturing process is rather new we started with a process risk analysis, something which is usually performed in the Engineer stage. Cleaning and sterilization where identified as the two main issues that should be addressed early in the project. We also decided to develop a “general worst case” product that will represent all type of cages within a specific dimension range.

We started to define a new cleaning and sterilization process for a “general” worst case mesh structure. We also defined a method for overall mechanical validation partly based on FEM calculations combined with mechanical tests. The reason for this approach is that a general mechanical validation combined with a general cleaning and sterilization validation gives our customer much freedom to bring cages in various shapes on the market. Having a general validation available, it is even possible to offer customized cages for specific users. In this stage some initial tests where performed to find out if the proposed processes will indeed show sufficient results.

Stage 2: Design

In this stage we focused on the design of the cages itself. Not only the definition of sizes and shape of the cages where important aspects, also the tolerance level at the cage-instrument interface is a critical aspect of the design. A lot of attention was paid to the determination of the cost of goods price. Since this is a relative new process we expect that the percentage of product that do not pass quality control is higher compared to conventional manufacturing methods. This will affect the cost of goods price. Another important aspect in this stage is the definition of the instrument set.

Stage 3: Engineer

After finishing the Design stage,  manufacturing drawings of all cage dimensions where completely detailed and prototypes where manufactured of the implants and instruments. Key instruments where designed in house and for all other instruments we have used a specialized supplier. For this particular project this stage was very short. Especially for the cages there was a lot of overlap between the design and engineer stage.

Stage 4: Validate

The Validate stage was the main part of the  project because all validation plans of the cleaning, sterilization and mechanical strength as developed in the Explore phase are carried out here. Especially for cleaning and sterilization validation much more extensive tests where needed compared to a conventional manufacturing process. All validation tests where carried out on the general cage “worst case” structure. Second part of the validation stage was to translate the validation results of the generic cage to the specific cage design that will be introduced to the market. This is partly done with design rationales and partly by additional mechanical testing to support the rationales. The clinical validation of  the cages was done through the clinical literature route.

Stage 5: Transfer

The project was completed in the Transfer stage. In this stage the technical file and design history file was completed and applied for CE mark to the  notified body. We decided to apply for CE in two steps. The first step was to obtain approval for the manufacturing process including cleaning, packaging and sterilisation of the “worst case cages”. The second step was to obtain approval for the specific cage itself, based on the obtained CE mark of the manufacturing process.

Recently, the first cages were introduced into the market. For specific information, don’t hesitate to contact us: 0031-88-5656600 or mail us at info@baatmedical.com.