Quality assurance is vital for accurate production of patient-specific joints and prostheses, therefore Baltic Orthoservice uses a multi-sensor CMM and laser scanner in conjunction with a micro-CT system. The multi-sensor CMM is used for fast surface and screw hole inspection of the 3D-printed implants. The XT H 225 CT system is used to guarantee internal structure quality and geometrical accuracy between CAD implant model and manufactured implant. The combination of these technologies enables Baltic Orthoservice to achieve the best accuracy and highest quality for a wide variety of medical devices.
The core business of Baltic Orthoservice is manufacturing 3D-printed patient-specific implants, endoprosthesis and surgical guides. Operating in the medical industry, the Research and Development (R&D) department is responsible for product development, prototype geometry investigations, quality assurance and final quality control. Paulius Luksevicius is the Engineer of Mechanics at Baltic Orthoservice, he explains, “3D printing is a complicated technology and has a big variation of processing parameters, consequently predicting the quality and geometry of printed objects is quite a challenge”.
Patient-specific implants are a ‘pre-planned’ treatment solution, which basically means that the whole surgery must be ‘pre-planned’ virtually, so that the implant can simply be put in place. In order to meet the virtual plan, it is vital to be 100% sure that implant geometry is exactly the same as the designed CAD model and the screw holes are milled at a high accuracy. To fulfil these goals, they use a variety of quality assurance equipment, including a multisensor CMM and micro-CT.
“The ALTERA CMM with LC15Dx laser scanner is irreplaceable when we need to perform fast quality assurance check-ups after each manufacturing and post-processing stage, especially to check spherical surfaces, bearing surfaces and screw hole angles”, Paulius states.
3D-printing enables production of implants with anatomically adapted surfaces
Pictured above, is the patient-specific acetabular implant GIGIT. Implants such as this are only used for complex hip joint cases – severe acetabular defects (W. G. Paprosky 2A-3B), or pelvic discontinuity. This implant is used to help recreate the anatomy of a hip joint and to restore its functions.
Milda Jokymaitytè, Clinical Engineer at Baltic Orthoservice explains, “Unlike standard modular implants used to treat severe clinical conditions, patient-specific hip implants are designed as a single device with anatomically adapted surfaces. This eliminates the risk of instability, and adapts the implant to the bone rather than the bone to the implant”. A major benefit of this procedure is that during surgery, there is no need to shape the bone in order to adapt it to the implant or use bone cement, meshes and augments to fill the bone defect. Patient-specific implants are designed using virtual anatomical bone models which are obtained from medical computed tomography (CT) scan of a patient.
For manufacturing patient-specific implants, Baltic Orthoservice uses DMLS technology (direct metal laser sintering). The implants then undergo a variety of post-processing steps, including heat treatment, surface polishing and milling for screw holes.
There are a number of medical device standards and regulations which must be met, which is why it is paramount for products to be of ultra-high accuracy. With such fine tolerances and strict standards to meet, the post-processing stages are repeated until the physical implant matches the desired virtual model exactly and quality assurance measures are taken following each step.
After each post-processing stage, the LC15Dx laser scanner is able to quickly show how the physical part matches the virtual model. Milda explains that “the LC15Dx on the ALTERA CMM is great for checking geometrical accuracy of implant screw holes at each transitional process”.
Developing a Quality Control Laboratory with top quality equipment
Since investing in additive manufacturing technologies in 2012, Baltic Orthoservice has also assembled a portfolio of quality assurance equipment. The goal is to guarantee the absolute best quality of product for its patients, and make patient specific implants more readily available.
“We, as manufacturers, must ensure the best quality of our products. Therefore we decided to develop the Quality Control Laboratory in our facilities and invest in high-quality equipment”, Paulius explains. “Alongside the multi-sensor CMM, Baltic Orthoservice therefore also uses a Nikon Metrology XT H 225 micro-CT system.”
Milda explains that laser scanning and micro-CT serve two different purposes and both excel in different areas. “The ALTERA CMM with LC15Dx is great for inspecting features and surfaces of biggersized implants, such as acetabular implant, for standard products like osteosynthesis plates and for standardized elements in patient-specific implants, i.e. screw holes or spherical shapes.” Milda continues: “The micro-CT system is a vital tool for non-destructive analysis of the internal structure and geometry for additive manufactured components”
For Baltic Orthoservice, the systems are used in tandem to complement each other. By using both of these technologies, Baltic Orthoservice can guarantee absolute accuracy – as is demanded in the medical industry – and to maintain its USP: producing patientspecific implants.
The highest accuracy: Nikon Metrology offers the complete solution As the Quality Control Laboratory was a new project to supplement the additive manufacturing facilities, there were no previous systems to be replaced. Baltic Orthoservice knew what was required and compared the best technologies on the market to find the right solution.
Paulius discusses that, “The first requirement was to have the capability to scan parts made from different types of materials. The working area was also important, but most importantly – accuracy”. The final choice was between Nikon Metrology and another leading competitor. To suit the needs outlined by Baltic Orthoservice, the Nikon Metrology laser scanner proved to be the outstanding solution. Paulius explains that the competitor was rejected due to “differences in laser scanning probe”. He cites the longevity and accuracy to be a major factor in the decision with the moving parts in the competitor’s probe to be a concern for potential complications and expensive maintenance.
A key advantage of the Nikon Metrology LC15Dx is its ability to scan reflective and multi-material surfaces thanks to the unique ESP technology. This means it maintains accuracy, speed and data quality by intelligently adapting the laser settings for each measured point in real-time. Its accuracy has a probing error comparable to that of tactile inspection (1.9 µm), and data collection speeds of 70,000 points per second. By maintaining such high standards when scanning difficult surfaces, this makes the LC15Dx an incredibly powerful tool for inspecting complex parts in the medical industry.
Ultimate quality assurance
Paulius concludes by discussing the results so far, “the Nikon solution offers better knowledge of what we are manufacturing, gives better precision and understanding of the 3D-printing errors and deviations. This means we achieve the best product quality and avoid the risk of implant failure during the operation, implants with Nikon quality assurance are more reliable and it is easier to prove their value”.
It’s clear to see how Nikon Metrology inspection solutions have played an important role in the production of 3D-printed medical implants. This has also been recognised by other manufacturers. Paulius explains, “very often our Quality Control Laboratory gets inquiries from other manufacturers in medical and industrial fields to perform standard part geometry inspection for them”. Whilst both the ALTERA with LC15Dx and XT H 225 have significant individual benefits, it is the combination of the two solutions that works so well for Baltic Orthoservice. The R&D team has a Quality Control Laboratory that possesses the best tools to cover all angles. So, it is with good reason that Baltic Orthoservice has absolute confidence in the quality of all final products. Whatever the case tasked with, all solutions will be made-to-measure with ultimate quality assurance.