Category Archives: Medical

Orthopedic Implants, Part 3 – Materials Must Provide Strength, Safety

For millions of individuals, orthopedic implants provide the ability to regain mobility and reduce pain. Just as surgical skill is required to implant these artificial joints, so is skillful construction and finish of the joint components themselves.

A leader in surface finishing for medical technologyRosler has extensive experience in shot blasting and mass finishing a wide range of medical devices from instruments to implants used specifically for joint replacement.

Our Orthopedic Implant Series continues with an overview of the most common materials used for these endoprosthetic implants.

Popular Materials

To date, the most common materials have been titanium, titanium alloys, and cobalt-chromium alloys. Both materials are very tough, resistant to corrosion, highly biocompatible, and absolutely reliable.

While stainless steel often is used for trauma implants, it is not very common in joint reconstruction implants because of its limited long-term ability to withstand corrosion in the human body. Plastics, primarily polyethylene (for example, UHMWPE), have also seen increased use for joint reconstruction implants.

The interface between two joint sections can consist of metal-on-plastic, metal-on-metal, ceramic-on-plastic, or ceramic-on-ceramic.

For example, the section of the knee tibia plate that interacts with the femoral component is protected with a polyethylene liner. Likewise, the acetabular cup of a hip implant can be lined with polyethylene, whereas the femoral head on the hip stem interacting with the acetabular cup may be made of metal.

Types of implants

Alternative Materials

In some cases, alternative materials may be used in the manufacturing process. Less used materials for orthopedic implants include:

  • Ceramic – Because of its excellent wear characteristics and the best biocompatibility among the known implant materials, ceramic is quickly becoming an excellent alternative to titanium and cobalt chrome.
  • PVD (Physical Vapor Deposition) – Joint reconstruction implants frequently receive a PVD coating, using, amongst other materials, titanium nitride (TiN), zirconium nitride (ZrN), or chromium nitride (CrN). Such coatings provide numerous technical advantages, including improved wear resistance, reduced friction, high biocompatibility, and decorative colors.
  • Plasma Coating – This material is primarily used to promote osseointegration on those surface areas of implants that must bond with the surrounding bone tissue. To ensure perfect adhe­sion of the coating, the respective surface area must be textured or roughened by shot blasting before coating.
Orthopedic implants made of alternative materials

The Rosler Way

Regardless of the industry or specific component, Rosler learns about your work piece and process to develop a solution and deliver precision surface finishing and process improvements. Our work in the medical industry and with orthopedic implants is no exception.

Whatever finishing your joint reconstruction process calls for, we are confident that we can collaborate to find a better way. Contact us to discuss your unique challenges.

Previous posts in the Orthopedic Implant Series include:

Upcoming posts in the series will include:

  • Part 4 – “Finishers Meet Standards, Face New Challenges.”
  • Part 5 – “Mass Finishing Offers Medical-Grade Polishing.”
  • Part 6 – “Shot Blasting Improves Longevity.”
  • Part 7 – “Processing Technology Evolves with Industry Advancements.”

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Patient-Specific Implants Call for Equally Customized Processing

Advancements in medical technology now allow for the development of Patient-Specific Implants (PSI). Specialized computer programs analyze x-rays, ultrasound, and MRI images to create surgical guides, tools, and implants tailored to the patient’s unique anatomy.

While still emerging, many medical industry suppliers have received FDA approval for PSI use. Like traditional implants, these implants must be carefully finished once created to ensure the work piece meets stringent medical safety standards while promoting patient comfort and long wear life.

The benefits of PSI use include shorter surgery times, better surgical outcomes, and cost savings.

True to its “apply innovation” tagline, Renishaw’s Medical and Healthcare Division has found great success in additively manufacturing PSI. Using CT scan-to-CAD software, one of the company’s most innovative advances is creating cranial plates using titanium powder.

When determining how to finish the implants to precise medical requirements and surgical demands, Renishaw trusted Rosler for help with mass finishing.

The Challenge



Renishaw cranial plates after polishing

Original commissioning neurosurgeon Bartolomé Oliver required the surface of Renishaw’s cranial PSI to be satin-like in order to best match the patient’s cranial contours. Renishaw Applications Engineer Andy Wescott’s job then became creating a repeatable and streamlined process to apply a satin and highly polished finish to the top of the cranial plates from their as-built condition. 

“Traditionally, post-processing these parts to a low surface roughness value was very manual and time-consuming,” Wescott said. “The post-process time for a large cranial plate was up to five hours. We needed to reduce that time and the amount of manual input because if an operator working on a part loses concentration for one second, they could burn a hole in your part.

“That makes one expensive bit of scrap.”

Finding a Better Way…

Since metal additively printed parts are now of such quality, they can be treated like any other metal part. And Rosler knows a thing or two about surface finishing metal parts, having been in the post-processing game with its mass finishing and shot blasting divisions for more than 80 years.

A more mechanized solution presented itself in the form of Rosler’s High-Energy Centrifugal Disc Finishing Machine FKS04.

Now, after a cranial plate comes out of the Renishaw AM250 machine, it undergoes only a small amount of manual operation to remove supports from printing and slightly improve the surface using a carbide burr and flap wheel.

It is then placed into Rosler’s FKS where it automatically goes through a three-step process to produce the impeccably smooth finish, reducing manual operating time to under an hour.

The clever part, which ensures repeatability on each and every part, comes from a little bit of Renishaw engineering know-how.

“We designed a tool to hold our parts in a particular orientation inside the tumbling bowl,” Wescott said. “Rather than just throwing parts into three media types and coming out with a sort of fixed part, our parts require precision. Certain features require protection from the tumbling media, so we’ve invented a tooling method that keeps parts face down in the media and only applies the surface finish where needed.”

The Rosler Way

Although there isn’t a one-size-fits-all solution for finishing, the collaboration between Renishaw and Rosler demonstrates that post-processing doesn’t have to be a grueling experience. Much like the additive manufacturing process itself, your finishing technique depends on your unique application. Contact Rosler today for help in finding a better way to meet your finishing needs.

Orthopedic Implants, Part 2 – Required Component Characteristics Define Finish

Joint reconstruction implants are subject to the same zero-defect performance and reliability standards as any other implant. However, because two components are always interacting with each other, dimensional accuracy is of particu­lar importance.

Within the medical industry, surface finishing experts such as Rosler assist implant manufacturers in achieving the exact finish needed for each surface of the joint.

In addition to increasing product popularity and demand for the manufacturer and providing medical professionals with safe and dependable joint replacements, ensuring that orthopedic implants have the exact finishing required enables the joint to function longer and more comfortably for the patient.

Continue reading Orthopedic Implants, Part 2 – Required Component Characteristics Define Finish

Orthopedic Implants, Part 1 – Surface Finishing Enhances Component Life, Function

Fueled by more active lifestyles and increased life expectancy,the market for knee, hip, and other replacement body jointsis on the rise. With more than $19 billion in annual worldwidesales, implants for joint reconstruction make up nearly 40 percentof all orthopedic product sales.

Thanks to significant advancements in materials and new or improvedsurface finishing technologies, today’s artificial hips andknees can last more than 20 years, giving the recipient decadesof comfort and agility.

Parts that are finished using modern mass finishing and shot blasting methods play a key role in extending the lifespan of orthopedic implants.

Rosler has extensive experience in these processes which often include cleaning, deburring/edge radiusing, surface smoothing, post-casting surface preparation, machining, CNC grinding, and, of course, final finishing. These finishing technologies make big differences in the quality and performance of such products.

Continue reading Orthopedic Implants, Part 1 – Surface Finishing Enhances Component Life, Function

Joint Reconstruction, Part 6 – Shot Blasting for Surface Finishing, Coating Preparation, and Increased Component Life Span

Like mass finishing, shot blasting is an exceptionally versatile surface treatment technology. Its applications range from general cleaning after casting and forging to shot peening and, even, cosmetic blasting for placing a fine, matte finish on the work pieces.

For shot blasting of orthopedic implants Rosler Metal Finishing recommends mainly air and occasionally wet blasting systems. The blast media is accelerated by compressed air and thrown at the work pieces through a blast nozzle, creating an extremely precise blast pattern compared to turbine blasting. Another advantage of air blasting is that it can be used with metallic, mineral as well as organic blast media.

These attributes and many more make this surface finishing method particularly useful in the medical industry

Continue reading Joint Reconstruction, Part 6 – Shot Blasting for Surface Finishing, Coating Preparation, and Increased Component Life Span

Joint Reconstruction, Part 5 – Mass Finishing for Smooth, polished surfaces

Mass finishing is a highly versatile finishing technology that can be used for a wide variety of different surface treatment operations including those in the medical industry. Therefore, it is no surprise that mass finishing processes are utilized at practically every manufacturing stage for all kinds of orthopedic implants.

Rosler Metal Finishing has decades of experience in mass finishing. In this installment of the Joint Reconstruction Series, we will compare the various machines used to provide precise finishing for endoprosthetic manufacturers.

Examples of Mass Finishing

Mass finishing is used for a variety of joint replacement work pieces including:

  • Descaling and edge radiusing of hip stems, knee femorals, and other implants after forging or casting, e.g. lost wax or investment casting. 
  • Deburring and surface smoothing of various implants after belt or CNC grinding.
  • Final polishing of knee femorals, femoral heads, and the inside of acetabular cups to Ra = 0.8 micro inches as the last finishing stage before implantation.
Continue reading Joint Reconstruction, Part 5 – Mass Finishing for Smooth, polished surfaces

Joint Reconstruction, Part 4 – Comparing Surface Finishing Methods

Shot blasting and mass finishing have become indispensable technologies for surface preparation and finishing of joint reconstruction implants. Their applications range from surface cleaning, deburring, edge radiusing after forging, casting, additive manufacturing, and machining to surface preparation for different kinds of coatings, shot peening for increasing the longevity of an implant, and placing an extremely smooth, high-gloss finish on the implants before they are inserted into the body.

Rosler Metal Finishing leverages its extensive experience in the medical industry to create customized solutions and equipment for the treatment of joint reconstruction implants.

This installment of the Joint Reconstruction Series will compare the working principles and features of utilizing shot blasting and mass finishing technologies for endoprosthetic implants.

Continue reading Joint Reconstruction, Part 4 – Comparing Surface Finishing Methods

Joint Reconstruction, Part 3 – Surface Finishing Standards

While choosing the right implant material is of utmost importance, as discussed in our previous Joint Reconstruction Series post, the significance of optimum surface treatment throughout the entire implant manufacturing process cannot be overstated.

This relates not only to the right surface finish – be it a high-gloss polish for low friction, a textured surface for easy osseointegration, or as preparation for subsequent coating, rounded edges, etc. – but also total compliance with the specified tight dimensional tolerances. The success of a joint implant is determined by the perfect match between the various implant components. This depends, to a large extent, on the surface treatment procedure(s).

With extensive experience in the medical industry, Rosler Metal Finishing is an expert in designing systems and solutions for the treatment of joint reconstruction implants utilizing shot blasting and mass finishing technologies.

Our Joint Reconstruction Series continues with an overview of the stringent finishing standards for endoprosthetic implants.

Continue reading Joint Reconstruction, Part 3 – Surface Finishing Standards

Joint Reconstruction, Part 2 – Material Standards

Joint reconstruction implants allow millions of individuals to regain mobility and reduce pain. Just as surgical skill is required to implant these artificial joints, so is skillful construction and finish of the joint components themselves.

A leader in surface finishing for medical technology, Rosler Metal Finishing has extensive experience in shot blasting and mass finishing a wide range of medical devices from instruments to implants used specifically for joint replacement.

Our Joint Reconstruction Series continues with an overview of the most common materials used for these endoprosthetic implants.

Material Standards

The most common materials used for joint reconstruction implants are currently titanium and titanium alloys and cobalt-chromium alloys. Both materials are very tough, corrosion-resistant, highly biocompatible, and have proven themselves to be absolutely reliable.

Continue reading Joint Reconstruction, Part 2 – Material Standards

Joint Reconstruction, Part 1 – Expertise for Endoprosthetics

With more than $18 billion in annual worldwide sales, implants for joint reconstruction make up nearly 40 percent of all orthopedic product sales. More active lifestyles and increased life expectation continue to contribute to the rapid growth of this market segment.

Thanks to significant advancements on the material side and enhanced surface finishing technologies, artificial hips and knees can last more than 20 years before they must be replaced. Rosler Metal Finishing’s shot blasting and mass finishing capabilities are examples of processes and equipment that have and continue to evolve to accommodate the demand for increased endoprosthetics which are also known as orthopedic joint reconstruction implants.

These techniques play a key role in intermediate processing steps including cleaning, deburring/edge radiusing, surface smoothing, and surface preparation for coatings after casting, forging, machining, CNC grinding as well as placing the final finish on the implants before they are inserted.

Continue reading Joint Reconstruction, Part 1 – Expertise for Endoprosthetics