The Best Possible Outcome: The Importance of Post-Processing to Optimize Surface Morphology in Spinal Implants
Various surface treatments for orthopedic implants serve different objectives, from the practicality of part identification through color coding (as seen in the top polyaxial pedicle screw with color anodized tulip), to enhancing the surface texture for better osseointegration potential (as displayed on the lower monoaxial pedicle screw which has been uniformly abraded with Himed’s biocompatible apatitic abrasive). Image: Joseph De Leo
Here at Himed, we are gearing up for the BIOMEDevice and the NASS trade shows in Boston. So we started asking ourselves what we were most excited about in orthopedic advancements in general, and spinal health in particular. The answer—perhaps not surprisingly for a surface treatment company—are the benefits that patients experience when spinal implants undergo optimizing surface treatments after manufacture.
In order to create the best possible spinal implants, the surface must be free of contaminants and textured in a way that creates an ideal environment for integration with the surrounding bone. That most often requires a post-processing surface treatment. And that's something Himed has spent decades pioneering and perfecting.
The market for spinal devices is growing
It’s a vital time for the world of spinal devices, as there’s been a broad expansion of the spinal sector in modern orthopedics. In 2019 and 2020, the FDA issued 1,555 orthopedic 510(k)s and 41% of them were for spine devices. When two out of five premarket notifications for orthopedic devices are for the spine, that’s a remarkable trend.
An increase in the ageing population, along with improved surgical procedures that are encouraging doctors and patients to explore spinal surgeries, are creating an increased demand for spinal procedures and the accompanying spinal devices.
As more device companies enter or expand their offerings in the spinal sector, many of them are looking for ways to set themselves apart from the competition. Turning to Himed for surface treatment is helping companies across the globe bring better spinal devices to market. Himed’s proprietary processes help improve surfaces for better osseointegration while removing contaminants to create the best possible version of an implant.
Despite recent and continued advancements, there is still room for improvements in the spinal device marketplace. Himed aims to work with device manufacturers to bring those advancements to life. After all, fully optimized spinal devices lead to better patient outcomes. And that’s always the primary goal for everyone in the biomedical industry.
The key to improving spinal implant success
Plates, pedicle screws, cages, rods and other spinal devices each have their specific function. And while the structure and mechanics of an implant is obviously important, no implant will be successful if the body rejects it. Titanium has proven itself over the years as being particularly conducive to integration with the body. Data shows that titanium and bone create a chemical reaction responsible for osseointegration at the chemical level.
Yet, all titanium implants do not share the same level of success.
What makes the difference when it comes to optimizing osseointegration? Often it is the surface of the implant itself. Two factors affect osseointegration: the presence of an ideal texture and the absence of residue.
Spinal spacers that have undergone Himed’s MATRIX Ti™ process display a biocompatible surface ideally textured to stimulate the human body’s natural healing response. Image: Joseph De Leo
Roughed titanium has been shown to better stimulate cells to create bone- and blood vessel-forming microenvironments than a smooth titanium surface. Residual contaminants left behind after additive manufacturing or after traditional finishing can be released into the body, creating an inflammatory response which can lead to implant failure.
To create a properly textured surface, while also removing potential contaminants, grit blasting is an ideal method. Traditionally, orthopedic devices were blasted with aluminum oxide or other metallic media. Unfortunately, even with thorough cleaning processes, traditional grit blasting leaves behind residue.
Blasting with hydroxyapatite
Decades ago, Himed pioneered grit-blasting for implant surfaces using a specially hardened form of hydroxyapatite (HA). The proprietary blasting media is fired through a micro-grit blaster nozzle using pressurized air. The accelerated particles are forcefully directed against the surface of the implant, where it can deburr, remove surface abnormalities, and add texture. We call our proprietary finishing technique MATRIX MCD™ and it represents a superior method for optimizing orthopedic implants.
One objective when subjecting a device to a surface-finishing process is to remove the possibility of potential contamination in the patient’s body—in the case of titanium additive manufacturing, the contaminants appear in the form of titanium beads that are a known byproduct of 3D-printed parts. If left unchecked, there’s a danger of the beads breaking off and being released into the body as a foreign object.
When removing that potential contaminant, it only makes sense to ensure that further contamination is not created. Unlike traditional grit blasting which leaves behind residue (even after cleaning processes), MATRIX MCD™ leaves nothing behind. After passivation, virtually none of the grit-blasting media remains. And because the HA grit blasting medium is a biocompatible and resorbable substance, if trace amounts were ever left behind, the HA would harmlessly assimilate into the patient’s body.
Unique and controllable surface morphology
Another key objective for surface treatments is optimizing the device for osseointegration. Studies have shown, and the practical consensus is, that surface roughness increases the responsiveness of bone-forming cells. The limiting factor in additive manufacturing of spinal implants is the surface texture. With current technology, 3D printed devices have a hard time producing submicron scale surfaces.
That’s where finishing with MATRIX MCD™ comes in.
MATRIX MCD™ grit-blast applications result in highly textured surfaces, which can be minutely controlled. Thanks to Himed’s Fully Automated Blasting System (FABS), we can fine-tune the texture on a device surface. We have the ability to adjust the particle size of the hydroxyapatite, the blast pressure, and the blast duration. Our engineers are also able to create custom masking so that the textured surface is properly targeted. Tailored to virtually any surface specification, a completely customizable output can be achieved.
Creating better spinal implants through optimized surfaces
The first few weeks after implant are the most critical for successful bone healing. Immediately after implant, the device interacts with the blood and serum coating the surface. EIther that biological environment begins to help differentiate stem cells, encouraging them to create osteoblasts and other bone-building cells. Or else the body begins to create an inflammatory response, which can lead to undesirable outcomes. That initial interaction is essential to the success of a spinal implant.
For the greatest potential of osseointegration and lowest risk of foreign contaminants—whether for additive manufactured devices or traditional subtractive manufacture—a device should ideally undergo a proper finishing process.
Spinal implants that undergo finishing with Himed’s MATRIX MCD™ apatitic abrasive set themselves apart from other devices on the market, simply because a fully optimized surface leads to a better patient outcome.
A distinguished final product
As the market for spinal implants widens, and the number of new devices entering the marketplace increases, many device manufacturers are feeling the pressure to improve their spinal offerings to stay competitive. What better way to distinguish a final product than through a cleaner, more bone-friendly surface? Free of contaminants and ideally textured to promote osseointegration, a spinal device that undergoes Himed’s MATRIX MCD™ process is destined for unparalleled success.
Call today to speak to an engineer about setting your spinal implants apart from the crowd.