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OEMs and suppliers see promise in the ability of new technology to expand the use of custom implants and bring greater personalization to orthopaedics.
Custom implants and instruments are not new; for years, they’ve been tailored to meet the patient’s specific anatomy with the potential to reduce surgery complications and improve the implants’ success rate. This seems like an obvious benefit to patients and manufacturers. However, more long-term clinical data is needed to prove that custom implants result in better patient outcomes than use of traditional implants. The cost-benefit must also be demonstrated in order for custom implants and custom instrumentation to fully penetrate the market.
“Ultimately, the answer lies in continued and better understanding of the patient benefits,” says James Thompson, Director of Medical Device and Pharmaceutical Industries within Siemens PLM Software. “That’s really where the boundary is today and will continue to be for the foreseeable future. It’s a relatively small percentage of the overall surgeries performed. Whether that grows to be the majority will depend on proven patient benefits, as well as the cost benefits.”
The hang-up for orthopaedic device companies has been and continues to be the ability to maintain volume, cost and speed to market when individual design, manufacturing and shipping processes are concerned. New software and manufacturing techniques have made it easier for some orthopaedic OEMs to adopt a custom implant model.
Custom implants can be produced using traditional manufacturing, such as CNC machining, and are often associated today with 3D printing or additive manufacturing.
With CNC machining, device manufacturers may use a slightly modified program to customize implants on a per-patient basis. Siemens provides automation that templates the manufacturing process and the CNC tool paths.
“When you update the underlying patient geometry, that causes an update in the template, and those changes automatically progress downstream to the programs that are updated on the CNC machines,” Thompson says.
Within Technologies provides software that creates micro lattice structures for 3D printed orthopaedic devices. “We’ve exploited the benefits of 3D printing and designed software that aligns itself with certain 3D printers to create a complex lattice structure that integrates with a solid substrate,” says Shane Fox, Business Development Specialist, Within Technologies. “We were able to design trabecular lattice structures that mimic organic bone growth, and promote osteointegration.”
After the component is designed digitally, it is exported to be manufactured.
Utilizing additive manufacturing to create custom implants has several benefits for manufacturers.
“Big companies find that the primary benefit is, it can reduce the costs and waste of materials,” Fox says. “By light-weighting or optimizing a component, you’re saving on materials. At times you can save 20 to 40 percent on material waste. We’ve been able to prove that certain orthopaedic designs are already able to produce parts cheaper through additive manufacturing than traditional.”
Design and development is still evolving in the realm of patient-specific implants, though.
“From a technology point of view, we’re trying to cut down on steps and time wasted in the user experience, and trying to add more features to our software to develop more accurate patient-specific implants,” Fox says.
Echoing Fox, Thompson says the production process for custom implants is not without its challenges.
“One of the unique challenges associated with custom implant procedures is establishing an “engineer-to-order” system that manages each patient case through the custom design and manufacturing processes,” Thompson says. “Such systems need to control and coordinate the case data and workflow from start to finish, including facilitating collaboration with physicians to accept initial design input and provide a means for review and approval of proposed custom components.”
ConforMIS knee implants are designed and manufactured to the patient’s specific anatomy to decrease size and fit issues.
Siemens sees additive manufacturing more in use for instrumentation, rather than for the implants themselves.
“Interfaces, usability and automation associated with CAD/CAM technology today make it a lot easier to train and have people do this personalized work,” Thompson says. “The technology has been around for years, so there’s not a lot of risk. There’s an increased level of knowledge and awareness about what that technology can do. For customized instruments, 3D printing has had a big impact—to be able to print these one-of-a-kind shaped instruments that align to patients’ anatomies. These days, it happens without too much difficulty because of internet-based collaboration and relatively low-level cost production from a global supply chain.”
Troy Vanderhoof, Marketing Director of Siemens PLM Software, notes the changes in manufacturing equipment used to produce these parts.
“Machining with high speeds is one of the modern technologies that, in comparison to conventional cutting, enables you to increase efficiency, accuracy and quality of work and at the same time decrease costs and machining time,” he says. “Look at the changes that have taken place in just the last 20 years:
• Speed: Maximum feed rates were 100 ipm. Now, 600 ipm is common and 1,200 ipm is better.
• Accuracy: Data density of 0.04-inch point departures was close and accurate. Now, closer than 0.004 inch is common and
may even be closer than 0.001 inch.
• Data/CPU: Files of 64 kilobytes were very large. Now, files regularly exceed ten and even 100 megabytes.
• Sculptured surfaces were used occasionally for aesthetics. Now, sculptured surfaces are widely used for both
function and appearance.”
Faster manufacturing processes also are contributing to companies abilities to maintain volume. Thompson said speed is not a barrier, and at least not one that can’t be overcome by adding machines and people. Fox added that some additive manufacturing printers can produce about 6,000 hip cups per year if running at full capacity (80 percent).
Medicrea and ConforMIS are two device manufacturers that have implemented a custom implant model.
Spine-focused Medicrea recently launched the UNiD patient-specific rod system, incorporating a process whereby surgeons preoperatively analyze, design and order the rod. The UNiD LAB engineers assist the surgeons throughout the process and create an implant for each specific patient.The company can produce parts in ten days between case planning and delivery.
“Several manufacturing technologies are used to produce these implants, depending upon their nature,” says David Ryan, Vice President of Product Development and Marketing, Medicrea. “For example, extruded rods used to fix and fuse the spine in the correct sagittal alignment are industrially contoured. Intervertebral devices, whether cage or corpectomy devices, are 3D printed.”
ConforMIS employs a similar process. Their process begins with a CT scan of the patient’s hip, affected knee and ankle to make certain that the leg is re-aligned to the neutral mechanical axis before the implant is designed. The technology, iFit®, uses a series of proprietary algorithms to convert the 2D CT scan of the patient’s knee into a 3D model that maps the articular surface of the joint, to define the affected area. Then, the software designs each customized femoral and tibial implant plus instrumentation from the 3D model.
The implants are manufactured in and ready for patients six weeks after their CT scan. Once the implant is ready, it is packaged and shipped directly to the surgeon.
Using a “just in time” manufacturing and delivery, implants are shipped right before the scheduled procedure, eliminating the need for hospitals to store multiple implants in inventory.
One certain benefit is that custom implants are pushing innovation in the orthopaedic industry and will continue to play a role in the industry’s growth.
“A key challenge in a mass manufacturing model for off-the-shelf knee implants is that important and sometimes essential innovations in implant or instrument design can take years to reach the market when mass produced, and implants in limited sizes are kept in hospital inventory,” says a ConforMIS representative. “As a result, new or more advanced implants are typically not fully adopted until older inventories are depleted. In a customized manufacturing model, in which products are developed as-needed for each patient, innovations can be incorporated into production much more rapidly. Improvements in design and applications of new materials and technologies can reach both surgeons and patients, faster.”
Send comments on this article to Carolyn LaWell.
