Image-to-Implant Production Offers Advantages in Knee Replacement (Orthopreneur)
While many medical devices lend themselves to a “one size fits all” production model, knee replacement implants do not. Variations in patient anatomy make it impossible for a limited range of “off-the-shelf” sizes to fit most patients like their own natural knees. To address this challenge, surgeons must first try to identify the implant that most closely matches a patient’s anatomy. During a typical knee replacement, the surgeon must remove excess bone and tissue to fit the patient to the implant. The result is an implant that can overhang bone and doesn’t reproduce the shape of the joint.
For many years, this has been the prevailing standard. Mass-produced implants are shipped to hospitals, where they are kept in inventory until needed, often for months or years. However, ConforMIS has developed a model to produce customized knee implants. Using digital imaging, 3D printing and other advanced technologies, each patient receives a customized knee implant designed to match his or her own natural knee. Importantly, the technology is able to support a highly automated and scalable production process whereby each customized implant can be produced as needed in lots of one, and then delivered in a “just in time” fashion immediately prior to surgery.
The image-to-implant manufacturing process for customized knee implants is based upon the capabilities of an advanced and proprietary technology platform known as iFit®. In the first phase of the process, patients undergo a CT scan that maps the topography of the individual joint. The imaging data also includes partial scans of the hip and ankle to ensure that the leg is properly straightened to a neutral mechanical axis. The technology then uses a series of proprietary algorithms to convert the two dimensional CT scan into a precise and highly detailed 3D model of the articular surface of the joint. At this point, the software designs each femoral and tibial implant, as well as all instrumentation, based on the 3D model. The automated process is streamlined for maximum efficiency.
To produce the implant, 3D additive manufacturing “prints” the wax molds used to cast the femoral components in cobalt-chromium-molybdenum. The customized implant is shipped to the hospital in time for surgery, reducing the need for hospitals to order multiple implants and store them in inventory.
In addition, the technology platform is used to design and manufacture a full range of surgical instrumentation needed to perform a customized knee replacement surgery. This process results in customized iJig® instruments with built-in orientation and alignment to the patient’s unique geometry. The instrumentation is produced using 3D printing and, like the customized knee, is designed for use in just one patient. One-time use instruments also eliminate the need to re-sterilize instruments after use, streamlining OR procedures further and helping to reduce the risk of infection.
The Impact of an Image-to-Implant Production Model
According to a 2010 study on satisfaction after total knee replacement, one in five patients reported dissatisfaction with ther results.1 In another recent study of patient satisfaction after total knee arthroplasty, 46 percent of dissatisfied patients reported that their knee “(did) not feel normal.”2 Up to three times as many patients with a total knee arthroplasty, relative to a similar control group without a knee replacement, reported some degree of difficulty with a variety of activities.3 Some of the factors that can lead to patient dissatisfaction include pain, poor function and unnatural feel that may be associated with sizing and shape compromises common to off-the-shelf implant designs.
A customized knee implant that is developed based on a 3D image of the patient’s own knee offers a precise fit that virtually eliminates sizing compromises and associated residual pain. Additionally, a customized implant that matches the distinct shape of the patient’s knee has been shown in a cadaveric study to better approximate natural kinematics vs. an off-the-shelf total knee, resulting in stability that is closer to the normal knee.4
In addition to the patient benefits associated with customization, the image-to-implant production model also supports more rapid product innovation and problem solving. With mass manufacturing of off-the-shelf knee implants, innovations developed by a manufacturer can take years to reach surgeons and patients. Updated implants may not be distributed until older inventories are depleted. In this model, manufacturers typically do not receive customer feedback about products until they are used, which can be many months after they are shipped. In a customized and immediate-use production model, surgeon and patient feedback can be incorporated into product design almost immediately. Based in part on this rapid response capability, ConforMIS has introduced a new product iteration every year since 2008. In each case, these innovations were available to patients within just a few weeks.
References
1. Bourne, R.B., et al; Patient Satisfaction after Total Knee Arthroplasty. Who is Satisfied and who is not? Clinical Orthopaedics and Related Research: 2010.
2. Noble et al; Patient Expectations Affect Satisfaction with Total Knee Arthroplasty, Clinical Orthopaedics and Related Research; 2006, 452: 35-43.
3. Nobel et at; Does Total Knee Replacement Restore Normal Knee Function? Clinical Orthopaedics and Related Research; 2005, 431: 157-165.
4. Patil, et al; Patient-Specific Implants and Cutting Guides Better Approximate Natural Kinematics than Standard Total Knee Arthroplasty. ORS Annual Meeting 2013, Vol. 38. Abstract # 0965.
Adam Hayden, MS, MBA, is Vice President, Marketing at ConforMIS Mr. Hayden leads product management, corporate communications, meetings and events and medical education for the organization. He provides over 15 years of leadership and medical device experience, including over ten years in orthopaedics alone. Most recently, Mr. Hayden led product management at ConforMIS with responsibility for all launched products and products in development. Prior to joining ConforMIS, Mr. Hayden held various senior marketing positions at Smith & Nephew and J&J DePuy. Prior to his career in orthopaedics, Mr. Hayden served as a Captain in the U.S. Army. Mr. Hayden has a BS in Mechanical Engineering from Cornell University, an MBA from the University of Colorado and an MS in Biomedical Engineering from the University of Michigan.
ConforMIS
www.conformis.com