3D printed medical implants gather pace

Every day, it seems, we at <i>Eureka</i> seem to receive a story positing a new potential medical application for 3D printing.

A brief scan of the relevant stories on our website includes headlines such as '3D printed organs on the way?' and '3D printing technique yields artificial blood vessels', for instance. However, while these applications represent a fascinating glimpse of the ways in which this technology may revolutionise medicine in the future, the fact is that 3D printing and additive manufacturing are already being employed in real-world medical applications in which the technologies' strengths are resulting in ever-greater levels of accuracy and surgical success, higher speeds and lower costs. A natural fit This is, of course, a fairly natural fit. After all, if one accepts that the ability to produce items in high detail at low volumes is at the heart of the additive manufacturing revolution. Just how these technologies can achieve these ends can be seen from a number of surgical examples. The use of 3D printing in surgery has paved the way for more accuracy in complicated operations, with a greater degree of success. For example, if a surgeon needs to remove a tumour from a patient but there is a chance that he or she will hit a nerve or an artery in doing so, the surgeon can create a 3D model of the tumour from the patient's CT scans using a 3D printer. The surgeon can then practise on the model before working on the patient. In this way, the surgeon will be able to make the necessary incisions with confidence. The possible harm or side effects of the surgery can also be avoided. When a patient has suffered considerable damage to their facial features, reconstructive surgeons now make use of 3D printers to create models out of which the prosthetics or the artificial skin will be made. What reconstructive surgeons do is to create a map of the patient's face on special software and using images taken with a 3D camera. From this facial mask, the surgeons will make a mask that will then guide them in conducting the reconstructive surgery. Mapping the face of the patient in this manner ensures a more accurate reconstruction of their bone structure. However, such applications – although still far from commonplace – are no longer rare. Increasingly, however, additive manufactured parts are being employed as implants as opposed to models. Additive fabrication technologies have evolved towards building medical implants that provide faster delivery, much easier customisation and better fit and function than is possible using conventional technology. Customisation of individual implants provides an immediate fit and eliminates the need of time-consuming adjustments during surgery. This saves time in the operating room and reduces operating costs as well as the risk of medical complications. Additive Manufacturing technology provides a means for fast and cost-efficient fabrication of implants with customised design. The fundamentals of additive fabrication also provide an opportunity to build implants in a manner very similar to the way in which nature develops bodies with lattice structures. This is extraordinarily beneficial in the fabrication of implants where a metal implant shall interface with living bone and tissue and provide quality of life for a human being. Electron Beam Melting (EBM) and Direct Metal Laser Sintering (DMLS) are both used commercially in the production of standard and customised implants. The relative freedom of shape afforded by additive manufacturing allows the most complex freeform geometries to be produced as a single part prior to surgery. As illustrated by the lower jaw reconstruction (shown on page 45), patient-specific implants can potentially be applied on a much wider scale than transplantation of human bone structures and soft tissues. The use of such implants yields excellent form and function, speeds up surgery and patient recovery, and reduces the risk of medical complications. Until recently, however, most long-term internal implants have tended to be metal. However, the recent announcement by Oxford Performance Materials (OPM) that it has received FDA 510(k) clearance for the OsteoFab Patient Specific Cranial Device (OPSCD) may change that. OsteoFab is OPM's brand for additively manufactured medical and implant parts produced from PEKK polymer. The OsteoFab technology is ideal for one-of implants specifically shaped to each patient's anatomy. One very desirable use of patient specific implants and the indication for the OPSCD is cranial implants to replace bony voids in the skull due to trauma or disease. FDA clearance of this device marks the first approval for an additively manufactured polymer implant. In addition to the importance of implant fit, implant material is a critical consideration. The OPSCD is manufactured from PEKK, an ultra high performance polymer used in biomedical implants and other highly demanding applications. OPM had traditionally sold PEKK as a raw material or in a semi-finished form, but began developing Additive Manufacturing technologies in 2006. Biomedical facility In 2011, OPM established a biomedical compliant manufacturing facility in to support its growing Additive Manufacturing business. As an implantable polymer, PEKK is unique in that is biocompatible, mechanically similar to bone, and radiolucent so as not to interfere with X-Ray equipment. Furthermore, OPM has recently completed testing which confirms that the OsteoFab implant surface is, in fact, osteoconductive. "It is our firm belief that the combination of PEKK and Additive Manufacturing is a highly transformative and disruptive technology platform that will substantially impact all sectors of the orthopedic industry," said Scott DeFelice, President and CEO of OPM. "We have sought our first approval within cranial implants because the need was most compelling; however, this is just the beginning. We will now move systematically throughout the body in an effort to deliver improved outcomes at lower overall cost."