The “bionic” era: Exploring the use of advanced technology in surgery

“We can rebuild him. We have the technology. We can make him better than he was. Better…stronger…faster.” So goes the voice-over from the opening sequence of the 1970s television series The Six Million Dollar Man, referring to lead character Steve Austin, who had received bionic limbs and a zoom-lens, infrared-capable eye after a nearly fatal accident. One could argue that the enduring popularity of the show demonstrates a public belief that technological advances in surgery can be used to improve human ability and well-being.

Today, as we stand at a metaphorical crossroads in surgical care, dedication to improving patient outcomes through advanced technology is stronger than ever. Improved collaboration between scientists in both medicine and engineering has resulted in advances that surpass the capabilities of their individual efforts.

The idea that surgeons can use advanced technology to augment the patient experience is not novel. Surgeons have long possessed the unique opportunity to harness society’s technological advances to better serve our patients. Notably, the once futuristic bionic body parts of the “Six Million Dollar Man” are closer to becoming a reality today. In leui of bionic legs and arms, patients receive three-dimensional (3-D) printed titanium pelvises, and the bionic eye is instead a pair of computerized glasses. Advances such as wearable technology, tumor cell detection with fluorophores and nanomaterials, and 3-D organ modeling and printing represent the next era in surgical care. Surgeons have established themselves as leaders throughout medical history, and we once again are poised to lead the charge into an exciting new age of technical innovation.

Optical illusion

Advances in infrared and fluorophore technology are allowing surgeons to have the ability to “see” what is typically outside the spectrum of normal human sight. The first example of this was the development of cutting-edge instruments designed to detect patterns of photon scatter and absorption.^1,2 This technology uses the near-infrared spectrum to distinguish healthy, well-perfused tissue from poorly perfused tissue, for instance, at sites of bowel or vascular anastomoses. Although the technology has been in use for some time now, it continues to evolve in exciting ways via the development of enhanced optics and patient-centered applications.

Epitomizing this evolution was the development of the fluorescence-assisted resection and exploration (FLARE) system in 2001 at the John Frangioni laboratory, Beth Israel Deaconess Medical Center, Boston, MA. Using near-infrared light in combination with a specially designed fluorescing dye designed to target specific tissues, researchers have discovered a way to advance the properties of a prototypical, non-specific fluorescent dye, such as indocyanine green. The dye, which is injected into the body, has an affinity for certain tissue components, and has been used to successfully identify sentinel lymph nodes in breast cancer and colon cancer, and vessels in free flap reconstruction.³

The next step in the development and utility of this technology was to engineer tissue-specific and cancer cell-specific fluorophores for real-time identification of structures and margins during surgery. Both bio- and nanomaterial development have allowed for the creation of targeted fluorophores that have this capability, and a number of talented surgeon-scientists in the field of fluorescence-guided surgery are paving the way for further advances in surgical oncology. For instance, Bouvet and colleagues have been able to demonstrate the effectiveness of fluorophore-tagged antibodies directed at common tumor antigens in combination with light-emitting diode (LED) cameras in a mouse model of pancreatic and colon cancer.⁴ Other applications of fluorescence-guided surgery have occurred in ovarian tumor debulking, glioblastoma multiforme resection, and urologic procedures. This promising field represents the marriage of innovation in engineering with modern surgical technique. The optical illusion of tumor and tissue planes can be exposed with the creative manipulation of proteins and light.

Wearable technology

The development of an “eye” that can zoom, take pictures, import data instantaneously, and telecommunicate is now a reality. Advances in computer technology have transcended the limitations of location and have moved from the desktop to the laptop to the mobile device, and now to head-mounted eyewear.

Surgeon researchers—particularly those familiar with the connection between improved dexterity and computer game usage—are currently exploring the next generation of crossover devices, with a particular emphasis on wearable technology. Hand gestures, voice activation, and gyroscopic control now replace manual data input for Google Glass, a device introduced by Google, Inc., Mountain View, CA, in early 2013. Google Glass, or simply Glass, is worn like a pair of regular reading glasses but allows the user to access a central processing unit and a holographic projector. The ultra-light frame houses a high-definition camera, microphone, and wireless connectivity, as well as a bone-conduction sound transducer and a remote touch pad.

Glass can take pictures, record videos, text, e-mail, teleconference, access medical records, and download images, all using voice or gesture command. Images are projected to the right upper corner of the wearer’s visual field, which makes using the device analogous to looking in your car’s rearview mirror. The beta testing program, called the Google Explorer Program, included many surgeons who volunteered to become early adopters of this technology and have used it to document preoperative time-outs, record key portions of an operation, look at image specimens, request intraoperative consultations via teleconferencing, run medical record or preoperative imaging queries, and even teach remotely.⁵ In terms of student instruction, the resident or medical student no longer has to look over the surgeon’s shoulders to view an operation; with Glass, he or she can observe the procedure directly from the surgeon’s point of view from a remote location.

Telementoring is also possible by remotely evaluating a trainee during simulations or while performing actual procedures. Investigators from Massachusetts General Hospital, Boston, recently evaluated the Glass as an augmented reality telementoring tool between chief surgical residents and interns.⁶ Despite continuing concerns over patient privacy and data security and the technology lacking the image resolution required for large-scale use in teaching, the authors were optimistic about the potential of this device in their review. They note that “the wearable technology revolution provides a unique opportunity for surgical educators to connect with trainees….this type of technology will undoubtedly continue to improve, and surgeons should provide feedback to shape the development of these devices for clinical applications.”⁶

Google Glass is just one type of wearable technology available today. The use of infrared or fluorescence-detecting goggles for augmented-reality surgery is another example of the “bionic eye” making its appearance in the surgical theater, the concept of which originated more than a decade ago in animal models.⁷ Using green fluorescence protein linked to paramagnetic nanoparticles, brain tumors were localized in rats with magnetic resonance imaging (MRI) and fluorescence-detecting cameras.⁷ More recently, in February 2014, researchers at Washington University-Barnes Jewish Hospital, St. Louis, MO, have developed and implemented the use of fluorescence-detecting goggles to visualize fluorescent breast cancer cells.⁸

The applications of computer-aided “bionic vision” extend beyond eyewear and fluorescent cells; the ability to translate the best features of this vision into technical skill remains the sine qua non of surgical care. The introduction of minimally invasive surgery signified a paradigm shift that illustrates the foundation of this concept, specifically advances in high-definition, live-image transmission, which led to less invasive surgery and improved patient outcomes. The traditional concept that optimal exposure necessitated large incisions transitioned to the adoption of smaller incisions using laparoscopic guidance for many procedures. Like any other change in health care, improved patient outcomes are the drivers behind medical innovation. Yet while the adoption of laparoscopic technology was a significant advancement in surgical history, it, too, came with its own challenges, thus perpetuating the cycle of innovation.

Augmented reality

In an effort to overcome the loss of depth perception that occurs with traditional two-dimensional laparoscopy and to render procedures safer for patients, stereoscopic adaptations to minimally invasive surgery are available. Stereoscopy refers to a technique that creates the illusion of a 3-D image via the combination of multiple two-dimensional images taken from different perspectives, such as the image projected in the working console of the da Vinci Robotic Surgical System. But augmented reality (AR), or the merging of real images with computer graphics to enhance the user’s perception, is taking stereoscopic surgery to the next level. First used in neurosurgery, orthopaedics, and otolaryngology, the applications of this technology are expanding to include urologic procedures and liver resections.⁹ By superimposing preoperative computed tomography (CT) or MRI images onto patient anatomy during a complex surgical procedure, multiple inputs converge to take the guesswork out of lesion detection or complex anatomy. Within the last five years, intraoperative robotic C-arm CT scanning has been used in laparoscopic nephrectomy and liver resections to enhance surgeon perception and improve technical precision.¹⁰

Perhaps more impressive is the implementation of an AR iPad application during a hepatic tumor resection in Germany in August 2013.¹¹ Using this app, the computer’s camera function can superimpose a patient’s preoperative CT images onto an organ in real time. In the app’s first trial, the iPad camera was held over the liver and the CT images were superimposed in the exact orientation of the organ, allowing the surgeon to “see” vessels, tumors, and other important anatomy. Touchscreen technology also allowed the surgeon to subtract anatomical structures from the image that had been resected in the procedure, modifying the image in real time. Thus, the surgeon was able to see different layers, modify tumor boundaries, and calculate residual liver volume using the imaging and computing power of AR.

Despite the amazing potential of technologies that provide surgeons with a “superhuman” eye, the incorporation of wearable technology and AR into the operating room has occurred on a limited basis. Regulatory and financial barriers, limited physician skill sets, and skepticism have contributed to a reluctance to incorporate these technologies. The biggest challenge in adopting new technology, however, is ongoing uncertainty regarding whether these advances actually enhance patient care. Fortunately, the number of reports and studies investigating the impact of these devices continues to grow.

3-D printing

Although surgeons have yet to implant legs capable of running at tremendous speeds and jumping to amazing heights, the profession is embracing 3-D-printing technology to achieve remarkable real-world feats. As health care becomes increasingly individualized, 3-D printing, also known as additive manufacturing, has become a tool for creating patient-specific models, implants, and assistance devices.

First developed in 1983, 3-D-printing technology has rapidly advanced over the last three decades toward smaller, cheaper, and higher-resolution printers. Home desktop models can be purchased for less than $500, while higher-end models range up to $750,000. The highest resolution printers can print detail to the 100 nm scale. The prevalence and quality of 3-D printers has fueled new bioengineering research focused on delivering individualized patient care.

Surgical modeling

The use of 3-D printers in health care initially gained traction in the mid-1990s when it was used to create models for complex craniofacial defect reconstruction and for the treatment of neurovascular disease.^12,13 CT or MRI images were converted into printer-ready files and produced using stereolithography, a technique involving laser polymerization of a photosensitive liquid resin.¹⁴ Models were found to be accurate to within 0.85 mm on average—an impressive result, especially considering how new the technology was at that time. As the technology became more widely available, it was applied to congenital heart defects, the premature infant upper airway, and craniopagus twins. Despite their accuracy for operative planning, the use of 3-D printed models was limited due to inadequate computer processor speed, expensive printers and printing materials, and the time required to print a model. Today, the speed and accuracy of 3-D-printed models has improved dramatically. A life-size aortic root model can be printed in slightly more than three hours using publicly available software on an open-source 3-D-printing system.¹⁵ Dimensional error is dependent on the printing method, but stereolithography has been reported as accurate to within 0.56 percent.¹⁶

Surgical implants

In the last three years, several well-publicized case reports using 3-D printed, patient-specific implants have emerged. Permanent implants fashioned by 3-D printers using osteoconductive titanium have been shown to be long-lasting and durable, even demonstrating osseointegrative properties.

In June 2011, an 83-year-old female with mandibular osteomyelitis underwent resection and reconstruction using a 3-D-printed titanium implant. Dutch and Belgian researchers and surgeons created the implant based on an MRI reconstruction of the patient’s mandible and printed the implant using a 3-D titanium powder laser sintering machine. Similarly, in the U.K. in 2013, a motorcycle accident survivor underwent a complex facial reconstruction using a custom-designed, 3-D-printed titanium implant to restore the facial skeleton. In 2011, MRI and CT scans were used to model and produce a 3-D-printed titanium pelvis, which was successfully implanted into a patient after he underwent surgery for a chondrosarcoma. After three years, the patient is reportedly doing well and ambulating with a cane. An equally sensational case occurred in February 2012 with the implantation of the first biodegradable surgical implant in the U.S. Under an emergency-use exemption, a bioresorbable tracheal splint was deployed at the University of Michigan, Ann Arbor, in a 20-month-old male with tracheobronchomalacia. The story made national headlines, and subsequently a second case was reported.¹⁷ These bioresorbable implants provide temporary support and scaffolding, which is then replaced by native tissue. These cases illustrate the applicability of 3-D printing to individualized patient care, enabling surgeons to create patient-specific implants that are precise in their form and function while achieving results superior to alternatively manufactured implants.

Prosthetic devices

3-D printing has enabled the layperson to construct functional prostheses for patients. In 2011, South African carpenter Richard Van As traumatically lost four fingers from his right hand. He collaborated with Ivan Owen, a special effects designer from the state of Washington, to create the first functional 3-D-printed hand. The prosthetic hand can be opened and closed by wrist extension and flexion, allowing the user to grip objects as narrow as a pencil or coin. News of their innovation spread quickly, and their next design was a prosthetic hand for a five-year-old boy in South Africa who was born without digits.¹⁸ Van As and Owen made their designs publicly available, and the open-source technology has allowed parents like Paul McCarthy to print a prosthetic hand for his 12-year-old son and young printing enthusiasts like 16-year-old Mason Wilde to create a prosthesis for a family friend’s nine-year-old son.¹⁸ As 3-D printers have become increasingly available to the public, developers have optimized designs and technology, allowing users with no formal training to create wearable, mechanical hands capable of purposeful grip for as little as $60.¹⁹ The low cost and accessibility of 3-D-printing technology has enabled tech-savvy patients the opportunity to take a therapeutic role in health care.

Despite successes in bone and prosthetic printing, the Holy Grail of 3-D printing is the development of printable, patient-specific organs and soft tissues. To achieve this goal, vascular networks will need to be incorporated into grafts that allow circulation at the cellular level. Creating diffuse and permeable vascular networks in 3-D grafts is a complex engineering problem that has seen some success through the use of sugar scaffolds. The sugar, when dissolved, leaves behind patent channels lined with living cells through which blood can be supplied. Although this technique shows promise, the clinical applications of 3-D printing will be limited to alloplastic implants and prostheses until the more intricate challenges of incorporating vessels can be overcome.²⁰
As 3-D printing has evolved to become cheaper, faster, and more precise, the technology has enabled physicians, researchers, and families to individualize care for patients. As vascularity and bioprinting of scaffolds and cells further evolves, the ultimate goal of manufacturing patient-specific, functional, live-tissue organ grafts may one day become a reality.

Conclusion

The futuristic science that was once the basis of a 1970s television show is now, in 2014, similar in complexity to the technology that is making its way into the surgical theater. The drive for improved patient outcomes has characterized surgeon mentality since the days of Ernest Codman, MD, FACS, a key figure in the founding of the American College of Surgeons (ACS), and remains evident in the innovations that are continuing to take place.

The changing national health care scene, the critical reappraisal of surgical education, and the technologic boom have put surgery at a pivotal crossroads in health care. The idea that “we have the technology…we can make him better…” is the idea that fuels the collaboration between industry and surgery, and it will steer the discipline into a new era of patient care. The bionic eye of science fiction, reinvented in the form of fluorophores, wearable technology, and augmented reality apps and super-powerful extremities reinvented in the form of printable prostheses represent areas of innovation decades in the making. Improvements in these technologies must be made before the barriers to their widespread adoption are overcome, but the advancements occurring in surgery make this era an exciting precursor to the coming advanced technology-driven age. As new generations of surgeons begin to use Google Glass and iPad apps, it is inevitable that advanced technology will continue to have a presence into the operating room.

Acknowledgements

The authors would like to acknowledge the support of the Resident and Associate Society-ACS Education Committee in the preparation of this article.

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