33.1 Introduction

Virtual reality is a computerized technology that generates realistic images, sounds, and sensations meant to simulate the user’s presence in a virtual or imaginary environment, one that can be explored by and interacted with by that very user. ¹ The effect can be created via a headset with a small screen that displays images in front of the user’s eyes, a series of multiple large screens, or other specially designed areas that can simulate the user’s presence in the virtual environment. Luckily, this technology has been expanded from its initial use as entertainment, and has found a place in several different disciplines with unbelievable implications. Currently, its technology allows for a vast application of its simulations, ranging from gorgeous, realistic, video game playing experiences to the training of chefs, airplane pilots, military personnel, and astronauts; to better understanding bias and other social constructs ^{2 ,​ 3} ; and to the treatment of anxiety disorders, ⁴ managing pain and anxiety in children, ⁵ and even the rehabilitation of stroke patients. ^{6 ,​ 7} Its applications are far-reaching, and its ability to contribute to spine surgery is rooted in its ability to generate rich simulated experiences. As it stands, spine surgery is a specialty that requires first and foremost much training, along with great geometrical precision ⁸ and control once that training is completed, considering the delicate nature of working around the spinal cord and its associated structures.

33.1.1 Virtual Reality as a Training Module

As mentioned earlier, virtual reality has the ability to simulate an elegant and intricate environment. With this in mind, it is reasonably straightforward to understand how a technology such as this may properly simulate an operative experience and its many nuances. Coincidentally, virtual reality (hereafter referred to as VR) simulators are already relatively well established as training modalities for surgery, and more specifically spine surgery ⁹ (Fig. 33‑1). Research has shown, for now, that simulators are promising training modalities with a host of benefits. First, VR simulators provide trainees with a rich variety of training opportunities, ⁹ and that simulator training has led to improved speed and accuracy of various surgical skills. ¹⁰ These simulator-trained skills have resulted in improved patient care and decreased patient discomfort. ¹¹ In addition, VR simulations pose no risk to patients, and require fewer resources, as simulator training is inherently independent of patients and cadavers. ⁹ Furthermore, the increase in ease of access allows for an increase in the frequency of training. Finally, objective assessments of trainees and surgeons can be performed, as exact measurements can be performed by the simulation, allowing for recording of the accuracy of instrumentation. ¹² This information can be used to evaluate the ability of surgeons, and further can even be used to investigate the effects of pharmacologic advancement of sleep-deprived physicians in the operating room. ^{13 ,​ 14}

Many centers now employ the use of VR simulators as means of training and assessing individual’s surgical skills. ⁹ However, for now, it seems as if its utility as a training module remains somewhat unclear for a couple of distinct reasons. First and perhaps most important, there is a lack of evidence regarding the study of patient outcomes. ⁹ Further adaptation of simulators will require improved study designs, longer term study periods, examination of nontechnical skills, and multidisciplinary team training. ⁹ As VR continues to improve, and as its applications continue to expand, it could potentially better simulate the operations performed by spine surgeons and further help train surgeons, residents, and students toward better patient outcomes. It is a technology that should be, and for now, has been, embraced by spine surgery as technology continues to produce unbelievable possibilities.

33.2 Augmented Reality

Augmented reality, not to be confused with, yet closely related to, VR, consists of a live direct or indirect view of a physical environment that is modified by other sensory inputs such as sound, video, and haptic feedback, among other modalities. Again, similarly with the roots and origins of VR, augmented reality finds its origins in the entertainment industry. Other industries are now finding applications for this type of experience enhancement, including the medical field, because of its ability to gather and share information rapidly. ¹⁴ Advanced augmented reality (hereafter referred to as AR) systems are able to overlay information regarding environments and its components in real time and in an interactive manner. Imagine someone wears glasses while driving that are able to relay real-time traffic information, or glasses that are able to project an updated flight itinerary while sprinting through a crowded airport. Now imagine this application in the operating room: existing images such as X-rays, ultrasounds, CT scans, and MRIs are blended together with surgical reference points and the patient lying on the operating table. Operating staff could potentially wear lenses that project patient’s current vital signs, patient’s relevant past medical history, and other information that may become relevant that would otherwise require breaking scrub.

33.2.1 Practical Applications in the Operating Room

What makes AR so exciting is that it already has some existing applications within the operating room. For example, AR is used as a means of projecting optimal port placement on abdomens prepared for laparoscopic surgery, ¹⁵ as a means to identify the position of lymph nodes during cancer surgeries, ¹⁶ and has found applications as specialized near infrared devices that can help detect tissue vascularity. ¹⁷ Furthermore, neurosurgical procedures have adopted some AR techniques during the management of extracranial–intracranial bypass surgery and intracranial arteriovenous malformation surgery. ^{18 ,​ 19}

There are currently many devices that are capable of offering a variety of augmented and virtual realities, all of which contain different gadgets and technologies and different approaches to providing similar experiences. Imagine a device such as HoloLens finds its way into the operating room as eyewear; this head-mounted unit is a pair of smart glasses that contain an inertial measurement unit consisting of an accelerometer, gyroscope, and magnetometer, along with a camera, four environment understanding sensors, microphone, and an ambient light sensor that are used to record surroundings and integrate them into an image of altered reality ²⁰ (Fig. 33‑2). This technology in fact already has applications within the medical field, as both Case Western Reserve University and the Cleveland Clinic are using them in a digital human anatomy course. ^{20 ,​ 21} Picture that this device, or other similar devices, is programmed with software targeting patient information mentioned previously. That spine surgery seems to benefit greatly from this technology is through image-based augmentation. Imagine a spine surgeon is able to view preoperative diagnostic images intraoperatively, helping guide surgical planning in terms of incision, instrumentation, and optimal approach, ¹⁴ all while being connected to a totality of patient information in safe way (Fig. 33‑3).

33.3 Virtual Reality and Augmented Reality as a Vehicle for Garnering Interest and Fostering Education

Apart from the applications of VR and AR previously mentioned, these simulation modalities also have a remarkable capacity of increasing the accessibility of information for those learning the art of spine surgery. Imagine the common scene where a medical student finds him/herself in a crowded operating room, struggling to see what the surgeon and residents are seeing within the operative field, attempting impossible and uncomfortable maneuvers to catch a glance of what is happening. Now imagine a scenario in which that same student is wearing a VR or AR headset, tucked away in the corner, out of the way, while being able to see a variety of multidimensional perspectives on the operation. And now imagine a scenario in which these perspectives are broadcasted worldwide. This technology could allow efficient sharing of information and techniques involved in spine surgery. ¹⁴ It also has implications for training residents. Junior residents would be able to virtually participate in complex cases, cases they are not yet qualified for in the operating room, helping them learn more quickly. ¹⁴

Fortunately, firms such as Medical Realities are working to make this latter image a reality. ²² Individuals will be able to engage and learn in virtual operative settings by purchasing their software. In April 2016, Dr. Shafi Ahmed, a cofounder of Medical Realities, became the first physician to broadcast an operation via VR. ²³ Now imagine a spine surgeon partakes in this concept, and students around the world are not only exposed to but able to interact with a virtual pedicle screw placement, a virtual posterior cervical laminectomy, or a virtual vertebroplasty. Other industries are also starting to take advantage of broadcasting information via VR. The Minnesota Vikings of the National Football League (NFL) just recently announced that they are partnering with VR firm Oculus and are launching an application that will allow for fans to view 360-degree footage within the stadium via VR simulation. ²⁴