Authors: Daniel Refai
Osama N. Kashlan
"Never before in history has innovation offered promise of so much to so many in so short a time."
Bill Gates' wise words ring true for the innovative technologies being developed in spine surgery. In the past few decades, there have been substantial improvements in spine instrumentation, biologics, and intraoperative neuronavigation that have drastically improved patient outcomes and further advanced technologies in the field.This exponential burst of technological innovation in spine surgery does not show any signs of slowing down. Here are five technologies that are expected to have the largest impact on spine surgery by 2020:
1. Metallurgy of Instrumentation
Historically, metals used in spinal instrumentation have been mostly composed of cobalt chrome, titanium, and stainless steel. The physical properties of the metals currently used in spine surgery and the amount of bony contact and in-growth needed for adequate strength have inhibited the ability to decrease the size of the hardware. The tide has changed recently with the influx of new metal alloys, such as molybdenum-rhenium that provides stronger, more durable constructs, while allowing for smaller sized products. The impact of utilizing this technology would be tremendous. For example, having smaller rods with smaller pedicle screw heads would provide for lower profile constructs that would decrease the prevalence of protruding, painful hardware in cachectic patients. Smaller hardware would be helpful in minimally invasive spine surgery. As an added benefit, molybdenum-rhenium alloys provide for decreased biofilm formation and allergenicity when compared to the traditional metals used in spine surgery.
2. 3D Printed Implants
3D printing is a technology that has already been implemented in neurosurgery. Neurosurgeons have used custom 3D printed cranial implants and 3D printed models of complex spine cases for preoperative planning. However, a growing interest in spine surgery is 3D printed implants. The benefits of 3D printed implants are multiple. First, these implants can be shaped and molded to custom fit the patient uniquely. Second, 3D printing is less wasteful in terms of materials because it uses additive manufacturing technology that builds a model up, rather than more traditional subtractive manufacturing that starts with a "block" and cuts it down to the shape needed. More importantly, utilizing additive manufacturing allows for personalization of porosity and pore size depending on a specific patient's bone quality. Studies performed in sheep demonstrate that 3D printed porous titanium alloy cages had increased peri-implant osteogenesis and ingrowth when compared to commercially available polyetheretherketone (PEEK) and plasma sprayed porous titanium coated PEEK implants. Lastly, 3D printed implants can have randomization of porosity and pore size, which may also improve integration and scaffolding. Until now, these technologies have been inhibited by cost and preparation time, but multiple developers have recently been successful in alleviating these challenges.
3. Nanotechnology Use in Spinal Implants
Novel implants utilizing nanotechnology blend the benefits of PEEK, its modulus of elasticity similar to bone and its improved ability to assess for fusion formation radiographically, and titanium, which allows for improved implant-endplate contact. This is performed with implants having interconnected porous titanium scaffolds molded around a PEEK core. Historically, most implants were smooth on a nanoscale. In contrast, new implants are manufactured with nanotopographies and nanoroughness that enhance signaling pathways to enhance bone growth and decrease implant related complications. As an added benefit, these implants can be coated with antibiotics to decrease the incidence of postoperative infections.
4. Operating Room Auotmation and Connectivity
Over the past 20 years, we have seen the remarkable effect navigation has had on spine surgery, specifically on placement of hardware. More recently, robotics have been introduced into spine surgery to assist with instrumentation. This field will disrupt spine surgery not in the placement of hardware, but in more advanced iterations of these products. Artificial intelligence will utilize machine learning and predictive analytics to assist in performing procedures such as laminectomies, diskectomies, rod formation, and interbody fusions through significantly smaller incisions. One can imagine a situation where complete automation of spine surgery is performed under the watchful eye of a surgeon. A robot formulates an appropriately sized incision at the correct level, docks a minimally-invasive tube, performs a hemilaminectomy and facetectomy, chooses an appropriately sized interbody cage and biologic, places it via a transforaminal approach, chooses appropriately sized pedicle screws and places them, formulates an appropriately sized rod with a perfect amount of lordosis, places and tightens set screws, and closes the incision at the end of the case. A surgeon may visualize the robot's progress either via virtual or augmented reality, a technology already utilized in spine education, or via a small endoscope attached to the robot arm. This automation may seem far-fetched to occur by 2020, but multiple companies are in process of developing a combination device similar to that described above.
5. Endoscopic Spine Surgery
Surgeons have utilized endoscopy in spine surgery for over two decades. However, with recent improvement in surgical instruments and imaging, this field is apt to expand drastically by 2020. With the ability to perform operations through a pencil-sized incision and respecting muscle plains, these procedures have the potential benefits of decreased postoperative infections, hospitalization times, time out of work, and chance of developing instability requiring future fusion. These operations are performed by a minority of surgeons in the U.S., but have grown more widespread elsewhere around the world in Asia, Europe, and South America. The industry sees this trend and is working on expanding or introducing endoscopic technologies into their product lines.
The five technologies listed above have tremendous potential to improve patient outcomes and surgical efficiency, and will be disruptive to the field of spine surgery by 2020. When the benefits of these new technologies outweigh the costs of innovation, the steep learning curves required, and the health economic barriers to widespread implementation, seismic disruption will occur in neurosurgery.