From the Annals of Weill Cornell Neurological SurgeryMinimally Invasive Spine Surgery: An Overview
Introduction
The entire field of surgery is in the midst of a dramatic transformation toward minimally invasive techniques and approaches. Driven by patient preferences and changing socioeconomics of medicine, minimally invasive surgery (MIS) techniques were initially embraced by general and specialty surgeons, with delayed emergence in spine surgery due to unique constraints. Historically, open approaches to the spine were necessary to ensure optimal surgical outcomes and patient safety. For example, during traditional open freehand placement of pedicle screw instrumentation, the surgeon needs to expose not only the screw entry point but also the surrounding anatomy in order to best estimate the optimal screw trajectory while avoiding injury to critical neurovascular structures. These techniques require long incisions with significant trauma to surrounding muscle and tissues. A larger surgical bed also predisposes to the risk of blood loss (with or without need for transfusion), risk of surgical site infection, and increased pain and narcotic requirements, resulting in longer hospital stays. In addition, in some cases of deformity or trauma, reliance on the knowledge of normal anatomic trajectories and visualization of surrounding anatomic structures may still result in malpositioned instrumentation. Use of newer intraoperative imaging techniques, in combination with powerful software, has allowed surgeons to supplement their understanding of the 3-dimensional (3D) anatomy of the spine with real-time navigation, avoiding the need for extensive exposure of surrounding landmarks. In fact, minimally invasive techniques have been associated with decreased postoperative narcotic requirements, lower blood loss, and shorter hospital stays.1,2 Minimally invasive spinal surgery (MISS) is now routinely used in the treatment of a growing variety of pathologies, including trauma, degenerative disease, and cancer. Though not all spine pathology is optimally treated with MISS, an estimated 75% of the approximately 1.2 million spinal procedures performed each year in the United States could be performed in whole, or in part, with MIS techniques.3
In addition to the technological factors which have enabled MIS implementation in spine surgery, socioeconomic and population factors have increased demand. In the United States, the need for surgical treatment of degenerative spinal conditions is predicted to increase as the population over 65 years old increases by 20% between 2015 and 2030.4 In this age group, there is a 68% rate of radiographic degenerative spinal deformity.5 Although not all patients or pathologies can be treated with MIS techniques, there is strong demand for MISS from patients. This demand has an economic impact on health care delivery as approximately 13% of employer-sponsored health care insurance dollars are part of “consumer-directed” plans, and this percentage is increasing.6 This has allowed patients to seek elective surgical care on the basis of their perceptions and preferences. Narain et al. administered a questionnaire to spine patients scheduled for a preoperative spine consultation7; among the 326 patients who responded to the questionnaire, the most important factors driving their preferences were long-term surgical outcomes, the recommendation of their surgeon, and the complication risk. They found that the majority of patients surveyed would prefer MIS to open surgery. Patients indicated they believed MIS is less painful, has a lower risk of complications, is less expensive, and requires a lower level of sedation. The patients surveyed perceived minimally invasive and open surgery to offer similar outcomes, with neither option increasing the chances of requiring a future reoperation. Most indicated they would seek the opinion of another surgeon if MISS options were not offered in their initial surgical consultation. Forty-four percent would travel “somewhat or much further” to seek the opinion of a surgeon who offered MISS. Interestingly, regarding surgeon skill, many patients preferred their surgeon to have more experience if offering open surgery instead of MISS. While patients did indicate that cost was not a prominent factor in deciding between MISS and open surgery, potential cost advantages have become a focus for hospital administrators as well as payors. Several retrospective studies have evaluated cost differences between MISS and open spinal surgery. Specifically, 14 studies have evaluated cost differences between minimally invasive and open laminectomy, microdiscectomy, transforaminal lumbar interbody fusion, posterior lumbar interbody fusion, and anterior lumbar interbody fusion (ALIF).8 All found MISS to be associated with reduction in direct costs of between 2% and 20%. In studies providing detailed accounting of direct costs, MISS procedures were associated with higher intraoperative direct costs but overall lower direct costs due to shorter length of hospital stay and fewer postoperative services needed during admission.
In the present article, part 1 of a 3-part series, we describe several of the unique approach techniques in MISS that have become foundational in their standalone use and their application in combination to achieve larger surgical goals. We then examine the current state of the field through an examination of the imaging and navigation technologies that have coevolved and shaped the field. In part 2 of this series (“Challenges Hindering Widespread Adoption of Minimally Invasive Spinal Surgery”),9 we present some of the challenges in MISS and proposed solutions. In the final article (“The Future of Minimally Invasive Spinal Surgery”),10 we discuss the future direction of MISS.
Section snippets
Unique Approaches in MISS
Successful minimally invasive techniques for resection, decompression, and fusion for a variety of pathologies throughout the spinal axis have been well described. Tubular retraction, endoscopy, the use of lateral corridors for interbody fusion, and navigated percutaneous pedicle screw insertion are techniques which have proven fundamental in MISS. These techniques are used in standalone surgeries or in combination with other techniques as part of a larger operation. Here, we describe these
Choosing the Right Approach
Table 2, Table 3, Table 4, Table 5 outline the indications, contraindications, spinal-level accessibility, and advantages/disadvantages of the common MISS approaches for lumbar fusion.
When evaluating the surgical approaches to a given spinal pathology at our institution, rather than employing a “one-size-fits-all” mentality toward MISS, we identify the open and minimally invasive approaches capable of dealing with a given pathology and select the best one for the individual patient. This
Fluoroscopy
The changes in intraoperative imaging modalities as they relate to pedicle screw placement illustrate the way that technological advances have shaped MISS. One of the first technologies adapted to pedicle screw placement was intraoperative fluoroscopy. With fluoroscopic methods, the meticulous exposure of surrounding landmarks that were required to ensure accurate starting points and trajectories for freehand screw placement was no longer necessary. Freehand techniques required the surgeon to
Robotic Spine Surgery
General surgeons and surgical subspecialists have successfully incorporated robots into routine use in the operating room for a variety of procedures, including cholecystectomy,49 radical prostatectomy,50 and colectomy.51 The ability to generate high-fidelity, real-time 3D CT–acquired anatomy and correlate it precisely with the spatial relationship of surgical instruments has provided the opportunity for automation. In robotic spinal instrumentation, a robotic arm (rigidly fixed to the surgical
Cortical Bone Trajectory
The ability to place spinal instrumentation with the aid of 3D intraoperative navigation has enabled the widespread investigation of different techniques with the goal of improving biomechanical stability and/or safety. In 2009, Santoni et al. described the cortical bone trajectory (CBT) for lumbar pedicle screws.56 Rather than using an entry point at the junction of the transverse process and facet and traveling mainly through cancellous bone as is the case with traditional pedicle screws, the
Virtual and Augmented Reality
Augmented reality (AR) in the operating room involves the virtual superimposition of anatomic structures or artificial targets onto actual patient anatomy. Either via specialized goggles or the eyepiece of the operative microscope, AR allows for lesions or areas of interest, such as pedicle screw starting points or surrounding anatomy, to be identified via CT or magnetic resonance imaging and superimposed in real time in the correct spatial orientation and position. In addition to robust
Conclusions
Technological advancements have enabled the safe adaptation of minimally invasive techniques in spine surgery. The best-quality evidence available suggests that in well-selected patients, MISS outcomes are similar to those achieved with open surgery and that MISS techniques offer a favorable safety profile. Although these increasingly technologically advanced techniques are accompanied by high upfront costs, studies to date suggest that the high upfront costs of MISS equipment are defrayed by
CRediT authorship contribution statement
Jacob L. Goldberg: Conceptualization, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, Visualization. Roger Härtl: Conceptualization, Investigation, Writing – review & editing, Visualization. Eric Elowitz: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing – original draft, Writing – review & editing, Visualization, Supervision.
Acknowledgments
The authors appreciate Dr. Philip Stieg for his leadership and support of “From the Annals of Weill Cornell Neurological Surgery” and Dr. Michael L. J. Apuzzo for his guidance and input in this project. They also acknowledge the contribution of Anne Stanford, ELS, who provided professional editing services.
References (66)
- et al.
Principles and fundamentals of minimally invasive spine surgery
World Neurosurg
(2018) - et al.
Challenges hindering widespread adoption of minimally invasive spine surgery.
World Neurosurg
(2022) - et al.
The future of minimally invasive spinal surgery
World Neurosurg
(2022) - et al.
Overview of minimally invasive spine surgery
World Neurosurg
(2020) - et al.
Transforaminal endoscopic lumbar discectomy and Foraminotomy with modified Radiofrequency nerve stimulator and continuous electromyography under general anesthesia
World Neurosurg
(2020) - et al.
Simultaneous lateral interbody fusion and pedicle screws (SLIPS) with CT-guided navigation
Clin Neurol Neurosurg
(2018) - et al.
Use of a quantitative pedicle screw accuracy system to assess new technology: initial studies on O-arm navigation and its effect on the learning curve of percutaneous pedicle screw insertion
SAS J
(2011) - et al.
Laparoscopic versus robot-assisted cholecystectomy: a retrospective cohort study
Int J Surg
(2014) A brief overview of the development of robot-assisted radical prostatectomy
Arab J Urol
(2018)- et al.
Cortical bone trajectory for lumbar pedicle screws
Spine J
(2009)
The era of cortical bone trajectory screws in spine surgery: a qualitative review with rating of evidence
World Neurosurg
Early complications after instrumentation of the lumbar spine using cortical bone trajectory technique
J Clin Neurosci
Minimally invasive lumbar pedicle screw fixation using cortical bone trajectory - screw accuracy, complications, and learning curve in 100 screw placements
J Clin Neurosci
Posterior lumbar interbody fusion with 3D-navigation guided cortical bone trajectory screws for L4/5 degenerative spondylolisthesis: 1-year clinical and radiographic outcomes
World Neurosurg
Microscope-Based augmented reality in degenerative spine surgery: initial experience
World Neurosurg
A modified microsurgical endoscopic-assisted transpedicular corpectomy of the thoracic spine based on virtual 3-dimensional planning
World Neurosurg
Surgical training using three-dimensional simulation in placement of cervical lateral mass screws: a blinded randomized control trial
Spine J
Minimally invasive versus open laminectomy/discectomy, transforaminal lumbar, and posterior lumbar interbody fusions: a systematic review
Cureus
Minimally invasive decompression versus open laminectomy for central stenosis of the lumbar spine: pragmatic comparative effectiveness study
BMJ
Trends for spine surgery for the elderly: implications for access to healthcare in north America
Neurosurgery
The aging of the global population: the changing epidemiology of disease and spinal disorders
Neurosurgery
Growth of consumer-directed health plans to one-half of all employer-sponsored insurance could save $57 billion annually
Health Aff (Millwood)
Patient perceptions of minimally invasive versus open spine surgery
Clin Spine Surg
Cost-effectiveness analysis in minimally invasive spine surgery
Neurosurg Focus
Microendoscopic approach to far-lateral lumbar disc herniation
Neurosurg Focus
Ten-step minimally invasive spine lumbar decompression and dural repair through tubular retractors
Oper Neurosurg (Hagerstown)
A novel minimally invasive presacral approach and instrumentation technique for anterior L5-S1 intervertebral discectomy and fusion: technical description and case presentations
Neurosurg Focus
Percutaneous axial lumbar interbody fusion (AxiaLIF) of the L5-S1 segment: initial clinical and radiographic experience
Minim Invasive Neurosurg
Minimally invasive multilevel percutaneous correction and fusion for adult lumbar degenerative scoliosis: a technique and feasibility study
J Spinal Disord Tech
Radiographic and clinical outcome after 1- and 2-level transsacral axial interbody fusion: clinical article
J Neurosurg Spine
Results and complications after 2-level axial lumbar interbody fusion with a minimum 2-year follow-up
J Neurosurg Spine
High rectal injury during trans-1 axial lumbar interbody fusion L5-S1 fixation: a case report
Spine
Complications of axial lumbar interbody fusion
J Neurosurg Spine
Cited by (0)
Conflict of interest statement: Roger Härtl reports the following: consulting in DePuy Synthes, Brainlab, and Ulrich; royalties from Zimmer Biomet; and investor in RealSpine. Eric Elowitz reports the following: consulting in Medtronic and Joimax. Jacob L. Goldberg has no conflicts to report.