Minimally Invasive Spine Surgery: An Overview.

Spinal surgery is undergoing a major transformation toward a minimally invasive paradigm. This shift is being driven by multiple factors, including the need to address spinal problems in an older and sicker population, as well as changes in patient preferences and reimbursement patterns. Increasingly, minimally invasive surgical techniques are being used in place of traditional open approaches due to significant advancements and implementation of intraoperative imaging and navigation technologies. However, in some patients, due to specific anatomic or pathologic factors, minimally invasive techniques are not always possible. Numerous algorithms have been described, and additional efforts are underway to better optimize patient selection for minimally invasive spinal surgery (MISS) procedures in order to achieve optimal outcomes. Numerous unique MISS approaches and techniques have been described, and several have become fundamental. Investigators are evaluating combinations of MISS techniques to further enhance the surgical workflow, patient safety, and efficiency.

Challenges Hindering Widespread Adoption of Minimally Invasive Spinal Surgery.

Minimally invasive spinal surgery (MISS) techniques offer several beneficial prospects and are being increasingly requested by patients. However, these techniques have not been uniformly adopted by spinal surgeons, and they remain controversial among some. Several barriers have prevented widespread adoption of MISS. These include concerns regarding high start-up costs, limited evidence base, and lack of surgeon training. In addition, the unique approaches involved in MISS expose spinal surgeons to unfamiliar anatomy. Further, while MISS can address a growing spectrum of spinal pathology, some conditions, as well as complications encountered during MISS procedures, require open surgery. This requires surgeons to not only acquire the new and specialized MISS skillset but also maintain their ability to perform open surgery. These factors present challenges common to developing and innovative surgical techniques. Here, we review the barriers preventing wider adoption of MISS and present a framework to promote the safe and effective growth of MISS.

The Future of Minimally Invasive Spinal Surgery.

Strong forces are pushing minimally invasive spinal surgery (MISS) to the forefront of spine care. Less-invasive surgical techniques have been enabled by a variety of technical advances. Despite the promise of MISS, however, several factors, including few training opportunities, perception of a steep learning curve, and high upfront costs, have limited the adoption of these techniques. The "6 T's" is a framework highlighting key factors that must be accounted for to ensure safe and effective MISS as techniques continually evolve. Further, technological advancement in endoscopy, robotics, and augmented/virtual reality is enhancing minimally invasive surgeries to make them even less invasive and safer for patients. The evolution of these new techniques and technologies is driving the future of MISS.

A systematic review of full endoscopic versus micro-endoscopic or open discectomy for lumbar disc herniation.

Aim: Endoscopic discectomies provide several advantages over other techniques such as traditional open lumbar discectomy (OLD) including possibly decreased complications, shorter hospital stay and an earlier return to work. Methods: An electronic database search including MEDLINE/PubMed, EMBASE, Scopus, Cochrane Database of Systematic Reviews and Cochrane Controlled trials (CENTRAL) were reviewed for randomized controlled trials (RCTs) only. Results: A total of nine RCTs met inclusion criteria. Three showed benefit of endoscopic discectomy over the comparator with regards to pain relief, with the remaining six studies showing no difference in pain relief or function. Conclusion: Based on review of the nine included studies, we can conclude that endoscopic discectomy is as effective as other surgical techniques, and has additional benefits of lower complication rate and superior perioperative parameters.

Lay abstract This systematic review investigates the use of a common surgical procedure, endoscopic discectomy, for the surgical treatment of lumbar disc herniation. It is a type of minimally invasive spine surgery (MISS) procedure, which has been shown to be not only effective in outcomes, but also optimal for peri-operative parameters, such as post-operative hospital stay, time duration of surgery and blood loss during the procedure. We utilized five search databases to collect data on only randomized controlled studies that investigated endoscopic discectomy compared with another surgical technique. Our results include nine randomized controlled trials, three of which showed improvement in pain scores for endoscopic discectomies. Consequently, in combination with the optimal peri-operative measures, it is concluded that endoscopic discectomy is a reasonable procedure to treat lumbar disc herniation surgically.

The effect of patient age on discharge destination and complications after lumbar spinal fusion.

Age is an important patient characteristic that has been correlated with specific outcomes after lumbar spine surgery. We performed a retrospective cohort study to model the effect of age on discharge destination and complications after a 1-level or multi-level lumbar spine fusion surgery. The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was used to identify patients who underwent lumbar spinal fusion surgery from 2013 through 2017. Perioperative outcomes were compared across ages 18 to 90 using multivariable nonlinear logistic regressioncontrolling for preoperative characteristics. A total of 61,315 patients were analyzed, with patients over 70 having a higher risk of being discharged to an inpatient rehabilitation center and receiving an intraoperative or postoperative blood transfusion. However, the rates of the other complications and outcomes analyzed in this study were not significantly different as patients age. In conclusion, advanced-age affects the discharge destination after a one- or multi-level fusion and intraoperative/postoperative blood transfusion after a one-level fusion. However, age alone does not significantly affect the risk of the other complications and outcomes assessed in this study. This study will help guide preoperative discussion with advanced-aged patients who are considering a 1-level or multi-level lumbar spine fusion surgery.

Transforaminal Endoscopic Lumbar Discectomy and Foraminotomy with Modified Radiofrequency Nerve Stimulator and Continuous Electromyography Under General Anesthesia.

BACKGROUND: Transforaminal endoscopic lumbar approaches involve working in Kambin's triangle. These procedures are performed on awake patients or under general anesthesia with continuous electromyography. Potential morbidity of this approach includes injury to exiting and traversing nerve roots, as substantial dissection or cauterization of overlying tissues is required for visualization. METHODS: We developed a novel connection system that accepts input from a bipolar radiofrequency probe to allow direct nerve stimulation in conjunction with electromyography. This study included 30 consecutive patients undergoing transforaminal endoscopic lumbar approaches for discectomies (73.3%), foraminal stenosis (23.3%), or lateral recess stenosis (3.3%). Demographic, operative, and outcomes data were collected. RESULTS: Average age of patients was 61.4 years, and the L4-5 segment was most commonly treated (65.6%). Electrophysiologic mapping of the exiting nerve root was attempted in 28 patients with an average stimulation threshold of 8.6 ± 0.9 mA. Mapping of the traversing nerve root was attempted in 12 patients with an average stimulation threshold of 6.0 ± 0.8 mA. There were no instances of new postoperative sensorimotor deficits or dysesthesia. These findings persisted through mean and median follow-up of 294 days and 165 days, respectively. No patient required subsequent lumbar surgery. CONCLUSIONS: Our modified instrumentation and technique allow for accurate identification of the exiting and traversing nerve roots with minimal changes to the workflow of transforaminal endoscopic lumbar approaches. Modification of a bipolar radiofrequency device connection arrangement is simple, inexpensive, and reusable. In this study, no patients developed injury or pain related to nerve root dysfunction.

Future Directions in Communication in Neurosurgery.

Modern-day care of the neurosurgery patient has grown increasingly complex and typically involves a variety of medical team members. Proper communication and transmission of clinical data within the neurosurgery team is required for successful outcomes, especially within the operating room. Effective communication is also critical to the patient-physician relationship and can aid in improving rapport and possibly reducing malpractice lawsuit risk. In addition, interactions exist between practicing neurosurgeons and members of the administration, often focusing on reimbursement and quality issues. Although most physicians would agree that communication between all these stakeholders should improve, certain barriers are present, including the adoption of newer technologies and the lack of formal training. In this article, we review current and projected trends relating to the enhancement of neurosurgical communication at all levels.

Communication in Neurosurgery-The Tower of Babel.

Clinical neurosurgery is a complex specialty with multiple participants, including a variety of providers, patients, family members, and administrators, who interact in complex fashions. Modern-day patient care requires near-constant team communication of vital, detailed clinical information; any breakdown in this process can result in patient harm. Medical communication practices with patients impact mutual rapport as well as the overall physician-patient relationship. Enhanced relationship-centered communication techniques have been shown to improve patient compliance and may positively influence malpractice litigation rates. Neurosurgeons frequently interact with other health care providers and members of the hospital administration on matters relating to billing, compliance, and quality. Communication among the stakeholders is complicated, however, by the fact that the participants may be speaking a variety of different, mutually unintelligible "languages." We discuss the details of the various types of information exchanges in neurosurgery, the key players involved, and the vulnerabilities to breakdowns in the system. In addition, we review the multifaceted, systems-level issues in neurosurgical communication and related weaknesses.

Barriers to the Enhancement of Effective Communication in Neurosurgery.

Communication issues play a major role within neurosurgery. There has been a growing awareness of the necessity of enhanced patient-centered communication between the physician and patient to improve patient satisfaction, compliance, and outcomes. In addition, the threat of malpractice litigation within neurosurgery is of particular concern, and improved communication may lead to some degree of risk mitigation. Within the neurosurgical and medical team, effective transmittal of vital clinical data is essential for patient safety. Despite the recent recognition of the critical role that communication plays in all aspects of medical care, multiple impediments hinder the improvement and use of effective techniques. We have identified 8 unique barriers to the advancement of communication practices: lack of recognition of the importance of communication skills; cognitive bias; sense that it "takes too much time"; cultural hierarchy within medicine; lack of formal communication skill training; fear that disclosure of medical errors will lead to malpractice litigation; the electronic medical record; and frequent shift changes and handoffs.

Posterior Lumbar Interbody Fusion with 3D-Navigation Guided Cortical Bone Trajectory Screws for L4/5 Degenerative Spondylolisthesis: 1-Year Clinical and Radiographic Outcomes.

OBJECTIVE: We describe our technique and evaluate clinical and radiographic outcomes for patients undergoing L4/5 posterior lumbar interbody fusion with 3D-navigation guided cortical bone trajectory screws (PLIF-CBT) for grade 1 or 2 degenerative spondylolisthesis with a minimum follow-up time of 12 months. METHODS: A single-institution series of 18 patients was evaluated with data prospectively collected and retrospectively analyzed. Pain and disability scores were collected preoperatively and at a minimum of 12 months postoperatively, including back and bilateral leg pain visual analog scores (VAS) and Oswestry Disability Index (ODI) scores. Radiographic fusion was assessed as complete, partial, or none based on the presence of bridging bones across the disc space, posterior elements, or both. RESULTS: Patients demonstrated statistically significant reductions in back pain VAS (P = 0.0025), leg pain VAS (P < 0.0001), and ODI (P < 0.0001) at a minimum of 12 months postoperatively. Radiographic fusion at an average of 14.9 months postoperatively was available for 16/18 patients, with 6 patients demonstrating fusion (4/6 with complete fusion; 2/6 with partial fusion). There were no instances of intraoperative complications or delayed complications requiring subsequent interventions. CONCLUSIONS: PLIF-CBT can be performed in a safe and reproducible fashion with excellent clinical outcomes at 1 year postoperatively. The outcomes did not correlate with fusion status, which was unexpectedly low at 37.5% without significant hardware abnormalities necessitating reoperations. PLIF-CBT offers several perioperative advantages compared with traditional open PLIF and requires longer-term studies to demonstrate its durability with regard to improvement in clinical pain and radiographic endpoints, including anterior and/or posterior element fusion.

The Impact of Cage Dimensions, Positioning, and Side of Approach in Extreme Lateral Interbody Fusion.

STUDY DESIGN: This is a retrospective single-center study. OBJECTIVE: The aim of the study was to evaluate the impact of cage characteristics and position toward clinical and radiographic outcome measures in patients undergoing extreme lateral interbody fusion (ELIF). SUMMARY OF BACKGROUND DATA: ELIF is utilized for indirect decompression and minimally invasive surgical treatment for various degenerative spinal disorders. However, evidence regarding the influence of cage characteristics in patient outcome is minimal. MATERIALS AND METHODS: Patients undergoing ELIF between 2007 and 2011 were included in a retrospective study. Demographic and perioperative data, as well as cage characteristics and side of approach were extracted. Radiographic parameters including lumbar lordosis, foraminal height, and disc height as well as clinical outcome parameters (Oswestry Disability Index and Visual Analog Scale) were measured preoperatively, postoperatively, and at the latest follow-up examination. Cage dimensions, in situ position, and type were correlated with radiographic and clinical outcome parameters. RESULTS: In total, 84 patients with a total of 145 functional spinal units were analyzed. At the last follow-up of 17.7 months, radiographic and clinical outcome measures revealed significant improvement compared with before surgery with both, 18 and 22 mm cage anterior-posterior diameter subgroups (P≤0.05). Among cage characteristics, 22 mm cages presented superior restoration of foraminal and disc heights compared with 18 mm cages (P≤0.05). Neither position of the cage (anterior vs. posterior), nor the type (parallel vs. lordotic) had a significant impact on restoration of foraminal height and lumbar lordosis. Moreover, the side of surgical approach did not influence the amount of foraminal height increase. CONCLUSIONS: Cage anterior-posterior diameter is the determining factor in restoration of foraminal height in ELIF. Cage height, type, positioning, and side of approach do not have a determining role in radiographic outcome in the present study. Sustainable foraminal height restoration is achieved by implantation of wider cages. LEVEL OF EVIDENCE: Level 3.

Are Locked Facets a Contraindication for Extreme Lateral Interbody Fusion?

BACKGROUND: Extreme lateral interbody fusion (ELIF) has gained popularity as a minimally invasive treatment allowing for indirect decompression of neural elements. However, evidence regarding the influence of facet degeneration (FD) and facet tropism (FT) toward indirect decompression is lacking. The aim of the study was to evaluate whether indirect decompression is impaired by FD and FT in patients undergoing ELIF. METHODS: Thirty-seven patients undergoing ELIF were included in a retrospective study. Radiographic parameters including disk height, segmental disk angle, foraminal area, FD, FT, and clinical outcome parameters (Oswestry Disability Index and Visual Analog Scale) were measured preoperatively and postoperatively. FD and FT were correlated with radiographic and clinical outcome parameters in order to determine predictors restricting indirect decompression. RESULTS: Thirty-seven patients with a total of 74 levels were analyzed. Clinical and radiographic outcome measures including central canal area (Δ = +17.2 mm2), mean disk height (Δ = +3 mm), and foraminal area (Δ = +9.9 mm2) revealed significant improvement compared with before surgery (P ≤ 0.05). Patients with severe FD (grade 4) were more likely to have FT ≥ 12 degrees (32.3%) than patients without/mild (grades 0 and 1; 10%) or moderate FD (grades 2 and 3; 13%), P ≤ 0.05. FD and FT did not affect disk height restoration, foraminal area, canal surface area, or clinical outcome measures (P ≥ 0.05). CONCLUSIONS: Indirect decompression of neural elements in ELIF is not impaired by FD and FT are not relative contraindications in patients undergoing ELIF.

Expandable Polyaryl-Ether-Ether-Ketone Spacers for Interbody Distraction in the Lumbar Spine.

Study Design Retrospective case series. Objective StaXx XD (Spine Wave, Inc., Shelton, CT, United States) is an expandable polyaryl-ether-ether-ketone (PEEK) wafer implant utilized in the treatment of lumbar degenerative disease. PEEK implants have been successfully used as interbody devices. Few studies have focused on expandable PEEK devices. The aim of the current study is to determine the radiographic and clinical outcome of expandable PEEK cages utilized for transforaminal lumbar interbody fusion in patients with lumbar degenerative diseases. Methods Forty-nine patients who underwent lumbar interbody fusion with implantation of expandable PEEK cages and posterior instrumentation were included. The clinical outcome was evaluated using the visual analog scale (VAS) and the Oswestry Disability Index (ODI). Radiographic parameters including disk height, foraminal height, listhesis, local disk angle of the index level/levels, regional lumbar lordosis, and graft subsidence were measured preoperatively, postoperatively, and at latest follow-up. Results At an average follow-up of 19.3 months, the minimum clinically important difference for the ODI and VAS back, buttock, and leg were achieved in 64, 52, 58, and 52% of the patients, respectively. There was statistically significant improvement in VAS back (6.42 versus 3.11, p < 0.001), VAS buttock (4.66 versus 1.97, p = 0.002), VAS leg (4.55 versus 1.96, p < 0.001), and ODI (21.7 versus 12.1, p < 0.001) scores. There was a significant increase in the average disk height (6.49 versus 8.18 mm, p = 0.037) and foraminal height (15.6 versus 18.53 mm, p = 0.0001), and a significant reduction in the listhesis (5.13 versus 3.15 mm, p = 0.005). The subsidence of 0.66 mm (7.4%) observed at the latest follow-up was not significant (p = 0.35). Conclusions Midterm results indicate that expandable PEEK spacers can effectively and durably restore disk and foraminal height and improve the outcome without significant subsidence.

Extreme lateral interbody fusion for unilateral symptomatic vertical foraminal stenosis.

PURPOSE: Asymmetric loss of disc height in adult deformity patients may lead to unilateral vertical foraminal stenosis and radiculopathy. The current study aimed to investigate whether restoration of foraminal height on the symptomatic side using extreme lateral interbody fusion (XLIF) would alleviate unilateral radiculopathy. METHODS: In a retrospective study, patients with single-level unilateral vertical foraminal stenosis and corresponding radicular pain undergoing XLIF were included. Functional data (visual analog scale (VAS) for buttock, leg and back, as well as Oswestry Disability Index (ODI)) and radiographic measurements (bilateral foraminal height, disc height, segmental coronal Cobb angle and regional lumbar lordosis) were collected preoperatively, postoperatively and at the last follow-up. RESULTS: Twenty-three patients were included, among whom 61 % had degenerative scoliosis. History of previous surgery at the level of index was present in 43 % of patients. Additional instrumentation was performed in 91 %. The foraminal height on the stenotic side was significantly increased postoperatively (p < 0.001), and remained significantly increased at the last follow-up of 11 ± 3.7 months (p < 0.001). Additionally, VAS buttock and leg on the stenotic side, VAS back and ODI were significantly improved postoperatively and at the last follow-up (p ≤ 0.001 for all parameters). The foraminal height on the stenotic side showed correlation with the VAS leg on the stenotic side, both postoperatively and the last follow-up (r = -0.590; p = 0.013, and r = -0.537; p = 0.022, respectively). CONCLUSIONS: Single-level XLIF is an effective procedure for treatment of symptomatic unilateral foraminal stenosis leading to radiculopathy. In deformity patients with radicular pain caused by nerve compression at a single level, when not associated with other symptoms attributable to general scoliosis, treatment with single-level XLIF can result in short- and mid-term satisfactory outcome.

Endoscopic lumbar foraminotomy.

Foraminal stenosis frequently causes radiculopathy in lumbar degenerative spondylosis. Endoscopic transforaminal techniques allow for foraminal access with minimal tissue disruption. However, the effectiveness of foraminal decompression by endoscopic techniques has yet to be studied. We evaluate radiographic outcome of endoscopic transforaminal foraminotomies performed at L3-L4, L4-L5, and L5-S1 on cadaveric specimens. Before and after the procedures, three dimensional CT scans were obtained to measure foraminal height and area. Following the foraminotomies, complete laminectomies and facetectomies were performed to assess for dural tears or nerve root damage. L3-L4 preoperative foraminal height increased by 8.9%, from 2.12±0.13cm to 2.27±0.14cm (p<0.01), and foraminal area increased by 24.8% from 2.21±0.18cm(2) to 2.72±0.19cm(2) (p<0.01). At L4-L5, preoperative foraminal height was 1.87±0.17cm and area was 1.78±0.18cm(2). Endoscopic foraminotomies resulted in a 15.3% increase of foraminal height (2.11±0.15cm, p<0.05) and 44.8% increase in area of (2.51±0.21cm(2), p<0.01). At L5-S1, spondylitic changes caused diminished foraminal height (1.26±0.14cm) and foraminal area (1.17±0.18cm(2)). Postoperatively, foraminal height increased by 41.6% (1.74±0.09cm, p<0.05) and area increased by 98.7% (2.08±0.17cm(2), p<0.01). Subsequent inspection via a standard midline approach revealed one dural tear of an S1 nerve root. Endoscopic foraminotomies allow for effective foraminal decompression, though clinical studies are necessary to further evaluate complications and efficacy.

Radiological and clinical outcomes following extreme lateral interbody fusion.

OBJECT: Extreme lateral interbody fusion (ELIF) is a popular technique for anterior fixation of the thoracolumbar spine. Clinical and radiological outcome studies are required to assess safety and efficacy. The aim of this study was to describe the functional and radiological impact of ELIF in a degenerative disc disease population with a longer follow-up and to assess the durability of this procedure. METHODS: Demographic and perioperative data for all patients who had undergone ELIF for degenerative lumbar disorders between 2007 and 2011 were collected. Trauma and tumor cases were excluded. For radiological outcome, the preoperative, immediate postoperative, and latest follow-up coronal Cobb angle, lumbar sagittal lordosis, bilateral foraminal heights, and disc heights were measured. Pelvic incidence (PI) and PI-lumbar lordosis (PI-LL) mismatch were assessed in scoliotic patients. Clinical outcome was evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS), as well as the Macnab criteria. RESULTS: One hundred forty-five vertebral levels were surgically treated in 90 patients. Pedicle screw and rod constructs and lateral plates were used to stabilize fixation in 77% and 13% of cases, respectively. Ten percent of cases involved stand-alone cages. At an average radiological follow-up of 12.6 months, the coronal Cobb angle was 10.6° compared with 23.8° preoperatively (p < 0.0001). Lumbar sagittal lordosis increased by 5.3° postoperatively (p < 0.0001) and by 2.9° at the latest follow-up (p = 0.014). Foraminal height and disc height increased by 4 mm (p < 0.0001) and 3.3 mm (p < 0.0001), respectively, immediately after surgery and remained significantly improved at the last follow-up. Separate evaluation of scoliotic patients showed no statistically significant improvement in PI and PI-LL mismatch either immediately postoperatively or at the latest follow-up. Clinical evaluation at an average follow-up of 17.6 months revealed an improvement in the ODI and the VAS scores for back, buttock, and leg pain by 21.1% and 3.7, 3.6, and 3.7 points, respectively (p < 0.0001). According to the Macnab criteria, 84.8% of patients had an excellent, good, or fair functional outcome. New postoperative thigh numbness and weakness was detected in 4.4% and 2.2% of the patients, respectively, which resolved within the first 3 months after surgery in all but 1 case. CONCLUSIONS: This study provides what is to the authors' knowledge the most comprehensive set of radiological and clinical outcomes of ELIF in a fairly large population at a midterm follow-up. Extreme lateral interbody fusion showed good clinical outcomes with a low complication rate. The procedure allows for at least midterm clinically effective restoration of disc and foraminal heights. Improvement in coronal deformity and a small but significant increase in sagittal lordosis were observed. Nonetheless, no significant improvement in the PI-LL mismatch was achieved in scoliotic patients.