Publications by authors named "Adam S Kanter"

120 Publications

Novel Distributed Loading Technique Using Multimaterial, Long-Segment Spinal Constructs to Prevent Proximal Junctional Pathology in Adult Spinal Deformity Correction-Operative Technique and Radiographic Findings.

World Neurosurg 2021 Aug 18. Epub 2021 Aug 18.

Mayfield Clinic, Cincinnati, Ohio, USA.

Background: Proximal junctional kyphosis (PJK) and proximal junction failure are common and costly complications after long-segment adult spinal deformity (ASD) correction. Although much research has focused on the concept of "softening the landing" to prevent proximal junction pathologies, long-segment constructs largely deviate from the force-deformation curve of the physiologic spine. Our novel distributed loading technique for ASD correction is described using multimaterial, long-segment constructs to create a biomechanically sound, yet physiologic, decremental stiffness toward the rostral end.

Methods: Operative steps detail the custom-designed constructs of dual-headed pedicle screws and varied rod diameters and materials (cobalt chromium or titanium) for an initial 20 patients (mean 66.6 ± 4.8 years). Standing scoliosis films were obtained preoperatively and at regular intervals postoperatively to assess for PJK.

Results: No patient had evidence of PJK or proximal junction failure at latest radiographic follow-up (mean 17.9 months, range 13-25 months). Radiographic findings for sagittal vertical axis averaged 11.2 ± 5.6 cm preoperatively and 3.6 ± 2.3 cm postoperatively. Compared with preoperative parameters, postoperative reductions in pelvic incidence-lumbar lordosis mismatch averaged 28.7 ± 12.9 degrees, and sagittal vertical axis averaged 7.6 ± 5.2 cm while PJA was essentially unchanged.

Conclusions: Preliminary results suggest that the distributed loading technique is promising for prevention of PJK with stiffness gradients that mimic the force-deformation curve of the physiologic posterior tension band. Our technique may optimize the degree of stress at the proximal junction without overwhelming the anterior column bony while remodeling and mature arthrodesis takes place.
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http://dx.doi.org/10.1016/j.wneu.2021.08.052DOI Listing
August 2021

Incidence of adjacent-segment surgery following stand-alone lateral lumbar interbody fusion.

J Neurosurg Spine 2021 Jun 18:1-5. Epub 2021 Jun 18.

Objective: Adjacent-segment disease (ASD) requiring operative intervention is a relatively common long-term consequence of lumbar fusion surgery. Although the incidence of ASD requiring reoperation is well described for traditional posterior lumbar approaches (2.5%-3.9% per year), it remains poorly characterized for stand-alone lateral lumbar interbody fusion (LLIF). In this study, the authors report their institutional experience with ASD requiring reoperation after LLIF over an extended follow-up period of 4 years.

Methods: Medical records were reviewed for 276 consecutive patients who underwent stand-alone LLIF by a single surgeon for degenerative spinal disorders. Inclusion criteria (single-stage, stand-alone LLIF without posterior supplementation, with no prior lumbar instrumentation, and a minimum of 4 years of follow-up) were met by 182 patients, who were analyzed for operative ASD incidence (per-year rate), demographics, and Oswestry Disability Index (ODI) score. Operative ASD was strictly defined as new-onset pathology following index surgery at directly adjacent levels to the prior construct. Operative, rather than symptomatic or radiographic, ASD was analyzed to provide a consistent and impactful endpoint while avoiding retrospective diagnosis.

Results: The study cohort of 182 patients had an operative ASD rate of 3.3% (n = 6 procedures) over 4 years of follow-up, for an incidence on Kaplan-Meier survival analysis of 0.88% (95% CI 0.67%-1.09%) per year. In comparing patients with operative ASD with those without, there were no significant differences in mean age (53.7 vs 56.2 years), male sex (33.3% vs 44.9%), smoking status (16.7% vs 25.0%), or number of levels fused (mean 1.33 vs 1.46). The operative ASD cohort had a greater mean BMI (37.3 vs 30.2, p < 0.01). Operative ASD patients had lower baseline ODI scores (33.8 vs 48.3, p = 0.02); however, no difference was observed in ODI at 6 weeks (34.0 vs 39.0) or 3 months (16.0 vs 32.8) postoperatively.

Conclusions: The incidence of ASD in LLIF for degenerative lumbar etiologies in this cohort was 0.88% (95% CI 0.67%-1.09%) per year. Meanwhile, the reported reoperation rates for ASD in posterior spinal approaches was 2.5% to 3.9% per year, which implies that LLIF may be preferable for well-selected patients.
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http://dx.doi.org/10.3171/2020.12.SPINE201218DOI Listing
June 2021

Load-Sharing Classification Score as Supplemental Grading System in the Decision-Making Process for Patients With Thoracolumbar Injury Classification and Severity 4.

Neurosurgery 2021 Aug;89(3):428-434

Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.

Background: Patients with Thoracolumbar Injury Classification and Severity (TLICS) score of 4 fall into a gray zone between surgical and conservative management. The integrity of posterior ligamentous complex (PLC) evaluated by magnetic resonance imaging (MRI) contributes to surgical decision-making. Load-sharing classification (LSC) may provide a modifier to further guide decision-making in these patients.

Objective: To evaluate associations between LSC score and MRI acquisition, compromise of PLC on MRI, and surgical intervention in TLICS 4 patients.

Methods: A cohort of 111 neurologically intact patients with isolated thoracolumbar burst fracture with TLICS 4 was evaluated. LSC score was determined based on degree of comminution (1-3), apposition (1-3), and kyphosis (1-3), total composite score of 3 to 9.

Results: Overall, 44 patients underwent MRI, 15 had PLC injury, and 32 (28.8%) underwent surgery. LSC score was higher in patients who had an MRI (median 6 vs 3, P < .001) and patients who had surgery (median 7 vs 4, P < .001). In univariate logistic regression, LSC score was associated with MRI acquisition (odds ratio [OR] 1.7; 1.32-2.12; P < .001), presence of PLC injury on MRI (OR 1.5; 1.2-2.0; P = .002) and, in multivariate logistic regression, undergoing surgical intervention (OR 3.7; 2.3-5.9; P < .001), independent of MRI or PLC injury.

Conclusion: LSC score in neurologically intact patients with isolated thoracolumbar burst fracture with TLICS 4 was independently associated with operative intervention. The application of LSC may further guide decision-making in this patient group.
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http://dx.doi.org/10.1093/neuros/nyab179DOI Listing
August 2021

Safety of lateral access to the concave side for adult spinal deformity.

J Neurosurg Spine 2021 May 14:1-5. Epub 2021 May 14.

1Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona; and.

Objective: Minimally invasive surgery (MIS) techniques, particularly lateral lumbar interbody fusion (LLIF), have become increasingly popular for adult spinal deformity (ASD) correction. Much discussion has been had regarding theoretical and clinical advantages to addressing coronal curvature from the convex versus concave side of the curve. In this study, the authors aimed to broadly evaluate the clinical outcomes of addressing ASD with circumferential MIS (cMIS) techniques while accessing the lumbar coronal curvature from the concave side.

Methods: A multi-institution, retrospective chart and radiographic review was performed for all ASD patients with at least a 10° curvature, as defined by the Scoliosis Research Society, who underwent cMIS correction. The data collected included convex versus concave access to the coronal curve, durable or sensory femoral nerve injury lasting longer than 6 weeks, vascular injury, visceral injury, and any additional major complication, with at least a 2-year follow-up. Neither health-related quality-of-life metrics nor spinopelvic parameters were included within the scope of this study.

Results: A total of 152 patients with ASD treated with cMIS correction via lateral access were identified and analyzed. Of these, 126 (82.9%) were approached from the concave side and 26 (17.1%) were approached from the convex side. In the concave group, 1 (0.8%) motor and 4 (3.2%) sensory deficit cases remained at 6 weeks after the operation. No vascular, visceral, or catastrophic intraoperative injuries were encountered in the concave group. Of the 26 patients in the convex group, 2 (7.7%) experienced motor deficits lasting longer than 6 weeks and 5 (19.2%) had lower-extremity sensory deficits.

Conclusions: It has been reported that lateral access to the convex side is associated with similar clinical and radiographic outcomes with fewer complications when compared with access to the concave side. Advantages to approaching the lumbar spine from the concave side include using one incision to access multiple levels, breaking the operative table to assist with curvature correction, easier access to the L4-5 disc space, the ability to release the contracted side, and, often, avoidance of the need to access or traverse the thoracic cavity. This study illustrates the largest reported cohort of concave access for cMIS scoliosis correction; few postoperative sensory and motor deficits were found.
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http://dx.doi.org/10.3171/2020.10.SPINE191270DOI Listing
May 2021

Surgery Related Factors Do Not Affect Short-Term Adjacent Segment Kinematics After Anterior Cervical Arthrodesis.

Spine (Phila Pa 1976) 2021 Apr 23. Epub 2021 Apr 23.

Department of Orthopaedic Surgery, University of Pittsburgh Medical Center Department of Neurosurgery, University of Pittsburgh Medical Center.

Study Design: Prospective cohort study.

Objective: To identify surgical factors that affect adjacent segment kinematics after anterior cervical discectomy and fusion (ACDF) as measured by biplane radiography.

Summary Of Background Data: Previous studies investigated the effect of surgical factors on spine kinematics as a potential etiology for adjacent segment disease (ASD). Those studies used static flexion-extension radiographs to evaluate range of motion. However, measurements from static radiographs are known to be unreliable. Furthermore, those studies were unable to evaluate the effect of ACDF on adjacent segment axial rotation.

Methods: Patients had continuous cervical spine flexion/extension and axial rotation movements captured at 30 images per second in a dynamic biplane radiography system preoperatively and 1 year after ACDF. Digitally reconstructed radiographs generated from subject-specific CT scans were matched to biplane radiographs using a previously validated tracking process. Dynamic kinematics, postoperative segmental kyphosis, and disc distraction were calculated from this tracking process. Plate-to-disc distance was measured on postoperative radiographs. Graft type was collected from the medical record. Multivariate linear regression was performed to identify surgical factors associated with 1-year post-surgery changes in adjacent segment kinematics. A secondary analysis was also performed to compare adjacent segment kinematics between each of the surgical factors and previously defined thresholds believed to be associated with adjacent segment degeneration.

Results: Fifty-nine patients completed preoperative and postoperative testing. No association was found between any of the surgical factors and change in adjacent segment flexion/extension or axial rotation range of motion (all p > 0.09). The secondary analysis also did not identify differences between adjacent segment kinematics and surgical factors (all p > 0.07).

Conclusions: Following ACDF for cervical spondylosis, factors related to surgical technique were not associated with short-term changes in adjacent segment kinematics that reflect the hypermobility hypothesized to lead to the development of ASD.Level of Evidence: 2.
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http://dx.doi.org/10.1097/BRS.0000000000004080DOI Listing
April 2021

The minimally invasive interbody selection algorithm for spinal deformity.

J Neurosurg Spine 2021 Mar 12:1-8. Epub 2021 Mar 12.

13Department of Neurological Surgery, Weill Cornell Medical College, New York, New York.

Objective: Minimally invasive surgery (MIS) for spinal deformity uses interbody techniques for correction, indirect decompression, and arthrodesis. Selection criteria for choosing a particular interbody approach are lacking. The authors created the minimally invasive interbody selection algorithm (MIISA) to provide a framework for rational decision-making in MIS for deformity.

Methods: A retrospective data set of circumferential MIS (cMIS) for adult spinal deformity (ASD) collected over a 5-year period was analyzed by level in the lumbar spine to identify surgeon preferences and evaluate segmental lordosis outcomes. These data were used to inform a Delphi session of minimally invasive deformity surgeons from which the algorithm was created. The algorithm leads to 1 of 4 interbody approaches: anterior lumbar interbody fusion (ALIF), anterior column release (ACR), lateral lumbar interbody fusion (LLIF), and transforaminal lumbar interbody fusion (TLIF). Preoperative and 2-year postoperative radiographic parameters and clinical outcomes were compared.

Results: Eleven surgeons completed 100 cMISs for ASD with 338 interbody devices, with a minimum 2-year follow-up. The type of interbody approach used at each level from L1 to S1 was recorded. The MIISA was then created with substantial agreement. The surgeons generally preferred LLIF for L1-2 (91.7%), L2-3 (85.2%), and L3-4 (80.7%). ACR was most commonly performed at L3-4 (8.4%) and L2-3 (6.2%). At L4-5, LLIF (69.5%), TLIF (15.9%), and ALIF (9.8%) were most commonly utilized. TLIF and ALIF were the most selected approaches at L5-S1 (61.4% and 38.6%, respectively). Segmental lordosis at each level varied based on the approach, with greater increases reported using ALIF, especially at L4-5 (9.2°) and L5-S1 (5.3°). A substantial increase in lordosis was achieved with ACR at L2-3 (10.9°) and L3-4 (10.4°). Lateral interbody arthrodesis without the use of an ACR did not generally result in significant lordosis restoration. There were statistically significant improvements in lumbar lordosis (LL), pelvic incidence-LL mismatch, coronal Cobb angle, and Oswestry Disability Index at the 2-year follow-up.

Conclusions: The use of the MIISA provides consistent guidance for surgeons who plan to perform MIS for deformity. For L1-4, the surgeons preferred lateral approaches to TLIF and reserved ACR for patients who needed the greatest increase in segmental lordosis. For L4-5, the surgeons' order of preference was LLIF, TLIF, and ALIF, but TLIF failed to demonstrate any significant lordosis restoration. At L5-S1, the surgical team typically preferred an ALIF when segmental lordosis was desired and preferred a TLIF if preoperative segmental lordosis was adequate.
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http://dx.doi.org/10.3171/2020.9.SPINE20230DOI Listing
March 2021

Effect of Ventral vs Dorsal Spinal Surgery on Patient-Reported Physical Functioning in Patients With Cervical Spondylotic Myelopathy: A Randomized Clinical Trial.

JAMA 2021 03;325(10):942-951

Neurosurgery, Cleveland Clinic Foundation, Cleveland, Ohio.

Importance: Cervical spondylotic myelopathy is the most common cause of spinal cord dysfunction worldwide. It remains unknown whether a ventral or dorsal surgical approach provides the best results.

Objective: To determine whether a ventral surgical approach compared with a dorsal surgical approach for treatment of cervical spondylotic myelopathy improves patient-reported physical functioning at 1 year.

Design, Setting, And Participants: Randomized clinical trial of patients aged 45 to 80 years with multilevel cervical spondylotic myelopathy enrolled at 15 large North American hospitals from April 1, 2014, to March 30, 2018; final follow-up was April 15, 2020.

Interventions: Patients were randomized to undergo ventral surgery (n = 63) or dorsal surgery (n = 100). Ventral surgery involved anterior cervical disk removal and instrumented fusion. Dorsal surgery involved laminectomy with instrumented fusion or open-door laminoplasty. Type of dorsal surgery (fusion or laminoplasty) was at surgeon's discretion.

Main Outcomes And Measures: The primary outcome was 1-year change in the Short Form 36 physical component summary (SF-36 PCS) score (range, 0 [worst] to 100 [best]; minimum clinically important difference = 5). Secondary outcomes included 1-year change in modified Japanese Orthopaedic Association scale score, complications, work status, sagittal vertical axis, health resource utilization, and 1- and 2-year changes in the Neck Disability Index and the EuroQol 5 Dimensions score.

Results: Among 163 patients who were randomized (mean age, 62 years; 80 [49%] women), 155 (95%) completed the trial at 1 year (80% at 2 years). All patients had surgery, but 5 patients did not receive their allocated surgery (ventral: n = 1; dorsal: n = 4). One-year SF-36 PCS mean improvement was not significantly different between ventral surgery (5.9 points) and dorsal surgery (6.2 points) (estimated mean difference, 0.3; 95% CI, -2.6 to 3.1; P = .86). Of 7 prespecified secondary outcomes, 6 showed no significant difference. Rates of complications in the ventral and dorsal surgery groups, respectively, were 48% vs 24% (difference, 24%; 95% CI, 8.7%-38.5%; P = .002) and included dysphagia (41% vs 0%), new neurological deficit (2% vs 9%), reoperations (6% vs 4%), and readmissions within 30 days (0% vs 7%).

Conclusions And Relevance: Among patients with cervical spondylotic myelopathy undergoing cervical spinal surgery, a ventral surgical approach did not significantly improve patient-reported physical functioning at 1 year compared with outcomes after a dorsal surgical approach.

Trial Registration: ClinicalTrials.gov Identifier: NCT02076113.
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http://dx.doi.org/10.1001/jama.2021.1233DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7944378PMC
March 2021

Revision Surgery Rates After Minimally Invasive Adult Spinal Deformity Surgery: Correlation with Roussouly Spine Type at 2-Year Follow-Up?

World Neurosurg 2021 04 11;148:e482-e487. Epub 2021 Jan 11.

Department of Neurosurgery University of California, San Francisco, San Francisco, California, USA.

Background: Spinopelvic parameters have hitherto dictated much of adult spinal deformity (ASD) correction. The Roussouly classification is used for the normal adult spine. We evaluated whether a correlation would be found between the Roussouly type and the rate of revision surgery in patients with ASD undergoing circumferential minimally invasive spinal (cMIS) correction.

Methods: A multicenter retrospective review of patients who had undergone cMIS surgery for ASD was performed. The inclusion criteria were age ≥18 years and 1 of the following: coronal Cobb angle >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, pelvic incidence (PI) to lumbar lordosis (LL) mismatch >10°, cMIS surgery, and a minimum of 2 years of follow-up data available. The patients were classified by Roussouly type, and the clinical and radiographic outcomes were evaluated.

Results: A total of 104 patients were included in the present analysis. Of the 104 patients, 41 had Roussouly type 1, 32 had type 2, 23 had type 3, and 8 had type 4. Preoperatively, the patients with type 4 had the highest PI (P = 0.002) and LL (P < 0.001). Postoperatively, the PI-LL mismatch, Cobb angle, and sagittal vertical axis were not different among the 4 groups. However, the patients with type 2 had had the highest rate of complications (type 1, 29.3%; type 2, 61.3%; type 3, 34.8%; type 4, 25.0%; P = 0.031). The reoperation rates were comparable (type 1, 19.5%; type 2, 38.7%; type 3, 13.0%; type 4, 12.5%; P = 0.097). The reoperation rates for adjacent segment degeneration or proximal junctional kyphosis were also comparable (P = 0.204 and P = 0.060, respectively).

Conclusions: We did not find a clear correlation between Roussouly type and the rate of revision surgery for adjacent segment disease or proximal junctional kyphosis in patients who had undergone cMIS surgery for ASD.
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http://dx.doi.org/10.1016/j.wneu.2021.01.011DOI Listing
April 2021

Impact of Frailty on Outcomes Following Spine Surgery: A Prospective Cohort Analysis of 668 Patients.

Neurosurgery 2021 02;88(3):552-557

The Wolff Center at the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Background: With an aging population, elderly patients with multiple comorbidities are more frequently undergoing spine surgery and may be at increased risk for complications. Objective measurement of frailty may predict the incidence of postoperative adverse events.

Objective: To investigate the associations between preoperative frailty and postoperative spine surgery outcomes including mortality, length of stay, readmission, surgical site infection, and venous thromboembolic disease.

Methods: As part of a system-wide quality improvement initiative, frailty assessment was added to the routine assessment of patients considering spine surgery beginning in July 2016. Frailty was assessed with the Risk Analysis Index (RAI), and patients were categorized as nonfrail (RAI 0-29) or prefrail/frail (RAI ≥ 30). Comparisons between nonfrail and prefrail/frail patients were analyzed using Fisher's exact test for categorical data or by Wilcoxon rank sum tests for continuous data.

Results: From August 2016 through September 2018, 668 patients (age of 59.5 ± 13.3 yr) had a preoperative RAI score recorded and underwent scheduled spine surgery. Prefrail and frail patients suffered comparatively higher rates of mortality at 90 d (1.9% vs 0.2%, P < .05) and 1 yr (5.1% vs 1.2%, P < .01) from the procedure date. They also had longer in-hospital length of stay (LOS) (3.9 d ± 3.6 vs 3.1 d ± 2.8, P < .001) and higher rates of 60 d (14.6% vs 8.2%, P < .05) and 90 d (15.8% vs 9.8%, P < .05) readmissions.

Conclusion: Preoperative frailty, as measured by the RAI, was associated with an increased risk of readmission and 90-d and 1-yr mortality following spine surgery. The RAI can be used to stratify spine patients and inform preoperative surgical decision making.
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http://dx.doi.org/10.1093/neuros/nyaa468DOI Listing
February 2021

Lateral Lumbar Interbody Fusion: Review of Surgical Technique and Postoperative Multimodality Imaging Findings.

AJR Am J Roentgenol 2021 08 9;217(2):480-494. Epub 2020 Sep 9.

Department of Radiology, University of Pittsburgh Medical Center, UPMC Presbyterian, 200 Lothrop St, Ste 200 E Wing, Pittsburgh, PA 15213.

The lateral lumbar interbody fusion (LLIF) approach is a minimally invasive surgery that can be used as an alternative to traditional lumbar interbody fusion techniques. LLIF accesses the intervertebral disk through the retroperitoneum and psoas muscle to avoid major vessels and visceral organs. The exposure of retroperitoneal structures during LLIF leads to unique complications compared with other surgical approaches. An understanding of the surgical technique and its associated potential complications is necessary for radiologists who interpret imaging before and after LLIF. Preoperative imaging must carefully assess the location of anatomic structures, including major retroperitoneal vasculature, lumbar nerve roots, lumbosacral plexus, and the genitofemoral nerve, relative to the psoas muscle. Multiple imaging modalities can be used in postoperative assessment including radiographs, CT, CT myelography, and MRI. Of these, CT is the preferred modality, because it can assess a range of complications relating to both the retroperitoneal exposure and the spinal instrumentation, as well as bone integrity and fusion status. This article describes surgical approaches for lumbar interbody fusion, comparing the approaches' indications, contraindications, advantages, and disadvantages; reviews the surgical technique of LLIF and relevant anatomic considerations; and illustrates for interpreting radiologists the normal postoperative findings and potential postsurgical complications of LLIF.
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http://dx.doi.org/10.2214/AJR.20.24074DOI Listing
August 2021

Preoperative Chronic Opiate Use and Patient Reported Outcomes Following Adult Spinal Reconstructive Surgery.

World Neurosurg 2020 11 19;143:e166-e171. Epub 2020 Jul 19.

Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA. Electronic address:

Background: Preoperative chronic narcotic use has been linked to poor outcomes after surgery for degenerative spinal disorders in the form of lower health-related quality of life scores, higher revision rates, increased infections, lower likelihood of return to work, and higher 90-day readmission rates. This study evaluated the impact of preoperative chronic narcotic use on patient reported outcome measures following adult spinal reconstructive surgery.

Methods: Patients who underwent adult spinal reconstructive surgery over 2 years at our institution were identified from a prospectively maintained spine registry. These patients were grouped into chronic opiate users as defined by a 6-month duration of use with a minimum morphine equivalent dose of 30 mg/day. Patient reported outcome measures were collected prospectively.

Results: Of 140 patients included for analysis, 30 (21.4%) patients were categorized as chronic opiate users. No differences were identified in mean preoperative patient reported outcome measures, including Oswestry Disability Index, health state, visual analog scale, and EQ-5D indices. At both 6 weeks and 6 months postoperatively, patients in the opiate group demonstrated significantly worse mean visual analog scale back pain scores relative to the nonopiate group. At 6 months postoperatively and at the last known clinical follow-up, Oswestry Disability Index scores were higher in the opiate group.

Conclusions: Chronic opiate use before adult spinal reconstructive surgery was associated with worse pain and disability following intervention. Further work is needed to understand the role of opiate weaning as part of a larger prehabilitation strategy for adult spinal reconstructive surgery.
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http://dx.doi.org/10.1016/j.wneu.2020.07.084DOI Listing
November 2020

Factors affecting approach selection for minimally invasive versus open surgery in the treatment of adult spinal deformity: analysis of a prospective, nonrandomized multicenter study.

J Neurosurg Spine 2020 Jun 19:1-6. Epub 2020 Jun 19.

5Department of Orthopaedic Surgery, Scripps Clinic, La Jolla, California.

Objective: Surgical decision-making and planning is a key factor in optimizing outcomes in adult spinal deformity (ASD). Minimally invasive spinal (MIS) strategies for ASD have been increasingly used as an option to decrease postoperative morbidity. This study analyzes factors involved in the selection of either a traditional open approach or a minimally invasive approach to treat ASD in a prospective, nonrandomized multicenter trial. All centers had at least 5 years of experience in minimally invasive techniques for ASD.

Methods: The study enrolled 268 patients, of whom 120 underwent open surgery and 148 underwent MIS surgery. Inclusion criteria included age ≥ 18 years, and at least one of the following criteria: coronal curve (CC) ≥ 20°, sagittal vertical axis (SVA) > 5 cm, pelvic tilt (PT) > 25°, or thoracic kyphosis (TK) > 60°. Surgical approach selection was made at the discretion of the operating surgeon. Preoperative significant differences were included in a multivariate logistic regression analysis to determine odds ratios (ORs) for approach selection.

Results: Significant preoperative differences (p < 0.05) between open and MIS groups were noted for age (61.9 vs 66.7 years), numerical rating scale (NRS) back pain score (7.8 vs 7), CC (36° vs 26.1°), PT (26.4° vs 23°), T1 pelvic angle (TPA; 25.8° vs 21.7°), and pelvic incidence-lumbar lordosis (PI-LL; 19.6° vs 14.9°). No significant differences in BMI (29 vs 28.5 kg/m2), NRS leg pain score (5.2 vs 5.7), Oswestry Disability Index (48.4 vs 47.2), Scoliosis Research Society 22-item questionnaire score (2.7 vs 2.8), PI (58.3° vs 57.1°), LL (38.9° vs 42.3°), or SVA (73.8 mm vs 60.3 mm) were found. Multivariate analysis found that age (OR 1.05, p = 0.002), VAS back pain score (OR 1.21, p = 0.016), CC (OR 1.03, p < 0.001), decompression (OR 4.35, p < 0.001), and TPA (OR 1.09, p = 0.023) were significant factors in approach selection.

Conclusions: Increasing age was the primary driver for selecting MIS surgery. Conversely, increasingly severe deformities and the need for open decompression were the main factors influencing the selection of traditional open surgery. As experience with MIS surgery continues to accumulate, future longitudinal evaluation will reveal if more experience, use of specialized treatment algorithms, refinement of techniques, and technology will expand surgeon adoption of MIS techniques for adult spinal deformity.
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http://dx.doi.org/10.3171/2020.4.SPINE20169DOI Listing
June 2020

Neuroanesthesia Guidelines for Optimizing Transcranial Motor Evoked Potential Neuromonitoring During Deformity and Complex Spinal Surgery: A Delphi Consensus Study.

Spine (Phila Pa 1976) 2020 Jul;45(13):911-920

Valley Anesthesiology Consultants, Phoenix, AZ.

Study Design: Expert opinion-modified Delphi study.

Objective: We used a modified Delphi approach to obtain consensus among leading spinal deformity surgeons and their neuroanesthesiology teams regarding optimal practices for obtaining reliable motor evoked potential (MEP) signals.

Summary Of Background Data: Intraoperative neurophysiological monitoring of transcranial MEPs provides the best method for assessing spinal cord integrity during complex spinal surgeries. MEPs are affected by pharmacological and physiological parameters. It is the responsibility of the spine surgeon and neuroanesthesia team to understand how they can best maintain high-quality MEP signals throughout surgery. Nevertheless, varying approaches to neuroanesthesia are seen in clinical practice.

Methods: We identified 19 international expert spinal deformity treatment teams. A modified Delphi process with two rounds of surveying was performed. Greater than 50% agreement on the final statements was considered "agreement"; >75% agreement was considered "consensus."

Results: Anesthesia regimens and protocols were obtained from the expert centers. There was a large amount of variability among centers. Two rounds of consensus surveying were performed, and all centers participated in both rounds of surveying. Consensus was obtained for 12 of 15 statements, and majority agreement was obtained for two of the remaining statements. Total intravenous anesthesia was identified as the preferred method of maintenance, with few centers allowing for low mean alveolar concentration of inhaled anesthetic. Most centers advocated for <150 μg/kg/min of propofol with titration to the lowest dose that maintains appropriate anesthesia depth based on awareness monitoring. Use of adjuvant intravenous anesthetics, including ketamine, low-dose dexmedetomidine, and lidocaine, may help to reduce propofol requirements without negatively effecting MEP signals.

Conclusion: Spine surgeons and neuroanesthesia teams should be familiar with methods for optimizing MEPs during deformity and complex spinal cases. Although variability in practices exists, there is consensus among international spinal deformity treatment centers regarding best practices.

Level Of Evidence: 5.
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http://dx.doi.org/10.1097/BRS.0000000000003433DOI Listing
July 2020

Relationship Between Preoperative Opioid Use and Postoperative Pain in Patients Undergoing Minimally Invasive Stand-Alone Lateral Lumbar Interbody Fusion.

Neurosurgery 2020 Jun 11. Epub 2020 Jun 11.

Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Background: Opioid use in the management of pain secondary to spinal disorders has grown significantly in the United States. However, preoperative opioid use may complicate recovery in patients undergoing surgical procedures.

Objective: To test our hypothesis that prolonged preoperative opioid use may lead to poorer patient outcomes following minimally invasive stand-alone lateral lumbar interbody fusion (LLIF) for lumbar degenerative disc disease.

Methods: A consecutive series of patients from a single institution undergoing LLIF between December 2009 and January 2017 was retrospectively analyzed. Patients were categorized according to the presence or absence of prescribed preoperative opioid use for at least 3 mo. Outcomes included the Oswestry Disability Index (ODI), visual analog scale (VAS), and Short Form 36 Physical and Mental Summary Scores (SF-36 PCS, SF-36 MCS).

Results: Of 107 patients, 57 (53.1%) were prescribed preoperative opioids. There was no significant difference in preoperative ODI, VAS score, SF-36 PCS, or SF-36 MCS between opioid use groups. Mean postoperative ODI was greater in patients with preoperative opioid use at 41.7 ± 16.9 vs 22.2 ± 16.0 (P = .002). Mean postoperative VAS score was greater in patients prescribed preoperative opioids, while magnitude of decrease in VAS score was greater in opioid-naïve patients (P = .001). Postoperative SF-36 PCS was 33.1 ± 10.6 in the opioid use group compared to 43.7 ± 13.1 in the nonuse group (P = .001).

Conclusion: Following LLIF, patients prescribed preoperative opioids had increased postoperative lumbar pain, disability, and subjective pain.
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http://dx.doi.org/10.1093/neuros/nyaa207DOI Listing
June 2020

Impact of endplate-implant area mismatch on rates and grades of subsidence following stand-alone lateral lumbar interbody fusion: an analysis of 623 levels.

J Neurosurg Spine 2020 Mar 6:1-5. Epub 2020 Mar 6.

Objective: Stand-alone lateral lumbar interbody fusion (LLIF) is a useful minimally invasive approach for select spinal disorders, but implant subsidence may occur in up to 30% of patients. Previous studies have suggested that wider implants reduce the subsidence rate. This study aimed to evaluate whether a mismatch of the endplate and implant area can predict the rate and grade of implant subsidence.

Methods: The authors conducted a retrospective review of prospectively collected data on consecutive patients who underwent stand-alone LLIF between July 2008 and June 2015; 297 patients (623 surgical levels) met inclusion criteria. Imaging studies were examined to grade graft subsidence according to Marchi criteria. Thirty patients had radiographic evidence of implant subsidence. The endplates above and below the implant were measured.

Results: A total of 30 patients with implant subsidence were identified. Of these patients, 6 had Marchi grade 0, 4 had grade I, 12 had grade II, and 8 had grade III implant subsidence. There was no statistically significant correlation between the endplate-implant area mismatch and subsidence grade or incidence. There was also no correlation between endplate-implant width and length mismatch and subsidence grade or incidence. However, there was a strong correlation between the usage of the 18-mm-wide implants and the development of higher-grade subsidence (p = 0.002) necessitating surgery. There was no significant association between the degree of mismatch or Marchi subsidence grade and the presence of postoperative radiculopathy. Of the 8 patients with 18-mm implants demonstrating radiographic subsidence, 5 (62.5%) required reoperation. Of the 22 patients with 22-mm implants demonstrating radiographic subsidence, 13 (59.1%) required reoperation.

Conclusions: There was no correlation between endplate-implant area, width, or length mismatch and Marchi subsidence grade for stand-alone LLIF. There was also no correlation between either endplate-implant mismatch or Marchi subsidence grade and postoperative radiculopathy. The data do suggest that the use of 18-mm-wide implants in stand-alone LLIF may increase the risk of developing high-grade subsidence necessitating reoperation compared to the use of 22-mm-wide implants.
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http://dx.doi.org/10.3171/2020.1.SPINE19776DOI Listing
March 2020

Should the Presence of Spondylodiscitis Alter the Surgical Treatment of Patients with Symptomatic Ventral Cervical Epidural Abscesses? An Institutional Analysiss.

World Neurosurg 2020 06 26;138:e282-e288. Epub 2020 Feb 26.

The Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.

Background: Spinal epidural abscess is a rare pathology with an incidence that has tripled in the past 2 decades. Ventral cervical epidural abscesses (vCEA) of the cervical spine pose particular treatment challenges because of the anatomical location. The aim of this report is to identify trends in the surgical management of these patients and to determine whether concomitant spondylodiscitis warrants fusion at the index surgery.

Methods: Patients presenting to a quaternary care institution from January 2009 to December 2018 with isolated vCEA were identified. Patients were excluded if they had dorsal or circumferential epidural abscesses. Clinical and radiographic data were collected. Patients with vCEA were stratified by the presence or absence of spondylodiscitis upon presentation. Clinical outcomes analyzed included neurological sequelae and the need for revision surgery.

Results: During the 10-year study period, 36 patients presented with symptomatic isolated vCEA and constituted the study cohort; 16 (44%) had concurrent spondylodiscitis. All 36 patients underwent surgical decompression; the initial surgical approach was anterior-only for 7 patients (19%), posterior-only for 27 patients (75%), and and a combined approach for 2 patients (6%). Four patients from the total cohort (11%) ultimately required a revision operation; all 4 were from the subset with concurrent spondylodiscitis (25% vs. 0%, P = 0.03).

Conclusions: vCEA can be evacuated safely and effectively by a variety of strategies in patients with neurologic deficits. Concomitant spondylodiscitis with cervical epidural abscess may warrant instrumented fusion as part of the initial surgical strategy.
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http://dx.doi.org/10.1016/j.wneu.2020.02.103DOI Listing
June 2020

The MISDEF2 algorithm: an updated algorithm for patient selection in minimally invasive deformity surgery.

J Neurosurg Spine 2019 Oct;32(2):221-228

11Department of Neurosurgery, Cornell Medical Center, New York, New York.

Objective: Minimally invasive surgery (MIS) can be used as an alternative or adjunct to traditional open techniques for the treatment of patients with adult spinal deformity. Recent advances in MIS techniques, including advanced anterior approaches, have increased the range of candidates for MIS deformity surgery. The minimally invasive spinal deformity surgery (MISDEF2) algorithm was created to provide an updated framework for decision-making when considering MIS techniques in correction of adult spinal deformity.

Methods: A modified algorithm was developed that incorporates a patient's preoperative radiographic parameters and leads to one of 4 general plans ranging from basic to advanced MIS techniques to open deformity surgery with osteotomies. The authors surveyed 14 fellowship-trained spine surgeons experienced with spinal deformity surgery to validate the algorithm using a set of 24 cases to establish interobserver reliability. They then re-surveyed the same surgeons 2 months later with the same cases presented in a different sequence to establish intraobserver reliability. Responses were collected and analyzed. Correlation values were determined using SPSS software.

Results: Over a 3-month period, 14 fellowship-trained deformity surgeons completed the surveys. Responses for MISDEF2 algorithm case review demonstrated an interobserver kappa of 0.85 for the first round of surveys and an interobserver kappa of 0.82 for the second round of surveys, consistent with substantial agreement. In at least 7 cases, there was perfect agreement between the reviewing surgeons. The mean intraobserver kappa for the 2 surveys was 0.8.

Conclusions: The MISDEF2 algorithm was found to have substantial inter- and intraobserver agreement. The MISDEF2 algorithm incorporates recent advances in MIS surgery. The use of the MISDEF2 algorithm provides reliable guidance for surgeons who are considering either an MIS or an open approach for the treatment of patients with adult spinal deformity.
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http://dx.doi.org/10.3171/2019.7.SPINE181104DOI Listing
October 2019

Less invasive spinal deformity surgery: the impact of the learning curve at tertiary spine care centers.

J Neurosurg Spine 2019 Aug 23:1-8. Epub 2019 Aug 23.

13Department of Neurological Surgery, University of California, San Francisco, California.

Objective: The past decade has seen major advances in techniques for treating more complex spinal disorders using minimally invasive surgery (MIS). While appealing from the standpoint of patient perioperative outcomes, a major impediment to adoption has been the significant learning curve in utilizing MIS techniques.

Methods: Data were retrospectively analyzed from a multicenter series of adult spinal deformity surgeries treated at eight tertiary spine care centers in the period from 2008 to 2015. All patients had undergone a less invasive or hybrid approach for a deformity correction satisfying the following inclusion criteria at baseline: coronal Cobb angle ≥ 20°, sagittal vertical axis (SVA) > 5 cm, or pelvic tilt > 20°. Analyzed data included baseline demographic details, severity of deformity, surgical metrics, clinical outcomes (numeric rating scale [NRS] score and Oswestry Disability Index [ODI]), radiographic outcomes, and complications. A minimum follow-up of 2 years was required for study inclusion.

Results: Across the 8-year study period, among 222 patients, there was a trend toward treating increasingly morbid patients, with the mean age increasing from 50.7 to 62.4 years (p = 0.013) and the BMI increasing from 25.5 to 31.4 kg/m2 (p = 0.12). There was no statistical difference in the severity of coronal and sagittal deformity treated over the study period. With regard to radiographic changes following surgery, there was an increasing emphasis on sagittal correction and, conversely, less coronal correction. There was no statistically significant difference in clinical outcomes over the 8-year period, and meaningful improvements were seen in all years (ODI range of improvement: 15.0-26.9). Neither were there statistically significant differences in major complications; however, minor complications were seen less often as the surgeons gained experience (p = 0.064). Operative time was decreased on average by 47% over the 8-year period.Trends in surgical practice were seen as well. Total fusion construct length was unchanged until the last year when there was a marked decrease in conjunction with a decrease in interbody levels treated (p = 0.004) while obtaining a higher degree of sagittal correction, suggesting more selective but powerful interbody reduction methods as reflected by an increase in the lateral and anterior column resection techniques being utilized.

Conclusions: The use of minimally invasive methods for adult spinal deformity surgery has evolved over the past decade. Experienced surgeons are treating older and more morbid patients with similar outcomes. A reliance on selective, more powerful interbody approaches is increasing as well.
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http://dx.doi.org/10.3171/2019.6.SPINE19531DOI Listing
August 2019

Relationship between body mass index and sagittal vertical axis change as well as health-related quality of life in 564 patients after deformity surgery.

J Neurosurg Spine 2019 Aug 9:1-6. Epub 2019 Aug 9.

1Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Objective: Obesity, a condition that is increasing in prevalence in the United States, has previously been associated with poorer outcomes following deformity surgery, including higher rates of perioperative complications such as deep and superficial infections. To date, however, no study has examined the relationship between preoperative BMI and outcomes of deformity surgery as measured by spine parameters such as the sagittal vertical axis (SVA), as well as health-related quality of life (HRQoL) measures such as the Oswestry Disability Index (ODI) and Scoliosis Research Society-22 patient questionnaire (SRS-22). To this end, the authors sought to clarify the relationship between BMI and postoperative change in SVA as well as HRQoL outcomes.

Methods: The authors performed a retrospective review of a prospectively managed multicenter adult spinal deformity database collected and maintained by the International Spine Study Group (ISSG) between 2009 and 2014. The primary independent variable considered was preoperative BMI. The primary outcome was the change in SVA at 1 year after deformity surgery. Postoperative ODI and SRS-22 outcome measures were evaluated as secondary outcomes. Generalized linear models were used to model the primary and secondary outcomes at 1 year as a function of BMI at baseline, while adjusting for potential measured confounders.

Results: Increasing BMI (compared to BMI < 18) was not associated with change of SVA at 1 year postsurgery. However, BMIs in the obese range of 30 to 34.9 kg/m2, compared to BMI < 18 at baseline, were associated with poorer outcomes as measured by the SRS-22 score (estimated change -0.47, 95% CI -0.93 to -0.01, p = 0.04). While BMIs > 30 appeared to be associated with poorer outcomes as determined by the ODI, this correlation did not reach statistical significance.

Conclusions: Baseline BMI did not affect the achievable SVA at 1 year postsurgery. Further studies should evaluate whether even in the absence of a change in SVA, baseline BMIs in the obese range are associated with worsened HRQoL outcomes after spinal surgery.
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http://dx.doi.org/10.3171/2019.4.SPINE18485DOI Listing
August 2019

Retrospective Multicenter Assessment of Rod Fracture After Anterior Column Realignment in Minimally Invasive Adult Spinal Deformity Correction.

World Neurosurg 2019 Oct 21;130:e400-e405. Epub 2019 Jun 21.

Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA. Electronic address:

Background: Anterior column realignment (ACR) was developed as a minimally invasive method for treating sagittal imbalance. However, rod fracture (RF) rates associated with ACR are not known. Our objective was to assess the rate of and risk factors for RF following ACR in deformity correction surgery.

Methods: We conducted a retrospective multicenter review of patients with adult spinal deformity (ASD) who underwent ACR for deformity correction. ASD was defined as coronal Cobb angle ≥20°, pelvic incidence-lumbar lordosis >10°, sagittal vertical axis ≥5 cm, pelvic tilt ≥25°, or thoracic kyphosis ≥60°. Inclusion criteria were ASD, age >18 years, use of ACR, and development of RF or full radiographs obtained at least 1 year after surgery that did not demonstrate RF.

Results: Ninety patients were identified, with mean follow-up of 2.3 ± 1.4 years (age, 64.1 ± 9.4; 54 [60%] women). The most common ACR location was L3/4 (42 cases; 47%). Mean fusion length was 7.5 ± 3.6 levels. Four (4.4%) of 90 patients developed RF within 12 months of surgery. RF occurred adjacent to ACR in all cases; RF was not associated with focal correction (P = 0.49), rod material (P = 0.8), degree of correction (P > 0.07), or interbody at L5/S1 (P = 0.06). RF was associated with longer fusion constructs in univariate (P = 0.002) and multivariate (P = 0.03) analyses.

Conclusions: RF occurred in 4.4% of patients with ASD who underwent ACR with a minimum of 1-year follow-up. RF was not associated with focal correction but appears to be associated with global correction and extent of fixation.
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http://dx.doi.org/10.1016/j.wneu.2019.06.096DOI Listing
October 2019

Lateral Approaches for the Surgical Treatment of Lumbar Spondylolisthesis.

Neurosurg Clin N Am 2019 Jul;30(3):313-322

Department of Neurosurgery, University of Pittsburgh Medical Center, 200 Lothrop Street, Suite B400, Pittsburgh, PA 15213, USA.

Spondylolisthesis is a common cause of lower back pain in people of all ages. When nonsurgical management is unsuccessful in treatment for lumbar spondylolisthesis, surgical treatment algorithms can be used. This article focuses on lateral lumbar interbody fusion (LLIF). It represents a minimally invasive approach that affords surgeons an increased ability to restore disc height, indirectly decompress the neural elements, and affect global spinal alignment. As the role for circumferential minimally invasive spine surgery continues to expand, the use of LLIF in the setting of spondylolisthesis-and other pathologies-will continue to represent a robust fusion option.
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http://dx.doi.org/10.1016/j.nec.2019.02.005DOI Listing
July 2019

Perioperative Neurological Complications Following Anterior Cervical Discectomy and Fusion: Clinical Impact on 317,789 Patients from the National Inpatient Sample.

World Neurosurg 2019 Aug 10;128:e107-e115. Epub 2019 Apr 10.

Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA. Electronic address:

Background: Perioperative neurologic complication after an anterior cervical discectomy and fusion (ACDF) is uncommon but may have significant clinical consequences.

Objective: We aim to estimate the incidence of perioperative neurologic complications, identify their risk factors, and evaluate their impact on morbidity and mortality after ACDF.

Methods: ACDF cases (n = 317,789 patients) were extracted from the National Inpatient Sample between 1999 and 2011. Based on their Elixhauser-van Walraven score (VWR), patients were classified as low (VWR < 5), moderate (5-14), or high risk (>14) for surgery. The primary outcome was perioperative neurologic complications. Secondary outcomes included morbidity (hospital length of stay >14 days or discharge disposition to a location other than home) and in-hospital mortality.

Results: The rate of perioperative neurologic complications, morbidity, and mortality after ACDF was 0.4%, 8.4%, and 0.1%, respectively. Perioperative neurologic complications were highly associated with in-house morbidity (odds ratio [OR], 3.7 [3.1-4.4]) and mortality (OR, 8.0 [4.1-15.5]). The strongest predictors for perioperative neurologic complications were moderate- (OR, 3.1 [2.6-3.7]) and high-risk VWR (OR, 5.4 [3.3-8.9]), postoperative hematoma/seroma formation (OR, 5.4 [3.9-7.4]), and obesity (OR, 1.9 [1.6-2.3]). The rate of perioperative neurologic complications increased from 0.2% to 0.7% from 1999 to 2011, which was temporally associated with the rise in moderate- (P = 0.002) and high-risk patients (P = 0.001) undergoing ACDF.

Conclusions: Perioperative neurologic complications are independent predictors of in-hospital morbidity and mortality after ACDF. Both morbidity and perioperative neurologic complications have increased between 1999 and 2011, which may be due, in part, to increasing numbers of moderate- and high-risk patients undergoing ACDF.
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http://dx.doi.org/10.1016/j.wneu.2019.04.037DOI Listing
August 2019

A New Piece of the Puzzle to Understand Cervical Sagittal Alignment: Utilizing a Novel Angle δ to Describe the Relationship among T1 Vertebral Body Slope, Cervical Lordosis, and Cervical Sagittal Alignment.

Neurosurgery 2020 03;86(3):446-451

Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Cervical alignment has become increasingly important in the planning of spine surgery. A relationship between the slope of T1 (T1S), the cervical lordosis (CL), and the overall cervical sagittal vertical axis (cSVA) has previously been demonstrated, but the exact nature of this relationship is poorly understood. In this study, we derive theoretical and empirical equations to better understand how T1S and CL affect cSVA. The first equation was developed on a theoretical basis using inherent trigonometric relationships of the cervical spine. By treating the cervical spine as the arc of a circumference, and by taking into account the cervical height (CH), the geometric relationship between theT1S, CL, and cSVA was described via a trigonometric identity utilizing a novel angle δ subtended by the CH and cSVA (δ = T1S-CL/2). The second equation was developed on an empiric basis by performing a multiple linear regression on data obtained from a retrospective review of a large multicenter deformity database. The theoretical equation determined that the value of cSVA could be expressed as: $cSVA\ = \ CH*{\rm{tan}}( {\pi /180*( {T1S - CL/2} )} )$. The empirical equation determined that value of cSVA could be expressed as: $cSVA=({1.1*T1} )\ - ( {0.43*CL} ) + 6.69$. In both, the sagittal alignment of the head over the shoulders is directly proportional to the T1S and inversely proportional to CL/2. These 2 equations may allow surgeons to better understand how the CL compensates for the T1S, to accurately predict the postoperative cSVA, and to customize cervical interbody grafts by taking into consideration each individual patient's specific cervical spine parameters.
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http://dx.doi.org/10.1093/neuros/nyz088DOI Listing
March 2020

Is achieving optimal spinopelvic parameters necessary to obtain substantial clinical benefit? An analysis of patients who underwent circumferential minimally invasive surgery or hybrid surgery with open posterior instrumentation.

J Neurosurg Spine 2019 Feb 22:1-6. Epub 2019 Feb 22.

12Department of Neurosurgery, University of California, San Francisco, California.

OBJECTIVEIt is now well accepted that spinopelvic parameters are correlated with clinical outcomes in adult spinal deformity (ASD). The purpose of this study was to determine whether obtaining optimal spinopelvic alignment was absolutely necessary to achieve a minimum clinically important difference (MCID) or substantial clinical benefit (SCB).METHODSA multicenter retrospective review of patients who underwent less-invasive surgery for ASD was conducted. Inclusion criteria were age ≥ 18 years and one of the following: coronal Cobb angle > 20°, sagittal vertical axis (SVA) > 5 cm, pelvic tilt (PT) > 20°, or pelvic incidence to lumbar lordosis (PI-LL) mismatch > 10°. A total of 223 patients who were treated with circumferential minimally invasive surgery or hybrid surgery and had a minimum 2-year follow-up were identified. Based on optimal spinopelvic parameters (PI-LL mismatch ± 10° and SVA < 5 cm), patients were divided into aligned (AL) or malaligned (MAL) groups. The primary clinical outcome studied was the Oswestry Disability Index (ODI) score.RESULTSThere were 74 patients in the AL group and 149 patients in the MAL group. Age and body mass index were similar between groups. Although the baseline SVA was similar, PI-LL mismatch (9.9° vs 17.7°, p = 0.002) and PT (19° vs 24.7°, p = 0.001) significantly differed between AL and MAL groups, respectively. As expected postoperatively, the AL and MAL groups differed significantly in PI-LL mismatch (-0.9° vs 13.1°, p < 0.001), PT (14° vs 25.5°, p = 0.001), and SVA (11.8 mm vs 48.3 mm, p < 0.001), respectively. Notably, there was no difference in the proportion of AL or MAL patients in whom an MCID (52.75% vs 61.1%, p > 0.05) or SCB (40.5% vs 46.3%, p > 0.05) was achieved for ODI score, respectively. Similarly, no differences in percentage of patients obtaining an MCID or SCB for visual analog scale back and leg pain score were observed. On multivariate analysis controlling for surgical and preoperative demographic differences, achieving optimal spinopelvic parameters was not associated with achieving an MCID (OR 0.645, 95% CI 0.31-1.33) or an SCB (OR 0.644, 95% CI 0.31-1.35) for ODI score.CONCLUSIONSAchieving optimal spinopelvic parameters was not a predictor for achieving an MCID or SCB. Since spinopelvic parameters are correlated with clinical outcomes, the authors' findings suggest that the presently accepted optimal spinopelvic parameters may require modification. Other factors, such as improvement in neurological symptoms and/or segmental instability, also likely impacted the clinical outcomes.
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http://dx.doi.org/10.3171/2018.11.SPINE181261DOI Listing
February 2019

Early and Late Reoperation Rates With Various MIS Techniques for Adult Spinal Deformity Correction.

Global Spine J 2019 Feb 10;9(1):41-47. Epub 2018 May 10.

University of California, San Francisco, CA, USA.

Study Design: A multicenter retrospective review of an adult spinal deformity database.

Objective: We aimed to characterize reoperation rates and etiologies of adult spinal deformity surgery with circumferential minimally invasive surgery (cMIS) and hybrid (HYB) techniques.

Methods: Inclusion criteria were age ≥18 years, and one of the following: coronal Cobb >20°, sagittal vertical axis >5 cm, pelvic tilt >20°, and pelvic incidence-lumbar lordosis >10°. Patients with either cMIS or HYB surgery, ≥3 spinal levels treated with 2-year minimum follow-up were included.

Results: A total of 133 patients met inclusion for this study (65 HYB and 68 cMIS). Junctional failure (13.8%) was the most common reason for reoperation in the HYB group, while fixation failure was the most common reason in the cMIS group (14.7%). There was a higher incidence of proximal junctional failure (PJF) than distal junctional failure (DJF) within HYB (12.3% vs 3.1%), but no significant differences in PJF or DJF rates when compared to cMIS. Early (<30 days) reoperations were less common (cMIS = 1.5%; HYB = 6.1%) than late (>30 days) reoperations (cMIS = 26.5%; HYB = 27.7%), but early reoperations were more common in the HYB group after propensity matching, largely due to infection rates (10.8% vs 0%, = .04).

Conclusions: Adult spinal deformity correction with cMIS and HYB techniques result in overall reoperation rates of 27.9% and 33.8%, respectively, at minimum 2-year follow-up. Junctional failures are more common after HYB approaches, while pseudarthrosis/fixation failures happen more often with cMIS techniques. Early reoperations were less common than later returns to the operating room in both groups, but cMIS demonstrated less risk of infection and early reoperation when compared with the HYB group.
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http://dx.doi.org/10.1177/2192568218761032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362559PMC
February 2019

Limitations of patient experience reports to evaluate physician quality in spine surgery: analysis of 7485 surveys.

J Neurosurg Spine 2019 Jan 11:1-4. Epub 2019 Jan 11.

1Department of Neurological Surgery and.

OBJECTIVEThe Clinician and Group Consumer Assessment of Healthcare Providers and Systems (CG-CAHPS) is a standardized patient experience survey that is used to evaluate the quality of care delivered by physicians. The authors sought to determine which factors influenced CG-CAHPS scores for spine surgery, and compare them to their cranial-focused cohorts.METHODSA retrospective study of prospectively obtained data was performed to evaluate CG-CAHPS scores. Between May 2013 and May 2017, all patients 18 years of age or older with an outpatient encounter with a neurosurgeon (5 spine-focused neurosurgeons and 20 cranial-focused neurosurgeons) received a CG-CAHPS survey. Three domains were assessed: overall physician rating, likelihood to recommend, and physician communication. Statistical analyses were performed using chi-square tests.RESULTSSeven thousand four hundred eighty-five patient surveys (2319 spine and 5166 cranial) were collected from patients presenting to the outpatient offices of an attending neurosurgeon. Analysis of the overall physician rating showed that 81.1% of spine neurosurgeons received a "top-box" score (answers of "yes, definitely"), whereas 86.2% of cranial neurosurgeons received a top-box response (p < 0.001). A similar difference was observed with the domains of "likelihood to recommend" and "physician communication." Overall physician rating was also significantly influenced by the general and mental health of the patients surveyed (p < 0.001). For spine surgeons seeing patients at more than one facility, the scores with respect to location were also significantly different in all domains for each individual provider (p < 0.001).CONCLUSIONSOverall, spine-focused neurosurgeon ratings differed significantly from those of cranial-focused neurosurgical subspecialty providers. Office location also affected provider ratings for spine neurosurgeons. These results suggest that physician ratings obtained via patient experience surveys may be representative of factors aside from just the quality of physician care provided. This information should be considered as payers, government, and health systems design performance programs based on patient experience scores.
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http://dx.doi.org/10.3171/2018.8.SPINE18104DOI Listing
January 2019

Risk factors and clinical impact of perioperative neurological deficits following thoracolumbar arthrodesis.

Interdiscip Neurosurg 2018 Dec 13;14:18-23. Epub 2018 Apr 13.

Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.

Objectives: The rates of arthrodesis performed in the United States and globally have increased tremendously in the last 10-15 years. Amongst the most devastating complications are neurological deficits including spinal cord injury, nerve root irritation, and cauda equine syndrome. The primary purpose of this study is to understand the risk factors for perioperative neurological deficits in patients undergoing thoracolumbar fusion.

Patients And Methods: Data from the Nationwide Inpatient Sample between the years of 1999-2011 was analyzed. Patients were between the ages of 18 and 80 who had thoracolumbar fusion. Excluded were patients who underwent the procedure as a result of trauma or a malignancy. A list of covariates, including demographic variables, preoperative and postoperative variables that are known to increase the risk of perioperative neurological deficits were compiled. Statistical analysis utilized univariate and multivariate logistic regression for comparisons between these covariates and the proposed outcomes.

Results: The analysis of 37,899 patients yielded an overall rate of perioperative neurological deficits and mortality of 1.20% and 0.27%, respectively. Risk factors for perioperative neurological deficits included increasing age (OR 1.023 95% CI 1.018-1.029), Van Walraven 5-14 (OR 1.535 95% CI 1.054-2.235), and preoperative paralysis (OR 2.551 95% CI 1.674-3.886). Furthermore, the data showed that being 65 years old or older doubled the risk for perioperative deficit (OR 1.655, CI 1.248-2.194, p < 0.001).

Conclusions: This population based study found that increasing age, higher comorbid burden, and preoperative paralysis increased the risk of perioperative neurological deficits while female gender and hypertension were found to be protective.
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http://dx.doi.org/10.1016/j.inat.2018.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7377338PMC
December 2018

Cost-Effectiveness of a Radio Frequency Hemostatic Sealer (RFHS) in Adult Spinal Deformity Surgery.

World Neurosurg 2019 Feb 1;122:171-175. Epub 2018 Nov 1.

Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.

Background: Patients undergoing posterior spinal fusion surgery can lose a substantial amount of blood. This can prolong operative time and require transfusion of allogeneic blood components, which increases the risk of infection and can be the harbinger of serious complications. Does a saline-irrigated bipolar radiofrequency hemostatic sealer (RFHS) help reduce transfusion requirements?

Methods: In an observational cohort study, we compared transfusion requirements in 30 patients undergoing surgery for adult spinal deformity using the RFHS with that of a historical control group of 30 patients in which traditional hemostasis was obtained with bipolar electrocautery and matched them for blood loss-related variables. Total expense to the hospital for the RFHS, laboratory expenses, and blood transfusions was used for cost calculations. The incremental cost-effectiveness ratio was calculated using the number of blood transfusions avoided as the effectiveness payoff.

Results: Using a multivariable linear regression model, we found that only estimated blood loss (EBL) was an independent significant predictor of transfusion requirement in both groups. We evaluated the variables of age, EBL, time duration of surgery, preoperative hemoglobin, hemoglobin nadir during surgery, body mass index, length of stay, and number of levels operated on. Mean EBL was greater in the control group (2201 vs. 1416 mL, P = 0.0099). The number of transfusions also was greater in the control group (14.5 vs. 6.5, P = 0.0008). In the cost-effectiveness analysis, we found that the RFHS cost $108 more (compared with not using the RFHS) to avoid 1 unit of blood transfusion.

Conclusions: The cost-effectiveness analysis revealed that if we are willing to pay $108 to avoid 1 unit of blood transfusion, the use of the RFHS is a reasonable choice to use in open surgery for adult spinal deformity.
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http://dx.doi.org/10.1016/j.wneu.2018.10.131DOI Listing
February 2019

The comprehensive anatomical spinal osteotomy and anterior column realignment classification.

J Neurosurg Spine 2018 Nov;29(5):565-575

9Neurological Surgery, University of California, San Francisco, California; and.

OBJECTIVESpinal osteotomies and anterior column realignment (ACR) are procedures that allow preservation or restoration of spine lordosis. Variations of these techniques enable different degrees of segmental, regional, and global sagittal realignment. The authors propose a comprehensive anatomical classification system for ACR and its variants based on the level of technical complexity and invasiveness. This serves as a common language and platform to standardize clinical and radiographic outcomes for the utilization of ACR.METHODSThe proposed classification is based on 6 anatomical grades of ACR, including anterior longitudinal ligament (ALL) release, with varying degrees of posterior column release or osteotomies. Additionally, a surgical approach (anterior, lateral, or posterior) was added. Reliability of the classification was evaluated by an analysis of 16 clinical cases, rated twice by 14 different spine surgeons, and calculation of Fleiss kappa coefficients.RESULTSThe 6 grades of ACR are as follows: grade A, ALL release with hyperlordotic cage, intact posterior elements; grade 1 (ACR + Schwab grade 1), additional resection of the inferior facet and joint capsule; grade 2 (ACR + Schwab grade 2), additional resection of both superior and inferior facets, interspinous ligament, ligamentum flavum, lamina, and spinous process; grade 3 (ACR + Schwab grade 3), additional adjacent-level 3-column osteotomy including pedicle subtraction osteotomy; grade 4 (ACR + Schwab grade 4), 2-level distal 3-column osteotomy including pedicle subtraction osteotomy and disc space resection; and grade 5 (ACR + Schwab grade 5), complete or partial removal of a vertebral body and both adjacent discs with or without posterior element resection. Intraobserver and interobserver reliability were 97% and 98%, respectively, across the 14-reviewer cohort.CONCLUSIONSThe proposed anatomical realignment classification provides a consistent description of the various posterior and anterior column release/osteotomies. This reliability study confirmed that the classification is consistent and reproducible across a diverse group of spine surgeons.
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http://dx.doi.org/10.3171/2018.4.SPINE171206DOI Listing
November 2018
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