Category: Spine

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Efficacy and Safety of C3 Laminectomy Combined with Open-Door Laminoplasty versus Open-Door Laminoplasty Alone: A Systematic Review and Meta-Analysis

World Neurosurg. (2024) 192:98-108

BACKGROUND: To evaluate efficacy and safety between C3 laminectomy + open-door laminoplasty and open-door laminoplasty alone.

METHODS: Electronic databases were systematically searched up to January 2024. Review Manager 5.4 was applied to manage the data and perform the review. Cochrane Library, PubMed, OVID, and Web of Science were searched for studies comparing C3 laminectomy + open-door laminoplasty and open-door laminoplasty alone. Forest plots were constructed for each analysis group.

RESULTS: After selection, 9 eligible articles included 10 comparison groups, with a combined 320 patients who underwent C3 laminectomy + open-door laminoplasty and 355 who underwent open-door laminoplasty alone. There was no difference in operative time, blood volume, Japanese Orthopaedic Association score, Japanese Orthopaedic Association recovery score, visual analog scale score, Neck Disability Index, complications, axial symptoms, T1 slope, range of motion, and cervical sagittal vertical axis. C3 laminectomy D open-door laminoplasty was superior in C2-C7 Cobb angle.

CONCLUSIONS: Although C3 laminectomy + open-door laminoplasty has theoretic advantages, meta-analysis results show that the 2 surgical procedures are similar in terms of clinical symptoms improvement, sagittal balance, and complications. C3 laminectomy combined + open-door laminoplasty is superior only in the preservation of cervical lordosis. The limited number of studies may affect the reliability and generalizability of the results. Future high-quality, multicenter randomized controlled trials are needed to verify efficacy and safety.

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Relationship between the pelvic incidence and the modified Oxford Hip score: a computed tomographic analysis

Acta Neurochirurgica (2024) 166:503

There is scant data on the relationship between skeletal maturity and pelvic parameters such as the pelvic incidence (PI). The aim of this study was to report on the relationship between PI and the modified Oxford Hip Score (mOHS) as a measure of skeletal maturity. We hypothesised a significant correlation would be determined between the mOHS and PI.

Methods CT performed for major trauma or abdominal pathology was assessed. The PI and segmental vertebral body angles, L1-L5, were obtained. The mOHS was used to assess maturity with total scores ranging from 16 to 25 (least-most mature). 193 scans were analysed. The mean age 9.7 years (range 4.0 – 15.7); 62 female (32%).

Results There were significant positive correlations between age and all components of the mOHS: FH (r = 0.765; p < 0.001), GT (r = 0.749; p < 0.001), LT (r = 0.704; p < 0.001), TC (r = 0.775; p < 0.001), IL (r = 0.642; p < 0.001) and mOHS (r = 0.811; p < 0.001). Mean PI for the cohort was 40.8 (s.d. 9.1; range 19.3–69.4). There were significant albeit weak correlations with FH (r = 0.213; p = 0.003), GT (r = 0.209; p = 0.004), LT (r = 0.247; p < 0.001), TC (r = 0.263; p = < 0.001), IL (r = 0.221; p = 0.002) and total mOHS (r = 0.255; p < 0.001). Multivariable linear regression indicated TC and LT the best predictors of PI. Significant correlations noted between L1 segmental lordosis and all components of the mOHS, strongest with triradiate (r=-0.406; p < 0.001).

Conclusions In this CT-based study, the mOHS correlated weakly with PI and proximal vertebral body lordosis. Of the mOHS components, triradiate and lesser trochanter cartilage status appeared to be best correlated with PI and may be anatomic variables to focus on in future research.

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Pedicle Subtraction Osteotomies for Surgical Correction of Fixed Sagittal Imbalance: A Meta-Analysis and Systematic Review

Neurosurgery 95:1223–1231, 2024

Disruption of the spine’s sagittal balance is associated with significant negative impacts on quality of life. Compared with other spinal osteotomies, pedicle subtraction osteotomy (PSO), which can potentially offer greater correction, is considered technically challenging and performed at lower rates. The aim of this study was to review the use of PSO to correct fixed sagittal imbalance and assess its efficacy and associated perioperative complications.

METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the PubMed, EBSCO host, MEDLINE, and Google Scholar databases were queried for full-text English manuscripts published from 1961 to 2022, exploring PSO for the management of fixed sagittal imbalance. Studies were included if they reported preoperative and postoperative radiographic measurements. The mean Methodological Index for Nonrandomized Studies (MINORS) for included articles was 9.6 ± 1.1. The outcomes of interest included etiology, operative time, blood loss, complications, radiographic outcomes, and patient-reported outcomes. Statistical analysis was performed using a random-effects, inverse variance-weighted meta-analysis of observational data. Pre and postoperative radiographic and clinical outcomes were compared using a Student t-test.

RESULTS: Fourteen studies with 595 patients were included. Meta-analysis showed that the mean operative time was 7.2 ± 2.0 hours, and the average blood loss was 2033 ± 629 mL. After PSO, there was a significant improvement in sagittal vertebral axis (12.41-3.92 cm, P = .0003), LL (13.35°-42.60°, P = .000002), PSO angle (5.11°to À26.91°, P = .0001), and Oswestry Disability Index (55.36-27.35, P = .02). Common complications include pseudarthrosis (8.1%), neurological deficits (7.8%), and proximal junctional failure (6.0%).

CONCLUSION: PSO offers significant correction of sagittal vertebral axis, lumbar lordosis, PSO angle, and Oswestry Disability Index scores despite its reduced utilization in recent years. Blood loss and high complication rates must be considered when evaluating the efficacy of this procedure; however, surgeon experience and operative techniques can be used to reduce morbidity.

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How Do the True Intraoperative Costs of Endoscopic Diskectomy Compare With Microdiskectomy for Lumbar Disk Herniations?

Operative Neurosurgery 27:690–697, 2024

Endoscopic lumbar diskectomy (ED) is a minimally invasive option for addressing lumbar disk herniations. With the introduction of value-based care systems, assessing the true cost of certain procedures is critical when creating reimbursement models and comparing procedures. Here, we compared the costs of performing a microdiskectomy (MD) and ED using time-driven activity-based costing.

METHODS: Total cost for the intraoperative episode was calculated using time-driven activity-based costing methodology. Individual costs were obtained by direct observation and electronic medical records and through querying multiple departments (business operations, sterile processing, plant operations, and pharmacy). Timestamps for all involved personnel and material resources were documented. A retrospective analysis was performed on 202 patients who underwent lumbar diskectomy through either MD (n = 167) or ED (n = 35) from 2018 to 2022. Personnel cost was calculated by multiplying the cost per unit time for each personnel type by the length of time spent in the operating room. Supply cost was calculated by aggregating the cost of all individual supplies, from medications to consumables to surgical trays, used during the case. Univariate and multivariable regression analyses were performed comparing the costs between these procedures.

RESULTS: The average intraoperative cost per case for ED and MD was $3915 ± $1025 and $3162 ± $954, respectively. Multivariable regression analysis revealed that ED had higher total cost ( β -coefficient: $912 ± $281, P = <.01) and supply cost ( β -coefficient: $474 ± $155, P = <.01) than MD. When accounting for surgeon as a covariate, however, total cost (P = .478) and supply cost (P = .468) differences between ED and MD were negligible.

CONCLUSION: ED has shown to be a better value option in addressing lumbar disk herniations, mostly because of advantages in perioperative care. Here, we show that when correcting for surgeon-level effects, the cost between the two procedures is statistically insignificant, reaffirming the value provided by ED.

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The Role of Pelvic Compensation in Sagittal Balance and Imbalance: The Impact of Pelvic Compensation on Spinal Alignment and Clinical Outcomes Following Adult Spinal Deformity Surgery

Neurosurgery 95:1307–1316, 2024

The Scoliosis Research Society (SRS)-Schwab system does not include a pelvic compensation (PC) subtype, potentially contributing to gaps in clinical characteristics and treatment strategy for deformity correction. It also remains uncertain as to whether PC has differing roles in sagittal balance (SB) or imbalance (SI) status. To compare radiological parameters and SRS-22r domains between patients with failed pelvic compensation (FPC) and successful pelvic compensation (SPC) based on preoperative SB and SI.

METHODS: A total of 145 adult spinal deformity patients who received deformity correction were analyzed. Radiographic and clinical outcomes were collected for statistical analysis. Patients were classified into 4 groups based on the median value of PT/PI ratio (PTr) and the cutoff value of SB. Patients with low PTr and high PTr were defined as FPC and SPC, respectively. Radiographic and clinical characteristics of different groups were compared.

RESULTS: Patients with SPC exhibited significantly greater improvements in lumbar lordosis, pelvic tilt, PTr, and T1 pelvic angle as compared to patients with FPC, irrespective of SB or SI. No apparent differences in any of SRS-22r domains were observed at follow-up when comparing the SB-FPC and SB-SPC patients. However, patients with SI-SPC exhibited significantly better function, self-image, satisfaction, and subtotal domains at follow-up relative to those with SI-FPC. When SI-FPC and SISPC patients were subdivided further based on the degree of PI-LL by adjusting for age, the postoperative function and self-image domains were significantly better in the group with overcorrection of PI-LL than undercorrection of PI-LL in SI-FPC patients. However, no differences in these SRS-22r scores were observed when comparing the subgroups in SI-SPC patients.

CONCLUSION: Flexible pelvic rotation is associated with benefits to the correction of sagittal parameters, irrespective of preoperative SB or SI status. However, PC is only significantly associated with clinical outcomes under SI. Patients with SIFPC exhibit poorer postoperative clinical outcomes, which should be recommended to minimize PI-LL.

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Impact of landmark crater creation on improving accuracy of pedicle screw insertion in robot-assisted scoliosis surgery

European Spine Journal (2024) 33:4730–4739

This study evaluated the impact of the Landmark Crater (LC) method on pedicle perforation rates in robot-guided surgery for pediatric scoliosis for each pedicle diameter.

Methods Seventy-six scoliosis patients underwent robot-assisted posterior spinal fusion. The cohort consisted of 19 male and 57 female patients, with a mean ± standard deviation age of 17.5 ± 7.7 years and a preoperative Cobb angle of 57.0 ± 18.5°. The LC method is a method in which craters that serves as a landmark are created in advance at the planned PS insertion site of all pedicles within the intraoperative CT imaging area. The patients were divided into the LC group, in which PS insertion was performed using the LC method, and the control group using the conventional PS insertion method. Overall and pedicle perforation rates for each pedicle outer diameter were compared between the groups by Fisher’s exact test.

Results The LC group exhibited a significantly lower pedicle major perforation rate than did the control group (2.7% vs. 6.2%, P = 0.001). The perforation rates in pedicles with a pedicle outer diameter > 6 mm, 4–6 mm, 2–4 mm, and < 2 mm were 0.61%, 1.6%, 5.1%, and 21%, in the LC group and 0.75%, 4.1%, 12%, and 50% in the control group, respectively.

Conclusion In robot-assisted surgery for pediatric scoliosis, the LC method enabled significantly lower pedicle perforation rates over the conventional method. Both the LC and conventional methods exhibited higher perforation rates for smaller pedicle diameters.

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Subtemporal Approach for the Treatment of Ruptured and Unruptured Distal Basilar Artery Aneurysms: Is There a Contemporary Use?

Operative Neurosurgery 27:581–596, 2024

Distal basilar artery aneurysms (DBAs) are high-risk lesions for which endovascular treatment is preferred because of their deep location, yet indications for open clipping nonetheless remain. The subtemporal approach allows for early proximal control and direct visualization of critical posterior perforating arteries, especially for posterior-projecting aneurysms. Our objective was to describe our clinical experience with the subtemporal approach for clipping DBAs in the evolving endovascular era.

METHODS: This was a retrospective, single-institution case series of patients with DBAs treated with microsurgery over a 21-year period (2002-2023). Demographic, clinical, and surgical data were collected for analysis.

RESULTS: Twenty-seven patients underwent clipping of 11 ruptured and 16 unruptured DBAs with a subtemporal approach (24 female; mean age 53 years). Ten patients had expanded craniotomies for treatment of additional aneurysms. The aneurysm occlusion rate was 100%. Good neurological outcomes as defined by the modified Rankin Scale score ≤2 and Glasgow Outcome Scale score ≥4 were achieved in 21/27 patients (78%). Two patients died before hospital discharge, one from vasospasm-induced strokes and another from an intraoperative myocardial infarction.

CONCLUSION: These results demonstrate that microsurgical clip ligation of DBAs using the subtemporal approach remains a viable option for complex lesions not amenable to endovascular management.

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Segmental Sagittal Alignment in Lumbar Spinal Fusion: A Review of Evidence-Based Evaluation of Preoperative Measurement, Surgical Planning, Intraoperative Execution, and Postoperative Evaluation

Operative Neurosurgery 27:533–548, 2024

Maintaining and restoring global and regional sagittal alignment is a well-established priority that improves patient outcomes in patients with adult spinal deformity. However, the benefit of restoring segmental (level-by-level) alignment in lumbar fusion for degenerative conditions is not widely agreed on. The purpose of this review was to summarize intraoperative techniques to achieve segmental fixation and the impact of segmental lordosis on patient-reported and surgical outcomes.

METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, PubMed, Embase, Cochrane, and Web of Science databases were queried for the literature reporting lumbar alignment for degenerative lumbar spinal pathology. Reports were assessed for data regarding the impact of intraoperative surgical factors on postoperative segmental sagittal alignment and patient-reported outcome measures. Included studies were further categorized into groups related to patient positioning, fusion and fixation, and interbody device (technique, material, angle, and augmentation).

RESULTS: A total of 885 studies were screened, of which 43 met inclusion criteria examining segmental rather than regional or global alignment. Of these, 3 examined patient positioning, 8 examined fusion and fixation, 3 examined case parameters, 26 examined or compared different interbody fusion techniques, 5 examined postoperative patient-reported outcomes, and 3 examined the occurrence of adjacent segment disease. The data support a link between segmental alignment and patient positioning, surgical technique, and adjacent segment disease but have insufficient evidence to support a relationship with patient-reported outcomes, cage subsidence, or pseudoarthrosis.

CONCLUSION: This review explores segmental correction’s impact on short-segment lumbar fusion outcomes, finding the extent of correction to depend on patient positioning and choice of interbody cage. Notably, inadequate restoration of lumbar lordosis is associated with adjacent segment degeneration. Nevertheless, conclusive evidence linking segmental alignment to patient-reported outcomes, cage subsidence, or pseudoarthrosis remains limited, underscoring the need for future research.

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Staged Versus Same-Day Surgery in Circumferential Minimally Invasive Deformity Correction

Neurosurgery 95:1040–1045, 2024

We sought to compare long-term clinical and radiographic outcomes in patients who underwent staged vs same-day circumferential minimally invasive surgery (cMIS) for adult spinal deformity (ASD).

METHODS: We reviewed staged and same-day cMIS ASD cases in a prospective multi-institution database to compare preoperative and 2-year clinical and radiographic parameters between cohorts.

RESULTS: A total of 85 patients with a 2-year follow-up were identified (27 staged, 58 same-day). Staged patients had more extensive surgeries and greater hospital length of stay (all P < .001). There were no significant differences in preoperative or 2-year postoperative clinical metrics between cohorts. Patients in the staged cohort also had greater preoperative coronal deformity and thus experienced greater reduction in coronal deformity at 2 years (all P < .01).

CONCLUSION: Patients undergoing staged or same-day cMIS correction had similar outcomes at 2 years postoperatively. Staged cMIS ASD correction may be more appropriate in patients with greater deformity, higher frailty, and who require longer, more extensive surgeries.

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Deep learning algorithm for fully automated measurement of sagittal balance in adult spinal deformity

European Spine Journal (2024) 33:4119–4124

Deep learning (DL) algorithms can be used for automated analysis of medical imaging. The aim of this study was to assess the accuracy of an innovative, fully automated DL algorithm for analysis of sagittal balance in adult spinal deformity (ASD).

Material and methods Sagittal balance (sacral slope, pelvic tilt, pelvic incidence, lumbar lordosis and sagittal vertical axis) was evaluated in 141 preoperative and postoperative radiographs of patients with ASD. The DL, landmark-based measurements, were compared with the ground truth values from validated manual measurements.

Results The DL algorithm showed an excellent consistency with the ground truth measurements. The intra-class correlation coefficient between the DL and ground truth measurements was 0.71–0.99 for preoperative and 0.72–0.96 for postoperative measurements. The DL detection rate was 91.5% and 84% for preoperative and postoperative images, respectively.

Conclusion This is the first study evaluating a complete automated DL algorithm for analysis of sagittal balance with high accuracy for all evaluated parameters. The excellent accuracy in the challenging pathology of ASD with long construct instrumentation demonstrates the eligibility and possibility for implementation in clinical routine.

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Cost-effectiveness of posterior lumbar interbody fusion and/or transforaminal lumbar interbody fusion for grade 1 lumbar spondylolisthesis: a 5-year Quality Outcomes Database study

J Neurosurg Spine 41:596–603, 2024

Posterior lumbar interbody fusion (PLIF) and/or transforaminal lumbar interbody fusion (TLIF), referred to as “PLIF/TLIF,” is a commonly performed operation for lumbar spondylolisthesis. Its long-term cost-effectiveness has not been well described. The aim of this study was to determine the 5-year cost-effectiveness of PLIF/TLIF for grade 1 degenerative lumbar spondylolisthesis using prospective data collected from the multicenter Quality Outcomes Database (QOD).

METHODS Patients enrolled in the prospective, multicenter QOD grade 1 lumbar spondylolisthesis module were included if they underwent single-stage PLIF/TLIF. EQ-5D scores at baseline, 3 months, 12 months, 24 months, 36 months, and 60 months were used to calculate gains in quality-adjusted life years (QALYs) associated with surgery relative to preoperative baseline. Healthcare-related costs associated with the index surgery and related reoperations were calculated using Medicare reimbursement–based cost estimates and validated using price transparency diagnosis-related group (DRG) charges and Medicare charge-to-cost ratios (CCRs). Cost per QALY gained over 60 months postoperatively was assessed.

RESULTS Across 12 surgical centers, 385 patients were identified. The mean patient age was 60.2 (95% CI 59.1–61.3) years, and 38% of patients were male. The reoperation rate was 5.7%. DRG 460 cost estimates were stable between our Medicare reimbursement–based models and the CCR-based model, validating the focus on Medicare reimbursement. Across the entire cohort, the mean QALY gain at 60 months postoperatively was 1.07 (95% CI 0.97–1.18), and the mean cost of PLIF/TLIF was $31,634. PLIF/TLIF was associated with a mean 60-month cost per QALY gained of $29,511. Among patients who did not undergo reoperation (n = 363), the mean 60-month QALY gain was 1.10 (95% CI 0.99–1.20), and cost per QALY gained was $27,591. Among those who underwent reoperation (n = 22), the mean 60-month QALY gain was 0.68 (95% CI 0.21–1.15), and the cost per QALY gained was $80,580.

CONCLUSIONS PLIF/TLIF for degenerative grade 1 lumbar spondylolisthesis was associated with a mean 60-month cost per QALY gained of $29,511 with Medicare fees. This is far below the well-established societal willingness-to-pay threshold of $100,000, suggesting long-term cost-effectiveness. PLIF/TLIF remains cost-effective for patients who undergo reoperation.

 

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Predictors of patient satisfaction in the surgical treatment of cervical spondylotic myelopathy

J Neurosurg Spine 41:611–618, 2024

Patients with cervical spondylotic myelopathy (CSM) experience progressive neurological impairment. Surgical intervention is often pursued to halt neurological symptom progression and allow for recovery of function. In this paper, the authors explore predictors of patient satisfaction following surgical intervention for CSM.

METHODS This is a retrospective review of prospectively collected data from the multicenter Quality Outcomes Database. Patients who underwent surgical intervention for CSM with a minimum follow-up of 2 years were included. Patient-reported satisfaction was defined as a North American Spine Society (NASS) satisfaction score of 1 or 2. Patient demographics, surgical parameters, and outcomes were assessed as related to patient satisfaction. Patient quality of life scores were measured at baseline and 24-month time points. Univariate regression analyses were performed using the chi-square test or Student t-test to assess patient satisfaction measures. Multivariate logistic regression analysis was conducted to assess for factors predictive of postoperative satisfaction at 24 months.

RESULTS A total of 1140 patients at 14 institutions with CSM who underwent surgical intervention were included, and 944 completed a patient satisfaction survey at 24 months postoperatively. The baseline modified Japanese Orthopaedic Association (mJOA) score was 12.0 ± 2.8. A total of 793 (84.0%) patients reported satisfaction (NASS score 1 or 2) after 2 years. Male and female patients reported similar satisfaction rates (female sex: 47.0% not satisfied vs 48.5% satisfied, p = 0.73). Black race was associated with less satisfaction (26.5% not satisfied vs 13.2% satisfied, p < 0.01). Baseline psychiatric comorbidities, obesity, and length of stay did not correlate with 24-month satisfaction. Crossing the cervicothoracic junction did not affect satisfactory scores (p = 0.19), and minimally invasive approaches were not associated with increased patient satisfaction (p = 0.14). Lower baseline numeric rating scale neck pain scores (5.03 vs 5.61, p = 0.04) and higher baseline mJOA scores (12.28 vs 11.66, p = 0.01) were associated with higher satisfaction rates.

CONCLUSIONS Surgical treatment of CSM results in a high rate of patient satisfaction (84.0%) at the 2-year follow-up. Patients with milder myelopathy report higher satisfaction rates, suggesting that intervention earlier in the disease process may result in greater long-term satisfaction.

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Comparison of rostral facet joint violations in robotic- and navigation-assisted pedicle screw placement for adult lumbar spine instrumentation

The Spine Journal 24 (2024) 2102−2109

Facet joint violation by pedicle screws may lead to adjacent-segment disease and postoperative pain. Previous studies have reported the incidence of rostral facet joint violation using various pedicle screw insertion techniques. However, the incidence of facet joint violations with robotic guidance has not been determined.

PURPOSE: To investigate and compare the incidence of rostral facet joint violation by pedicle screws under robotic guidance and computerized tomography (CT) navigation guidance.

STUDY DESIGN/SETTING: Retrospective matched cohort.

PATIENT SAMPLE: All patients who underwent robotic-assisted lumbar fusion at a major spine center up until 2023 were retrospectively identified and matched 1:3 to patients undergoing CT navigation guidance based by on age, sex, rostral vertebral level, and length of construct. Inclusion criteria consisted of age greater than 18 years, bilateral pedicle screw fixation, and presence of a postoperative CT scan of the lumbar spine or abdomen/pelvis at any point in the postoperative period.

OUTCOME MEASURES: Rostral facet joint violations.

METHODS: Descriptive statistics were used to compare cohorts: frequencies, chi-squared analysis for categorical variables, and t-test for continuous variables.

RESULTS: A total of 408 rostral pedicle screws were implanted in 204 patients (Robot: 102; Navigation: 306). Overall, 13 (12.3%) rostral facet joint violations were observed in the robot cohort and 75 (24.5%) in the navigation cohort (p=.01). Specifically, fewer robotic violations were observed at the L2 (3.5% vs 32.1%, p=.003) and L3 levels (3.9% vs 18.1%, p=.08) compared to navigation. No difference was observed at L4 and L5. Bilateral violations are significantly reduced with robotic approaches (5.3% vs 14.4%, p=.03). Lastly, more facet joint violations were observed during open approaches (robot: 18.8%, navigation: 27.3%) than percutaneous approaches (robot: 11.6%, navigation: 7.1%) in both groups (p<.001). The rate of L4 facet violations was 18.8% in the robotic cohort and 27.3% in the navigation cohort. The rate of L5 facet violations was 31.3% in the robotic cohort and 29.2% in the navigation cohort.

CONCLUSIONS: Use of robotic assistance in lumbar pedicle screws significantly reduced the rate of rostral facet joint violations compared to navigation guidance at L2 and L3 levels, but not at L4 and L5, with facet violations approaching nearly one-third of the patients at L5 screws. Rostral facet violations can play a significant role in adjacent segment degeneration and disease. Technical factors and trajectory issues likely play a role and addressing these components should minimize unintended facet violation and proximal adding on.

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Can titanium surface technology reduce cost for biologics in anterior lumbar interbody fusion?

J Neurosurg Spine 41:589–595, 2024

Advances in surface architecture and technology have made interbody fusion devices more bioactive, with the hope of facilitating the fusion process more successfully. The advent of these increasingly bioactive implants may reduce reliance on more expensive biologics that have previously been used to achieve high fusion rates.

METHODS A retrospective review of prospectively collected data (August 2018–December 2019) was conducted of consecutively performed anterior lumbar interbody fusions in which an acid-etched, nanosurface-modulated, titanium interbody device packed only with corticocancellous allograft chips and local blood was used. Minimum follow-up was 1 year, and inclusion required available imaging and outcome metrics preoperatively and at 1 year. Fusion and subsidence were assessed via CT scans and/or dynamic radiographs. Health-related quality-of-life measures (Oswestry Disability Index [ODI], visual analog scale [VAS] back/leg) were collected pre- and postoperatively.

RESULTS In total, 55 patients met inclusion criteria (1 year of follow-up, available imaging, and outcome metrics). A total of 69 lumbar levels were treated in these 55 patients. The mean age was 67 ± 12.1 years, with 47% female patients. Roughly one-third (35%) had previous spine surgery, and approximately one-tenth (9.1%) had prior spinal fusion. A total of 20.6% were treated at multiple levels (mean levels per patient 1.2, minimum 1, maximum 3). The mean preoperative patient-reported outcomes were as follows: ODI 39.71 ± 18.15, VAS back 6.49 ± 2.19, and VAS leg 5.41 ± 2.71. One year after surgery, the mean improvements in patient-reported outcomes (vs preoperative scores) were as follows: ODI −22.9 ± 13.08 (p < 0.001), VAS back −3.75 ± 2.03 (p < 0.001), VAS leg −3.73 ± 2.32 (p < 0.001). All levels achieved fusion at 1 year postoperatively based on CT scans (65/69 levels) or dynamic radiographs (4/69 levels, change in score < 5% on flexion-extension radiographs). Four of the 65 levels were assigned to the grade 3 category according to a CT-based grading system, meaning cranial and caudal endplate bone apposition to the implant on both surfaces with no clear intervertebral bone connection through or around the implant. Sixty-one of 65 were found to have contiguous intervertebral bone bridging and thus were assigned to grade 1 (n = 54) or grade 2 (n = 7). Low-grade graft subsidence (Marchi grade 0 or I) occurred in 9 levels (13.0%) and high-grade subsidence (Marchi grade II or III) in 4 levels (5.8%). No patients required reoperation at the level of anterior lumbar interbody fusion and no radiographic or clinical evidence of pedicle screw loosening or failure was observed.

CONCLUSIONS The combination of advances in materials science and surface technology as demonstrated with a nanotechnology titanium cage resulted in the ability to obtain lumbar interbody fusion with allograft chips and local blood alone. Achieving high fusion rates with low-cost biologics/allograft provides for an attractive pathway toward reducing the cost of reconstructive spine care, and a potential incremental benefit for healthcare economics.

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Comparison of accuracy, revision, and perioperative outcomes in robot-assisted spine surgeries: systematic review and meta-analysis

J Neurosurg Spine 41:519–531, 2024

Pedicle screw placement guidance is critical in spinal fusions, and spinal surgery robots aim to improve accuracy and reduce complications. Current literature has yet to compare the relative merits of available robotic systems. In this review, the authors aimed to 1) assess the current state of spinal robotics literature; 2) conduct a meta-analysis of robotic performance based on accuracy, speed, and safety; and 3) offer recommendations for robotic system selection.

METHODS Following PRISMA guidelines, the authors conducted a systematic literature review across PubMed, Embase, Cochrane Library, Web of Science, and Scopus as of April 28, 2022, for studies on approved robots for placing lumbar pedicle screws. Three reviewers screened and extracted data relating to the study characteristics, accuracy rate, intraoperative revisions, and reoperations. Secondary performance metrics included operative time, blood loss, and radiation exposure. The authors statistically compared the performance of the robots using a random-effects model to account for variation within and between the studies. Each robot was also compared with performance benchmarks of traditional techniques including freehand, fluoroscopic, and CT-navigated insertion. Finally, we performed a Duval and Tweedie trim-and-fill test to assess for the presence of publication bias.

RESULTS The authors identified 46 studies, describing 4670 patients and 25,054 screws, that evaluated 4 different robotic systems: Mazor X, ROSA, ExcelsiusGPS, and Cirq. The weighted accuracy rates of Gertzbein-Robbins classification grade A or B screws were as follows: ExcelsiusGPS, 98.0%; ROSA, 98.0%; Mazor, 98.2%; and Cirq, 94.2%. No robot was significantly more accurate than the others. However, the accuracy of the ExcelsiusGPS was significantly higher than that of traditional methods, and the accuracies of the Mazor and ROSA were significantly higher than that of fluoroscopy. The intraoperative revision rates were Cirq, 0.55%; ROSA, 0.91%; Mazor, 0.98%; and ExcelsiusGPS, 1.08%. The reoperation rates were Cirq, 0.28%; ExcelsiusGPS, 0.32%; and Mazor, 0.76% (no reoperations were reported for ROSA). Operative times were similar for all robots. Both the ExcelsiusGPS and Mazor were associated with significantly less blood loss than the ROSA. The Cirq had the lowest radiation exposure. Robots tended to be more accurate and generally their use was associated with fewer reoperations and less blood loss than freehand, fluoroscopic, or CT-navigated techniques.

CONCLUSIONS Robotic platforms perform comparably based on key metrics, with high accuracy rates and low intraoperative revision and reoperation rates. The spinal robotics publication rate will continue to accelerate, and choosing a robot will depend on the context of the practice.

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Safe resection of a complex type 3 foramen magnum meningioma with dorsal displacement of the neurovascular bundle

Acta Neurochirurgica (2024) 166:376

We describe techniques for safe resection of a Type 3 foramen magnum meningioma with dorsal displacement of the accessory nerve rootlets and vertebral artery which limits ventral access to the tumor.

Method Partial sectioning of the accessory nerve rootlets may help create larger working space. Topical lidocaine placement on the rootlets of the spinal accessory nerve may mitigate trapezius muscle contraction and facilitates further progress throughout tumor resection.

Conclusion Creating safe working corridors between the lower cranial nerves through mobilization or partial sectioning of rootlets in the case of CN XI facilitates tumor resection through a far lateral approach.

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Comparison of biportal endoscopic and microscopic tubular paraspinal approach for foraminal and extraforaminal lumbar disc herniation

J Neurosurg Spine 41:473–482, 2024

Foraminal and extraforaminal lumbar disc herniation (FELDH) is an important pathological condition that can lead to lumbar radiculopathy. The paraspinal muscle–splitting approach introduced by Reulen and Wiltse is a reasonable surgical technique. Minimally invasive procedures using a tubular retractor system have also been introduced. However, surgical treatment is considered more challenging for FELDH than for central or subarticular lumbar disc herniations (LDHs). Some researchers have proposed uniportal extraforaminal endoscopic lumbar discectomy through a posterolateral approach as an alternative for FELDH, but heterogeneous clinical results have been reported. Recently, the biportal endoscopic (BE) paraspinal approach has been suggested as an alternative. The aim of this study was to compare the clinical outcomes of BE and microscopic tubular (MT) paraspinal approaches for decompressive foraminotomy and lumbar discectomy (paraLD) in patients with FELDH.

METHODS Ninety-one consecutive patients with unilateral lumbar radiculopathy and FELDH underwent paraLD. Demographic and perioperative data were collected. Clinical outcomes were evaluated using the visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI) for spinal disability, and the modified Macnab criteria for patient satisfaction. Postoperative complications and reoperation rates were also evaluated.

RESULTS In total, 76 patients were included in the final analysis. Among them, 43 underwent BE paraLD (group A) and the remaining 33 underwent MT paraLD (group B). The demographic and preoperative data were not statistically different between the groups. All patients showed significant improvements in VAS back, VAS leg, and ODI scores compared with baseline values (p < 0.05). The improvement in VAS back scores was significantly better in group A than in group B on postoperative day 2 (p < 0.001). However, all clinical parameters were comparable between the two groups after postoperative year 1 (p > 0.05). According to the modified Macnab criteria, 86.1% and 72.7% of the patients had excellent or good outcomes in groups A and B, respectively. No intergroup differences were observed (p = 0.367). In addition, there were no differences in the total operation time or amount of surgical drainage. Postoperative complications were not significantly different between the two groups (p = 0.301); however, reoperation rates were significantly higher in group B (p = 0.035).

CONCLUSIONS BE paraLD is an effective treatment for FELDH and is an alternative to MT paraLD. In particular, BE paraLD has advantages of early improvement in postoperative back pain and low reoperation rates.

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Transforaminal lumbar interbody fusion subsidence

J Neurosurg Spine 41:463–472, 2024

The aims of this study were to 1) define the incidence of transforaminal lumbar interbody fusion (TLIF) interbody subsidence; 2) determine the relative importance of preoperative and intraoperative patient- and instrumentation-specific risk factors predictive of postoperative subsidence using CT-based assessment; and 3) determine the impact of TLIF subsidence on postoperative complications and fusion rates.

METHODS All adult patients who underwent one- or two-level TLIF for lumbar degenerative conditions at a multi-institutional academic center between 2017 and 2019 were retrospectively identified. Patients with traumatic injury, infection, malignancy, previous fusion at the index level, combined anterior-posterior procedures, surgery with greater than two TLIF levels, or incomplete follow-up were excluded. Interbody subsidence at the superior and inferior endplates of each TLIF level was directly measured on the endplate-facing surface of both coronal and sagittal CT scans obtained greater than 6 months postoperatively. Patients were grouped based on the maximum subsidence at each operative level classified as mild, moderate, or severe based on previously documented < 2-mm, 2- to 4-mm, and ≥ 4-mm thresholds, respectively. Univariate and regression analyses compared patient demographics, medical comorbidities, preoperative bone quality, surgical factors including interbody cage parameters, and fusion and complication rates across subsidence groups.

RESULTS A total of 67 patients with 85 unique fusion levels met the inclusion and exclusion criteria. Overall, 28% of levels exhibited moderate subsidence and 35% showed severe subsidence after TLIF with no significant difference in the superior and inferior endplate subsidence. Moderate (≥ 2-mm) and severe (≥ 4-mm) subsidence were significantly associated with decreases in cage surface area and Taillard index as well as interbody cages with polyetheretherketone (PEEK) material and sawtooth surface geometry. Severe subsidence was also significantly associated with taller preoperative disc spaces, decreased vertebral Hounsfield units (HU), the absence of bone morphogenetic protein (BMP) use, and smooth cage surfaces. Regression analysis revealed decreases in Taillard index, cage surface area, and HU, and the absence of BMP use predicted subsidence. Severe subsidence was found to be a predictor of pseudarthrosis but was not significantly associated with revision surgery.

CONCLUSIONS Patient-level risk factors for TLIF subsidence included decreased HU and increased preoperative disc height. Intraoperative risk factors for TLIF subsidence were decreased cage surface area, PEEK cage material, bullet cages, posterior cage positioning, smooth cage surfaces, and sawtooth surface designs. Severe subsidence predicted TLIF pseudarthrosis; however, the causality of this relationship remains unclear.

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Accurate placement of thoracolumbar pedicle screws using a handheld iOS-based navigation device

The Spine Journal 24 (2024) 1671−1677

Accurate pedicle screw placement is a challenge with reported misplacement rates of 10% and higher. A handheld navigation device (HND) may provide accuracy equal to CT-based navigation (CT-Nav) but without the cost and complexity.

OBJECTIVE: To study the accuracy of a handheld navigation device for pedicle screw placement. STUDY DESIGN: This prospective cross-sectional study with consistently applied reference standard enrolled 20 patients undergoing 92 pedicle screw placements.

PATIENTS: Patients who underwent pedicle screw placement between May 2022 and September 2022.

OUTCOME MEASURES: Pedicle screw placement accuracy per Gertzbein−Robbins.

METHODS: Once the screw pilot hole was established, the proposed trajectory of the HND was compared with that proposed by CT-Nav. Postoperatively, screw accuracy was graded according to Gertzbein−Robbins by a blinded radiologist based on CT scans. Accuracy was compared between the two systems and published control for fluoroscopy assisted and CT-Nav placement using Bayesian posterior distribution.

RESULTS: The trajectory proposed by the HND and CT-Nav were in agreement in 98.9% (95% Exact CI; 94.09%−99.97%). The HND accuracy was 98.9% with 91 screws rated “A” and 1 rated “C”. Noninferiority to fluoroscopic placement was achieved because the one-sided normalapproximation 95% CI Lower Bound (LB) of 95.3% is greater than the Performance Goal (PG) of 83.4%. Posthoc analysis demonstrated that the probability of superiority of the HND relative to the historical accuracy rate of 91.5% for fluoroscopy assisted procedures is >0.999 and that the HND’s accuracy rate is within 4.5% of CT-Nav of 95.5% is >0.999. No adverse events or intra-operative complications associated with HND were observed. There was 1 (1.1%) intra-operative repositioning and no reoperations for any reason.

CONCLUSIONS: The accuracy rate of the HND was 98.9%, and the proposed trajectory matched with CT-Nav in 98.9% of the time. This is superior to the historical published accuracy rate for fluoroscopy-assisted procedures and equivalent to the historical published accuracy rate for CT-Nav.

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Full-endoscopic lumbar discectomy for lumbar disc herniation in young adults: 199 consecutive cases treated by a single surgeon with a mean 3.7-year follow-up

J Neurosurg Spine 41:369–377, 2024

Lumbar disc herniation (LDH) is rare in young adults. The present study aimed to evaluate the clinical outcomes of full-endoscopic lumbar discectomy (FELD) for LDH in young adults and to determine the risk factors that predict unfavorable outcomes of FELD for LDH in young adults.

METHODS A retrospective two-center cohort study was performed between January 2015 and October 2021 at the authors’ institutions. Clinical outcomes were assessed using the visual analog scale (VAS) for low-back pain and leg pain and the Oswestry Disability Index (ODI). The modified Macnab criteria were used to evaluate clinical efficacy at the last follow-up, and the global outcomes were classified into 4 groups, namely excellent, good, fair, and poor. The fair and poor groups were defined as unfavorable outcomes.

RESULTS One hundred ninety-nine patients were analyzed in this study (mean age 18.5 years, mean BMI 25.1 kg/m 2 , male/female sex ratio 2.8). The duration from the onset of symptoms to the operation was in general prolonged with age. The VAS and ODI scores significantly improved after surgery. A total of 17 of 195 single-segment cases had unfavorable outcomes based on the modified Macnab criteria. Lateral disc herniation (OR 3.72, 95% CI 1.14–12.12, p = 0.029) and high preoperative VAS score (OR 1.98, 95% CI 1.13–3.46, p = 0.017) were identified as risk factors for unfavorable outcomes after FELD.

CONCLUSIONS FELD for LDH in young adults is safe and effective. Preoperative VAS score and lateral disc herniation are risk factors of nonfavorable outcomes after surgery and may be a useful index for surgical procedure selection.

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