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OBJECTIVE Cervical disc replacement (CDR) is an alternative treatment to anterior cervical discectomy and fusion (ACDF), which is the current gold standard, for degenerative cervical diseases such as cervical spondylotic myelopathy and cervical radiculopathy. CDR has several theoretical benefits over ACDF, including preservation of motion, earlier return to unrestricted activity, and potentially a lower risk of adjacent-segment disease. Recent literature has reported positive clinical results for CDR, but few studies have investigated the long-term risk of revision surgery of CDR versus ACDF. The purpose of this study was to identify and analyze the epidemiological, clinical, and operative risk factors that affect revision rates following single-level CDR and ACDF procedures. METHODS A retrospective cohort was extracted from the Statewide Planning and Research Cooperative System using ICD-9 and CPT codes. Inclusion criteria were adult patients undergoing primary, subaxial (C3–7), single-level ACDF or CDR for cervical radiculopathy and/or cervical spondylotic myelopathy between 2005 and 2013. Survivability was defined as the time between the index procedure and the presence of a subsequent discharge record for cervical spinal fusion or disc replacement. Statistical analyses were performed using chi-square tests, t-tests, Cox proportional hazards models, and a Kaplan-Meier plot. RESULTS A total of 7450 patients were included in this study (6615 ACDF and 835 CDR). When adjusted for patient demographics, the hazard ratios showed no significant differences in the incidence of revision risk between the two cohorts. The CDR cohort had a higher incidence of postoperative dysphagia (p < 0.05). Patients undergoing ACDF had a longer average hospital stay (2.8 vs 1.9 days, p < 0.001). There was no significant difference in time to revision surgery (p = 0.486). CONCLUSIONS CDR and ACDF have both been shown to be effective treatments for cervical spine disease. CDR patients had a shorter average inpatient hospital stay compared with ACDF patients but tended to experience dysphagia more frequently. There was a tendency toward increased survivability of CDR; however, this was not found to be statistically significant at any time point. The large size and heterogeneity of each cohort and the availability of > 10 years of surveillance data differentiate this study from other published literature. This investigation has limitations inherent to large data analysis studies, including the implementation and inaccuracy of diagnosis and procedural coding; however, this reflects real-world use of coding by practitioners.

BackgroundThe impact of anesthetic technique on spine surgery outcomes is controversial. Using a large national sample of patients, we compared outcomes after lumbar decompression under regional anesthesia (RA: spinal or epidural) or general anesthesia (GA).MethodsA retrospective population-based study of American College of Surgeons National Surgical Quality Improvement Program data (2009–2019). Patients were propensity score (PS) matched 3:1 (GA:RA) on demographic and surgical variables. The primary outcome was the association between anesthetic type and any complication (cardiac, pulmonary, renal, transfusion, stroke, infectious, deep vein thrombosis/pulmonary embolus). Secondary outcomes included the association between anesthetic type and individual complications, readmission and length of stay (LOS). Unadjusted comparisons (OR, 95% CI), logistic regression and adjusted generalized linear modeling (parameter estimate, PE, 95% CI) were performed before and after PS matching.ResultsOf 1 51 010 cases, 149 996 (99.3%) were performed under GA, and 1014 (0.67%) under RA. After matching, 3042 patients with GA were compared with 1014 patients with RA. On unadjusted analyses, RA was associated with lower odds of complications (OR 0.43, 0.3 to 0.6, pConclusionsCompared with GA, RA was associated with fewer complications, less blood transfusion and shorter LOS after spine surgery. Although statistically significant, the magnitude of effects was small and requires further prospective study.

We sought to characterize trends in demographics, comorbidities, and postoperative complications among patients undergoing primary and revision cervical disc replacement (pCDR/rCDR) procedures.In this retrospective database study, the Premier Healthcare database was queried from 2006 to 2019. Annual proportions or medians were calculated for patient and hospital characteristics, comorbidities, and postoperative complications associated with CDR surgery. Trends were assessed using linear regression analyses with year of service as the sole predictor.A total of 16,178 pCDR and 758 rCDR cases were identified, with a median (IQR) age of 46 (39; 53) and 51 (43; 60) years among patients, respectively. The annual number of both procedures increased between 2006 and 2019, from 135 to 2220 for pCDR (p0.001), and from 17 to 49 for rCDR procedures (p0.001), with radiculopathy being the main indication for surgery in both groups. Mechanical failure was identified as a major indication for rCDR procedures with an increase over time (p = 0.002). Baseline patient comorbidity burden (p = 0.045) and complication rates (p0.001) showed an increase. For both procedures, an increase in outpatient surgeries and procedures performed in rural hospitals was seen (pCDR: p = 0.045; p = 0.006; rCDR: p = 0.028; p = 0.034).PCDR and rCDR procedures significantly increased from 2006 to 2019. At the same time, comorbidity burden and complication rates increased, while procedures were more often performed in an outpatient and rural setting. The identification of these trends can help guide future practice and lead to further areas of research.

Studies have shown that site-specific bone density measurements had more predictive value for complications than standard whole-region measurements. Recently, MRI-based assessments of vertebral bone quality (VBQ) were introduced. However, there have been few studies that investigate the association between site-specific MRI bone assessment and osteoporosis-related complications in patients undergoing lumbar interbody fusion. In this work, we created a novel site-specific MRI-based assessment of the endplate bone quality (EBQ) and assessed its predictive value for severe cage subsidence following standalone lateral lumbar interbody fusion (SA-LLIF).To investigate the predictive value of a novel MRI-based bone assessment for severe cage subsidence after SA-LLIF.Retrospective cohort study.Patients who underwent SA-LLIF from 2008 to 2019 at a single, academic institution with available preoperative lumbar CT and T1-weighted MRIs.Association between EBQ and severe subsidence after SA-LLIF.We retrospectively reviewed the records of SA-LLIF patients treated between 2008 and 2019. EBQ was measured using preoperative non-contrast T1-weighted MRIs of the lumbar spine. EBQ was defined as the average value of signal intensity of both endplates divided by that of the cerebrospinal fluid space at the level of L3. Bivariate and multivariable analyses with generalized linear mixed models were performed and set binary severe subsidence as the outcome.Two hundred five levels in 89 patients were included. Fifty levels (24.4%) demonstrated severe subsidence. Bone mineral density measured by quantitative computed tomography was significantly lower in the subsidence group. Both VBQ and EBQ were significantly higher in the subsidence group. The EBQ plus Modic change (MC) model demonstrated that the effect of EBQ was independent of MC. In multivariate analyses adjusted with QCT-vBMD, EBQ showed a significant association with cage subsidence whereas VBQ only showed a marginal trend. The EBQ-based prediction model for severe subsidence showed better goodness of fit compared to the VBQ-based model.High EBQ was an independent factor for severe cage subsidence after SA-LLIF and the EBQ-based model showed better goodness of fit compared to VBQ- or MC-based models. EBQ assessment before SA-LLIF may provide insight into a patient's risk for severe subsidence.

Osteoporosis is a risk factor for instrumentation failure in spine surgery. Bone strength is commonly assessed by bone mineral density (BMD) as a surrogate marker. However, BMD represents only a portion of bone strength and does not capture the qualitative dimensions of bone. Recently, the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score was introduced as a novel marker of bone quality. However, it is still unclear if the VBQ score correlates with in-vivo bone microstructure.The aims of the study were (1) to demonstrate differences in MRI-based (VBQ) and in-vivo (microcomputed tomography; μCT) bone quality between osteopenic/osteoporotic and normal bone, (2) to show the correlation between VBQ, bone microstructure and volumetric BMD (vBMD), and (3) to determine the predictive value of the VBQ score for the prevalence of osteopenia/osteoporosis.Retrospective cross-sectional study.267 patients who underwent posterior lumbar fusion surgery from 2014 to 2021 at a single academic institution. Bone biopsies were harvested intraoperatively in 118 patients.VBMD, VBQ score, and bone microstructure parameters derived from μCT.Quantitative computed tomography (QCT) measurements were performed at the lumbar spine and the L1/L2 average was used to categorize patients with a vBMD ≤120mg/cm267 patients (55.8% female, age 63.3 years, BMI 29.7 kg/mThis study demonstrated for the first time that the VBQ score is associated with trabecular microstructure determined by μCT. The bone microstructure and VBQ score were significantly different in patients with impaired vBMD. However, the ability to predict osteopenia/osteoporosis with the VBQ score was moderate. The VBQ score appears to reflect additional bone quality characteristics and might have a complementary role to vBMD. This enhances our understanding of the biological background of the radiographic VBQ score and might be a take-off point to evaluate the clinical utility of it as non-invasive screening tool for bone quality.

To investigate whether (1) there is a difference between patients with normal or sagittal spinal and spinopelvic malalignment in terms of their paraspinal muscle composition and (2) if sagittal malalignment can be predicted using muscle parameters.A retrospective review of patients undergoing posterior lumbar fusion surgery was conducted. A MRI-based muscle measurement technique was used to assess the cross-sectional area, the functional cross-sectional area, the intramuscular fat and fat infiltration (FI) for the psoas and the posterior paraspinal muscles (PPM). Intervertebral disc degeneration was graded for levels L1 to S1. Sagittal vertical axis (SVA; ≥ 50 mm defined as spinal malalignment), pelvic incidence (PI) and lumbar lordosis (LL) were measured, and PI-LL mismatch (PI-LL; ≥ 10° defined as spinopelvic malalignment) was calculated. A receiver operating characteristic (ROC) analysis was conducted to determine the specificity and sensitivity of the FIOne hundred and fifty patients were analysed. The PI-LL and SVA malalignment groups were found to have a significantly higher FISignificant differences in the muscle composition between normal and malalignment groups with respect to FI

To develop a decision-making pathway for primary SA-LLIF. Furthermore, we analyzed the agreement of this pathway and compared outcomes of patients undergoing either SA-LLIF or 360-LLIF. A decision-making pathway for SA-LLIF was created based on the results of interviews/surveys of senior spine surgeons with over 10 years of experience. Internal validity was retrospectively evaluated using consecutive patients undergoing either SA-LLIF or 360-LLIF between 01/2018 and 07/2020 with 3D-printed Titanium cages. An outcome assessment looking primarily at revision surgery and secondary at cage subsidence, changes in disk and foraminal height, global and segmental lumbar lordosis, duration of surgery, estimated blood loss, and length of stay was carried out. 78 patients with 124 treated levels (37 SA-LLIF, 41 360-LLIF) were retrospectively analyzed. The pathway showed a direct agreement (SA-LLIF) of 100.0% and an indirect agreement (360-LLIF) of 95.1%. Clinical follow-up averaged 13.5 ± 6.5 months including 4 revision surgeries in the 360-LLIF group and none in the SA-LLIF group (p = 0.117). Radiographic follow-up averaged 9.5 ± 4.3 months, with no statistically significant difference in cage subsidence rate between the groups (p = 0.440). Compared to preoperative images, patients in both groups showed statistically significant changes in disk height (p

OBJECTIVE Medial migration of the vertebral artery (VA) can be a risk factor for injury during anterior procedures. CT angiography (CTA) has been considered the gold standard for the evaluation of various areas of the arterial anatomy. MRI and nonenhanced CT are more commonly used as routine preoperative imaging studies, but it is unclear if these modalities can safely exclude the anomalous course of the VA. The aims of this cross-sectional observational study were to investigate risk factors for medially migrated VA on CTA and to evaluate the diagnostic accuracy of MRI and nonenhanced CT for high-risk VA anatomy in the subaxial cervical spine. METHODS The records of 248 patients who underwent CTA for any reason at a single academic institution between 2007 and 2018 were reviewed. The authors included MRI and nonenhanced CT taken within 1 year before or after CTA. An axial VA position classification was used to grade VA anomalies in the subaxial cervical spine. The multivariable linear regression analysis with mixed models was performed to identify the risk factors for medialized VA. The sensitivity and specificity of MRI and nonenhanced CT for high-risk VA positions were calculated. RESULTS A total of 175 CTA sequences met the inclusion criteria. The mean age was 63.8 years. Advanced age, disc and pedicle levels, lower cervical levels, and left side were independent risk factors for medially migrated VA. The sensitivities of MRI and nonenhanced CT for the detection of grade 1 or higher VA position were only fair, and the sensitivity of MRI was lower than that of nonenhanced CT (0.31 vs 0.37, p < 0.001), but the specificities were similarly high for both modalities (0.97 vs 0.97). With the combination of MRI and nonenhanced CT, the sensitivity significantly increased to 0.50 (p < 0.001 vs MRI and vs CT alone) with a minimal decrease in specificity. CONCLUSIONS Axial images of MRI and nonenhanced CT demonstrated high specificities but only fair sensitivities. Nonenhanced CT demonstrated better diagnostic value than MRI. When combining both modalities the sensitivity improved, but a substantial proportion of medialized VAs could not be diagnosed.

Compare fusion at two independent timepoints (early and late) between 3D-printed titanium (Ti) and polyetheretherketone (PEEK) cages in patients undergoing standalone lateral lumbar interbody fusion (SA-LLIF). We hypothesized that 3D-printed Ti cages show higher fusion rates at an early timepoint compared to PEEK.A retrospective study of patients undergoing SA-LLIF with 3D-printed Ti cages and PEEK cages between 11/2016 and 01/2020 at a single academic institution was done. Fusion was assessed for each treated level using multiplanar reconstructed computed tomography (CT) scans. Presence of fully bridged interbody trabecular bone or continuous bone centered in the cage was considered as fusion.In total, 91 patients (136 levels) were included in the final analysis, 49 patients (72 levels) in the early group and 42 patients (64 levels) in the late group. CT scans were performed on average 8.2±1.8 months postoperatively for the early group and 18.9±7.7 months for the late group. In the early group, fusion was significantly higher for 3D-printed Ti cages compared to PEEK cages (95.8% versus 62.5%; P=0.002), whereas in the late group no significant difference was seen (94.7% versus 80.0%; P=0.258).In SA-LLIF, porous 3D-printed Ti cages showed significantly higher fusion rates at an early timepoint compared to PEEK. However, the difference in fusion rates between 3D-printed Ti cages and PEEK cages was found not to be significantly different at a later timepoint in another patient group. This might support the assumption that 3D-printed Ti cages with a porous architecture are more osteoconductive compared to PEEK and tend to fuse earlier.

STUDY DESIGN Retrospective descriptive study. OBJECTIVE To create topographical maps of occipital bone thickness and venous sinus (VS) presence to assess the risks of screw insertion in four commercially available occipital plates. SUMMARY OF BACKGROUND DATA Craniocervical junction instability and deformity are serious pathological conditions that require posterior fixation of the occipital bone to the cervical vertebrae. Insertion of occipital bone screws requires evaluation of both occipital bone thickness for effective internal fixation and intracranial venous sinus presence for vascular injury prevention. Despite the surgical risks, there is a paucity of research on safe screw placement. METHODS We created a matrix of 231 standardized measurement points to analyze the occipital bone thickness and venous sinus presence in cervical spine CT angiograms. These measurements were used to create topographical maps of occipital bone thickness and likelihood of venous sinus presence, which we then compared to the screw hole configurations of four occipital plates. RESULTS 100 patients were assessed. Maximum occipital bone thickness of 13.9 ± 3.3 mm was midline in the occipital bone, 45 mm from the foramen magnum, around the external occipital protuberance (EOP). Regions with thicknesses >8 mm were 2 cm lateral to the EOP at the level of the superior nuchal line and 2.5 cm inferior to the EOP. The area with the highest VS presence rate was around the EOP and the superior nuchal line. The right transverse VS was more prominent in both sexes. CONCLUSION There is a limited area of the occipital bone with thicknesses for enough screw purchase. Previous studies have shown 8 mm as the minimum screw length to reduce the risk of implant failure. In our analysis, only "T"-shaped plates had configurations with thicknesses >8 mm for each screw hole. For every screw hole in the analyzed occipital plates, there was a possibility of venous sinus presence ranging from 8-33%.Level of Evidence: 5.

This study aims to compare the early subsidence rate (6–12 months) of standalone novel 3D-printed titanium (Ti) versus polyetheretherketone (PEEK) interbody cages after lateral lumbar interbody fusion (LLIF). A retrospective study of 113 patients (186 levels) who underwent LLIF surgery with Ti or PEEK cages was conducted. Early subsidence was measured in each treated level using the Marchi et al. classification in radiographs or CT scans acquired at 6–12 months follow-up. Multivariate logistic regression analyses with generalized mixed models, setting subsidence as the outcome variable and including cage type (Ti vs PEEK) as well as significant and trending variables (p

Study design Retrospective observational study. Objectives To investigate the spinal cord safety margins for C2 instrumentation. Summary of background data Intraoperative spinal cord injury during C2 spine surgery is a rare, but potentially life-threatening complication. Pre-operative planning for C2 instrumentation mainly focuses on C2 pedicle bony dimensions on CT and the vertebral artery location and few studies have evaluated C2 spinal cord safety margins. Methods We measured two distances in C2 bilaterally: 1) C2 pedicle to dura distance (P-D), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and the dural sac, 2) C2 pedicle to spinal cord (P-SC), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and spinal cord. We defined the distances above 4 mm as safe for instrumentation. Result A total of 146 patients (mean age 71.2, 50.7% female) were included. The average distances were 5.5 mm for C2 left P-D, 5.9 mm for C2 right P-D, 10.1 mm for C2 left P-SC and 10.6 mm for C2 right P-SC. Twenty eight (21.4%) patients had C2 P-D distances under 4 mm and out of those 2 (7%) patients had distances under 2 mm. There were more female patients with C2 P-D distances under 4 mm compared to males. No patient had C2 P-SC distances under 4 mm. Conclusion We demonstrated that around 20% of patients had C2 P-D distance below 4 mm, but no patient had C2 P-SC distance less than 4 mm. Since a lateral misplacement can lead to a potentially fatal vertebral artery injury, medial screw trajectory is recommended for C2 pedicle instrumentation with consideration of these safety margins.Level of Evidence: 3.

The objective of this study is to determine the bone mineral density (BMD) changes in adjacent vertebra following anterior cervical discectomy and fusion (ACDF). Consecutive patients undergoing ACDF with available preoperative and postoperative computed tomography (CT) imaging were included. Quantitative CT measurements of screw-free cervical and first thoracic vertebra were performed. Comparisons between pre- and postoperative BMD in the vertebrae one or two levels above the upper instrumented vertebra (UIV + 1, UIV + 2) and one level below the lowest instrumented vertebra (LIV + 1) were assessed. Seventy-two patients (men, 66.7%) met the inclusion criteria. The patient population was 91.7% Caucasian with a mean age of 55.0 years. The mean interval (±SD) between surgery and secondary CT was 157 ± 23 days. Preoperative BMD (±SD) in UIV + 1 was 300.6 ± 66.2 mg/cm3 . There was a significant BMD loss of 1.5% at UIV + 1 after surgery, resulting in a postoperative BMD of 296.2 ± 64.8 mg/cm3 (p = .029). At UIV + 2 and LIV + 1, no significant differences between pre- and postoperative BMD (304.7 ± 75.7 mg/cm3 vs. 299.8 ± 74.3 mg/cm3 , 197.3 ± 50.4 mg/cm3 vs. 200.8 ± 48.7 mg/cm3 , p = .113 and p = .078, respectively) were observed. Clinical significance Our results demonstrate a small BMD decrease of 1.5% at UIV + 1. This suggests that the effect of ACDF surgery on the adjacent levels might be smaller compared to the previously described lumbar BMD loss of 10%-20% following posterior lumbar fusion procedures.

Retrospective cohort analysis.To elucidate trends in the utilization of intraoperative neuromonitoring (IONM) during elective anterior cervical decompression and fusion (ACDF) procedures in New York State using the Statewide Planning and Research Cooperative System (SPARCS) and to determine if utilization of IONM resulted in a reduction in postoperative neurologic deficits.IONM has been available to spinal surgeons for several decades. It has become increasingly prevalent in all facets of spinal surgery including elective ACDF procedures. The utility of IONM for preventing neurologic deficit in elective spine procedures has recently been called into question.The SPARCS database was accessed to perform a retrospective cohort study comparing monitored versus unmonitored ACDF procedures between 2007 to 2018 as defined by International Classification of Disease-9 and 10 Procedural Coding System (ICD-9 PCS, ICD-10 PCS) codes. Patient demographics, medical history, surgical intervention, pertinent in-hospital events, and urban versus rural medical center (as defined by the US Office of Management and Budget) were recorded. Propensity-score-matched (PSM) comparisons were used to identify factors related to the utilization of IONM and risk factors for neurologic deficits following elective ACDF.A total of 70,838 (15,092 monitored [21.3%] and 55,746 [78.7%] unmonitored) patients' data were extracted. The utilization of IONM since 2007 has increased in a linear fashion from 0.9% of cases in 2007 to 36.7% by 2018. Overall, baseline characteristics of patients who were monitored during cases differed significantly from unmonitored patients in age, race/ethnicity, insurance type, presence of myelopathy or radiculopathy, and Charlson Comorbidity Index (CCI); however, only race/ethnicity was statistically significant when analyzed using PSM. When comparing urban and rural medical centers, there is a significant lag in adoption of the technology with no monitored cases in rural centers until 2012 with significant fluctuations in utilization compared to steadily increasing utilization among urban centers. During 2017-2018 reporting of neurologic deficit after surgery resembled literature-established norms. Pooled analysis of these years revealed that incidence of neurological complication occurred more frequently in monitored cases than unmonitored (3.0% vs. 1.4%, P0.001).The utility of IONM for elective ACDF remains uncertain; however, it continues to gain popularity for routine cases. For medical centers that lack similar resources to centers in more densely populated regions of New York State, reliable access to this technology is not a certainty. In our analysis of intraoperative neurological complications, it appears that IONM is not protective against neurologic injury.

Background: Advanced glycation end products (AGEs) have been shown to accumulate in bone and are gaining interest in connective tissue research. Aims: To investigate the intrarater reliability, two-timepoint agreement and correlations within and between two commercially available skin autofluorescence (SAF) AGE devices. Methods: Healthy volunteers were enrolled in a prospective study at a single academic institution. Each participant underwent SAF analysis by two different, commercially available devices on two occasions, 14 days apart. Upon enrollment, a general survey about the participant’s lifestyle and health status was completed and followed up on for any changes at timepoint two. Results: In total, 40 participants (F:M ratio 5:3) with an average age of 39.0 ± 12.5 years were analyzed. For the AGE reader (skin) and AGE sensor (fingertip), both intrarater reliability and two-timepoint agreement were excellent with an interclass correlation coefficient (ICC) > 0.90 and a strong correlation within both machines. However, there was no correlation between both machines for either timepoint. In total, 4 participants were identified as outliers above the +2SD. Additionally, 5 participants with dark-colored skin could not be measured with the AGE reader at timepoint one and 4 at timepoint two. In contrast, all participants were able to undergo SAF analysis with the AGE sensor, irrespective of their skin type. Conclusions: Both machines showed excellent intrarater reliability and two-timepoint agreement, but the skin AGE reader might have limited applicability in individuals with dark-colored skin. Future research on AGEs might take our findings into consideration.

Anterior (ALIF) and lateral (LLIF) lumbar interbody fusion is associated with significant postoperative pain, opioid consumption and length of stay. Transversus abdominis plane (TAP) blocks improve these outcomes in other surgical subtypes but have not been applied to spine surgery. A retrospective study of 250 patients was performed to describe associations between TAP block and outcomes after ALIF/LLIF. The electronic medical records of 129 patients who underwent ALIF or LLIF with TAP block were compared to 121 patients who did not. All patients were cared for under a standardized perioperative care pathway with comprehensive multimodal analgesia. Differences in patent demographics, surgical factors, length of stay (LOS), opioid consumption, opioid-related side effects and pain scores were compared in bivariable and multivariable regression analyses. In bivariable analyses, TAP block was associated with a significantly shorter LOS, less postoperative nausea/vomiting and lower opioid consumption in the post-anesthesia care unit (PACU). In multivariable analyses, TAP block was associated with significantly shorter LOS (β − 12 h, 95% CI (− 22, − 2 h); p = 0.021). Preoperative opioid use was a strong predictive factor for higher opioid consumption in the PACU, opioid use in the first 24 h after surgery and longer LOS. We did not find significant differences in pain scores at any times between the groups. TAP block may represent an effective addition to pain management and opioid-reducing strategies and improve outcomes after ALIF/LLIF. Prospective trials are warranted to further explore these associations.

Background The preoperative assessment of C2 morphology is important for safe instrumentation. Sclerotic changes are often seen in C2 pedicles. Evaluating the diameter measurements solely might not accurately assess the safety of screw insertion. We have proposed a novel grading system of the C2 pedicle that includes sclerosis and evaluated the predictive value of this grading system with the surgeon's safety evaluation. Methods We reviewed and measured the dimensional values in 220 cervical computed tomography angiograms. Additionally, we used a grading system that divides the findings into 5 grades according to the width measurement and degree of sclerosis in the C2 pedicle. Two spine surgeons independently classified the pedicles as follows: safe (minimal risk of pedicle violation), caution needed (caution to minimize pedicle violation), or dangerous (a high risk of pedicle violation). Finally, we compared the measurements and the surgeons' safety assessments. Results A total of 411 pedicles of 203 patients (mean age, 69.5 years; 49.5% women) were included. Of the 411 C2 pedicles, 170 were classified as high risk by ≥1 surgeon. Between the dimensional measurements and grading system, the sclerotic grade showed the best predictive value. Conclusions We have introduced a novel tool to evaluate the safety of C2 pedicle screw placement. Our results suggest that our pedicle width–sclerosis grading system is reproducible and predicts the surgeon's assessment of safe screw placement better than C2 pedicle diametrical measurements alone.

Study DesignRetrospective clinical study.PurposeTo describe postoperative height changes and identify the predictive factors of spinal height (SH) changes among patients with adult spinal deformity (ASD) who underwent circumferential lumbar fusion with instrumentation.Overview of LiteraturePostoperative height changes remain an important issue after spinal fusion surgery that affects the overall satisfaction with surgery. Previous studies of postoperative height change have focused exclusively on young patients with adolescent idiopathic scoliosis (AIS).MethodsWe retrospectively reviewed the clinical and imaging data of ASD patients who underwent lumbar corrective circumferential fusion of ≥3 levels (n=106). SH was defined as the vertical distance between C2 and S1 on a standing lateral image. As potential predictors of postoperative height change, the number of lateral lumbar interbody fusion (LLIF) levels, change in spino-pelvic parameters, total number of levels fused, and pedicle subtraction osteotomies (PSO) were documented. Univariate and multivariate linear regression analyses were performed to identify the predictors of postoperative height change.ResultsThe mean SH change was −2.39±50.8 mm (range, −160 to 172 mm). The univariate analyses showed that the number of LLIF levels (coefficient=10.9, p=0.03), the absolute coronal vertical axis change (coefficient=0.6, p=0.01), and the absolute Cobb angle change (coefficient=−0.9, p=0.03) were significant predictors for height change. Patients with PSOs (n=14) tended to have a shorter height postoperatively (coefficient=−26.1); however, this difference was not significant (p=0.07). Multivariate analyses conducted with variables of pp=0.04, R2=0.11).ConclusionsUtilizing a modified definition of SH used in previous AIS studies, we demonstrated that patients with ASD lose SH postoperatively and that PT change was an independent contributor of SH change.

BackgroundErector spinae plane blocks are used to improve outcomes after spine surgery, but pain frequently outlasts the duration of single injection blocks. We hypothesized continuous erector spinae plane (cESP) catheters would provide superior analgesia. We terminated a prospective double-blinded randomized clinical trial (RCT) comparing outcomes after multilevel spine surgery among patients randomized to saline versus ropivacaine cESP catheters. We present two cases of undesired epidural spread of ropivacaine and discuss etiology, management, and future research directions.Case presentationNine out of 44 patients (planned) enrolled in the RCT; 6/9 were randomized to receive ropivacaine infusions via bilateral cESP catheters. Two patients underwent uncomplicated posterior lumbar fusion and were recovering well with minimal pain and opioid requirements through postoperative day 1. Both had new-onset urinary retention and bilateral lower extremity numbness, weakness and paresthesias (24 and 30 hours after infusion-start time, respectively). One patient underwent MRI, which was remarkable for an epidural fluid collection compressing the thecal sac. Infusions were stopped, cESP catheters were removed and symptoms fully resolved over the next 3–5 hours.ConclusionsUnwanted neuraxial spread of local anesthetic from cESP catheters may be a unique consideration after spine surgery, accounted for by unpredictable local anesthetic distribution within disrupted surgical planes. Future studies are indicated to determine optimal catheter regimens together with guidance for extended monitoring in parallel with further studies of efficacy in spine surgery cohorts.Trial registration numberNCT05494125.

The concept of sagittal spinal malalignment is well established in spinal surgery. However, the effect of musculature on its development has not been fully considered and the position of the pelvis is mostly seen as compensatory and not necessarily a possible cause of sagittal imbalance.This study aimed to investigate the influence of the posterior paraspinal muscles (PPM, erector spinae, and multifidus) and the psoas muscle on spinopelvic and spinal alignment.Retrospective cross-sectional study.Patients undergoing posterior lumbar fusion between 2014 and 2021 for degenerative conditions at a tertiary care center, with preoperative lumbar magnetic resonance imaging (MRI) within 12 months prior the surgery and a preoperative whole spine radiograph were included.PPM and psoas muscle measurements including the cross-sectional area (CSA), the functional cross-sectional area (fCSA), the amount of intramuscular fat (FAT), and the percentage of fat infiltration (FI). Spinopelvic measurements including lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), and sagittal vertical axis (SVA).A T2-weighted MRI-based quantitative assessment of the CSA, the fCSA and the amount FAT was conducted, and FI was further calculated. The regions of interest included the psoas muscle and the PPM on both sides at the L4 level that were summarized and normalized by the patient's height (cmA total of 150 patients (53.3% female) were included in the final analysis with a median age of 65.6 years and a median BMI of 28.2 kg/mThis study demonstrated the potential role of posterior paraspinal muscles and psoas muscle on pelvic retroversion and elucidated the relation to sagittal spinal malalignment. Although we cannot establish causality, we propose that increasing FI