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Background: The integration of artificial intelligence (AI), particularly large language models (LLMs) like ChatGPT-4, is transforming healthcare. ChatGPT's potential to assist in decision-making for complex cases, such as spinal metastasis treatment, is promising but widely untested. Especially in cancer patients who develop spinal metastases, precise and personalized treatment is essential. This study examines ChatGPT-4's performance in treatment planning for spinal metastasis cases compared to experienced spine surgeons. Materials and Methods: Five spine metastasis cases were randomly selected from recent literature. Consequently, five spine surgeons and ChatGPT-4 were tasked with providing treatment recommendations for each case in a standardized manner. Responses were analyzed for frequency distribution, agreement, and subjective rater opinions. Results: ChatGPT's treatment recommendations aligned with the majority of human raters in 73% of treatment choices, with moderate to substantial agreement on systemic therapy, pain management, and supportive care. However, ChatGPT's recommendations tended towards generalized statements, with raters noting its generalized answers. Agreement among raters improved in sensitivity analyses excluding ChatGPT, particularly for controversial areas like surgical intervention and palliative care. Conclusions: ChatGPT shows potential in aligning with experienced surgeons on certain treatment aspects of spinal metastasis. However, its generalized approach highlights limitations, suggesting that training with specific clinical guidelines could potentially enhance its utility in complex case management. Further studies are necessary to refine AI applications in personalized healthcare decision-making.

Introduction: The vertebral bone quality (VBQ) score that is based on non-contrast enhanced T1-weighted MRI was recently introduced as a novel measure of bone quality in the lumbar spine and shown to be a significant predictor of healthy versus osteopenic/osteoporotic bone., Research Question: This study aimed to assess possible correlations between the VBQ score and the functional cross-sectional area (FCSA) of psoas and lumbar spine extensor muscles., Material and Methods: Patients who underwent fusion surgery between 2014 and 2017 and had lumbar MRI and CT scans within 6 months prior to surgery were included. The FCSA was assessed at L3-L5 using a pixel intensity threshold method. The VBQ score was calculated by dividing the signal intensity (SI) of the vertebrae L1-L4 through the SI of the cerebrospinal fluid at L3. Volumetric bone mineral density (vBMD) was assessed by quantitative CT., Results: 80 patients (58.8% female, median age 68.8 years) were included. Overall prevalence of osteopenia/osteoporosis was 66.3%, with no significant differences between men and women. The mean (SD) VBQ score was significantly smaller in men, at 2.26 (0.45) versus women at 2.59 (0.39) ( p  = 0.001). After adjusting for age and BMI, a significant negative correlation was seen between the VBQ score and psoas FCSA at L3 ( β  = -0.373; p  = 0.022), but only in men., Conclusion: Our results highlight sex differences in the VBQ score that were not demonstrated by vBMD and suggest a potential role of this novel measure to assess not only bone quality, but also spinal muscle quantity., Competing Interests: Authors MM, LAS, DAA, LO, SNM, MM, HH, ETT, and JS have no relevant financial or non-financial interests to disclose. Author AAS declares financial interests: Royalties: Ortho Development, Corp.; Private Investments: Vestia Ventures; MiRUS Investment, LLC; ISPH II, LLC; ISPH 3, LLC; and VBros Venture Partners X, Centinel Spine; Consulting Fees: Clariance, Inc., Kuros Biosciences AG, Medical Device Business Service, Inc.; Speaking and Teaching Arrangements: DePuy Synthes Products, Inc.; Scientific Advisory Board: Clariance, Inc., and Kuros Biosciences AG; Trips/travel: Medical Device Business; Research Support: Spinal Kinetics, Inc. Author FPC declares financial interests: Royalties: Accelus; Private Investiments: Orthobond Corporation, Spine Biopharma, LLC; Healthpoint Capital Partners, LP; Tissue Differentiation Intelligence, LLC; VBVP VI, LLC; VBVP X, LLC; Woven Orthopedic Technologies; 4WEB Medical, Inc; ISPH II, LLC; ISPH 3 Holdings, LLC; Ivy Healthcare Capital Partners, LLC; Medical Device Partners II, LLC; Medical Device Partners III, LLC; Consulting Fees: Accelus, DePuy Synthes, 10.13039/100007064NuVasive, Inc; Spine Biopharma, LLC; Board Member: Medical Device Partners, LLC; Orthobond Corporation, Spine Biopharma, LLC; Woven Orthopedic Technologies; Healthpoint Capital Partners, LP; Research Support: 4WEB Medical, Inc; Camber Spine, Centinel Spine, 10.13039/100014468Mallinckrodt Pharmaceuticals. Author 10.13039/501100006131FPG declares financial interests: Royalties: 10.13039/100007064NuVasive, Inc.; Ortho Development Corp., DePuy Synthes Spine; Private Investments: Bonovo Orthopedics, Inc.; Healthpoint Capital Partners, LP; Tissue Differentiation Intelligence; BICMD; Consulting Fees: OrthoDevelopment Corp; Spineart USA, Inc.; 10.13039/100007064NuVasive, Inc; DePuy Synthes Spine; 10.13039/100009933Ethicon, Inc.; Advisory Board: Spineart USA, Inc.; Healthpoint Capital Partners, LP. Author 10.13039/501100015049APH declares financial interests: Research Support: 10.13039/100007064NuVasive, Inc.; Kuros Biosciences AG; Fellowship Support: 10.13039/100007064NuVasive, Inc.; Kuros Biosciences AG., (© 2023 The Authors.)

Background: The purpose of this study was to identify independent risk factors for incidental durotomy (ID) during decompressive lumbar spine surgery, and to describe its treatment., Methods: This retrospective review includes 650 patients who underwent lumbar decompression at a tertiary institution between January 2015 and October 2019. Data collection was obtained through one independent researcher. The incidence rate and treatment of ID was evaluated by a chart review of operative notes, patient charts, physiotherapy reports, and nursing reports., Results: The incidence rate of ID was 12.6%. The most common reason for admission was disc herniation (63.2%), followed by vertebral stenosis (22.1%). ID resulted in significantly longer operation time (P=0.0001) and length of hospitalization (P=0.0001). A correlation between ID and patient's diagnosis (P=0.0078) as well as the chosen type of surgery (P=0.0404) with an Odds Ratio to cause ID of 1.9 for laminectomy and 1.6 for undercutting compared to microdiscectomy were found. However, age, sex, surgeon experience, lumbar level, revision surgery, as well as multilevel surgery were not significantly correlated with the incidence of ID. Dural tears were closed with dural sealant (47.2%), polyester 4-0 sutures (11.1%) or a combination of both (37.5%) and the majority of patients had bed rest of at least two days. By usage of these treatment methods no patient needed reoperation., Conclusions: Diagnosis of vertebrostenosis as well as laminectomy were significantly correlated with the incidence of ID. Treatment with intraoperative closure and postoperative bed rest even though not standardized led to complication free outcomes.

Purpose: The vertebral bone quality (VBQ) score based on magnetic resonance imaging (MRI) was introduced as a bone quality marker in the lumbar spine. Prior studies showed that it could be utilized as a predictor of osteoporotic fracture or complications after instrumented spine surgery. The objective of this study was to evaluate the correlation between VBQ scores and bone mineral density (BMD) measured by quantitative computer tomography (QCT) in the cervical spine., Methods: Preoperative cervical CT and sagittal T1-weighted MRIs from patients undergoing ACDF were retrospectively reviewed and included. The VBQ score in each cervical level was calculated by dividing the signal intensity of the vertebral body by the signal intensity of the cerebrospinal fluid on midsagittal T1-weighted MRI images and correlated with QCT measurements of the C2-T1 vertebral bodies. A total of 102 patients (37.3% female) were included., Results: VBQ values of C2-T1 vertebrae strongly correlated with each other. C2 showed the highest VBQ value [Median (range) 2.33 (1.33, 4.23)] and T1 showed the lowest VBQ value [Median (range) 1.64 (0.81, 3.88)]. There was significant weak to moderate negative correlations between and VBQ Scores for all levels [C2: p < 0.001; C3: p < 0.001; C4: p < 0.001; C5: p < 0.004; C6: p < 0.001; C7: p < 0.025; T1: p < 0.001]., Conclusion: Our results indicate that cervical VBQ scores may be insufficient in the estimation of BMDs, which might limit their clinical application. Additional studies are recommended to determine the utility of VBQ and QCT BMD to evaluate their potential use as bone status markers., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: The sole determination of volumetric bone mineral density (vBMD) is insufficient to evaluate overall bone integrity. The accumulation of advanced glycation endproducts (AGEs) stiffens and embrittles collagen fibers. Despite the important role of AGEs in bone aging, the relationship between AGEs and vBMD is poorly understood. We hypothesized that an accumulation of AGEs, a marker of impaired bone quality, is related to decreased vBMD., Methods: Prospectively collected data of 127 patients undergoing lumbar fusion were analyzed. Quantitative computed tomography (QCT) measurements were performed at the lumbar spine. Intraoperative bone biopsies were obtained and analyzed with confocal fluorescence microscopy for fluorescent AGEs, both trabecular and cortical. Spearman's correlation coefficients were calculated to examine relationships between vBMD and fAGEs, stratified by sex. Multivariable linear regression analysis with adjustments for age, sex, body mass index (BMI), race, diabetes mellitus and HbA1c was used to investigate associations between vBMD and fAGEs., Results: One-hundred and twenty-seven patients (51.2% female, 61.2 years, BMI of 28.7 kg/m 2 ) with 107 bone biopsies were included in the final analysis, excluding patients on anti-osteoporotic drug therapy. In the univariate analysis, cortical fAGEs increased with decreasing vBMD at (r = -0.301; p = 0.030), but only in men. In the multivariable analysis, trabecular fAGEs increased with decreasing vBMD after adjusting for age, sex, BMI, race, diabetes mellitus and HbA1c (β = 0.99;95%CI=(0.994,1.000); p = 0.04)., Conclusion: QCT-derived vBMD measurements were found to be inversely associated with trabecular fAGEs. Our results enhance the understanding of bone integrity by suggesting that spine surgery patients with decreased bone quantity may also have poorer bone quality., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Lumbar fusion surgery has become a standard procedure in spine surgery and commonly includes the posterior placement of pedicle screws. Bone quality is a crucial factor that affects pedicle screw purchase. However, the relationship between paraspinal muscles and the bone quality of the pedicle is unknown. The aim of the study was to determine the relationship between paraspinal muscles and the ex vivo bony microstructure of the lumbar pedicle., Methods: Prospectively, collected data of patients undergoing posterior lumbar fusion for degenerative spinal conditions was analyzed. Pre-operative lumbar magnetic resonance imaging (MRI) scans were evaluated for a quantitative assessment of the cross-sectional area (CSA), functional cross-sectional area (fCSA), and the proportion of intramuscular fat (FI) for the psoas muscle and the posterior paraspinal muscles (PPM) at L4. Intra-operative bone biopsies of the lumbar pedicle were obtained and analyzed with microcomputed tomography (µCT) scans. The following cortical (Cort) and trabecular (Trab) bone parameters were assessed: bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), connectivity density (CD), bone-specific surface (BS/BV), apparent density (AD), and tissue mineral density (TMD)., Results: A total of 26 patients with a mean age of 59.1 years and a mean BMI of 29.8 kg/m 2 were analyzed. fCSA PPM showed significant positive correlations with BV/TV Trab (ρ = 0.610; p < 0.001), CD Trab (ρ = 0.679; p < 0.001), Tb.N Trab (ρ = 0.522; p = 0.006), Tb.Th Trab (ρ = 0.415; p = 0.035), and AD Trab (ρ = 0.514; p = 0.007). Cortical bone parameters also demonstrated a significant positive correlation with fCSA PPM (BV/TV Cort : ρ = 0.584; p = 0.002; AD Cort : ρ = 0.519; p = 0.007). FI Psoas was negatively correlated with TMD Cort (ρ =  - 0.622; p < 0.001)., Conclusion: This study highlights the close interactions between the bone microstructure of the lumbar pedicle and the paraspinal muscle morphology. These findings give us further insights into the interaction between the lumbar pedicle microstructure and paraspinal muscles., (© 2022. The Author(s) under exclusive licence to SICOT aisbl.)

Osteosarcopenia is a common condition among elderly and postmenopausal female patients. Site-specific bone mineral density is more predictive of bone-related complications. Few studies have investigated muscle-bone associations. Our results demonstrated that in women, significant positive associations between paraspinal muscles FCSA and vBMD exist at different lumbosacral levels. These regional differences should be considered when interpreting bone-muscle associations in the lumbar spine., Introduction: There is increasing evidence between bone and muscle volume associations. Previous studies have demonstrated comorbidity between osteoporosis and sarcopenia. Recent studies showed that sarcopenic subjects had a fourfold higher risk of concomitant osteoporosis compared to non-sarcopenic individuals. Although site-specific bone mineral density (BMD) assessments were reported to be more predictive of bone-related complications after spinal fusions than BMD assessments in general, there are few studies that have investigated level-specific bone-muscle interactions. The aim of this study is to investigate the associations between muscle functional cross-sectional area (FCSA) on magnetic resonance imaging (MRI) and site-specific quantitative computed tomography (QCT) volumetric bone mineral density (vBMD) in the lumbosacral region among spine surgery patients., Methods: We retrospectively reviewed a prospective institutional database of posterior lumbar fusion patients. Patients with available MRI undergoing posterior lumbar fusion were included. Muscle measurements and FCSA were conducted and calculated utilizing a manual segmentation and custom-written program at the superior endplate of the L3-L5 vertebrae level. vBMD measurements were performed and calculated utilizing a QCT pro software at L1-L2 levels and bilateral sacral ala. We stratified by sex for all analyses., Results: A total of 105 patients (mean age 61.5 years and 52.4% females) were included. We found that female patients had statistically significant lower muscle FCSA than male patients. After adjusting for age and body mass index (BMI), there were statistically significant positive associations between L1-L2 and S1 vBMD with L3 psoas FCSA as well as sacral ala vBMD with L3 posterior paraspinal and L5 psoas FCSA. These associations were not found in males., Conclusions: Our results demonstrated that in women, significant positive associations between the psoas and posterior paraspinal muscle FCSA and vBMD exist in different lumbosacral levels, which are independent of age and BMI. These regional differences should be considered when interpreting bone and muscle associations in the lumbar spine., (© 2022. International Osteoporosis Foundation and National Osteoporosis Foundation.)

Study Design: A retrospective cross-sectional study., Objective: To assess the association between spinal muscle morphology and spinopelvic parameters in lumbar fusion patients, with a special emphasis on lumbar lordosis (LL)., Summary of Background Data: Maintenance of sagittal alignment relies on muscle forces, but the basic association between spinal muscles and spinopelvic parameters is poorly understood., Materials and Methods: Patients operated between 2014 and 2017 who had both lumbar magnetic resonance imaging scan and standing whole-spine radiographs within six months before surgery were included. Muscle measurements were conducted on axial T2-weighted magnetic resonance images at the superior endplate L3-L5 for the psoas and L3-S1 for combined multifidus and erector spinae (paraspinal) muscles. A pixel intensity threshold method was used to calculate the total cross-sectional area (TCSA) and the functional cross-sectional area (FCSA). Spinopelvic parameters were measured on lateral standing whole-spine radiographs and included LL, pelvic incidence (PI), PI-LL mismatch, pelvic tilt, sacral slope, thoracic kyphosis, and sagittal vertical axis. Analyses were stratified by biological sex. Multivariable linear regression analyses with adjustments for age and body mass index (BMI) were performed., Results: A total of 104 patients (62.5% female) were included in the analysis. The patient population was 90.4% White with a median age at surgery of 69 years and a median BMI of 27.8 kg/m 2 . All muscle measurements were significantly smaller in women. PI, pelvic tilt, and thoracic kyphosis were significantly greater in women. PI-LL mismatch was 6.1° (10.6°) in men and 10.2° (13.5°) in women ( P =0.106), and sagittal vertical axis was 45.3 (40.8) mm in men and 35.7 (40.8) mm in women ( P =0.251). After adjusting for age and BMI, paraspinal TCSA at L3-L5, and paraspinal FCSA at L4 showed significant positive associations with LL in women. In men, psoas TCSA at L5 and psoas FCSA at L5 showed significant negative associations with LL, but none of the paraspinal muscle measurements., Conclusion: Our findings indicate that psoas and lumbar spine extensor muscles interact differently on LL among men and women, creating a unique mechanical environment., Level of Evidence: Level 4., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Background Context: The importance of bone status assessment in spine surgery is well recognized. The current gold standard for assessing bone mineral density is dual-energy X-ray absorptiometry (DEXA). However, DEXA has been shown to overestimate BMD in patients with spinal degenerative disease and obesity. Consequently, alternative radiographic measurements using data routinely gathered during preoperative evaluation have been explored for the evaluation of bone quality and fracture risk. Opportunistic quantitative computed tomography (QCT) and more recently, the MRI-based vertebral bone quality (VBQ) score, have both been shown to correlate with DEXA T-scores and predict osteoporotic fractures. However, to date the direct association between VBQ and QCT has not been studied., Purpose: The objective of this study was to evaluate the correlation between VBQ and spine QCT BMD measurements and assess whether the recently described novel VBQ score can predict the presence of osteopenia/osteoporosis diagnosed with QCT., Study Design/setting: Cross-sectional study using retrospectively collected data., Patient Sample: Patients undergoing lumbar fusion from 2014-2019 at a single, academic institution with available preoperative lumbar CT and T1-weighted MRIs were included., Outcome Measures: Correlation of the VBQ score with BMD measured by QCT, and association between VBQ score and presence of osteopenia/osteoporosis., Methods: Asynchronous QCT measurements were performed. The average L1-L2 BMD was calculated and patients were categorized as either normal BMD (>120 mg/cm 3 ) or osteopenic/osteoporotic (≤120 mg/cm 3 ). The VBQ score was calculated by dividing the median signal intensity of the L1-L4 vertebral bodies by the signal intensity of the cerebrospinal fluid on midsagittal T1-weighted MRI images. Inter-observer reliability testing of the VBQ measurements was performed. Demographic data and the VBQ score were compared between the normal and osteopenic/osteoporotic group. To determine the area-under-curve (AUC) of the VBQ score as a predictor of osteopenia/osteoporosis receiver operating characteristic (ROC) analysis was performed. VBQ scores were compared with QCT BMD using the Pearson's correlation., Results: A total of 198 patients (53% female) were included. The mean age was 62 years and the mean BMI was 28.2 kg/m 2 . The inter-observer reliability of the VBQ measurements was excellent (ICC of 0.90). When comparing the patients with normal QCT BMD to those with osteopenia/osteoporosis, the patients with osteopenia/osteoporosis were significantly older (64.9 vs. 56.7 years, p<.0001). The osteopenic/osteoporotic group had significantly higher VBQ scores (2.6 vs. 2.2, p<.0001). The VBQ score showed a statistically significant negative correlation with QCT BMD (correlation coefficient = -0.358, 95% CI -0.473 - -0.23, p<.001). Using a VBQ score cutoff value of 2.388, the categorical VBQ score yielded a sensitivity of 74.3% and a specificity of 57.0% with an AUC of 0.7079 to differentiate patients with osteopenia/osteoporosis and with normal BMD., Conclusions: We found that the VBQ score showed moderate diagnostic ability to differentiate patients with normal BMD versus osteopenic/osteoporotic BMD based on QCT. VBQ may be an interesting adjunct to clinically performed bone density measurements in the future., Competing Interests: Declarations of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2022 Elsevier Inc. All rights reserved.)

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/cm 3 . 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/cm 3 (p = .029). At UIV + 2 and LIV + 1, no significant differences between pre- and postoperative BMD (304.7 ± 75.7 mg/cm 3 vs. 299.8 ± 74.3 mg/cm 3 , 197.3 ± 50.4 mg/cm 3 vs. 200.8 ± 48.7 mg/cm 3 , 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., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Study Design: Retrospective descriptive study., Objective: The aim of this study was 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 VS 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 VS presence in cervical spine CT angiograms. These measurements were used to create topographical maps of occipital bone thickness and likelihood of VS presence, which we then compared to the screw hole configurations of four occipital plates., Results: Hundred 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 VS presence ranging from 8% to 33%.Level of Evidence: 5., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Study Design: Retrospective observational study., Objective: The aim of this study was 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. Preoperative 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: 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, and 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 >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 PD, 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 <4 mm and of those two (7%) patients had distances <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 <4 mm., Conclusion: We demonstrated that around 20% of patients had C2 P-D distance <4 mm, but no patient had C2 P-SC distance <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., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: 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., Methods: 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., Results: 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., Conclusion: 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., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background Context: The thoracic spine is a common location for vertebral fractures as well as instrumentation failure after long spinal fusion procedures. The association between those complications and bone mineral density (BMD) are well recognized. Due to the overlying sternum and ribs in the thoracic spine, projectional BMD assessment tools such as dual energy x-ray absorptiometry (DXA) are limited to the lumbar spine. Quantitative computed tomography circumvents several shortcomings of DXA and allows for level-specific BMD measurements. Studies comprehensively quantifying BMD of the entire thoracic spine in patients undergoing spine surgery are limited., Purpose: The objective of this study was: (1) to assess the reliability of thoracic QCT measurements, (2) to determine possible level-specific BMD variation throughout the thoracic spine and (3) to assess the correlation between BMDs of the T1-T12 spinal levels., Study Design/setting: Cross-sectional observation study., Patient Sample: Patients undergoing spine surgery from 2016-2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study., Outcome Measures: The outcome measure was BMD measured by QCT., Methods: Patients undergoing spine surgery from 2016-2020 at a single, academic institution with available preoperative CT imaging of the thoracic spine were included in this study. Subjects with previous instrumentation at any thoracic level, concurrent vertebral fractures, a Cobb angle of more than 20 degrees, or incomplete thoracic spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of T1-T12 were performed. To assess inter- and intra-observer reliability, a validation study was performed on 120 vertebrae in 10 randomly selected patients. The interclass correlation coefficient (ICC) was calculated. A pairwise comparison of BMD was conducted and correlations between each thoracic level were evaluated. The statistical significance level was set at p<.05., Results: 60 patients (men, 51.7%) met inclusion criteria. The study population was 90% Caucasian with a mean age of 62.2 years and a mean BMI of 30.2 kg/m 2 . The inter- and intra-observer reliability of the thoracic QCT measurements was excellent (ICC of 0.97 and 0.97, respectively). The trabecular BMD was highest in the upper thoracic spine and decreased in the caudal direction (T1 = 182.3 mg/cm 3 , T2 = 168.1 mg/cm 3 , T3 = 163.5 mg/cm 3 , T4 = 164.7 mg/cm 3 , T5 = 161.4 mg/cm 3 , T6 = 152.5 mg/cm 3 , T7 = 143.5 mg/cm 3 , T8 = 141.3 mg/cm 3 , T9 = 143.5 mg/cm 3 , T10 = 145.1 mg/cm 3 , T11 = 145.3 mg/cm 3 , T12 = 133.6 mg/cm 3 ). The BMD of all thoracic levels cranial to T6 was statistically higher than the BMD of all levels caudal to T6 (p < .001). Nonetheless, significant correlations in BMD among all measured thoracic levels were observed, with a Pearson's correlation coefficient ranging from 0.74 to 0.97., Conclusions: There is significant regional BMD variation in the thoracic spine depending on spinal level. This BMD variation might contribute to several clinically relevant phenomena. First, vertebral fractures occur most commonly at the thoracolumbar junction including T12. In addition to mechanical reasons, these fractures might be partially attributed to thoracic BMD that is lowest at T12. Second, the optimal upper instrumented vertebra (UIV) for stopping long fusions to the sacrum and pelvis is controversial. The BMD of surgically relevant upper thoracic stopping points (T2-T4) was significantly higher than the BMD of lower thoracic stopping points (T10-T12). Besides stress concentration at the relatively mobile lower thoracic segments, the low BMD at these levels might contribute to previously suggested higher rates of junctional failures with short fusions., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Anterior cervical discectomy and fusion (ACDF) is a safe and effective procedure but has approach-related complications like postoperative dysphagia and dysphonia (PDD). Patient-reported outcome measures including the Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) have been used for the assessment of PDD. Various factors have been described that affect ACDF outcomes, and our aim was to investigate the effect of workers' compensation (WC) status., Methods: We included patients who underwent ACDF from 2015 to 2018 stratified according to insurance status: WC/non-WC. PDDs were assessed using the HSS-DDI score. We conducted logistic regression analyses. Statistical significance was set at P < 0.05., Results: We included 287 patients, 44 (15.33%) WC and 243 (84.67%) non-WC. A statistical comparison revealed a clinically relevant difference in the HSS-DDI total score and both subdomains (P = 0.015; dysphagia P = 0.021; dysphonia P = 0.002). Additional logistic regression analysis adjusting for preoperative Neck Disability Index scores resulted in no clinically relevant differences in the HSS-DDI total score and both subdomains (total score P = 0.420; dysphagia P = 0.531; dysphonia 0.315)., Conclusions: WC status was associated with a worse HSS-DDI score but could not be shown to be an independent risk factor for PDD. The preoperative NDI score was a strong predictor for PDD with a clinically relevant difference in the HSS DDI score (P < 0.0001). Surgeon awareness of risk factors for PDD such as WC status, even if it could not be shown as independent, is important as it may influence surgical decision making and managing patient expectations., (Copyright © 2021. Published by Elsevier Inc.)

Background Context: It has been reported in previous studies that a decreased bone mineral density (BMD) as measured by dual X-ray absorptiometry (DXA) is associated with subsidence. However, there is limited research on the role of volumetric BMD (vBMD) as measured by quantitative computed tomography (QCT). Further, metabolic conditions such as obesity and type 2 diabetes have been associated with poor bone quality, but the impact of these metabolic conditions on on subsidence rates following lateral lumbar interbody fusion (LLIF) remains unclear. As such, risk factors for subsidence following LLIF is an area of ongoing research., Purpose: The purpose of this study is to identify risk factors for subsidence following LLIF with a focus on metabolic conditions and vBMD as measured by QCT., Study Design/setting: Retrospective cohort study at a single academic institution., Patient Sample: Consecutive patients undergoing LLIF with or without posterior screws from 2014 to 2019 at a single academic institution who had a pre-operative CT and radiological imaging including radiographs or CT scans between 5 and 14 months post-operatively to assess for cage subsidence., Outcome Measure: Subsidence prevalence following LLIF., Methods: We reviewed patients undergoing LLIF with or without posterior screws from 2014 to 2019 with a follow-up ≥5 months. Cage subsidence was assessed using the grading system by Marchi et al. Endplate volumetric BMD (EP-vBMD), vertebral bone volumetric BMD (VB-vBMD), BMI, and diabetes status were measured. Univariable analysis and multivariable logistic regression analyses with a generalized mixed model were conducted. Ad hoc analysis, including receiver operative characteristic curve analysis, was used for identifying the cut-off values in significant continuous variables for subsidence. Chi-Squared and ANOVA tests were used for categorical comparisons., Results: Five hundred sixty-seven levels in 347 patients were included in the final analysis. Mean age (± SD) was 61.7 ± 11.1yrs, 50.3% were male, and 89.6% were Caucasian. Subsidence was observed in 160 levels (28.2%). Multivariable analysis demonstrated an absence of posterior screws [OR = 2.854 (1.483 - 5.215), p=.001] and decreased EP-vBMD [0.996 (0.991 - 1.000), p=.032] were associated with an increased risk of subsidence. Increased BMI and diabetes status were not associated with increased rates of subsidence. Patients without posterior screws and low EP-vBMD experienced subsidence at 44.9% of levels., Conclusions: Our results demonstrated that decreased EP-vBMD and standalone status were significantly associated with increased rates of subsidence following LLIF independent of BMI or diabetes status. Further analysis demonstrated that patients with a decreased EP-vBMD and without posterior screws experienced subsidence nearly 2.5 times higher than patients with no risk factors. In patients with a low EP-vBMD undergoing LLIF, posterior screws should be considered., (Copyright © 2021 Elsevier Inc. All rights reserved.)

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.

Background Context: Postoperative dysphagia and dysphonia (PDD) are prevalent complications after anterior cervical discectomy and fusion (ACDF). Identification of risk factors for these complications is necessary for effective prevention. Recently, patient reported outcome measures (PROM) have been used to determine PDD after ACDF. The Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) is a validated PROM that specifically assesses dysphagia and dysphonia after anterior cervical spine surgery., Purpose: To identify the perioperative risk factors for PDD utilizing the HSS-DDI., Study Design/setting: Observational study of prospectively collected data at a single academic institution., Patient Sample: Patients undergoing anterior cervical discectomy and fusion from 2015 to 2019 who enrolled in the prospective data collection., Outcome Measure: The HSS-DDI administered 4 weeks, 8 weeks, and 4-6 months after surgery., Methods: As potential risk factors, the data on demographic factors, analgesic medications, history of psychiatric illness, preoperative sagittal alignment, surgical factors, preoperative diagnoses, and preoperative Neck Disability Index (NDI) scores were collected. Bivariate and multivariable regression analyses utilizing the Tobit model were conducted., Results: 291 patients were included in the final analysis. The median HSS-DDI at 4-weeks, 8 weeks, and 4-6 months postoperatively, were 80.7, 92.7, and 98.4, respectively. Multivariable analysis demonstrated that current smoking, previous cervical spine surgery, preoperative C2-7 angle, upper level surgery, multilevel surgery, opioid use, and a high preoperative NDI score, were independent contributing factors to a low HSS-DDI score at 4-weeks follow-up. Intraoperative topical steroid use was an independent protective factor for a low HSS-DDI score. Opioid use and high NDI score remained independent factors at 4-6 months. Sub-domain analysis demonstrated that prior cervical surgery, preoperative C2-7 angle, multilevel surgery, and intraoperative topical steroid use were significant for dysphagia only. Current smoking was significant for dysphonia only., Conclusions: Our results showed that preoperative opioid use and a high preoperative NDI score are novel independent risk factors for postoperative dysphagia and dysphonia in addition to other known factors., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: We measured the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) immunoglobulin G (IgG) antibodies among surgeons and anesthesiologists and associated antibody status with coronavirus disease 2019 (COVID-19) clinical illness., Methods: A cross-sectional study of SARS-CoV-2 IgG seroprevalence with a survey assessing demographics, SARS-CoV-2 exposure risk, and COVID-19 illness. The primary outcome was the period prevalence of SARS-CoV-2 IgG antibodies associated with COVID-19 illness., Results: One hundred forty three surgeons and anesthesiologists completed both serology and survey testing. We found no significant relationships between antibody status and clinical role (anesthesiologist, surgeon), mode of commuting to work, other practice settings, or place of residence. SARS-CoV-2 IgG seroprevalence was 9.8%. Positive IgG status was highly correlated with presence of symptoms of COVID-19 illness., Conclusions: These results suggest the relative safety of surgeons and anesthesiologists where personal protective equipment (PPE) is available and infection control protocols are implemented., Competing Interests: Conflict of Interest: None declared., (Copyright © 2021 American College of Occupational and Environmental Medicine.)

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., (Copyright © 2021. Published by Elsevier Inc.)

Study Design: Retrospective clinical study., Purpose: To 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 Literature: Postoperative 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)., Methods: We 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., Results: The 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 p<0.20 showed that pelvic tilt (PT) change is an independent contributor to SH change (coefficient=-0.99, p=0.04, R2=0.11)., Conclusions: Utilizing 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.

Lateral lumbar interbody fusion (LLIF) and pedicle subtraction osteotomy are common procedures to correct adult spinal deformities. Little is known about returning postoperatively to a high-performance sport such as skiing after spinal surgery. We report a case of an alpine skier who underwent a LLIF procedure combined with a posterior corrective osteotomy and posterior instrumentation, who had difficulties returning to skiing postoperatively because of new spinal biomechanics. The case report describes the possible consequences of spinal sagittal deformity surgery on postoperative skiing. A 63-year-old man with a complex lumbar spinal surgery history showed severe adjacent segment degenerative spondylolistheses at L1-L2 and at L5-S1. A lateral approach at L1-L2 combined with a posterior corrective osteotomy at L3 and instrumentation from T10 to the pelvis were performed. At his 1-year follow up, he made excellent progress and returned to skiing. However, he reported that skiing did not feel the same, and his center of gravity felt as if it shifted backwards. Consequently, he placed a 2-cm wedge in his ski binding, which improved his skiing experience. Sagittal vertical axis changes after spinal surgery affect the biomechanics of the entire body. After surgery, the body's ligaments, muscles, and fascia adapt to the new body posture. Activities such as skiing, where body posture plays an essential role, are particularly affected by spine surgeries. Surgeons should discuss this issue before spinal surgery with patients, especially if patients are involved in high-intensity sports., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2020 ISASS.)

Purpose: High body mass index (BMI) is positively correlated with bone mineral density (BMD) in healthy adults; however, the effect of BMI on regional segmental BMDs in the axial skeleton is unclear. In addition, obese patients often have glucose intolerance and patients with lumbar spine pathology commonly have a history of epidural steroid injections (ESIs). The purpose of this study is to evaluate the effect of these patient factors on regional differences in BMD measured by quantitative computed tomography (QCT) in a lumbar fusion patient cohort., Methods: The data were obtained from a database comprised of clinical and preoperative CT data from 296 patients who underwent primary posterior lumbar spinal fusion from 2014 to 2017. QCT-vBMDs of L1 to L5, S1 body, and sacral alae were measured. Multivariate linear regression analyses were performed with setting vBMDs as the response variables. As explanatory variables, age, sex, race, current smoking, categorized BMI, diabetes, and ESI were chosen a priori., Results: A total of 260 patients were included in the final analysis. Multivariate analyses demonstrated that obese and morbidly obese patients had significantly higher vBMD in the sacral alae (SA). Diabetes showed independent positive associations with vBMDs in L1, L2, and the SA. Additionally, patients with an ESI history demonstrated significantly lower vBMD in the SA., Conclusions: Our results demonstrate that obesity, diabetes, and epidural steroids affected vBMD differently by lumbosacral spine region. The vBMD of the SA appeared to be more sensitive to various patient factors than other lumbar regions.

Study Design: Retrospective case series., Objective: The aim of this study was to investigate the association of Modic type endplate changes with the risk of severe subsidence after standalone lateral lumbar interbody fusion (SA-LLIF)., Summary of Background Data: It has been reported that certain endplate radiolographic features are associated with higher regional bone mineral density (BMD) in the adjacent vertebrae in the lumbar spine. It remains unclear whether these changes have protective effects against osteoporotic complications such as cage subsidence after lumbar surgery., Methods: We reviewed patients undergoing SA-LLIF from 2007 to 2016 with a follow-up >6 months. Cage subsidence was assessed utilizing the grading system by Marchi et al. As potential contributing factors for cage subsidence, we measured the endplate volumetric BMD (EP-vBMD) and the standard trabecular volumetric BMD measurement in the vertebral body. Modic changes (MC) on magnetic resonance imaging were measured as a qualitative factor for endplate condition. Univariate analysis and multivariate logistic regression analyses with a generalized mixed model were conducted., Results: Two hundred six levels in 97 patients were included in the final analysis. Mean age (± SD) was 66.7 ± 10.7. Sisty-sdpercent of the patients were female. Severe subsidence was observed in 66 levels (32.0%). After adjusting for age, bone morphogenetic protein (BMP) use, and number of levels fused, the presence of MC type 2 was significantly associated with lower risk of severe subsidence (OR = 0.28 [0.09-0.88], P = 0.029). Whereas, EP-vBMD did not demonstrate a statistical significance (p = 0.600)., Conclusion: The presence of a Modic type 2 change was significantly associated with lower odds of severe subsidence after SA-LLIF. Nonetheless, this significant association was independent from regional EP-vBMD values. This finding suggests that microstructural and/or material property changes associated with Modic type 2 changes might have a protective effect in this patient population., Level of Evidence: 4.

Purpose: The purpose of this study is to investigate the predictive value of the hyoid horizontal positional change on the severity of dysphagia and dysphonia (PDD) after anterior cervical discectomy and fusion (ACDF) comparing pre-vertebral soft-tissue thickness (PVST)., Methods: This is a retrospective observational study with prospectively collected data at a single academic institution. ACDF patients between 2015 to 2018 who had complete self-reported PDD surveys and pre- and postoperative lateral cervical radiographs were included in the analysis. PDD was assessed utilizing the Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI). The hyoid-vertebral distance (HVD) and PVST (the averages of C2 to C7 levels (PVSTC2-7) and all operating levels (PVSTOP)) were assessed preoperatively and upon discharge. The associations among postoperative changes of HVD, PVSTs, and the 4-week HSS-DDI score were evaluated., Results: Of the 268 patients with a HSS-DDI score assessment, 209 patients had complete data. In univariate analyses, HVD and PVSTC2-7 changes demonstrated significant correlations with HSS-DDI, whereas PVSTOP showed no significant association. After adjusting with sex and operating level, the changes in HVD (p = 0.019) and PVSTC2-7 (p = 0.009) showed significant associations with the HSS-DDI score and PVSTOP showed no significant association. PVSTC2-7 could not be evaluated in 12% of patients due to measurement difficulties of PVST at lower levels., Conclusion: We introduce a novel potential predictive marker for PDD after ACDF. Our results suggest that HVD can be utilized for the risk assessment of PDD, especially in PVST unmeasurable cases, which accounts for over 10% of ACDF patients.

Background: Postoperative dysphagia is a common complication after anterior cervical surgery, and it can be measured using patient-reported outcome measures (PROMs). The Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) is a condition-specific PROM to evaluate dysphagia and dysphonia after anterior cervical discectomy and fusion (ACDF). The minimum clinically important difference (MCID) of the HSS-DDI has not, to our knowledge, been established. Other PROMs have been used to assess dysphagia (SWAL-QOL and MD Anderson Dysphagia Inventory [MDADI]) in ACDF. Currently, few studies have addressed the MCIDs of these PROMs., Questions/purposes: To determine (1) the minimum detectable changes (MDC) of the HSS-DDI, SWAL-QOL, and MDADI using a distribution-based approach, and (2) the MCID of the HSS-DDI, SWAL-QOL, and MDADI, using an anchor-based approach., Methods: We used a longitudinally maintained database that was originally established for the HSS-DDI development and validation study. In all, 323 patients who underwent elective ACDF were assessed for enrollment eligibility; 83% (268 of 323) met the inclusion criteria and completed the HSS-DDI Week 4 survey. We set six outcomes: distribution-based MDCs for the (1) HSS-DDI, (2) SWAL-QOL, (3) MDADI, in addition to anchor-based MCIDs for the (4) HSS-DDI, (5) SWAL-QOL, and (6) MDADI. The HSS-DDI consists of 31 questions and ranges 0 (worst) to 100 (normal). We used the focused SWAL-QOL, which consists of 14 selected items from the original SWAL-QOL and ranges from 0 (worst) to 100 (normal). The MDADI is a 20-item survey and ranges from 20 (worst) to 100 (normal). A distribution-based approach is used to calculate values defined as the smallest difference above the measurement error. An anchor-based approach is used to determine the MCIDs based on an external scale, called an anchor, which indicates the minimal symptom change that is considered clinically important. All 268 patients were used for the distribution-based (0.5 SD) HSS-DDI MDC analysis. The first 16% (44 of 268) of patients completed retesting of the HSS-DDI via a telephone interview and were used for another distribution-based (standard error of measurement: SEM) MDC analysis. The number of patients for the test-retest group was determined based on the previously reported minimum required sample size of reliability studies. The first 63% (169 of 268, SWAL-QOL and 168 of 268, MDADI) of patients completed two other surveys for the external validation of the HSS-DDI, and were used for the SWAL-QOL and MDADI 0.5 SD analyses. Among the patients, 86% (230 of 268) completed the Week 8 HSS-DDI survey that was used for the anchor-based HSS-DDI MCID analysis, and 56% (SWAL-QOL, 150 of 268 and MDADI, 151 of 268) of patients completed the Week 8 surveys that were used for the SWAL-QOL and MDADI MCID analyses. Subjective improvement grades from the previous assessment were used as the anchor. The MCIDs were calculated as the mean score changes among those who reported little better or greater in the improvement assessment and receiver operating characteristic (ROC) curve analyses. We adopted the higher value of these two as the MCID for each PROM., Results: The distribution-based MDCs for the HSS-DDI total score, SWAL-QOL, and MDADI were 11 of 100, 9 of 100, and 8 of 80 points, respectively, using the 0.5 SD method. Using the SEM-based method, the MDC for the HSS-DDI total score was 9 of 100 points. Regarding the anchor-based MCIDs, the values calculated with the mean score change method were consistently higher than those of ROC analysis and were adopted as the MCIDs. The MCIDs were 10 for the total HSS-DDI total score, 8 for the SWAL-QOL, and 6 for the MDADI., Conclusions: Improvements of less than 10 points for the HSS-DDI score, 9 points for the SWAL-QOL, and 6 points for the MDADI are unlikely to be perceived by patients to be clinically important. Future studies on dysphagia after anterior cervical surgery should report between-group differences in light of this, rather than focusing on p values and statistical significance., Level of Evidence: Level III, therapeutic study.

Objective: Osteoporosis is a metabolic bone disease that increases the risk for fragility fractures. Screening and diagnosis can be achieved by measuring bone mineral density (BMD) using quantitative CT tomography (QCT) in the lumbar spine. QCT-derived BMD measurements can be used to diagnose osteopenia or osteoporosis based on American College of Radiology (ACR) thresholds. Many reports exist regarding the disease prevalence in asymptomatic and disease-specific populations; however, osteoporosis/osteopenia prevalence rates in lumbar spine fusion patients without fracture have not been reported. The purpose of this study was to define osteoporosis and osteopenia prevalence in lumbar fusion patients using QCT., Methods: A retrospective review of prospective data was performed. All patients undergoing lumbar fusion surgery who had preoperative fine-cut CT scans were eligible. QCT-derived BMD measurements were performed at L1 and L2. The L1-2 average BMD was used to classify patients as having normal findings, osteopenia, or osteoporosis based on ACR criteria. Disease prevalence was calculated. Subgroup analyses based on age, sex, ethnicity, and history of abnormal BMD were performed. Differences between categorical groups were calculated with Fisher's exact test., Results: Overall, 296 consecutive patients (55.4% female) were studied. The mean age was 63 years (range 21-89 years). There were 248 (83.8%) patients with ages ≥ 50 years. No previous clinical history of abnormal BMD was seen in 212 (71.6%) patients. Osteopenia was present in 129 (43.6%) patients and osteoporosis in 44 (14.9%). There were no prevalence differences between sex or race. Patients ≥ 50 years of age had a significantly higher frequency of osteopenia/osteoporosis than those who were < 50 years of age., Conclusions: In 296 consecutive patients undergoing lumbar fusion surgery, the prevalence of osteoporosis was 14.9% and that for osteopenia was 43.6% diagnosed by QCT. This is the first report of osteoporosis disease prevalence in lumbar fusion patients without vertebral fragility fractures diagnosed by QCT.

Background Context: Clinically, the association between bone mineral density (BMD) and surgical instrumentation efficacy is well recognized. Although several studies have quantified the BMD of the human lumbar spine, comprehensive BMD data for the cervical spine is limited. The few available studies included young and healthy patient samples, which may not represent the typical cervical fusion patient. Currently no large scale study provides detailed BMD information of the cervical and first thoracic vertebrae in patients undergoing anterior cervical spine surgery., Purpose: The objective of this study was to determine possible trabecular BMD variations throughout the cervical spine and first thoracic vertebra in patients undergoing anterior cervical discectomy and fusion (ACDF) and to assess the correlation between BMDs of the spinal levels C1-T1., Study Design/setting: This is a retrospective case series., Patient Sample: Patients undergoing ACDF from 2015 to 2018 at a single, academic institution with available preoperative CT imaging were included in this study., Outcome Measures: The outcome measure was BMD measured by QCT., Methods: Patients that underwent ACDF from 2015 to 2018 at a single, academic institution were included in this study. Subjects with previous cervical instrumentation or missing/incomplete preoperative cervical spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of the lateral masses of C1 and the C2-T1 vertebral bodies were performed. For this purpose, an elliptical region of interest that consisted exclusively of trabecular bone was selected. Any apparent sclerotic levels that might affect trabecular QCT measurements were excluded from the final analysis. Interobserver reliability of measurements was assessed by calculating the interclass correlation coefficients (ICC). Pairwise comparison of BMD was performed and correlations between the various cervical levels were evaluated. The statistical significance level was set at p<.05., Results: In all, 194 patients (men, 62.9%) met inclusion criteria. The patient population was 91.2% Caucasian with a mean age of 55.9 years and mean BMI of 28.2 kg/m 2 . The ICC of cervical QCT measurements was excellent (ICC 0.92). The trabecular BMD was highest in the mid-cervical spine (C4) and decreased in the caudal direction (C1 average=253.3 mg/cm 3 , C2=276.6 mg/cm 3 , C3=272.2 mg/cm 3 , C4=283.5 mg/cm 3 , C5=265.1 mg/cm 3 , C6=235.3 mg/cm 3 , C7=216.8 mg/cm 3 , T1=184.4 mg/cm 3 ). The BMD of C7 and T1 was significantly lower than those of all other levels. Nonetheless, significant correlations in BMD among all measured levels were observed, with a Pearson's correlation coefficient ranging from 0.507 to 0.885., Conclusions: To the authors' knowledge this is the largest study assessing trabecular BMD of the entire cervical spine and first thoracic vertebra by QCT. The patient sample consisted of patients undergoing ACDF, which adds to the clinical relevance of the findings. Knowledge of BMD variation in the cervical spine might be useful to surgeons utilizing anterior cervical spine plate and screw systems. Due to the significant variation in cervical BMD, procedures involving instrumentation at lower density caudal levels might potentially benefit from a modification in instrumentation or surgical technique to achieve results similar to more cephalad levels., (Copyright © 2020. Published by Elsevier Inc.)

We investigated the effect of posterior lumbar fusion surgery on the regional volumetric bone mineral density (vBMD) measured by quantitative computed tomography. Surgery negatively affected the regional vBMD in adjacent levels. Interbody fusion was independently associated with vBMD decline and preoperative epidural steroid injections (ESIs) were associated with less postoperative vBMD decline., Introduction: Few studies investigate postoperative BMD changes after lumbar fusion surgery utilizing quantitative computed tomography (QCT). Additionally, it remains unclear what preoperative and operative factors contribute to postoperative BMD changes. The purpose of this study is to investigate the effect of lumbar fusion surgery on regional volumetric bone mineral density (vBMD) in adjacent vertebrae and to identify potential modifiers for postoperative BMD change., Methods: The data of patients undergoing posterior lumbar fusion with available pre- and postoperative CTs were reviewed. The postoperative changes in vBMD in the vertebrae one or two levels above the upper instrumented vertebra (UIV+1, UIV+2) and one level below the lower instrumented vertebra (LIV+1) were analyzed. As potential contributing factors, history of ESI, and the presence of interbody fusion, as well as various demographic/surgical factors, were included., Results: A total of 90 patients were included in the study analysis. Mean age (±SD) was 62.1 ± 11.7. Volumetric BMD (±SD) in UIV+1 was 115.4 ± 36.9 mg/cm 3 preoperatively. The percent vBMD change in UIV+1 was - 10.5 ± 12.9% (p < 0.001). UIV+2 and LIV+1 vBMD changes showed similar trends. After adjusting with the interval between surgery and the secondary CT, non-Caucasian race, ESI, and interbody fusion were independent contributors to postoperative BMD change in UIV+1., Conclusions: Posterior lumbar fusion surgery negatively affected the regional vBMDs in adjacent levels. Interbody fusion was independently associated with vBMD decline. Preoperative ESIs were associated with less postoperative vBMD decline, which was most likely a result of a preoperative decrease in vBMD due to ESIs.

Background: An injury of the vertebral artery (VA) is one of the most catastrophic complications in the setting of cervical spine surgery. Anatomic variations of the VA can increase the risk of iatrogenic lacerations., Objective: To propose a novel and reproducible classification system that describes the position of the VA based on a 2-dimensional map on computed tomography angiographs (CTA)., Methods: This cross-sectional retrospective study reviewed 248 consecutive CTAs of the cervical spine at a single academic institution between 2007 and 2018. The classification consists of a number that characterizes the location of the VA from the medio-lateral (ML) aspect of the vertebral body. In addition, a letter describes the VA location from the anterior-posterior (AP) aspect. The reliability and reproducibility were assessed by 2 independent raters on 200 VAs., Results: The inter- and intrarater reliability values showed the classification's reproducibility. The inter-rater reliability weighted κ-value for the ML aspect was 0.93 (95% CI: 0.93-0.93). The unweighted κ-value was 0.93 (95% CI: 0.86-1.00) for "at-risk" positions (ML grade ≥1), and 0.87 (95% CI: 0.75-1.00) for "high-risk" positions (ML grade ≥2). The weighted κ-value for the intrarater reliability was 0.94 (95% CI: 0.95-0.95). The unweighted κ-values for the intrarater reliability were 0.95 (95% CI: 0.91-0.99) for "at-risk" positions, and 0.87 (95% CI: 0.78-0.96) for "high-risk" positions., Conclusion: The proposed classification is reliable, reproducible, and independent of individual anatomic size variations. The use of this novel grading system could improve the understanding and interdisciplinary communication about VA anomalies., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Purpose: Quantitative computed tomography (QCT) is an alternate imaging method to dual X-ray absorptiometry to measure bone mineral density (BMD). One advantage of QCT is that it allows site-specific volumetric BMD (vBMD) measurements in a small region. In this study, we utilized site-specific, endplate vBMD (EP-vBMD) as a potential predictive marker of severe cage subsidence in standalone lateral lumbar interbody fusion (SA-LLIF) patients and conducted a retrospective comparative study between EP-vBMD and trabecular vBMDs (Tb-vBMD) in the vertebrae., Methods: Patients undergoing SA-LLIF from 2007 to 2016 were retrospectively reviewed. EP-vBMD was defined as the average of the upper and lower endplate volumetric BMDs measured in cortical and trabecular bone included in a 5-mm area of interest beneath the cage contact surfaces. We compared Tb-vBMDs and EP-vBMDs between disk levels that had severe cage subsidence and levels with no severe subsidence., Results: Both EP-vBMD and Tb-vBMD could be measured in 210 levels of 96 patients. Severe cage subsidence was observed in 58 levels in 38 patients. Median (IQR) Tb-vBMD was 120.5 mg/cm 3 (100.8-153.7) in the non-severe subsidence group and 117.9 mg/cm 3 (90.6-149.5) in the severe subsidence group (p = 0.393), whereas EP-vBMD was significantly lower in the severe subsidence group than the non-severe subsidence group (non-severe subsidence 257.4 mg/cm 3 (216.3-299.4), severe subsidence 233.5 mg/cm 3 (193.4-273.3), p = 0.026)., Conclusion: We introduced a novel site-specific vBMD measurement for cage subsidence risk assessment. Our results showed that EP-vBMD was a reproducible measurement and appeared more predictive for severe cage subsidence after SA-LLIF than Tb-vBMD. These slides can be retrieved under Electronic Supplementary Material.

Brachioradial pruritus is a rare condition characterized by chronic localized itching of the dorsolateral upper extremities. Although the exact pathophysiology is still unknown, cervical nerve compression is thought to be a cause. We present the case of a 56-year-old man with a 6-year history of disabling chronic bilateral upper extremity pruritus and pain as well as concurrent neck pain. The patient presented to our office after multiple inconclusive diagnostic evaluations (dermatology, rheumatology, neurology, and psychiatry) and unsatisfactory multimodal conservative treatment attempts. His symptoms markedly impeded his ability to get restful sleep. Imaging of the cervical spine revealed multilevel cervical spondylosis, spinal stenosis with cord compression, and multilevel foraminal stenosis. The patient underwent successful multilevel anterior cervical decompression and fusion and was instantly symptom-free. The present case highlights that patients complaining of itching of the dorsolateral forearms of seemingly unknown etiology should undergo a workup of the cervical spine. If conservative treatment fails, surgical decompression may be considered in select patients., Competing Interests: Dr. Hughes or an immediate family member has received research or institutional support from 4WEB Medical, NuVasive, Inc., and Pfizer, Inc. None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Salzmann, Dr. Okano, Ms. Shue., (Copyright © 2020 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Objective: There have been some reports on the association between spinal balance parameters and regional bone mineral density (BMD), but the results are controversial. The purpose of this study is to evaluate the relationship between spinopelvic parameters and regional volumetric BMDs (vBMDs) measured by quantitative computed tomography (QCT) in the lumbosacral region of patients undergoing lumbar fusion surgery., Methods: The data of consecutive patients undergoing posterior lumbar spinal fusion with preoperative computed tomography was reviewed. QCT measurements were conducted in L1-S1 vertebral trabecular bone. The associations between spinopelvic sagittal parameters and vBMDs were evaluated. Multivariate analyses adjusted with age, gender, race, and body mass index were conducted with vBMD as the response variable., Results: A total of 144 patients were included in the final analyses. Mean age (± standard deviation) was 65.4 ± 11.8 years. Mean vBMD in L1 (± standard deviation) was 118.3 ± 37.4 mg/cm 3 . After adjusting by cofactors, lumbar lordosis was negatively associated with vBMDs in all levels from L1 to L5 (% regression coefficients and adjusted R 2 values: L1, -0.438, 0.268; L2, -0.556, 0.296; L3, -0.608, 0.362; L4, -0.554, 0.228; L5, -0.424, 0.194), but not in S1. Sacral slope was negatively associated with vBMD only at L4 (% coefficient, -0.588; R 2 , 0.208). Other parameters were not significantly associated with vBMDs at any levels., Conclusions: Higher lumbar lordosis was associated with lower vBMDs in all lumbar spine levels. Our results suggest that BMD is affected not only by metabolic factors but also by the mechanical environment. Further longitudinal studies are needed to elucidate this effect of vBMD on clinical outcomes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

N-terminal telopeptide (NTX) is a bone resorption marker that is commonly referenced in clinical practice. Bone remodeling is also associated with changes in mineral components. Fourier transform infrared spectroscopy (FTIR) is utilized in the assessment of bone material properties and some parameters are reported to have associations with bone remodeling. The aim of this cross-sectional study is to investigate the relationship between uNTX levels and FTIR parameters, utilizing prospectively collected study data for patients who underwent lumbar fusion surgery. Bone specimens were taken from iliac crest (IC) and vertebrae (V). Cortical (C) and trabecular (T) bones were separately analyzed. 22 patients (mean age 60.0 years (35.9-73.3), male : female 9 : 13) were included in the final analysis. Women showed significantly higher uNTX levels (male : female, median [range] 21.0 [11.0-39.0] : 36.0 [15.0-74.0] nM·BCE/mM, p =0.033). Among women, a significant positive correlation was observed between uNTX and mineral-to-matrix ratio in IC-C. Among men, uNTX demonstrated significant negative correlation with collagen crosslinks (XLR: ratio of mature to immature collagen crosslinks) in IC-C, V-T, and V-C. In addition, uNTX was positively correlated with acid phosphate substitution (HPO 4 , a parameter of new bone formation) in IC-C, IC-T, and V-C. After age adjustment, HPO 4 in IC-T and V-C among men showed significant positive associations with uNTX (IC-T: p =0.018, R 2  = 0.544; V-C: p =0.007, R 2  = 0.672). We found associations between FTIR parameters and uNTX in men, but not in women. The correlations between uNTX and FTIR parameters in men might suggest a better balance of bone breakdown (uNTX) and new bone formation (FTIR parameters: XLR, HPO 4 ) than in women., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Ichiro Okano et al.)

Background Context: It has been reported that degenerative disc disease (DDD) is associated with higher spinal bone mineral density (BMD) based on previous studies that used dual X-ray absorptiometry (DXA). However, DDD is often associated with proliferative bone changes and can lead to an overestimation of BMD measured with DXA. Trabecular volumetric BMD (vBMD) in the vertebral body measured with quantitative computed tomography (QCT) is less affected by those changes and can be a favorable alternative to DXA for patients with degenerative spinal changes., Purpose: The purpose of this study is to investigate the effect of DDD on regional trabecular vBMDs in the vertebral body measured by QCT., Study Design/setting: Cross-sectional observational study at a single academic institution., Patients Sample: Consecutive patients undergoing posterior lumbar spinal fusion between 2014 and 2017 who had a routine preoperative CT scan and magnetic resonance imaging (MRI) within a 90-day interval., Outcome Measures: Regional trabecular vBMDs in the vertebral body by QCT., Methods: QCT measurements were conducted in L1-S1 vertebral trabecular bone. Any apparent sclerotic lesions that might affect vBMD values were excluded from the region of interest. The vBMDs of each level were defined as the average vBMD of the upper and lower vertebrae. To evaluate DDD, Pfirrmann grade, Modic grade, total end plate score, and vacuum phenomenon were documented. Univariate regression analysis and multivariate analyses with a linear mixed model adjusted with individual variability of segmental vBMDs were conducted with vBMD as the response variable., Results: Of 143 patients and 715 disc levels, 125 patients and 596 discs met our inclusion criteria. Mean vBMD (±standard deviation [SD]) of all levels was 119.0±39.6 mg/cm 3 . After adjusting for all covariates, Pfirrmann grade was not an independent contributor to vBMD, but the presence of any Modic change (type 1, β=6.8, p≤.001; type 2, β=6.7, p<.001; type 3, β=43.6, p<.001), high TEPS (score 10-12, β=14.2, p<.001), or vacuum phenomenon (β=9.0, p<.001) was shown to be independent contributors to vBMD., Conclusions: Our results showed that the presence of certain end plate lesions (Modic changes and high TEPS) on MRI was significantly associated with increased regional QCT-vBMDs in the vertebral body, but no significant association was observed with disc nucleus pathology, unless it was associated with a vacuum phenomenon. When end plate lesions with Modic changes and high TEPS are present at the measuring level, care must be taken to interpret vBMD values, which might be overestimations even if the trabecular area appears normal., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Lateral lumbar interbody fusion can be performed without supplemental posterior instrumentation. Previous reports have shown favorable results with stand-alone lateral lumbar interbody fusion (SA-LLIF); however, a reoperation rate of up to 26% has been reported. It remains unclear what perioperative factors are associated with early failure after SA-LLIF. The objective of this study is to determine perioperative factors that increase the risk of early revisions after SA-LLIF., Methods: Data of consecutive patients with SA-LLIF were reviewed. All revisions or recommendations for revision surgery within 12 months after the LLIF procedure were documented. As potential contributors, operative levels, preoperative clinical diagnosis, number of fusion levels, and the average L1/L2 quantitative computed tomography-volumetric bone mineral density value were obtained along with other demographic factors. Cage subsidence (grade 0-III as per Marchi et al.), was also evaluated in patients who had radiographs/computed tomography between 6 and 12 months postoperatively (n = 122). Logistic regression analyses were conducted., Results: Of 133 eligible patients, 21 (15.8%) underwent revision surgery and 4 (3.0%) were recommended for revision surgery within 1 year primarily because of neurologic symptoms or pain (68%). Baseline demographics showed no significant difference between the revision and the nonrevision group. The average number of levels fused was 2.12 (revision group) and 2.14 (nonrevision group) (P = 0.55). Significantly more patients in the revision group had the diagnosis of foraminal stenosis (64.0% vs. 39.8%; P = 0.04)., Conclusions: Patients with foraminal stenosis were more likely to have early revision surgery after SA-LLIF primarily because of neurologic symptoms/pain. This information can assist in preoperative discussions and management of patient expectations., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Lateral lumbar interbody fusion (LLIF) has often been associated with postoperative lumbar plexus symptoms, including pain, paresthesia, and motor deficits in the lower extremities, especially the anterior thigh regions. Previous studies have suggested that LLIF procedures at L4-L5 will be associated with a greater motor deficit rate than other levels. However, it is unclear which level has the greatest risk of pain and paresthesia. The purpose of the present retrospective observational study was to investigate the difference in the incidence of early postoperative thigh symptoms (pain and paresthesia) stratified by procedure level among patients who had undergone standalone LLIF., Methods: We reviewed the data from consecutive patients who had undergone LLIF at a single academic institution. A total of 285 standalone LLIF cases without preoperative motor deficits were identified. The incidence of postoperative thigh pain and paresthesia at the 6-week postoperative follow-up examination was assessed at all levels from T12-L1 to L4-L5., Results: A total of 81 patients (28.4%) had anterior thigh pain and 62 (21.8%) had anterior thigh paresthesia. The presence of ≥3 levels fused (odds ratio [OR], 2.96; P = 0.004) and surgery at L2-L3 (OR, 2.59; P = 0.001) were significant risk factors for postoperative anterior thigh paresthesia on univariate analysis but were not associated with anterior thigh pain. Multivariate analyses demonstrated that only surgery L2-L3 was an independent risk factor for anterior thigh paresthesia (OR, 2.09; P = 0.049)., Conclusions: Our results have demonstrated that standalone LLIF at the L2-L3 was significantly associated with a greater incidence of postoperative anterior thigh paresthesia but that the incidence of postoperative thigh pain showed no significant association with any operative level., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Bone mineral density (BMD) is not the sole predictor of fracture development. Qualitative markers including bone collagen maturity contribute to bone fragility. Bone and related type I collagen containing connective tissues degenerate in parallel fashion. With aging, changes in skin collagen content and quality have been observed that can be detected on ultrasound (US) as a decrease in dermal thickness and an increase in reticular layer echogenicity. We hypothesized that US dermal thickness and echogenicity correlate with bone collagen maturity. Data of 43 prospectively enrolled patients (mean age 61 years, 24 females), who underwent instrumented, posterior lumbar fusion was analyzed. Besides preoperative quantitative computed tomography (QCT) and skin US measurements, intraoperative bone biopsies were obtained and analyzed with Fourier-transform infrared spectroscopy. Among men, there was no correlation between US measurements and collagen maturity. Among women, dermal layer thickness correlated negatively with collagen maturity in trabecular bone of the iliac crest (r = -0.51, p = 0.01) and vertebra (r = -0.59, p = 0.01) as well as in cortical bone of the iliac crest (r = -0.50, p = 0.02) and vertebra (r = -0.50, p = 0.04). In addition, echogenicity correlated positively with collagen maturity in trabecular vertebral bone (r = 0.59, p = 0.01). In both genders, US measurements showed no correlation with QCT BMD. In summary, ultrasound skin parameters are associated with bone quality factors such as collagen maturity, rather than bone quantity (BMD). Ultrasound of the skin may thereby be an easy and accessible take off point for diagnosis of bone collagen maturity and connective tissue degeneration in the future. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2508-2515, 2019., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

Background: Lateral lumbar interbody fusion (LLIF) is a relatively new procedure. It was established as a minimally invasive alternative to traditional open interbody fusion. LLIF allows the surgeon to access the disc space via a retroperitoneal transpsoas muscle approach. Theoretical advantages of the LLIF technique include preservation of the longitudinal ligaments, augmentation of disc height with indirect decompression of neural elements, and insertion of large footprint cages spanning the dense apophyseal ring bilaterally 1,2 . The original 2-incision LLIF technique described by Ozgur et al., in 2006, had some inherent limitations 3 . First, it substantially limited direct visualization of the surgical field and may have endangered nerve and vascular structures. Additionally, it often required multiple separated incisions for multilevel pathologies. Finally, for surgeons with experience in traditional open retroperitoneal surgery, utilization of their previously acquired skills may have been difficult with this approach. To overcome these limitations, we adopted the mini-open lateral approach, which allows for visualization, palpation, and electrophysiologic neurologic confirmation during the procedure 4 ., Description: As detailed below, the patient is positioned in the lateral decubitus position and a single incision is carried out centered between the target discs. For single-level LLIF, the incision spans approximately 3 cm and can be lengthened in small increments for multilevel procedures. After blunt dissection, the retroperitoneal space is entered. The psoas muscle is split under direct visualization, carefully avoiding the traversing nerves with neurosurveillance 5 . A self-retaining retractor is used, and after thorough discectomy, the disc space is sized with trial components. The implant is filled with bone graft materials and is introduced using intraoperative fluoroscopy., Alternatives: The 2-incision LLIF technique or traditional anterior or posterior lumbar spine interbody fusion techniques might be used instead., Rationale: LLIF offers the reported advantages of minimally invasive surgery, such as reduced tissue trauma during the approach, low blood loss, shorter length of stay, decreased recovery time, and less postoperative pain. LLIF allows for the placement of a relatively larger interbody cage spanning the dense apophyseal ring bilaterally. The lateral approach preserves the anterior longitudinal ligament and posterior longitudinal ligament. These structures allow for powerful ligamentotaxis and provide extra stability for the construct. Compared with other approaches, LLIF has a reduced risk of visceral and vascular injuries, incidental dural tears, and perioperative infections. Although associated with approach-related complications such as motor and sensory deficits, LLIF can be a safe and versatile procedure 1,2 ., (Copyright © 2019 by The Journal of Bone and Joint Surgery, Incorporated.)

Soccer is the most popular sport in the world, with more than 270 million participants. It is characterized by repetition of short and intense actions that require high-coordination capacity. It is a sport where interactions with other players put the athletes at risk for traumatic injuries. Lower-limb injuries are the most prevalent injuries in soccer. Spine injuries are less frequent; however, they can impose serious and debilitating sequelae on the athlete. These injuries can be associated with long recovery periods preventing return to play. Moreover, specific repetitive activities (heading, kicking, etc.) can lead to chronic injuries. The cervical spine is particularly at risk for degenerative changes. Considerations for when an athlete should undergo spinal surgery and the timing of return to play present a difficult challenge to spine specialists. The objective of this article is to review the epidemiology, diagnosis, treatment, and prevention of spinal injuries in soccer.

Objective: Lateral lumbar interbody fusion (LLIF) at the L4-L5 level is a controversial topic in the spine data. The aim of the present study was to compare the rate of nerve-related motor deficits in patients undergoing LLIF with and without L4-L5 involvement., Methods: The clinical data from consecutive patients who had undergone LLIF from 2006 to 2016 at a single academic institution were retrospectively reviewed for new postoperative motor weakness of the quadriceps or tibialis anterior muscle. The patients were divided into 2 groups according to L4-L5 involvement. Regression analysis was performed to examine the association of LLIF at L4-L5 and the risk of new motor deficits., Results: A total of 872 patients met inclusion criteria. The rate of new motor deficits at the 6-week postoperative visit in the L4-L5 group was 13.1%, which was significantly greater than that in the non-L4-L5 group at 5.5% (P < 0.001). After adjustment for potential confounders in multivariate logistic regression models, L4-L5 was still significantly associated with an increased risk of new motor deficit (odds ratio, 2.290; P = 0.008). Of the 686 patients with a minimum follow-up of 6 months, persistent nerve-related motor deficits at the last follow-up examination were recorded in 2.5% of the L4-L5 group and 0.4% of the non-L4-L5 group (P = 0.065)., Conclusions: The results from the present large study are in line with previous investigations reporting an initial increased risk of new motor deficits for LLIF performed at L4-L5. However, most new motor deficits were transient in nature and had resolved over time., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Study Design: Retrospective database analysis., Objective: To identify preoperative risk factors for emergency department (ED) visit and unplanned hospital readmission after primary anterior cervical discectomy and fusion (ACDF) at 30 and 90 days., Summary of Background Data: Limited data exist to identify factors associated with ED visit or readmission after primary ACDF within the first 3 months following surgery., Methods: Patients undergoing ACDF from 2005 to 2012 were identified in the Statewide Planning and Research Cooperative System database. Multivariable regression models were created based on patient-level and surgical characteristics to identify independent risk factors for hospital revisit., Results: Of 41,813 patients identified, 2514 (6.0%) returned to the ED within 30 days of discharge. Risk factors included age < 35, black race (OR 1.19), Charlson Comorbidity index score > 1, length of stay (LOS) greater than 1 day (OR 1.23), and fusion of > 2 levels (OR 1.17). Four thousand six hundred nine (11.0%) patients returned to the ED within 90 days. Risk factors mirrored those at 30 days. Patients having private insurance or those discharged to rehab were less likely to present to the ED. One thousand three hundred ninety-four (3.3%) patients were readmitted by 30 days. Risk factors included male sex, Medicare, or Medicaid insurance (OR 1.71 and 1.79 respectively), Charlson comorbidity index > 1, discharge to a skilled nursing facility (OR 2.90), infectious/pathologic (OR 3.296), or traumatic (OR 1.409) surgical indication, LOS > 1 day (OR 1.66), or in-hospital complication. 2223 (5.3%) patients were readmitted by 90 days. Risk factors mirrored those at 30 days. No differences in readmission were seen based on race or number of levels fused. Patients aged 18 to 34 were less likely to be readmitted versus patients older than 35., Conclusion: Insurance status, comorbidities, and LOS consistently predicted an unplanned hospital visit at 30 and 90 days. Although nondegenerative surgical indications and in-hospital complications did not predict ED visits, these factors increased the risk for readmission., Level of Evidence: 3.

Background Context: Quantitative computed tomography (QCT) of the lumbar spine is used as an alternative to dual-energy X-ray absorptiometry in assessing bone mineral density (BMD). The average BMD of L1-L2 is the standard reportable metric used for diagnostic purposes according to current recommendations. The density of L1 and L2 has also been proposed as a reference value for the remaining lumbosacral vertebrae and is commonly used as a surrogate marker for overall bone health. Since regional BMD differences within the spine have been proposed, it is unclear if the L1-L2 average correlates with the remainder of the lumbosacral spine., Purpose: The aim of this study was to determine possible BMD variations throughout the lumbosacral spine in patients undergoing lumbar fusion and to assess the correlation between the clinically used L1-L2 average and the remaining lumbosacral vertebral levels., Study Design/setting: This is a retrospective case series., Patient Sample: Patients undergoing posterior lumbar spinal fusion from 2014 to 2017 at a single, academic institution with available preoperative CT imaging were included in this study., Outcome Measures: The outcome measure was BMD measured by QCT., Methods: Standard QCT measurements at the L1 and L2 vertebra and additional experimental measurements of L3, L4, L5, and S1 were performed. Subjects with missing preoperative lumbar spine CT imaging were excluded. The correlations between the L1-L2 average and the other vertebral bodies of the lumbosacral spine (L3, L4, L5, S1) were evaluated., Results: In total, 296 consecutive patients (55.4% female, mean age of 63.1 years) with available preoperative CT were included. The vertebral BMD values showed a gradual decrease from L1 to L3 and increase from L4 to S1 (L1=118.8 mg/cm 3 , L2=116.6 mg/cm 3 , L3=112.5 mg/cm 3 , L4=122.4 mg/cm 3 , L5=135.3 mg/cm 3 , S1=157.4 mg/cm 3 ). There was strong correlation between the L1-L2 average and the average of the other lumbosacral vertebrae (L3-S1) with a Pearson's correlation coefficient (r=0.85). We also analyzed the correlation between the L1-L2 average and each individual lumbosacral vertebra. Similar relationships were observed (r value, 0.67-0.87), with the strongest correlation between the L1-L2 average and L3 (r=0.87)., Conclusions: Our data demonstrate regional BMD differences throughout the lumbosacral spine. Nevertheless, there is high correlation between the clinically used L1-L2 average and the BMD values in the other lumbosacral vertebrae. We, therefore, conclude the standard clinically used L1-L2 BMD average is a useful bone quantity measure of the entire lumbosacral spine in patients undergoing lumbar spinal fusion., (Copyright © 2018. Published by Elsevier Inc.)

Background Context: Sacral fractures are a rare but potentially devastating complication. Long-fusion constructs, including the sacrum, that do not extend to the pelvis may result in sacral fractures. Besides established risk factors including gender, age, and number of levels fused, body mass index (BMI), pelvic parameters, and bone mineral density (BMD) have also been proposed as potential risk factors for postoperative sacral fractures. The literature supporting this, however, is limited., Purpose: The aim of the present study was to assess whether preoperative pelvic parameters, BMI, or BMD of patients with sacral fracture are different compared with age, gender, and fusion level-matched non-fracture controls., Study Design/setting: This is a case-control study., Patient Sample: Patients undergoing posterior instrumented fusion at a single academic institution between 2002 and 2016 were included in the study., Outcome Measures: The outcome measure was occurrence of a postoperative sacral fracture., Methods: Patients with sacral fractures after posterior instrumented spinal fusion, including the sacrum, were retrospectively identified and matched 2:1 with non-fracture controls based on gender, age, and number of levels fused. Patients with concurrent spinopelvic fixation or missing preoperative computed tomography (CT) imaging were excluded. Preoperative sagittal balance was assessed using lateral radiographs. Quantitative computed tomography (QCT) assessment included standard measurements at L1/L2 and additional experimental measurements of the S1 body and sacral ala., Results: Twenty-one patients with sacral fracture were matched to non-fracture controls. The majority of the patients with sacral fracture was female (76.2%) and of advanced age (mean 66.4 years). Fracture and control groups were well matched with respect to gender, age, and number of levels fused. Standard measurements at L1/L2 showed no significant difference in BMD between the fracture and the control groups (109.9 mg/cm 3 vs. 116.4 mg/cm 3 , p=.414). Similarly, there was no significant BMD differences between the groups using the experimental measurements of the S1 body (183.6 mg/cm 3 vs. 176.2 mg/cm 3 , p=.567) and the sacral ala (8.9 mg/cm 3 vs. 4.8 mg/cm 3 , p=.616). Mean preoperative pelvic incidence-lumbar lordosis mismatch and pelvic tilt were not significantly different between the groups. Univariate conditional logistic regression analysis revealed that the odds of experiencing a sacral fracture was approximately six times higher for obese patients compared with normal or underweight patients. After controlling for BMI in multivariate conditional logistic regression models, BMD was still not significantly associated with the odds of experiencing sacral fractures., Conclusions: To our knowledge, this is the first study to assess the association of preoperative BMD measured by QCT, pelvic parameters, and BMI with postoperative sacral fractures in a large patient cohort. Interestingly, our data do not show any difference in preoperative pelvic parameters and BMD between the groups. This is in line with previous reports that indicate only a few patients with sacral fracture after fusion surgery have clear evidence of osteoporosis. Bone mineral density as a measure of bone quantity, rather than bone quality, may not be as important in these fractures as previously thought. Obesity, however, was associated with higher odds of experiencing postoperative sacral fractures. The present study thereby challenges the widespread concept that obesity is a protective factor against fractures in the elderly. In summary, our results suggest that BMI and gender, more than pelvic parameters and BMD, are risk factors for postoperative sacral fractures., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Study Design: Retrospective case-control study., Objective: To report culturing patterns and results in the setting of presumed aseptic revision spinal surgery., Summary of Background Data: The indications for obtaining cultures in revision spinal surgery remain unclear in the absence of a definitive diagnosis of infection. Culture results and risk factors for having positive cultures in this setting have not been previously studied., Methods: We retrospectively reviewed 595 consecutive revision spine surgeries performed by four senior spine surgeons between 2008 and 2013. Preoperative workup revealed the diagnosis of infection in 17 cases which were excluded from review. The remaining 578 presumed aseptic cases were included. Univariate and multivariate analyses were performed to identify variables associated with obtaining cultures and risk factors for positive cultures., Results: Cultures were obtained in 112 (19.4%) cases and were positive in 40.2%. Pseudarthrosis was the most common revision diagnosis when cultures were obtained (49.1%) and Propionibacterium acnes was the most common organism isolated from positive cultures (48.8%). Regarding culture results, multivariate analysis demonstrated that male sex (odds ratio [OR] = 3.4) and pseudarthrosis (OR = 4.1) were significantly associated with having positive cultures while fusion procedures (OR = 0.3) were negatively correlated, with area under the curve (AUC) 0.71., Conclusion: Unexpected positive cultures occurred commonly and P. acnes was the predominant isolated organism. Male sex, pseudarthrosis, and non-fusion cases predicted positive cultures. Considering these results, we recommend cultures be obtained in revision cases for pseudarthrosis, even in the setting of negative infectious work-up preoperatively., Level of Evidence: 4.

Study Design: Retrospective radiological review and analysis of 79 patients who underwent primary anterior cervical discectomy and fusion (ACDF) of 2 or 3 levels between 2011 and 2013., Purpose: This study aimed to determine the effect of the local placement of a steroid-soaked gelatin sponge after ACDF on prevertebral soft tissue swelling., Overview of Literature: Although ACDF has become a popular choice for cervical fusion, the surgical involvement of the delicate anatomy of the neck frequently results in tissue irritation and edema. Swelling of the prevertebral soft tissue may consequently lead to mild-to-severe complications, ranging from dysphonia to dyspnea., Methods: Out of the 79 patients who underwent primary ACDF, 52 received a gelatin sponge soaked with 40 mg of Depo-Medrol placed adjacent to the operated cervical levels. Prevertebral soft tissue swelling was detected using postoperative lateral X-ray. The radiographic values were compared to those of 27 patients who did not receive the treatment., Results: Soft tissue swelling was markedly decreased in patients who received the placement of the steroid-soaked gelatin sponge next to their fused levels after surgery compared with that in patients who did not receive it. No complications were documented with the use of steroids., Conclusions: The placement of a steroid-soaked gelatin sponge markedly reduces postoperative soft tissue swelling following 2- or 3-level primary ACDF.

Study Design: Retrospective state database analysis., Objective: To quantify the 30- and 90-day emergency department (ED) utilization and inpatient readmission rates after primary cervical arthrodesis, to stratify these findings by surgical approach, and to describe risk factors and conditions precipitating these events., Summary of Background Data: Limited data exist on ED utilization and hospital readmission rates after cervical spine arthrodesis., Methods: The New York State all-payer health-care database was queried to identify all 87,045 patients who underwent primary subaxial cervical arthrodesis from 1997 through 2012. Demographic data and clinical information were extracted. Readmission data were available for the entire study period, whereas ED utilization data collection began later and was therefore analyzed starting in 2005. Incidences of these events within 30 and 90 days of discharge as well as trends over time were tabulated. The conditions prompting these encounters were also collected. Data were analyzed with respect to surgical approach., Results: The hospital readmission rate was 4.2% at 30 days and 6.2% at 90 days postoperatively. Approximately 6.2% of patients were managed in the ED without inpatient admission within 30 days and 11.3% within 90 days of surgery. The most common conditions prompting such events were dysphagia or dysphonia, respiratory complications, and infection. ED utilization and readmission rates were lowest after anterior surgeries. A preoperative Charlson Comorbidity Index of 1 or greater and traumatic pathologies were associated with increased risk of subsequent ED utilization or hospital readmission. Thirty-day hospital readmission rates declined after 2010, whereas 30-day ED utilization continued to increase., Conclusion: Patient comorbidities, traumatic pathologies, and surgical approach are associated with increased postoperative complications. Anterior procedures carry the lowest risk, followed by posterior and then circumferential. Awareness of these findings should help to encourage development of strategies to minimize the rate of postoperative ED utilization and hospital readmission., Level of Evidence: 3.

Background: Dysphagia and dysphonia are common complications after anterior cervical spine surgery; however, reported prevalences vary greatly due to a lack of reliable clinical standards for measuring postoperative swallowing and speech dysfunction. The Hospital for Special Surgery Dysphagia and Dysphonia Inventory (HSS-DDI) was developed as a patient-derived, patient-reported instrument to measure dysphagia and dysphonia more accurately after anterior cervical spine surgery than existing indices., Methods: This multiphase survey-development study implemented a mixed-methods approach. Phase 1 involved qualitative assessment of postoperative patient-reported swallowing or speaking deficiencies to assemble a draft survey. Phase 2 established test-retest reliability and finalized the 31-item HSS-DDI. Phase 3 compared the HSS-DDI with the Swallowing-Quality of Life (SWAL-QOL) questionnaire and the M.D. Anderson Dysphagia Inventory (MDADI) for validity and responsiveness., Results: Phase 1, performed to formulate the draft survey, included 25 patients who were asked about speech and swallowing dysfunction after anterior cervical spine surgery involving at least 3 vertebral levels. Phase 2 included 49 patients who completed the draft survey twice. The mean scores (and standard deviation) for each administration of the HSS-DDI were 67 ± 24 and 75 ± 22, the Cronbach alpha coefficients were both 0.97, and the intraclass correlation coefficient was 0.80. The 31-item HSS-DDI was finalized with all but 2 items having weighted kappa values of ≥0.40. Phase 3 included 127 patients and established external validity, with most correlation coefficients between the HSS-DDI and the SWAL-QOL and MDADI ranging from 0.5 to 0.7. Internal validity was established by identifying worsening HSS-DDI scores with increases in the number of vertebral levels involved (p = 0.02) and in the Surgical Invasiveness Index (p = 0.006). HSS-DDI responsiveness ascertained by effect size (0.73) was better than that of the SWAL-QOL and MDADI. The average administration time for the HSS-DDI was 2 minutes and 25 seconds., Conclusions: The HSS-DDI is efficient, valid, and more responsive to change after anterior cervical spine surgery than existing surveys., Clinical Relevance: The HSS-DDI fills a gap in postoperative assessment by providing a reliable, more clinically sensitive, patient and condition-specific evaluation of dysphagia and dysphonia prospectively and longitudinally.

Background: The rate of cervical spinal fusion has been increasing significantly. However, there is a paucity of literature describing trends based on surgical approach using complete population databases. We investigated the approach-based trends in epidemiology, indications, and in-hospital outcomes of cervical spinal fusion., Methods: New York's Statewide Planning and Research Cooperative System database was queried to identify patients who underwent primary subaxial cervical fusion from 1997 to 2012. Demographic and clinical information was obtained. Subgroup analyses were performed based on surgical approach: anterior (A), posterior (P), and circumferential (C)., Results: A total of 87,045 cervical fusions were included. Over the study period, the population-adjusted annual fusion rate increased from 23.7 to 50.6 per 100,000 population (P < 0.001). A fusion was most common (85.2%), followed by P (12.3%), and C (2.5%). Mean ages were 49.8 ± 11.9, 59.9 ± 15.2, and 55.1 ± 14.5 years (P < 0.001), respectively. Although rates remained steady among younger patients, they increased for older patients. Overall, degenerative conditions were the predominant indications for surgery and increased in rate over time. The mean length of stay was: A, 3.1 ± 10.5; P, 9.1 ± 14.1; and C, 14.1 ± 22.5 days (P < 0.001). Rates of in-hospital complications were A, 3.0%; P, 10.5%; and C, 18.9% (P < 0.001), and mortality was A, 0.3%, P, 1.8%, and C, 2.5% (P < 0.001)., Conclusions: The rate of subaxial spinal fusions increased 114% from 1997 to 2012 in New York State. Rates remained stable in younger patients but increased in the older population. Preoperative indications and postoperative courses differed significantly among the various approaches, with patients undergoing anterior fusion having better short-term outcomes., (Copyright © 2018 Elsevier Inc. All rights reserved.)