Are the Umbilicus and Iliac Crests Truly at the Level of L4 to L5? A Computed Tomography-Based Study of Surface Anatomy of the Anterior Lumbar Spine.

BACKGROUND: This study aimed to determine whether the iliac crests are truly at the level of L4 to L5, accounting for patient demographic and anthropometric characteristics. METHODS: We measured the umbilicus and iliac crests relative to the lumbar spine using computed tomography of patients without spinal pathology, accounting for the influences of patient height, weight, body mass index (BMI), sex, race, and ethnicity. RESULTS: A total of 834 patients (391 men and 443 women) were reviewed. The location of the umbilicus relative to the lumbar spine demonstrated a unimodal distribution pattern clustered at L4, while the iliac crests were most frequently located from L4 to L5. Iliac crests were located above the L4 to L5 disc space 26.5% of the time. Iliac crests were located at the L4 to L5 disc space 29.8% of the time. No correlations were observed between the umbilicus and iliac crests with patient height, weight, or BMI. There was no difference in the location of the umbilicus with respect to patient sex, race, and ethnicity. The locations of the iliac crests were cephalad in women compared with men and in Hispanics compared with African American, Caucasian, and Asian patients. CONCLUSIONS: The iliac crests were located above the level of the L4 to L5 disc space approximately 26% of the time. The umbilicus is most frequently at the level of the L4 vertebral body. Patient height, weight, and BMI do not influence the location of the umbilicus or the iliac crests relative to the lumbar spine. Patient sex and ethnicity influence the location of the iliac crests but not the umbilicus relative to the lumbar spine. CLINICAL RELEVANCE: Modern neurosurgical techniques require clearance of the iliac crests during anterior and anterolateral approaches. Understanding the level of the iliac crests is crucial in planning for transpsoas fusion approaches.

Assessment of Anteroposterior Diameter and Interpedicular Distance in the Approximation of Cervical Spinal Canal Area.

Rationale and objectives This study seeks to generate a model based on two linear measurements, anteroposterior (AP) diameter and interpedicular (IPD) distance, to approximate the cervical central canal (CCC) area in a non-pathologic patient population by employing area calculations of shapes such as ellipse, rectangle, and triangle. Secondarily, this study aims to generate second-order approximations (SOAs), using the aforementioned shape approximations, to increase the utility of this linear measurement-based model. Methods The authors reviewed medical and radiographic records of patients aged 18-35 who received computed tomography (CT) imaging of the cervical spine to collect AP diameter, IPD distance, and area of the CCC from C2-3 to C6-7. Subsequently, shape approximations were calculated for each patient at all cervical spine levels. Lastly, SOAs were generated by combining optimal ratios of shape approximations to improve the statistical reliability of approximations. Results The ellipse shows the closest approximation to manual measurements of the individual shape approximations. Percent error analysis demonstrated the superiority of the ellipse, followed by the rectangle, and lastly the triangular approximation. The highest correlation of approximations was observed at C6-7. All individual shape approximations demonstrated statistical differences from manual measurements. SOAs combining ellipse and rectangle measurements demonstrated superior accuracy and were not statistically different from manual measurements. Conclusion Individual shape approximations based on AP diameter and IPD distance show some value as a model for the assessment of the CCC area. SOAs demonstrated greater utility than individual shape approximations and show promise as a linear measurement-based tool to assess the CCC area.

Anatomic Parameters for Diagnosing Congenital Lumbar Stenosis Based on Computed Tomography of 1,000 Patients.

INTRODUCTION: Quantitative parameters for diagnosis of congenital lumbar stenosis (CLS) have yet to be universally accepted. This study establishes parameters for CLS using CT, assessing the influences of patient sex, race, ethnicity, and anthropometric characteristics. METHODS: Interpedicular distance (IPD), pedicle length, canal diameter, and canal area were measured using 1,000 patients between 18 and 35 years of age who were without spinal pathology. RESULTS: Irrespective of disk level, threshold values for CLS were 16.1 mm for IPD, 3.9 mm for pedicle length, 11.5 mm for canal diameter, and 142.5 mm2 for canal area. Notable differences based on patient sex were observed, with men demonstrating larger CLS threshold values with respect to IPD and canal area across all vertebral levels from L1 to L5. Based on patient anthropometric factors, no strong or moderate associations were observed between any spinal measurement and patient height, weight, or body mass index across all levels from L1 to L5. However, notable differences were observed based on patient race and ethnicity from L1 to L5. Asian patients demonstrated the largest pedicle lengths, followed by White, Hispanic, and Black patients in descending order. White patients demonstrated the largest IPD, canal AP diameter, and canal area, followed by Asian, Hispanic, and Black patients in descending order. Black patients demonstrated the smallest values across all anatomic measurements relative to Asian, White, and Hispanic patients. CONCLUSION: This study reports 25,000 measurements of lumbar central canal dimensions to establish quantitative thresholds for the diagnosis of CLS. Although not influenced by patient height, weight, or body mass index as one might intuit, canal dimensions were influenced by patient sex, race, and ethnicity. These findings may help explain differences in predisposition or prevalence of lumbar nerve root compression among patients of different races, which can be important when considering rates of surgery and access to care.

Migration of Bullet Fragment 11 Years after Initial Gunshot Wound leads to Cervical Prevertebral Abscess: A Case Report.

Introduction: Literature showcases conflicting findings regarding the outcomes of ballistic fragment removal from the spine in gunshot wounds (GSW) patients. Further research in this area is needed to better comprehend the nuances of risks and benefits surrounding ballistic fragment removal from the spine in GSW patients. In this case report, we discuss the late-onset cervical prevertebral abscess which developed when a previously embedded bullet fragment migrated into the retropharyngeal space 11 years after an initial GSW. Case Report: A 29-year-old male sustained a gunshot wound to the face in 2011. He was stabilized with a posterior C3-C6 lateral mass instrumentation and fusion. There were no attempts to remove the bullet fragments. In 2023, the patient returned with worsening neck pain. Imaging demonstrated a retropharyngeal abscess with interval rotation of the ballistic fragment by 90°. An abscess was noted anterior to the cervical vertebrae with a freely mobile ballistic fragment within. Conclusion: This case highlights several questions: What is the criteria for radiographic surveillance of retained hardware? If there is documented movement, should this trigger further investigation? What complications can occur that warrant careful removal?

Morphometric analysis of cervical disc space height and interpedicular distance using computed tomography.

Background: This study utilized computed tomography (CT) to establish normative radiographic morphometric measurements of cervical disc space height (DSH) and interpedicular distance (IPD) and document the influence of patient sex, race, ethnicity, and anthropometric characteristics. Methods: Cervical CTs of 1000 patients between 18 and 35 years of age without known spinal pathology were reviewed. Statistical analyses included the assessment of associations between patient height, weight, sex, race, and ethnicity regarding DSH and IPD. Results: Irrespective of disc level, average DSH measurements were as follows: anterior height of 2.6 ± 1.0 mm, middle height of 4.1 ± 1.2 mm, and posterior height of 1.8 ± 1.0 mm. IPD was only measured between C3 and C7 vertebrae, and irrespective of disc level, the mean IPD measurement was 21.1 ± 1.5 mm. Significant differences for anterior, middle, posterior DSH, and IPD were observed in all disc levels. Significant differences in DSH and IPD were observed for all anthropometric factors of sex, race, and ethnicity relative to vertebral level. Males had significantly larger DSH and IPD measurements across all vertebral levels compared to females. Caucasians had larger DSH and IPD at select vertebral levels compared to African Americans and Hispanics. Conclusion: This study describes measurements of DSH and IPD between C2 and T1 levels in 1000 healthy 18-35-year-old subjects without known pathology. DSH and IPD measurements varied based on patient sex, race, ethnicity, and disc level.

Social determinants of health and disparities in spine surgery: a 10-year analysis of 8,565 cases using ensemble machine learning and multilayer perceptron.

BACKGROUND CONTEXT: The influence of SDOH on spine surgery is poorly understood. Historically, researchers commonly focused on the isolated influences of race, insurance status, or income on healthcare outcomes. However, analysis of SDOH is becoming increasingly more nuanced as viewing social factors in aggregate rather than individually may offer more precise estimates of the impact of SDOH on healthcare delivery. PURPOSE: The aim of this study was to evaluate the effects of patient social history on length of stay (LOS) and readmission within 90 days following spine surgery using ensemble machine learning and multilayer perceptron. STUDY DESIGN: Retrospective chart review. PATIENT SAMPLE: 8,565 elective and emergency spine surgery cases performed from 2013 to 2023 using our institution's database of longitudinally collected electronic medical record information. OUTCOMES MEASURES: Patient LOS, discharge disposition, and rate of 90-day readmission. METHODS: Ensemble machine learning and multilayer perceptron were employed to predict LOS and readmission within 90 days following spine surgery. All other subsequent statistical analysis was performed using SPSS version 28. To further assess correlations among variables, Pearson's correlation tests and multivariate linear regression models were constructed. Independent sample t-tests, paired sample t-tests, one-way analysis of variance (ANOVA) with post-hoc Bonferroni and Tukey corrections, and Pearson's chi-squared test were applied where appropriate for analysis of continuous and categorical variables. RESULTS: Black patients demonstrated a greater LOS compared to white patients, but race and ethnicity were not significantly associated with 90-day readmission rates. Insured patients had a shorter LOS and lower readmission rates compared to non-insured patients, as did privately insured patients compared to publicly insured patients. Patients discharged home had lower LOS and lower readmission rates, compared to patients discharged to other facilities. Marriage decreased both LOS and readmission rates, underweight patients showcased increased LOS and readmission rates, and religion was shown to impact LOS and readmission rates. When utilizing patient social history, lab values, and medical history, machine learning determined the top 5 most-important variables for prediction of LOS -along with their respective feature importances-to be insurance status (0.166), religion (0.100), ICU status (0.093), antibiotic use (0.061), and case status: elective or urgent (0.055). The top 5 most-important variables for prediction of 90-day readmission-along with their respective feature importances-were insurance status (0.177), religion (0.123), discharge location (0.096), emergency case status (0.064), and history of diabetes (0.041). CONCLUSIONS: This study highlights that SDOH is influential in determining patient length of stay, discharge disposition, and likelihood of readmission following spine surgery. Machine learning was utilized to accurately predict LOS and 90-day readmission with patient medical history, lab values, and social history, as well as social history alone.

Evolving Effects of the COVID-19 Pandemic on Hip Fracture Outcomes: A Retrospective Comparison of Pre, Early, and Late Pandemic Timepoints.

INTRODUCTION: Hospital systems were strained during the COVID-19 pandemic, and although previous studies have shown that surgical outcomes in healthy hip fracture patients were unaffected in the initial months of the pandemic, subsequent data are limited. This study examined the evolution of hip fracture care throughout the COVID-19 pandemic. METHODS: A retrospective review (level III evidence) was done of surgically treated adult hip fractures at a Level 1 academic trauma center from January 2019 to September 2022, stratified into three groups: pre, early, and late pandemic. Continuous variables were evaluated with the Student t-test and one-way analysis of variance, categorical variables were evaluated with chi-squared, P < 0.05 considered significant. RESULTS: Late pandemic patients remained in the hospital 30.1 hours longer than early pandemic patients and 35.7 hours longer than prepandemic patients (P = 0.03). High-energy fractures decreased in the early pandemic, then increased in late pandemic (P < 0.01). Early pandemic patients experienced more myocardial infarctions (P < 0.01). No significant differences in time to surgery, revision surgery, 90-day mortality, or other adverse events were noted. CONCLUSION: To our knowledge, this is the longest study evaluating hip fracture outcomes throughout the COVID-19 pandemic. These results are indicative of an overburdened regional health system less capable of facilitating patient disposition.

Correlations among MRI-based cervical and thoracic vertebral bone quality score, CT-based Hounsfield Unit score, and DEXA t-score in assessment of bone mineral density.

BACKGROUND: Further optimization of the validated vertebral bone quality (VBQ) score using magnetic resonance imaging (MRI) may expand its clinical utility for bone mineral density (BMD) assessment. This study evaluated the correlations among cervical and thoracic VBQ scores, the validated Hounsfield Unit (HU) measured on computed tomography (CT), and dual-energy x-ray absorptiometry (DEXA) values. METHODS: We retrieved the medical and radiographic records of 165 patients who underwent synchronous MRI of the cervical and thoracic spine, as well as DEXA and CT imaging of the spine obtained within 1 year of each other between 2015 and 2022. Radiographic data consisted of the MRI-based cervical and thoracic VBQ scores, CT-based HU, and DEXA T-scores of the spine and hip. Patient age, sex, body mass index (BMI), and ethnicity were also obtained. RESULTS: Mean cervical and thoracic VBQ scores were 3.99 ± 1.68 and 3.82 ± 2.11, respectively. Mean HU and DEXA T-scores of the spine and hip were 135.75 ± 60.36, -1.01 ± 1.15, and -0.47 ± 2.27. All correlations among VBQ, HU, and DEXA were insignificant except for weak correlations between cervical and thoracic VBQ, and cervical VBQ and HU. No correlations were observed between radiographic scores and patient age or BMI. No differences based on ethnicity or sex were observed with respect to cervical or thoracic VBQ, HU, or DEXA. CONCLUSION: Cervical and thoracic VBQ scores are distinct from Hounsfield Unit and DEXA values. VBQ scoring in the cervical and thoracic spine is not influenced by patient age, ethnicity, sex, or BMI.

Multilayer Perceptron Neural Network Analysis of Fluoroscopic Working Angle on Transcatheter Aortic Valve Implantation Complications.

BACKGROUND: We sought to determine whether there is a relationship between the fluoroscopic working angle used to achieve a co-planar view during the deployment of the prosthesis during transcatheter aortic valve implantation (TAVI) and rates of complications, including paravalvular leaks, complete heart block, annular rupture, stroke, valve embolization, discharge to a skilled nursing facility and death within thirty days. METHODS: All patients undergoing TAVI at our institution from 2015 to 2022 were retrospectively analyzed. Images were reviewed to determine the fluoroscopic working angle during deployment, and medical records were used to determine the incidence and type of complication. A multilayer perceptron was employed to evaluate the predictive ability of the fluoroscopic working angle during deployment on complications of one-day and 30-day paravalvular leak, 30-day mortality, the need for a new pacemaker, discharge to a skilled nursing facility, stroke and the requirement for emergency intervention. RESULTS: Eight hundred and thirty-four patients were included in the study. Fluoroscopic working angle had excellent predictive value for stroke (area under the receiver operating characteristic curve (AUROC) of 0.812), one-day (AUROC 0.850), and 30-day paravalvular leak (AUROC 0.801). However, feature importance and scaled weighting analysis indicated that only a working angle in the left anterior oblique/cranial quadrant was informative for the development of an outcome of interest specific to a working angle quadrant (30-day paravalvular leak). CONCLUSION: Fluoroscopic working angle may be a useful way to further refine well-established risk calculi during TAVI.

Morphometric analysis of cervical neuroforaminal dimensions from C2-T1 using computed tomography of 1,000 patients.

BACKGROUND: Race and sex differences are not consistently reported in the literature. Fundamentally, anatomical differences of cervical neuroforaminal dimensions (CNFD) amongst these groups would be important to know. PURPOSE: To establish normative radiographic morphometric measurements of CNFD and uncover the influence of patient sex, race, and ethnicity while also considering anthropometric characteristics. STUDY DESIGN: Retrospective radiographic morphometric study. PATIENT SAMPLE: A total of 1,000 patients between 18 and 35 years of age who were free of spinal pathology. OUTCOME MEASURES: Foraminal height, axial width, and area of cervical neural foramen. METHODS: Cervical CTs were reviewed to measure CNFD, defined as follows: foraminal height, axial width, and area. Statistical analyses were performed to assess associations between CNFD, and patient height, weight, sex, race, and ethnicity. RESULTS: CNFD measurements followed a bimodal distribution pattern moving caudally from C2-T1. Irrespective of disc level, cervical CNFD were as follows: left and right widths of 6.6±1.5 and 6.6±1.5 mm, heights of 9.4±2.4 and 9.4±3.2 mm, and areas of 60.0±19.5 and 60.6±20.7 mm2. Left and right foraminal width were highest at C2-C3 and lowest at C3-C4. Left and right foraminal height were highest at C7-T1 and C6-C7, respectively and lowest at C3-C4. Left and right foraminal areas were highest at C2-C3 and lowest at C3-C4. Significant differences were observed for all CNFD measurements across disc levels. CNFD did not vary based on laterality. Significant CNFD differences were observed with respect to patient sex, race, and ethnicity. Male height and area were larger compared to females. In contrast, female foraminal width was larger compared to males. The Asian cohort demonstrated the largest foraminal widths. White and Hispanic patients demonstrated the largest foraminal heights and areas. Black patients demonstrated the smallest foraminal widths, heights, and areas. Patient height and weight were only weakly correlated with CNFD measurements across all levels from C2-T1. CONCLUSIONS: This study describes 36,000 normative measurements of 12,000 foramina from C2-T1. CNFD measurements vary based on disc level, but not laterality. Contrasting left- versus right-sided neuroforamina of the same level may aid in determining the presence of unilateral stenosis. Patient sex, race, and ethnicity are associated with CNFD, while patient anthropometric factors are weakly correlated with CNFD.

Clinical and Radiographic Outcomes of Anterior Lumbar Interbody Fusion With Anterior Plate Fixation.

BACKGROUND: Reports on the outcomes following instrumented anterior lumbar interbody fusion (ALIF) with anterior plate fixation are limited. The aim of this study was to assess the clinical and radiographic outcomes of patients undergoing ALIF with anterior plate fixation.  Methods: Medical records and radiographic imaging were reviewed for 100 patients who received ALIF with anterior plate fixation between 2008 to 2021 and completed at least one year of follow-up and postoperative imaging. Prospectively collected patient data included indication for surgery, BMI, age, number and location of levels treated, complications, reoperation rates, fusion rate, and measurements of global lordosis, disc space height, and segmental angulation.  Results: A total of 100 patients were included in this study. The mean length of follow-up was 81.37 months. Changes in preoperative-to-postoperative Oswestry Disability Index (ODI) and Visual Analog Score (VAS) demonstrated improvements of 30.86% and 18.56%, respectively. Major vascular injuries occurred in 3% of the cases. A hardware failure rate of 5% was observed. The reoperation rate was 10%. The radiographic fusion rate derived from computed tomography (CT) and plain film was 95.45% and 88.87%, respectively. Postoperative global lordosis demonstrated a 6.08% increase. Postoperative segmental angulation measurements increased by 57.74%. No statistically significant differences in clinical or radiographic outcomes were observed based on the spine level of fusion or the number of fusions performed.  Conclusions: ALIF with anterior plate fixation achieved an adequate fusion rate with improvements in ODI and VAS scores meeting minimal clinically important difference thresholds. Postoperative disc space heights demonstrated significant improvements compared to preoperative measurements.

Analysis of reasons for medical malpractice litigation due to anterior cervical discectomy and fusion.

Background: Anterior cervical discectomy and fusions (ACDF) are among the most common cervical spine operations, with over 137,000 surgeries performed annually. Understanding reasons underlying malpractice pertaining to ACDF may inform physicians of practices to improve delivery of patient care and mitigate malpractice. The aim of our study was to analyze the causes and outcomes for lawsuits pertaining to ACDF. Methods: The Westlaw Edge and Verdict Search databases were queried for malpractice claims utilizing the keywords "anterior cervical discectomy and fusion" and "ACDF". Inclusion criteria was based on relevance of case grievance(s) to ACDF. Data collected included date of case hearing, plaintiff demographics, defendant specialty, verdict ruling, location of filed claim, monetary award, and sustained injuries. Results: Fifty cases were included in this study after excluding 1933 cases. Of the 50 cases, 34 (68%) resulted in a defendant outcome, 8 (16%) resulted in a plaintiff outcome, and 8 (16%) resulted in settlement. Plaintiff verdicts resulted in an average monetary payment of $9.70 million, while settlements resulted in an average payment of $2.06 million. Reasons for litigation were divided into 10 categories, most commonly improper postoperative management (20%), hardware failure (18%), intraoperative error (14%), off-label use of implants (14%), and insufficient informed consent (12%). Conclusions: Malpractice claims due to ACDF are associated with higher frequencies of plaintiff verdicts and higher monetary costs compared to other spinal surgery procedures. There does not appear to be supporting evidence that spinal cord neuromonitoring is mandatory for ACDF procedures from a medicolegal standpoint.

Recent Trends in the Effect of Race and Gender on the Orthopedics Match.

Introduction Orthopedics has a reputation for being competitive but not diverse. Leaders of the orthopedics community have been making efforts to increase the participation of women and minorities in the field by raising awareness and strengthening pipeline programs. We aim to explore the trends in the risk of not matching by comparing the proportions of women and underrepresented populations in the applicant pools versus proportions in residency programs. Simultaneously, we aim to evaluate if women or underrepresented population applicants exhibit a lower likelihood of applying to orthopedics compared to male and White applicants. Methods The study received an IRB exemption. The authors collected Accreditation Council for Graduate Medical Education (ACGME) data books for the years 2015-2016 to 2022-2023 to obtain demographic information on orthopedic residents in training during each of those academic years. The pool of corresponding applicants (for example: residents in training during the 2021-2022 academic year would consist of five classes, made up of applicants from 2016-2017 to 2020-2021) was then tabulated from Electronic Residency Applications Service (ERAS) statistics, which are publicly available on the Association of American Medical Colleges (AAMC) website. The race and gender composition of the applicant pool was compared to that of corresponding enrolled residents to calculate the relative risk (RR) of women not matching compared to men and underrepresented population applicants (Blacks, Hispanics, Asians, and Native Americans) compared to White applicants. ERAS data was subsequently used to calculate the percentages of each demographic applying to all residency programs and orthopedic programs. Results For female applicants into orthopedic residency, they had a similar RR of going unmatched when compared to their male counterparts. In the academic year 2020-2021, there was an exception to this as women had a slightly higher RR of going unmatched. All underrepresented populations had a higher risk of not matching compared to White applicants for all cycles, peaking for residents in training in 2020-2021. The trendline improved for residents in the following year. Throughout the study, women accounted for 46.61% of applicants applying for any residency; however, they only accounted for 16.98% of applicants applying for orthopedic residency. A similar discrepancy is noted among Asian applicants but not Black or Hispanic applicants. Conclusions Underrepresented populations were increasingly less likely to match into orthopedics relative to White applicants until 2021. In the academic year of 2021-2022, there was an improvement in this trend for all studied underrepresented populations. Although the exact explanation for this is unclear, it is associated with the transition to virtual applicant interactions. The female gender did not appear to be a consistent advantage or disadvantage in the match. Women and Asian applicants were less likely to apply to orthopedics than other specialties.

Association Between Vertebral Bone Quality Score and Dual-Energy X-ray Absorptiometry for the Assessment of Bone Mineral Density in Adolescent Patients.

BACKGROUND: The MRI-based vertebral bone quality (VBQ) score is an assessment tool for bone mineral density (BMD) that has been validated in adults against the clinical standard of dual-energy X-ray absorptiometry (DEXA). However, VBQ has yet to be validated against DEXA for use in adolescents. This study evaluated the associations between adolescent VBQ scores, DEXA Z-scores, and BMD values. METHODS: The radiographic records of 63 consecutive patients between the ages of 11 and 21 who underwent MRI of the abdomen and pelvis and DEXA of the spine and hip were retrieved. The collected radiographic data consisted of the MRI-based VBQ score, DEXA Z-score, and BMD values of the femoral neck, L1-4 vertebrae, and total body. The VBQ score was calculated by taking the median signal intensity (MSI) from L1-L4 and the SI of the L3 cerebrospinal fluid (CSF). The VBQ score was derived as the quotient of MSIL1-L4 divided by SICSF. RESULTS: A mean VBQ score of 2.41 ± 0.29 was observed. Strong correlations of -0.749 (p<0.0001) and -0.780 (p<0.0001) were detected between the VBQ score and DEXA femoral neck and spine Z-scores, respectively. Correlations between VBQ score and DEXA femoral neck, spine, and total body BMD scores were -0.559 (p<0.0001), -0.611 (p<0.0001), and -0.516 (p<.0001), respectively. No significant correlations were found between the VBQ score and age, BMI, weight, or height. A mean difference in VBQ score of -0.155 (p=0.035) was observed between sexes. VBQ demonstrated moderate predictive ability for DEXA-derived Z-scores and BMD scores. CONCLUSIONS: VBQ scores were strongly correlated with DEXA Z-scores and moderately correlated with BMD values. The VBQ score can also be used by adolescent patients as an accessory tool to assess bone health.

Oblique lateral interbody fusion at L5-S1: feasibility, surgical approach window, incision line, and influencing factors.

PURPOSE: The primary aim of this study was to describe the feasibility, surgical approach window (SAW), and incision line (IL) for oblique lateral interbody fusion at L5-S1 (OLIF51) using computed tomography (CT). A secondary aim was to identify associations among approach characteristics and demographic and anthropometric factors. METHODS: We performed a radiographic study of 50 male and 50 female subjects who received abdominal CT imaging. SAW was measured as the distance from the midline to the medial border of the iliac vessel. IL was measured at the skin surface corresponding to the distance between the center of the disc space and SAW lateral margin. OLIF51 feasibility was defined as the existence of at least a 1-cm SAW without retraction of soft tissues. RESULTS: For the left side, the OLIF51 SAW and IL were 12.1 ± 4.6 and 175.1 ± 55.3 mm. For the right side, these measures were 10.0 ± 4.3 and 185.0 ± 52.5 mm. Correlations of r = 0.648 (p < 0.001) and r = 0.656 (p < 0.001) were observed between weight and IL on the left and right sides, respectively. OLIF51 was not feasible 23% of the time. CONCLUSION: To our knowledge, this is the largest CT study to determine the feasibility of performing an OLIF51. Without the use of retraction, OLIF51 is not feasible 23% of the time. Left-sided OLIF51 allows for a larger surgical approach window and smaller incision compared to the right side. Larger incisions are required for adequate surgical exposure in patients with higher weight.

Adding Vertebral Bone Quality to the Fusion Risk Score: Does It Improve Predictions of Postoperative Complications?

STUDY DESIGN: Retrospective review of prospectively collected data. OBJECTIVE: The current study evaluates whether the addition of the Vertebral Bone Quality (VBQ) score to the Fusion Risk Score (FRS) improves its ability to predict perioperative outcomes. SUMMARY OF BACKGROUND DATA: The FRS was developed to assess preoperative risk in patients undergoing thoracic and lumbar fusions. It includes patient-derived and surgical variables, but it does not include one that directly accounts for bone health. The VBQ score allows assessment of bone quality and has been shown to correlate to DEXA-measured bone mineral density (BMD) scores. METHODS: The VBQ score was weighted based on a regression model and then added to the FRS (FRS/VBQ). The ability of the two scores to predict the outcomes was then assessed using the area under the curve (AUC). PATIENT SAMPLE: Patients undergoing elective thoracic and lumbar spinal fusion from January 2019 to June 2020 were included. OUTCOME MEASURES: The study evaluated various perioperative adverse outcomes, including major and minor adverse events, discharge other than home, extended length of stay, 90-day emergency department visits, 90-day readmission, and 90-day and 2-year reoperation rates. RESULTS: A total of 353 met the inclusion and exclusion criteria. The FRS/VBQ demonstrated improved predictive ability compared with the FRS alone when evaluating 90-day reoperation. Both scores showed fair predictive ability for any adverse event, major adverse events, minor adverse events, and 2-year reoperation rates, with AUCs ranging from 0.700 to 0.737. Both had poor predictive ability for the other outcomes. CONCLUSIONS: Adding VBQ to the FRS significantly enhances its predictive accuracy for reoperation rate. This updated risk score provides a more comprehensive understanding of a patient's preoperative risk profile, aiding both patients and physicians in assessing surgical risks and optimizing outcomes through preoperative risk stratification. LEVEL OF EVIDENCE: 3.

Prediction of In-Hospital Mortality Following Vertebral Fracture Fixation in Patients With Ankylosing Spondylitis or Diffuse Idiopathic Skeletal Hyperostosis: Machine Learning Analysis.

BACKGROUND: Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are distinct pathological entities that similarly increase the risk of vertebral fractures. Such fractures can be clinically devastating and frequently portend significant neurological injury, thus making their prevention a critical focus. Of particular significance, spinal fractures in patients with AS or DISH carry a considerable risk of mortality, with reports on 1-year injury-related deaths ranging from 24% to 33%. As such, the purpose of this study was to conduct machine learning (ML) analysis to predict postoperative mortality in patients with AS or DISH using the Nationwide Inpatient Sample Healthcare Cost and Utilization Project (HCUP-NIS) database. METHODS: HCUP-NIS was queried to identify adult patients carrying a diagnosis of AS or DISH who were admitted for spinal fractures and underwent subsequent fusion or corpectomy between 2016 and 2018. Predictions of in-hospital mortality in this cohort were then generated by three independent ML algorithms. RESULTS: An in-hospital mortality rate of 5.40% was observed in our selected population, including a rate of 6.35% in patients with AS, 2.81% in patients with DISH, and 8.33% in patients with both diagnoses. Increasing age, hypertension with end-organ complications, spinal cord injury, and cervical spinal fractures each carried considerable predictive importance across the algorithms utilized in our analysis. Predictions were generated with an average area under the curve of 0.758. CONCLUSIONS: This study's application of ML algorithms to predict in-hospital mortality among patients with AS or DISH identified a number of clinical risk factors relevant to this outcome. CLINICAL RELEVANCE: These findings may serve to provide physicians with an awareness of risk factors for in-hospital mortality and, subsequently, guide management and shared decision-making among patients with AS or DISH.

Correlations among Cervical, Thoracic, and lumbar Hounsfield Unit measurements for assessment of bone mineral density.

OBJECTIVE: Bone mineral density assessment using Hounsfield Unit (HU) currently depends upon the availability of computed tomography (CT) of the lumbar spine. The primary aim of this study was to evaluate the associations among HU measurements of the cervical (CHU), thoracic (THU), and lumbar (LHU) spine. The secondary aim of this study was to analyze the influence of patient demographic and anthropometric characteristics on HU measurements. METHODS: Radiographic records of 165 patients who underwent CT of the cervical, thoracic, and lumbar spine were retrieved. The CHU, THU, and LHU were calculated by obtaining the mean signal intensity from the medullary portions of C3-C7, T8-T12, and L1-L4 vertebral bodies. RESULTS: Mean CHU, THU, and LHU values were 266.26 ± 88.69, 165.57 ± 55.06, and 166.45 ± 51.38. Significant differences of 100.69, 99.81, and 0.88 were observed between CHU and THU (p <.001), CHU and LHU (p <.001), and THU and LHU (p =.023). Correlations of 0.574, 0.488, and 0.686 were observed between CHU and THU (p <.001), CHU and LHU (p <.001), and THU and LHU (p <.001). No differences in HU based on sex, age, height, weight, or ethnicity were observed. Multivariate regression models demonstrated R2 values of 0.770 - 0.790 (p <.001) in prediction of LHU. CONCLUSIONS: Hounsfield Unit measurements derived from the cervical and thoracic spine correlate with the validated lumbar Hounsfield Unit. Hounsfield Unit measurements do not vary based on sex, ethnicity, age, height, or weight.

Normative Measurements of L1-S1 Segmental Angulation, Disk Space Height, and Neuroforaminal Dimensions Using Computed Tomography.

BACKGROUND AND OBJECTIVES: To establish normative anatomic measurements of lumbar segmental angulation (SA) and disk space height (DSH) in relation to neuroforaminal dimensions (NFDs), and to uncover the influence of patient demographic and anthropometric characteristics on SA, DSH, and NFDs. METHODS: NFDs, SA, and anterior, middle, and posterior DSH were measured using computed tomography of 969 patients. NFDs were defined as sagittal anterior-to-posterior width, foraminal height, and area. Statistical analyses were performed to assess associations among SA, DSH, NFDs, and patient height, weight, body mass index, sex, and ethnicity. RESULTS: SA and DSH measurements increased moving caudally from L1 to S1. Foraminal width decreased moving caudally from L1 to S1. Foraminal height and area demonstrated unimodal distribution patterns with the largest values clustered at L2-L3 on the right side and L3-L4 on the left. Significant differences in SA, DSH, and NFD measurements were observed based on the disk level. Inconsistent, marginal NFD differences were observed based on laterality. Across all disk levels, only weak-to-moderate correlations were observed between SA and DSH in relation to NFDs. Patient height, weight, and body mass index were only weakly associated with SA, DSH, and NFDs. Based on patient sex, significant differences were observed for SA, DSH, and NFD measurements from L1 to S1, with males demonstrating consistently larger values compared with females. Based on patient race and ethnicity, significant differences in SA and NFD measurements were observed from L1 to S1. CONCLUSION: This study describes 48 450 normative measurements of L1-S1 SA, DSH, and NFDs. These measurements serve as representative models of normal anatomic dimensions necessary for several applications including surgical planning and diagnosis of foraminal stenosis. Normative values of SA and DSH are not moderately or strongly associated with NFDs. SA, DSH, and NFDs are influenced by sex and ethnicity, but are not strongly or moderately influenced by patient anthropometric factors.

Normative Measurements of L1 to S1 Neuroforaminal Dimensions Derived From Plain Film Radiography, Computed Tomography, and Magnetic Resonance Imaging.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To report normative measurements of L1 to S1 lumbar neuroforamina on plain film radiography (PFR), computed tomography (CT), and magnetic resonance imaging (MRI), accounting for patients' sex and ethnicity. BACKGROUND: The quantitative criteria fothe diagnosis of neuroforaminal stenosis remains unknown. Acquiring a thorough understanding of normative foraminal dimensions is a key step in formulating objective parameters for neuroforaminal stenosis. PATIENTS AND METHODS: We measured 988 images from 494 patients between 18 and 35 years old without spinal pathology who received PFR, CT, or MRI within 1 year of each other. Neuroforaminal measurements were defined as the height, area, and sagittal and axial widths. Statistical analyses were performed to assess relationships among PFR, CT, and MRI-derived neuroforaminal measurements, as well as the influence of patients' sex and ethnicity. RESULTS: 330 PFR, 377 CT, and 281 MRI were measured. Of these, 213 PFR and CT, 117 PFR and MRI, and 164 MRI and CT intrapatient images were compared. Statistically significant differences were observed among PFR, CT, and MRI measurements across all levels L1 to S1. PFR measurements were larger compared with those derived from CT and MRI. Weak-to-moderate correlations were observed between PFR and CT, PFR and MRI, and CT and MRI, with the magnitude of correlation decreasing caudally from L1 to S1. Variations in neuroforaminal anatomy were observed based on sex and ethnicity. CONCLUSION: This study reports 25,951 measurements of normal L1 to S1 neuroforaminal anatomy assessed by PFR, CT, and MRI. The values reported in this study may be used as normative reference measurements of the lumbar neuroforamina. PFR measurements of the neuroforamina are larger compared with those derived from CT and MRI across all levels from L1 to S1. There is a poor correlation between PFR, CT, and MRI when measuring the lumbar neuroforamina. Differences in neuroforaminal anatomy are evident based on patients' sex and ethnicity.