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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.

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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.

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Estudios de Factibilidad , Vértebras Lumbares , Fusión Vertebral , Humanos , Fusión Vertebral/métodos , Masculino , Femenino , Persona de Mediana Edad , Vértebras Lumbares/cirugía , Vértebras Lumbares/diagnóstico por imagen , Anciano , Sacro/cirugía , Sacro/diagnóstico por imagen , Adulto , Tomografía Computarizada por Rayos X

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BACKGROUND: The kidneys, ribs, liver, spleen, and iliac crests can pose access-related issues to the disc space during both anterior-to-psoas (ATP) and transpsoas (TP) surgical approaches. The aim of this study was to identify and compare the presence and degree of obstruction caused by these structures for the ATP and TP approaches bilaterally from L1 to S1 using abdominal computed tomography. METHODS: Presence of obstruction by a given structure was recorded if the structure was within ATP or TP borders. Degree of obstruction was calculated as the quotient of the structure measurement within the ATP or TP approach divided by the entire corridor length at the point of obstruction. RESULTS: The percentage of time the left kidney was present during the ATP vs TP approaches at L1 to L2 was 44% vs 89% (P < 0.001), at L2 to L3 was 26% vs 75% (P < 0.001), and at L3 to L4 was 5% vs 19% (P < 0.001). For the right kidney, these values were 37% vs 78% (P < 0.001), 43% vs 71% (P < 0.001), and 11% vs 18% (P < 0.001). The percentage of time the left rib was present during ATP vs TP approaches was 41% vs 81% (P < 0.001) at L1 to L2 and 11% vs 26% (P = 0.413) at L2 to L3. With respect to the liver, the ATP approach was obstructed 56%, 30%, and 9% of the time at the levels of L1 to L2, L2 to L3, and L3 to L4; the liver was not present in L1 to L4 TP approach. CONCLUSIONS: This study is the first to both characterize and compare nonneurological structures at risk during ATP and TP fusion approaches bilaterally from L1 to S1 using abdominal computed tomography. Findings suggest the ATP approach poses less structures at risk relative to the TP approach with respect to the kidneys, ribs, and iliac crests bilaterally. The TP approach offers advantages compared with ATP approach with respect to the liver and spleen. CLINICAL RELEVANCE: Findings from this study are clinically relevant for ATP and TP surgical approach planning.

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BACKGROUND: Although the radiographic parameters for diagnosing central lumbar canal stenosis are well described, parameters for the diagnosis of neuroforaminal stenosis (NFS) are less well defined. Previous studies have used magnetic resonance imaging (MRI) and radiography to describe neuroforaminal dimensions (NFDs). Those methods, however, have limitations that may substantially distort measurements. Existing literature on the use of computed tomography (CT) to investigate normal NFDs is limited. METHODS: This anatomic assessment evaluated CT imaging of 300 female and 300 male subjects between 18 and 35 years of age to determine normal NFDs, specifically the sagittal anteroposterior width, axial anteroposterior width, craniocaudal height, and area. Statistical analyses were performed to assess differences in NFDs according to variables including sex, age, height, weight, body mass index, and ethnicity. RESULTS: Overall, mean NFDs were 9.08 mm for sagittal anteroposterior width, 8.93 mm for axial anteroposterior width, 17.46 mm for craniocaudal height, and 134.78 mm 2 for area (n = 6,000 measurements each). Male subjects had larger NFDs than females at multiple levels. Both Caucasian and Asian subjects had larger NFDs than African-American subjects at multiple levels. There were no associations between foraminal dimensions and anthropometric factors. CONCLUSIONS: This study describes CT-based L1-S1 NFDs in young, healthy patients who presented with reasons other than back pain or pathology affecting the neuroforamen. Dimensions were influenced by sex and ethnicity but were not influenced by anthropometric factors. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

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BACKGROUND AND OBJECTIVES: Spinal fusion through the anterior-to-psoas (ATP) technique harbors several approach-related risks. We used abdominal computed tomography imaging to analyze the L1-L5 ATP fusion approach measurements, feasibility, degree of obstruction by non-neurological structures, and the influence of patient characteristics on ATP approach dimensions. METHODS: The vascular window, psoas window, safe window, and incision line anterior and posterior margins for the ATP approach were measured on abdominal computed tomography imaging. The feasibility of approach and the presence of kidneys, ribs, liver, spleen, and iliac crests within the ATP approach were also measured. Correlation and regression models among radiographic measurements and patient age, height, weight, and body mass index (BMI) were analyzed as well as differences in approach measurements based on sex. RESULTS: Safe window and incision line measurements were more accommodating for the left-sided vs right-sided ATP approach. At L4-5, the ATP approach was not feasible 18% of the time on the left side vs 60% of the time on the right side. The spleen was present 22%, 10%, and 3% of the time from L1-4, while the liver was present 56%, 30%, and 9% of the time. The iliac crests were not observed within ATP parameters. Patient age, height, weight, and BMI did not strongly correlate with approach measurements, although ATP dimensions did differ based on sex. CONCLUSION: This study reports characteristics of the ATP approach including approach measurements, feasibility, non-neurological structures at risk, and influencing factors to approach measurements. While incision line measurements are larger for male patients compared with female patients at the lower lumbar levels, safe window sizes are similar across all levels L1-L5. The kidneys, ribs, spleen, and liver are potential at-risk structures during the ATP approach, although the iliac crests pose limited concern for ATP technique. Patient characteristics such as age, height, weight, and BMI do not markedly affect ATP approach considerations.

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Vértebras Lumbares , Imagen por Resonancia Magnética , Humanos , Masculino , Femenino , Vértebras Lumbares/cirugía , Estudios de Factibilidad , Imagen por Resonancia Magnética/métodos , Tomografía Computarizada por Rayos X , Adenosina Trifosfato

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PURPOSE: The primary aim was to measure the safe corridor (SC), surgical incision anterior margin (AM), and posterior margin (PM) for OLIF bilaterally from L1 to L5. The secondary aim was to determine the feasibility of approach via the SC. The tertiary aim was to analyze the influence of demographic and anthropometric factors on OLIF parameters. METHODS: We performed a radiographic analysis of 100 subjects who received an abdominal CT. Measurements of the AM, PM, and SC were obtained as well as patient age, sex, height, weight, and BMI. The intraclass correlation coefficient was used to evaluate interrater reliability. To assess associations among variables, Pearson's correlation tests and multivariate linear regression models were constructed. Sex differences were analyzed using Student's t tests. RESULTS: At L1-2, L2-3, L3-4, and L4-5, the PM was 6.6, 8.2, 9.4, and 10.2 cm on the left side and 7.2, 7.7, 8.8, and 9.5 cm on the right side in relation to the disk space center. The SC was less than 1 cm 1%, 3%,3%, and 18% of the time on the left side, and 15%, 12%,29%, and 60% on the right side. None of the anthropometric factors demonstrated a strong correlation with incision location. SC was larger on the left side. Interrater ICC was .934. CONCLUSIONS: This study is the first to provide guidelines on the appropriate location of the incision line during OLIF based on SC from L1 to L5. SC measurements do not vary by sex. OLIF is more feasible via a left-sided approach.

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Fusión Vertebral , Herida Quirúrgica , Humanos , Masculino , Femenino , Estudios de Factibilidad , Reproducibilidad de los Resultados , Vértebras Lumbares/cirugía , Tomografía Computarizada por Rayos X

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INTRODUCTION:  Spinal epidural abscess (SEA) is a rare process with significant risk for morbidity and mortality. Treatment includes an extended course of antibiotics with or without surgery depending on the clinical presentation. Both non-operative and surgically treated patients require close follow-up to ensure the resolution of the infection without recurrence and/or progression of neurologic deficits. No previous study has looked specifically at follow-up in the SEA population, but the review of the literature does show evidence of varying degrees of difficulty with follow-up for this patient population. METHODS:  This retrospective review looked at follow-up for 147 patients with SEA at a single institution from 2012 to 2021. Statistical analyses were performed to assess differences between groups of surgical versus non-surgical patients and those with adequate versus inadequate follow-up. RESULTS: Sixty-two of 147 (42.2%) patients had inadequate follow-up (less than 90 days) with their surgical team, and 112 of 147 (76.2%) patients had inadequate follow-up (less than 90 days) with infectious disease (ID). The primary statistically significant difference between patients with adequate versus inadequate follow-up was found to be surgical status with those treated surgically more likely to have adequate follow-up than those treated non-operatively. CONCLUSION: Improved follow-up in surgical patients should be considered as a factor when deciding on surgical versus non-operative treatment in the SEA patient population. Extra efforts coordinating follow-up care should be made for SEA patients.