The prevalence and clinical significance of transitional vertebrae: a radiologic investigation using whole spine spiral three-dimensional computed tomographic images

Lumbosacral transitional vertebra on whole-spine CT: prevalence and association with rib abnormalities

OBJECTIVE

To determine the prevalence of lumbosacral transitional vertebrae (LSTV) and rib abnormalities and investigate the association between LSTV subtypes and rib abnormalities using whole-spine CT.

MATERIALS AND METHODS

The vertebral levels were counted caudally from the cervical vertebra, based on the eighth being the first thoracic vertebra, the twentieth as the first lumbar vertebra, and the twenty-fifth being the first sacral vertebra using sagittal reconstructed CT. Sacralization is when 23 vertebrae are found, whereas lumbarization is the presence of 25 vertebrae.

RESULTS

This retrospective study included 551 patients (407 females and 144 males). There is no evidence of a difference in age and sex that was observed between the LSTV and no LSTV groups (95% CIs; - 0.34, 3.08; p = 0.12 and p = 0.24, respectively). LSTV were reported in 16.3% of participants, consisting of 12.3% of sacralization and 4.0% of lumbarization. The incidence rate of lumbarization was significantly high in male participants (p = 0.031). Rib abnormalities were reported in 14.0% of participants, consisting of 12.6% of twelfth hypoplastic rib and 1.5% of lumbar rib. In patients with LSTV, all twelfth hypoplastic ribs were found in the sacralization group and all lumbar ribs were found in the lumbarization group (p < 0.001). The types based on the Castellvi classification demonstrated a significant difference between the sacralization and lumbarization groups (p = 0.007).

CONCLUSION

The findings of our study suggest that patients with sacralization and lumbarization are predisposed to having twelfth hypoplastic ribs and lumbar ribs, respectively.

Does fast running limit numerical variability of the vertebral column in rabbits and hares (Leporidae: Lagomorpha)?

In mammalian vertebral columns, locomotive ability is expected to be an evolutionary driver of variation in the number of vertebrae; in species evolved to run fast or have a flexible vertebral column, they generally have limited numerical variation and low occurrence of malformed vertebrae to maintain their running performance. Although this hypothesis is supported among species sharing similar locomotive constraints (e.g. dorsomobile versus dorsostable species), whether it applies at the within-species level is unknown. We test this hypothesis using species of Leporidae (rabbits and hares) with different locomotive abilities: we examined the number of presacral vertebrae and the frequency of abnormalities in 504 specimens from 4 species, representing cursorial, saltatorial and generalist modes. Our results show that the cursorial leporids had the lowest numerical variability and fewest abnormalities within species, although this was not statistically different from saltatorial or generalist species. We also identified 11 conditions of vertebral abnormality previously unexplored and theorize that each may pose different degrees of locomotive impairment and effects on species' fitness. The lack of statistical support for the hypothesis at a finer phylogenetic level suggests further research is needed to understand whether numerical variability is under stabilizing selection or a developmental response to locomotive constraints in cursorial animals.

Prevalence and characteristics of lumbar ribs: a meta-analysis with anatomical and clinical considerations

BACKGROUND

Lumbar ribs (LR) are a rare and relatively unknown anatomical abnormality of the lumbar spine. The literature provides better understanding regarding other spinal congenital variations like cervical ribs or lumbosacral transitional vertebrae, which are rather commonly recognised conditions. Thus, this meta-analysis aimed to provide data on prevalence and key characteristics of LR.

METHODS

Relevant databases were systematically searched for studies reporting the prevalence, laterality and geographic distribution of LR. No exclusion criteria based on language and date of original articles were employed. The pooled prevalence estimates (PPE) were calculated using a random-effects model. To assess the between-study heterogeneity, the I2 statistic and Chi-square test were utilized. Throughout the investigation, the PRISMA guidelines were adhered to scrupulously. Evaluation of the included studies' reliability was made with the AQUA tool.

RESULTS

In total, 9 studies were included in this meta-analysis. The pooled prevalence estimate (PPE) of LR was 2.1% (95%CI: 1.0-4.6). In studies based on CT imaging, LR were found in 1.6% (95%CI: 0.6-4.3) of patients and in Xray based studies in 2.1% (95%CI: 0.4-11.1) of patients. Lumbar ribs were bilateral in majority of individuals (65.4%, 95%CI: 39.4-84.6) and could be most frequently encountered in Europe with PPE of 2.8% (95%CI: 3.0-20.0), then in East Asia with PPE of 1.5% (95%CI: 1.0-19.2) and Middle East with PPE of 1.1% (95%CI: 0.6-20.0).

CONCLUSIONS

The findings of our study indicate that LR are a common anatomical variation of lumbar spine, contrary to previous beliefs. In a clinical practice, when a patient presents with a non-specific low back pain, a possible occurrence of LR should be taken into consideration. The presence of LR may be misleading for surgeons and result in wrong-level spine surgeries.

Lumbarization and sacralization: Domains of their co-occurrence with other costal-vertebral transformations are not identical

OBJECTIVES

This study evaluates whether sacralization of a lumbar vertebra and lumbarization of a sacral vertebra are a paired duality but with opposite expressions; the former is associated with 23 presacral vertebrae (PSV) and the latter with 25 PSV. Are sacralization and lumbarization local phenomena, involving only vertebra (V) 24 and V25, or are they associated with other costal-vertebral transformations?

MATERIALS AND METHODS

Study sample is of skeletonized humans, 431 females and 1405 males, who were 20-49 years of age-at-death and who died in the United States in the 20th and 21st centuries. Data collected are numbers of PSV and sacral vertebrae, presence of rib of V7, position of diaphragmatic vertebra, and transverse process and rib lengths of V5-V9, V18-V19, and V21-V22.

RESULTS

Females and males differ significantly in numbers of PSV. Both sexes show significant differences among individuals with 23 PSV, 24 PSV, and 25 PSV: (1) individuals with 23 PSV have the shortest ribs, whereas those with 25 PSV have the longest ribs, of V18 and V19; and (2) individuals with 23 PSV have the highest frequency of 6 sacral vertebrae, whereas those with 25 PSV have the highest frequency of 5 sacral vertebrae.

DISCUSSION

Individuals with 23 PSV and 25 PSV show posterior and anterior homeotic transformation, respectively, of the thoracic-lumbar and lumbar-sacral boundaries, but only individuals with 25 PSV show transformation of the sacral-coccygeal boundary. As co-occurring costal-vertebral transformations differ between sacralization and lumbarization, inferentially the set of genes that influences these vertebrae also differs.

Effect of lumbosacral transitional vertebra on developmental alterations of the hip: a quantitative investigation of the lumbo-pelvic-hip complex via whole-body computed tomography

Background

Lumbosacral transitional vertebra (LSTV) is a common spinal variant, with the reported prevalence varying from 8.1% to 36%. LSTV has been shown to alter the lumbo-pelvic parameters and reduce the benefits of total hip arthroplasty, but the specific effects of LSTV on hip development remain unclear. The aim of this study was thus to investigate the impact of LSTV on developmental alterations of the hip.

Methods

A total of 310 individuals were categorized into three groups according to whole-body computed tomography (CT) imaging: a group with sacralization of 23 presacral vertebrae (PSV) (n=102), a group with lumbarization of 25 PSV (n=108), and a normal control group with 24 PSV (n=100). Quantitative parameters of the lumbo-pelvic-hip complex (LPHC) including lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), axial and sagittal acetabular anteversion angle (AAA), center-edge (CE) angle, Sharp angle, and femoral neck-shaft angle (FNSA) were measured and analyzed. Statistical analyses were used to compare the differences of these quantitative parameters among the three groups and to assess the relationship between hip and lumbar-pelvic parameters.

Results

Significant differences between each pair of three groups and the LSTV subgroups were only found in the sagittal AAA (left side: P=0.008; right side: P<0.001), with no differences found for the other parameters. Compared to the normal group (24 PSV), both the 23 PSV and 25 PSV groups exhibited increased values in the sagittal AAA, especially in the right side of the 23 PSV group. Only the sagittal AAA showed low-to-moderate positive correlations with pelvic parameters of PI (r=0.195-0.429; P=0.001-0.08) and PT (r=0.239-0.605; P=0.001-0.03).

Conclusions

Variations of LSTV are correlated with the hip anatomical development via LPHC transmission and may potentially reduce the sagittal acetabular coverage, particularly in the 23 PSV subtype on the right side.

Frequency of Coexistent Spinal Segment Variants: Retrospective Analysis in Asymptomatic Young Adults

BACKGROUND AND PURPOSE

Spinal segment variants are highly prevalent and can potentially lead to incorrect spinal enumeration and, consequently, interventions or surgeries at the wrong vertebral levels. Our aim was to assess the prevalence of spinal segment variants and to study the potential association among these variants in a population without histories of spine symptoms.

MATERIALS AND METHODS

Consecutive computed tomography exams of 450 young adults originally evaluated for non-spinal conditions and without a history of spinal diseases from a single institution. In addition to using descriptive statistics for reporting frequencies of spinal segment variants, the association between these variants was studied by calculating odds ratios and their 95% confidence interval. Consecutive CT exams were evaluated to determine the total number of presacral segments, presence of cervical rib, thoracolumbar transitional vertebra, iliolumbar ligament, and lumbosacral transitional vertebra.

RESULTS

The spinal segment distribution variants (an atypical number of presacral segments or an atypical distribution of thoracolumbar vertebrae), cervical rib, thoracolumbar transitional vertebra, and lumbosacral transitional vertebra were reported in 23.8%, 4.2%, 15.3%, and 26.4% of cases in our study population. The presence of a cervical rib or a thoracolumbar transitional vertebra was associated with concurrent lumbosacral transitional vertebra (OR = 3.28; 95% CI, 1.29-8.47 and 1.87; 95% CI, 1.08-3.20, respectively). The inability to visualize the iliolumbar ligament was also associated with the presence of cervical ribs (OR = 3.06; 95% CI, 1.18-7.80).

CONCLUSIONS

In a population of asymptomatic young adults, spinal segment variants are both highly prevalent with a high rate of coexistence. When a spinal segment variant (eg, transitional vertebra) is diagnosed, additional imaging might be considered for accurate spine enumeration before interventions or operations.

Evaluation of spinopelvic parameters in patients with lumbosacral transitional vertebra: a cross sectional and comparative study

INTRODUCTION

Lumbosacral transitional vertebra (LSTV) is the most common congenital anomaly of the lumbosacral junction and is a frequent cause of back pain in young patients with a prevalence of 4.6% to 36% in different regions.

OBJECTIVE

The objective of this study was to evaluate spinopelvic parameters in patients with lumbosacral transitional vertebra and to compare them with the same parameters of low back ache patients without lumbosacral transitional vertebra.

METHODS

This was a cross-sectional and comparative study conducted among low back ache patients presenting to our tertiary care center. Low back ache patients presenting to the outpatient department of AIIMS Jodhpur were screened for LSTV using radiographs. The spinopelvic parameters of those with LSTV were measured using Surgimap software and compared with the parameters of low back ache patients without LSTV. An Independent sample t-test was done and p-values were calculated.

RESULTS

The spinopelvic parameters, pelvic incidence, pelvic tilt and lumbar lordosis differed significantly in the patients with LSTV. Pelvic incidence was higher in the group with LSTV (58.5+9.3) when compared to the group without LSTV (50+8.8) with a p-value (<0.001). Pelvic tilt was higher in the group with LSTV (19.4+8.8) when compared to the group without LSTV (13.6+7.8) with a p-value (0.001). Lumbar lordosis was significantly higher in the group with LSTV (57.6+13.2) when compared to the group without LSTV (50.7+12.2) with a p-value (0.007). No significant differences were obtained in sacral slope and Pelvic-incidence and lumbar lordosis mismatch.

CONCLUSION

LSTV alters the spinopelvic parameters. Altered spinopelvic parameters predispose to spondylolisthesis, degenerative disc disease, and facet joint arthritis and are important in preoperative planning in spine and pelvic surgeries.

Addressing Challenges of Opportunistic Computed Tomography Bone Mineral Density Analysis

Computed tomography (CT) offers advanced biomedical imaging of the body and is broadly utilized for clinical diagnosis. Traditionally, clinical CT scans have not been used for volumetric bone mineral density (vBMD) assessment; however, computational advances can now leverage clinically obtained CT data for the secondary analysis of bone, known as opportunistic CT analysis. Initial applications focused on using clinically acquired CT scans for secondary osteoporosis screening, but opportunistic CT analysis can also be applied to answer research questions related to vBMD changes in response to various disease states. There are several considerations for opportunistic CT analysis, including scan acquisition, contrast enhancement, the internal calibration technique, and bone segmentation, but there remains no consensus on applying these methods. These factors may influence vBMD measures and therefore the robustness of the opportunistic CT analysis. Further research and standardization efforts are needed to establish a consensus and optimize the application of opportunistic CT analysis for accurate and reliable assessment of vBMD in clinical and research settings. This review summarizes the current state of opportunistic CT analysis, highlighting its potential and addressing the associated challenges.

Thoracolumbar transitional vertebrae: Quantitative differentiation and associated numeric variation in the vertebral column using skeletal remains

Transitional vertebrae at the thoracolumbar region are called thoracolumbar transitional vertebrae (TLTV) and retain physical features from the thoracic and lumbar regions. Since TLTV were first classified 40 years ago, there has been much discrepancy regarding its features, identification and clinical relevance. Vertebral body levels are used in the medical field as a frame of reference to locate specific organs, vessels, nerves or landmarks. Any numeric variation or deviation in the vertebral column may lead to clinical errors. Previous findings have suggested a high association between numeric variation and the presence of TLTV. Therefore, the aim of this study was to identify the types of TLTV observed and to identify any possible associated numeric variation in the vertebral column. This study also aimed to validate the established technique to quantitatively differentiate TLTV from T12 and L1 at the thoracolumbar junction using skeletal remains from a South African population group. Skeletal remains (n = 187) remains from the Pretoria bone collection were assessed. Measurements were taken of the angle of the superior zygapophyseal processes of the last thoracic vertebra (T12), the first lumbar (L1), and identified TLTV. The results indicate a TLTV prevalence of 35% (n = 66/187). The results show that each vertebral type (T12, L1, TLTV) fall into independent confidence intervals: T12 is 188° ± 9.22 (CI: 187° < μ < 189.6°), 110° ± 7.52 (CI: 109.2° < μ < 111.3°) in L1, and 135° ± 24.51 (CI: 130.4° < μ < 139.1°) in the TLTV. This study observed that 70% of cases with TLTV was associated with numeric variation in the spine, both homeotic and meristic and that TLTV has a 35% prevalence. The results clearly show that quantitative morphometric analysis can effectively differentiate TLTV from other vertebral types at the thoracolumbar junction in skeletal remains.

If you look this way, you will see it: cranial shift in adolescent idiopathic scoliosis

INTRODUCTION

Anatomical variations in the spine can be seen in each transitional border, either toward the skull as 'cranial shifts' or away as caudal shifts. Cranial shifting (CS) occurs when there is presence of occipitalization, C7 cervical costae or prominent transverse processes, thoracolumbar transitional vertebrae (TLTV) at T12 level, L5 sacralization, and sacrococcygeal fusion. We termed the coexistence of sacralization of L5 and absence or remarkable reduction of T12 rib size in AIS as Abul cranial shift (ACS). In this descriptive clinical study, primary aim was to investigate the incidence of ACS in AIS.

METHODS

Retrospective analysis of 187 surgically treated AIS cases was performed. Demographic data were recorded. The incidence of the specific set of anatomic variations including lumbosacral transitional vertebrae, TLTV, transverse process changes in C7 vertebrae, and posterior lumbosacral neural arch cleft formations (NACf) were evaluated in the radiological images.

RESULTS

36 (19%) of 187 cases had ACS. ACS was detected in only 1 of 19 male cases (5%), while in 35 of 168 female cases (21%). Forty-one cases had sacralization of L5 (22%). There were only eleven pair of ribs in 14 (7%) of 187 cases and 10 (28%) of 36 ACS cases. Forty cases had NACf (21%). ACS and NACf coexistence were observed in 8 (22%) of 36 ACS cases.

CONCLUSION

Accurate spinal column assessment is critical in adolescent idiopathic scoliosis (AIS). ACS may be observed in up to one in five AIS cases and its presence should not be neglected to avoid wrong level surgery.

An Automated Treatment Planning Framework for Spinal Radiation Therapy and Vertebral-Level Second Check

PURPOSE

Complicating factors such as time pressures, anatomic variants in the spine, and similarities in adjacent vertebrae are associated with incorrect level treatments of the spine. The purpose of this work was to mitigate such challenges by fully automating the treatment planning process for diagnostic and simulation computed tomography (CT) scans.

METHODS AND MATERIALS

Vertebral bodies are labeled on CT scans of any length using 2 intendent deep-learning models-mirroring 2 different experts labeling the spine. Then, a U-Net++ architecture was trained, validated, and tested to contour each vertebra (n = 220 CT scans). Features from the CT and auto-contours were input into a random forest classifier to predict whether vertebrae were correctly labeled. This classifier was trained using auto-contours from cone beam computed tomography, positron emission tomography/CT, simulation CT, and diagnostic CT images (n = 56 CT scans, 751 contours). Auto-plans were generated via scripting. Each model was combined into a framework to make a fully automated clinical tool. A retrospective planning study was conducted in which 3 radiation oncologists scored auto-plan quality on an unseen patient cohort (n = 60) on a 5-point scale. CT scans varied in scan length, presence of surgical implants, imaging protocol, and metastatic burden.

RESULTS

The results showed that the uniquely designed convolutional neural networks accurately labeled and segmented vertebral bodies C1-L5 regardless of imaging protocol or metastatic burden. Mean dice-similarity coefficient was 85.0% (cervical), 90.3% (thoracic), and 93.7% (lumbar). The random forest classifier predicted mislabeling across various CT scan types with an area under the curve of 0.82. All contouring and labeling errors within treatment regions (11 of 11), including errors from patient plans with atypical anatomy (eg, T13, L6) were detected. Radiation oncologists scored 98% of simulation CT-based plans and 92% of diagnostic CT-based plans as clinically acceptable or needing minor edits for patients with typical anatomy. On average, end-to-end treatment planning time of the clinical tool was less than 8 minutes.

CONCLUSIONS

This novel method to automatically verify, contour, and plan palliative spine treatments is efficient and effective across various CT scan types. Furthermore, it is the first to create a clinical tool that can automatically verify vertebral level in CT images.

Vertebrae at the thoracolumbar junction: A quantitative assessment using CT scans

The thoracolumbar junction is often associated with traumatic injuries, due to its biomechanical instability. Reasons for this instability are currently still under debate; however, contributing factors such as the rapid change in spinal curvature and facet orientation from the thoracic to lumbar transition have been implicated. Normally, the superior facet orientation in the thoracic region is angled in a coronal plane, whereas vertebrae in the lumbar region have facets angled in the sagittal plane. Distinguishing between thoracic, lumbar, and transitional vertebrae at the thoracolumbar junction based on articular facet angles, using quantitative methods on CT scans has, to the authors' knowledge, not yet been reported in the literature. Therefore, this study aimed to evaluate whether quantitative measurements can be clinically applied and used to differentiate vertebrae at the thoracolumbar junction using CT scans and, additionally, to record possible cases of congenital defects or variations observed in the spine. A sample (n = 173) of CT scans representative of the Windhoek population in Namibia was retrospectively assessed using radio-imaging software. Measurements of the angle formed by the superior facets of the vertebrae at the thoracolumbar junction (T11-L1) were recorded. Based on the results of this study, quantitative morphometry of the superior facet of vertebrae can differentiate between thoracic, lumbar,. and transitional vertebrae at the thoracolumbar junction. All individuals with identified thoracolumbar transitional vertebrae (TLTV) in this sample had at least one other congenital anomaly of the spine.

Prediction of successful caudal epidural injection using color Doppler ultrasonography in the paramedian sagittal oblique view of the lumbosacral spine

Background

Ultrasound-guided caudal epidural injection (CEI) is limited in that it cannot confirm drug distribution at the target site without fluoroscopy. We hypothesized that visualization of solution flow through the inter-laminar space of the lumbosacral spine using color Doppler ultrasound alone would allow for confirmation of drug distribution. Therefore, we aimed to prospectively evaluate the usefulness of this method by comparing the color Doppler image in the paramedian sagittal oblique view of the lumbosacral spine (LS-PSOV) with the distribution of the contrast medium observed during fluoroscopy.

Methods

Sixty-five patients received a 10-mL CEI of solution containing contrast medium under ultrasound guidance. During injection, flow was observed in the LS-PSOV using color Doppler ultrasonography, following which it was confirmed using fluoroscopy. The presence of contrast image at L5-S1 on fluoroscopy was defined as “successful CEI.” We then calculated prediction accuracy for successful CEI using color Doppler ultrasonography in the LS-PSOV. We also investigated the correlation between the distribution levels measured via color Doppler and fluoroscopy.

Results

Prediction accuracy with color Doppler ultrasonography was 96.9%. The sensitivity, specificity, positive predictive value, and negative predictive value were 96.7%, 100%, 100%, and 60.0%, respectively. In 52 of 65 patients (80%), the highest level at which contrast image was observed was the same for both color Doppler ultrasonography and fluoroscopy.

Conclusions

Our findings demonstrate that color Doppler ultrasonography in the LS-PSOV is a new method for determining whether a drug solution reaches the lumbosacral region (i.e., the main target level) without the need for fluoroscopy.