Elsevier

The Spine Journal

Volume 11, Issue 9, September 2011, Pages 858-862
The Spine Journal

Clinical Study
The prevalence of transitional vertebrae in the lumbar spine

https://doi.org/10.1016/j.spinee.2011.08.005Get rights and content

Abstract

Background context

Lumbosacral transitional vertebrae (LSTVs) are a congenital vertebral anomaly of the L5–S1 junction in the spine. This alteration may contribute to incorrect identification of a vertebral segment, leading to wrong-level spine surgery and poor correlation with clinical symptoms. Although several studies describe the occurrence of this anomaly in back pain populations, investigation of the prevalence in the American general population is lacking.

Purpose

To establish the prevalence rates for LSTVs in the general population.

Study design

Retrospective review.

Patient sample

Consecutive kidney-urinary bladder (KUB) radiographs of subjects from the past 2 years (2008–2009).

Outcome measures

Clinical demographics, number of lumbar vertebrae, L5–S1 transverse process (TP) height, and rib length.

Methods

Consecutive adult KUB studies of adult subjects were queried with clear visibility of the last rib’s vertebral body articulation, all lumbar TPs, and complete sacral wings. Exclusion criteria consisted of any radiologic evidence of previous lumbosacral surgery that would obstruct our measurements. A total of 1,100 abdominal films were reviewed, and 211 were identified as being adequate for the measurement of the desired parameters.

Results

Two hundred eleven subjects were identified as eligible for the study, and 75 (35.6%) were classified as positive for a transitional lumbosacral vertebra. The most common anatomical variant was the Castellvi Type IA (14.7%). The average age at the time of the KUB study was 59.8 years (18–95 years). One hundred ninety-seven subjects (93.4%) presented five lumbar (nonribbed) vertebrae, and only 14 (6.6%) had six lumbar vertebrae.

Conclusions

The significance of lumbosacral transitional level changes to the establishment of pain, degenerative changes, stenosis, and disc disease have been well documented in symptomatic patients. Although LSTV’s role in low back pain remains controversial, our study has shown that, when the same criteria are used for classification, prevalence among the general population and symptomatic patients may be similar.

Introduction

Evidence & Methods

Transitional vertebrae are common and have surgical implications. This study assesses their prevalence detected on abdominal films in 1,100 United States subjects.

Approximately one-third of subjects studied were found to have transitional vertebrae of various configurations. In more than 5%, the number of lumbar levels was only 4. Approximately 15% of the subjects had nonmobile or minimally-mobile caudal segments.

The presence of transitional vertebrae can impact identification of intraoperative levels (McCulloch's “most common cause of wrong-level surgery”), clinical findings (prefixed versus postfixed lumbosacral plexus), and the anterior approach (a shift in the level of bifurcation). This study confirms previous reports on the diversity of native anatomy and potential for erroneous surgical planning or execution.

—The Editors

The vertebral column supports the weight and burdens of the upper body. This weight subjects the spine to an increasing magnitude of vertical compression forces, transmitted axially toward the lumbosacral joint. At this point, the transference of most forces occurs between L5–S1 vertebral bodies and the articular facets; it then extends horizontally via the ligaments to the sacrum, then downward to the lower extremities [1]. Whenever anomalous articular facets are present between L5–S1, load can be conveyed from the L5 transverse processes (TPS) through the iliolumbar ligaments [2].

Lumbosacral transitional vertebra (LSTV) is a congenital vertebral anomaly of the L5–S1 junction in the spine. Definite manifestations are lumbarization of S1 (nonfusion between the first two sacral segments) or sacralization of the fifth lumbar vertebra (fusion between L5 and the first sacral segment). This alteration may contribute to incorrect identification of a vertebral segment, which can lead to spine surgery at the wrong level and unresolved symptoms [3]. Interestingly, McCulloch and Waddell [4] showed that the L5 nerve always originates in the “last mobile” segment of the spine, and Hughes and Saifuddin [5] reported nearly a 70% absence of the iliolumbar ligaments in subjects with lumbosacral transitional segments, confirming that presence of a transitional state disrupts normal spinal biomechanics and anatomy.

Kidney-urinary bladder or abdominal radiographs have many clinical uses and are most often indicated for patients who exhibit signs of intestinal obstruction or visceral perforation. They can also be used to verify the placement of nasogastric feeding tubes and assess the urinary system. This study uses abdominal radiographs for a different purpose, that is, to provide a radiographic image of the lumbar spine, especially our area of interest, L5–S1. Given the vast range of purposes for which abdominal radiographs are obtained, the images from a radiographic study initially performed for abdominal indications would provide a diverse sample that represents the general population and therefore be appropriate for a study that evaluates subjects for LSTVs.

Several studies describe the occurrence of this anomaly in a back pain population [6], [7], [8], [9], [10], [11]; however, investigation of the prevalence in the American general population is lacking. Therefore, our study aims to establish the prevalence rates for LSTVs in the American general population, with the hypothesis that it will be lower than the back pain–associated prevalence reported in the literature.

Section snippets

Methods

After institution review board approval for this retrospective study, a list of consecutive adult KUB studies was queried at our institution. Inclusion criteria were subject's age at time of X-ray older than 18 years; and KUB films available with clear visibility of last rib's vertebral body articulation, all lumbar TPs, and complete sacral wing. Exclusion criteria consisted of any radiologic evidence of previous lumbosacral surgery that would obstruct our measurements. A total of 1,100

Results

Two hundred eleven subjects, 107 men and 104 women, were identified as eligible for the study; average age was 59.8 years (18–95 years). Of them, 75 (35.6%) were classified as positive for transitional lumbosacral vertebra, with a gender distribution of 40 (19%) men and 35 (16.6%) women. The most common anatomical variant was the Castellvi Type IA (14.7%), followed by Type IB (8.53%), Type IIA (4.3%), Type IIB (3.8%), Type IIIA (1.9%), Type IIIB (1.4%), and Type IV (0.9%). Statistical

Discussion

The prevalence of LSTV available in the literature ranges between 4% and 36%, with a mean of 12.3% [14], but most focus on European and Asian contemporary populations associated with low back pain and rates for specific radiographic types of transitional states are scarce and unclear. This study found a prevalence rate of 35.6% for lumbosacral transitional state on a general population and also defines the occurrence rate for each subtype of the Castellvi [13] radiographic classification system

Conclusion

This study focuses on the evaluation of gross radiographic morphology of sacra bearing accessory articulations with the L5 vertebrae in the general population. Although it is assumed that the presence of transitional vertebra is associated with degenerative changes of the lumbosacral spine, the true prevalence of these vertebrae in an asymptomatic American population is not known.

In this study, we have established the incidence of this phenomenon and provided data concerning the distribution of

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  • Influence of lumbosacral transitional vertebrae on spinopelvic parameters using biplanar slot scanning full body stereoradiography―analysis of 291 healthy volunteers

    2022, Journal of Orthopaedic Science
    Citation Excerpt :

    LL was strongly positively correlated with PI in the normal and LSTV groups, even with the difference in the location the sacral base (Fig. 6, Table 4). LSTV are common congenital vertebral anomalies of L5-S1 that have a wide range of morphologic features [20–22]. In general, the lowest rib-bearing vertebra is labeled T12, the lowest lumbar transverse process with a square appearance is labeled L5, and the first vertebral body with a rhomboid appearance is labeled S1 [3].

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Author disclosure: AA: Nothing to disclose. PAR: Nothing to disclose. CMD: Nothing to disclose. JMS: Royalties: Titan Spine (C); Stock Ownership: Titan Spine (60,000 shares, 5%), Etex Corp. (15,000 shares, 1%), Paradigm Spine (157,500 shares, 5%); Consulting: Titan Spine (B); Speaking/Teaching Arrangements: Synthes Spine (F); Scientific Advisory Board: Titan Spine (Nonfinancial); Research Support (Staff/Materials): Paradigm Spine (D, Paid directly to institution/employer); Fellowship Support: Synthes Spine (E, Paid directly to institution/employer).

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