Low back pain (LBP) is one of the most prevalent musculoskeletal complaints, affecting up to 80% of individuals during their lifetime². Among its structural and anatomical contributors, lumbo-sacral transitional vertebra (LSTV) represents a notable yet under-recognized variant. LSTV refers to either sacralization of the lowest lumbar vertebra or lumbarization of the uppermost sacral segment, leading to altered load distribution, asymmetrical motion, and potential early degeneration at adjacent levels³. The reported prevalence of LSTV varies from 4% to 36% in different populations ⁴. Its association with chronic low back pain—termed Bertolotti’s syndrome⁵ when symptomatic—remains debated, though increasing evidence supports its role in adjacent segment degeneration and radiculopathy. The Castellvi classification system (Types I–IV)¹ remains the most widely used radiological categorization based on morphology and degree of articulation/fusion with the sacrum.

Data regarding the prevalence and clinical implications of LSTV in South Kashmir are scarce. The present hospital-based study aims to determine the prevalence, morphological types, and degenerative associations of LSTV among symptomatic chronic low back pain patients, using both X-ray and MRI, and to highlight the tendency toward more severe degeneration in unilateral cases.

conducted in the Department of Orthopaedics and Department of Radiology, MMABM Hospital, GMC Anantnag, South Kashmir, from June 2024 to May 2025. Institutional ethics approval was obtained, and informed consent was taken from all participants. Inclusion Criteria: • Patients aged 16–80 years presenting with chronic low back pain (duration > 12 weeks). • Availability of X-ray and/or MRI of the lumbo-sacral spine with adequate visualization of the lumbo-sacral junction. Exclusion Criteria: • History of spinal trauma, infection, tumor, or previous spine surgery. • Congenital deformities other than LSTV. • Poor-quality or incomplete imaging studies. Imaging Protocol: • X-ray: Anteroposterior (AP) and lateral views of the lumbo-sacral spine. • MRI: Sagittal and axial T1- and T2-weighted sequences covering L3 to S2. Radiological Evaluation: All images were independently reviewed by one radiologist and one orthopaedic spine surgeon. LSTV was classified according to Castellvi’s system:1 • Type I: Dysplastic transverse process (>19 mm). • Type II: Incomplete fusion or pseudo-articulation with sacrum. • Type III: Complete fusion. • Type IV: Mixed—fusion on one side, pseudo-articulation on the other. Laterality (unilateral/bilateral) was noted. Associated findings included adjacent segment disc degeneration, facet arthropathy, foraminal narrowing, and nerve root compression. Statistical Analysis: Descriptive statistics were applied for prevalence and distribution. Comparisons between unilateral and bilateral LSTV were made using chi-square and t-tests, with p < 0.05 considered significant. Analyses were performed using SPSS.

A total of 208 patients (age range 16–80 years) 88 Males and 120 females were evaluated.

• LSTV prevalence: 35% (n = 73) of chronic low back pain patients.
• Castellvi classification: Type II was most frequent (40%), followed by Type I (30%), Type III (20%), and Type IV (10%).
• Laterality: Unilateral LSTV in 79% (n=58) of cases, bilateral in 20% (n=15).
• Degenerative findings:
  • Adjacent segment disc degeneration (mainly L4–L5) in 70% (n=51) of LSTV cases.
  • More severe and earlier degenerative changes in unilateral LSTV compared with bilateral variants (p < 0.05).
  • Facet arthropathy above transitional level in 60% (n=44) of LSTV cases.
• Radiculopathy: Present in a majority of LSTV patients, frequently correlating with foraminal stenosis or disc protrusion above the transitional level.

MRI often revealed subtle pseudo-arthrosis and disc dehydration that were not evident on X-ray, highlighting MRI’s superior diagnostic utility.

The present study reports an LSTV prevalence of approximately 35% among chronic low back pain patients in South Kashmir—comparable to rates reported in similar hospital-based cohorts across India (range 25–40%)^6,7. The predominance of Castellvi Type II aligns with literature⁸ suggesting pseudo-articulation as a key pain generator due to abnormal stress transfer. Unilateral LSTV cases demonstrated significantly greater degeneration at the cranial adjacent disc level⁹, consistent with asymmetric mechanical loading. The high rate of adjacent segment disc degeneration and radiculopathy observed reinforces the biomechanical implications of transitional anatomy and altered motion at the lumbo-sacral junction may precipitate early degenerative changes and neural compression ¹⁰. MRI proved essential for accurately classifying LSTV and assessing related soft-tissue and neural findings⁹—beyond what X-ray alone could offer. Recognition of this variant is clinically relevant, especially when planning interventional procedures or surgery¹¹, as incorrect level identification can occur in the presence of LSTV.

Strengths:

• Combined use of X-ray and MRI.
• Inclusion of symptomatic chronic LBP cohort (clinically relevant).
• Analysis of laterality and degeneration patterns.

Limitations:

• Single-centre design and limited sample size.
• Absence of asymptomatic control group.
• Cross-sectional nature limits causal inference.

Lumbo-sacral transitional vertebra is a common anatomical variant among chronic low back pain patients in South Kashmir, observed in about 35% of cases. Unilateral variants demonstrate more severe and asymmetric degenerative changes. Adjacent segment disc degeneration and radiculopathy are frequent radiological and clinical associations. Routine evaluation for LSTV using both X-ray and MRI should be incorporated into diagnostic work-up of chronic low back pain, facilitating appropriate classification and management.

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Conflict of Interest

None declared.

Funding

No external funding was received for this study.