Prevalence, types and radiological features of thoracolumbar transitional vertebra - a CT based cross sectional study

Cross sectional study To study the Prevalence of Thoracolumbar transitional vertebra(TLTV), its morphological types and its association with Lumbosacral transitional vertebra (LSTV). Thoracolumbar transitional vertebrae are under-recognized congenital anomalies with reported prevalence ranging from 2% to 15%. While LSTVs have been extensively studied, TLTVs remain underreported. A total of 350 patients who underwent CT scans including the thoracolumbar junction between July 2023 and May 2025 were analyzed. Patients were divided into group 1 (symptomatic back pain, spinal trauma or patients undergoing spine surgery) and asymptomatic patients in group 2 (pathology in abdomen/thorax whose CT included the thoracolumbar area). Rib and transverse process lengths, and facet joint angles at T11, T12, and L1 levels were measured. Co-existing LSTVs were also recorded. Statistical analysis was conducted using the independent t-test. Out of the 350 CT patients, 160 patients were in group 1 and 190 in group 2. TLTVs were identified in 39 of 350 patients (11.1%) - 21(13.1%) patients in group 1 and 18 patients(9.5%) in group 2 (p > 0.05). Type C (absent rib) was the most common morphological variant seen in 23 of 39 TLTVs. TLTVs were significantly associated with shorter T12 ribs and more sagittally oriented T12 facet angles. Sudden transitions in facet orientation were observed between T11 and T12 levels in TLTVs. LSTVs were found in 10.4% of cases, and 7.4% had both TLTV and LSTV. TLTVs are relatively common anatomical variants, most often characterized by absent 12th ribs and altered facet morphology. Recognition of these variants on imaging may assist in accurate vertebral level identification and surgical planning. Further studies incorporating pedicle morphometry, biomechanics, and surgical outcomes are warranted to clarify their clinical significance.