The association between variations in the number of thoracic and lumbar vertebrae and rib morphology in adolescent idiopathic scoliosis

Preoperative counting of thoracic and lumbar vertebrae is crucial in adolescent idiopathic scoliosis (AIS) due to reported anatomical variations and potential surgical site misidentification. This study investigated characteristics associated with the vertebral number variations AIS, particularly focusing on rib morphology. Based on three-dimensional computed tomography, patients were categorized into the non-variant number group, comprising individuals with 12 thoracic and 5 lumbar vertebrae, and the variant number group, comprising individuals with different numbers of vertebrae. Additionally, the most caudal rib morphology was classified as normal, unilateral, or hypoplastic. A total of 359 patients were included in our study (41 males, 318 females, age: 16.3 ± 3.1 years), with 44 patients (12.3