Analysis of the sacroiliac joint vacuum phenomenon in adolescent thoracic idiopathic scoliosis (Lenke types 1 and 2)

Abstract

The sacroiliac joint (SIJ) is the largest axial joint in the human body, and the SIJ vacuum phenomenon (SIJ VP) is a common finding in computed tomography studies of the abdomen, pelvis, and lumbosacral spine in adults, with the incidence increasing with age. Adolescent idiopathic scoliosis (AIS) is an abnormal spinal curvature that appears during adolescence and places abnormal stress on the SIJs. This retrospective observational study aimed to investigate the incidence of the SIJ VP in thoracic AIS (Lenke types 1 and 2). Sixty-seven patients with AIS (age: 12-19 years) and 76 controls (age: 11-19 years) were retrospectively analyzed to investigate SIJ VP, subchondral bone cysts, and SIJ degeneration (Eno classification: type 0, no degenerative change; type 1, mild degenerative changes; type 2, substantial degenerative changes; and type 3, ankylosis). SIJ degeneration was defined as type ≥ 2. The association between SIJ VP, cysts, SIJ degeneration, and sagittal/coronal spinopelvic alignment was assessed. SIJ VP (59% vs. 35.5%, P