COA: Sagittal plane analysis of the spine and pelvis in adult idiopathic scoliosis

Background There has been an increasing recognition of the importance of sagittal spinopelvic alignment in patients with scoliosis as it relates to clinical outcomes. However, the changes seen in sagittal spinopelvic alignment in adult idiopathic scoliosis patients is poorly defined. This study was conducted to evaluate the sagittal alignment of pelvis and spine in adult idiopathic scoliosis patients.Methods The sagittal parameters of the spine and pelvis were analyzed in lateral standing radiographs of 124 patients (mean age 47.4 years) with adult idiopathic scoliosis, including thoracic kyphosis (TK), thoracolumbar junction kyphosis (TLJ), lumbar lordosis (LL), pelvic incidence (PI), sacrum slope (SS), pelvic tilt (PT) and C7 plumb line (C7PL). The patients were divided into three groups according to the age: 20-40 years, 41-64 years, and ≥65 years. The parameters were compared with those in normal adults and adolescent idiopathic scoliosis (AIS) patients. The relationship between all parameters as well as age and sagittal parameters were analyzed.Results The PI in patients with adult idiopathic scoliosis was 58.1°±13.0°, which was significantly higher than that in normal adults. The PT (19.9°±10.6°) was also higher than that in both normal adults and AIS patients, while the SS (38.1°±12.0°) was similar or smaller. As age increased, C7PL, PT and TJL increased while LL decreased. There was no relationship between age and both PI and TK. PT had the strongest statistical association with the C7PL.Conclusions PI is higher in adult idiopathic scoliosis than normal subjects. The PT is the most relevant pelvic parameter to the global sagittal alignment of the spine. Age significantly influences sagittal parameters of the spine and pelvis except the PI and TK.