Incidence of pars defects in adolescent idiopathic scoliosis: an MRI study

Objective: In this study, our aim was to present the incidence rate of pars defect in patients with adolescent idiopathic scoliosis, based on MRI findings. Methods: Two-hundred twenty adolescent idiopathic scoliosis (AIS) patients with MRI scans, taken either as a preoperative investigation or due to other symptoms between 2006 and 2008, were included in the study. The scans were reviewed for pars defect independently by two expe¬rienced musculoskeletal radiology consultants. Results: Among the 220 patients, 9 patients (4.09%; 8 female, 1 male) were found to have a pars defect. The mean age of the affected patients was 14 (range: 11-20) years. We noted two lumbar/thoracolumbar curves (Lenke 5), four King Type 1, one King Type 2 and two King Type 3 curves. All scoliotic deformities were non-structural. Bilateral pars defect was noted in eight (89%) of these patients. All of the pars defects were at the L5 vertebral level. Conclusion: Our study revealed a 4.09% incidence rate of pars defect in AIS patients which appeared similar to those previously reported in roentgenographic studies.