Risk factors for vertebral bridging in residual adolescent idiopathic scoliosis with thoracolumbar/lumbar curves

Abstract

BackgroundAlthough vertebral bridging in residual adolescent idiopathic scoliosis (AIS) can make corrective surgery more complicated, no study has investigated the risk factors. The purpose of this research was to determine risk factors for vertebral bridging in individuals with residual AIS with thoracolumbar/lumbar (TL/L) curves. MethodsForty-two pre-operative patients with residual AIS and TL/L curves (3 males, 39 females: age 41.9 ± 18.0 years) were divided into bridging (n = 17) and non-bridging (n = 25) groups. All patients were 20 years or older with a diagnosis of AIS in adolescence. The bridging group consisted of patients with third or more degree bridging by the Nathan classification. ResultsThere were significant differences in age, absolute value of apical vertebral translation (AVT), C7 translation, and L3,4 tilt between groups. There was no significant difference in TL/L Cobb angle. Multivariate analyses and ROC curves demonstrated that older age was a significant risk factor for vertebral bridging (odds ratio [OR]: 1.08; 95% confidence interval: 1.02–1.14; P = 0.004), with a cutoff value of 38.0 years old. ConclusionsThis study indicates that patients >38 years old are at risk for vertebral bridging in residual AIS. Because of the higher risk of vertebral bridging and other degenerative changes, residual AIS patients about 40 years of age are at a critical point for treatment strategy. Because appropriate surgical time should not be missed, regular follow-up is required even after 30 years of age, especially if the patient with residual AIS has a large TL/L curve indicated for surgery.