Factors influencing the residual rib hump after posterior spinal fusion for adolescent idiopathic scoliosis with Lenke 1 and 2 curves

Abstract

BackgroundDespite remarkable improvement in Cobb angle after surgery for scoliosis, many patients have a residual rib hump. We studied the factors responsible for this hump and their influence on patient satisfaction. MethodsWe recruited 2 men and 38 women (mean age 14.9years) who underwent skip pedicle screw fixation combined with direct vertebral body derotation for adolescent idiopathic scoliosis with Lenke type 1 and 2 curves. Hump size was evaluated by measuring apical trunk rotation (ATR). Patients with postoperative ATR ≤10° were categorized as group A and those with postoperative ATR >10° as group B. We analyzed postoperative self-image and satisfaction subscores of the SRS-22 questionnaire. We also compared the rate of postoperative improvement in ATR between patients who underwent additional Ponte osteotomy and those who did not. ResultsPreoperative ATR, preoperative apical translation, and preoperative and postoperative apical rotation significantly differed between groups A and B. In contrast, Cobb angles before and after surgery, Cobb angle correction rates, apical translation after correction, and postoperative self-image and satisfaction scores did not differ significantly between the groups. However, the rate of improvement in ATR showed a strong correlation with self-image (correlation coefficient 0.64) and satisfaction (correlation coefficient 0.52). This improvement rate did not differ significantly between subjects who underwent additional Ponte osteotomy and those who did not. ConclusionsPreoperative apical rotation and ATR were clearly related to postoperative residual hump. For decreasing the postoperative rib hump, removal of the deformation by apical rotation was considered more important than correction of Cobb angle. Patient satisfaction and self-image scores were not significantly related to postoperative residual hump size, but they were influenced by improvement in ATR.