Proximal Junctional Kyphosis After Posterior Spinal Instrumentation and Fusion in Young Children With Congenital Scoliosis A Preliminary Report on its Incidence and Risk Factors

Study Design. A retrospective study. Objective. To determine the incidence and risk factors of proximal junctional kyphosis (PJK) in young children who underwent posterior instrumented spinal fusion. Summary of Background Data. PJK is a well-recognized postoperative complication in adults and adolescents. However, there is a paucity of valid data with regard to PJK in young children with congenital scoliosis (CS) who were treated with posterior correction surgery. Methods. This study reviewed the charts and radiographs of a consecutive series of young children with CS who underwent posterior instrumentation and fusion (>= 4 levels) from January 2008 to May 2013. The patients were followed up for more than 24 months. Radiographic measurements were made preoperatively and throughout the follow-up period. From sagittal images, the following values were obtained: proximal junctional angle, sagittal vertical axis, pelvic incidence, thoracic kyphosis, lumbar lordosis, and segmental kyphosis. Results. Totally 113 children were recruited in this study. The average age at surgery was 6.6 years, and the average follow-up period was 48.8 months. PJK occurred in 21 of the 113 patients and were mostly classified as ligamentous failure. In comparison with the non-PJK group, the PJK group showed greater preoperative Thoracic kyphosis (TK) (45.98 vs. 37.38, P = 0.027), longer fusion levels (6.6 vs. 5.4, P< 0.01), and greater segmental kyphosis (SK) change (30.18 vs. 11.28, P = 0.002). Both a change in SK greater than 308 and a preoperative TK greater than 408 were independent risk factors associated with PJK. In the PJK group, the average PJA increased by 12.48 at 3 months postoperatively and followed by slight improvement till the final follow-up. Conclusion. This study demonstrates a high rate of PJK in young children after correction surgery for CS. PJK mainly occurs within 3 months postoperatively and its risk factors include preoperative hyperkyphosis, over-correction of kyphosis, and ligamentous failure.