Proximal junctional kyphosis in Lenke 5 AIS patients: the important factor of pelvic incidence

BackgroundThe purpose of the study was to investigate whether pelvic incidence (PI) will affect the occurrence of PJK in Lenke 5 AIS patients after correction surgery and try to explore a better surgical scheme based on PI.MethodsLenke 5C AIS patients that underwent correction surgery with a minimum of a 2-year follow-up were identified. Demographic and radiographic data were collected preoperatively, postoperatively, and at the final follow-up. The comparison between the PJK and the Non-PJK group was conducted and the subgroup analysis was performed based on the preoperative value of PI to investigate the potential mechanism of PJK. Clinical assessments were performed using the Scoliosis Research Society (SRS)-22 questionnaire.ResultsThe mean preoperative Cobb angle of the TL/L curve was 53.4 degrees 8.6. At the final follow-up, the mean TL/L Cobb angle was drastically decreased to 7.3 degrees +/- 6.8 (P= 45 degrees), but the main risk factor of PJK should be different. For patients with low PI, overcorrection of LL should be strictly avoided during surgery. For patients with high PI, the selection of UIV should not be at or cephalad to the apex of thoracic kyphosis to retain more mobile thoracic segments.