Proximal junctional kyphosis following correction surgery in the Lenke 5 adolescent idiopathic scoliosis patient

Abstract Background To investigate the risk factors of proximal junctional kyphosis (PJK) in Lenke 5 AIS patients after all-pedicle instrumentation and correction, and to compare the difference of radiographic and clinical outcome between PJK and Non-PJK populations. Method Medical records of Lenke 5 AIS patients were reviewed from January 2008 to January 2013, included posteroanterior and lateral full spine X-ray films preoperatively, postoperatively (4–7 days after surgery), and at final follow-up. Demographic data and radiologic parameters were evaluated. Based on the proximal junctional angle (PJA) at final follow-up, those patients were divided into 2 groups: PJK group (n = 35, PJA≧10°), and Non-PJK group (n = 52, PJA Results The current study recruited 87 Lenke 5 AIS patients with average follow-up of 4.67 ± 1.17 years. Significant differences between PJK and Non-PJK groups were observed as follows: UIV(P = 0.010), the disruption of junctional ligaments ( P P  = 0.001), TK( P P  = 0.014)], postoperative variables [TLK(P = 0.004), and PJA ( P P 0.001). Binary logistic regression showed that the disruption of junctional ligaments, postoperative PJA and UIV (upper instrumented vertebra) at proximal or lower thoracic levels were the main risk factors of PJK [Odds Ratio (OR) = 5.114, 2.345, and 6.212, respectively]. However, the SRS-22 scores did not change significantly in PJK and Non-PJK groups. Conclusion Greater postoperative PJA, disruption of junctional ligaments, UIV at lower thoracic levels were the main risk factors for PJK in Lenke 5 AIS patients. Recommedation: Preserve junctional ligaments in those individuals with UIV located in the lower thoracic region.