• Emmanuelle Ferrero, Nicolas Bocahut, Yan Lefevre, Pierre Roussouly, Sebastien Pesenti, Walid Lakhal, Thierry Odent, Christian Morin, Jean-Luc Clement, Roxane Compagnon, de Gauzy Jérôme Sales JS Pediatric Orthoapedic Department, Purpan University Hospital, Toulouse, France., Jean-Luc Jouve, Keyvan Mazda, Kariman Abelin-Genevois, Brice Ilharreborde, and Groupe d’Etude sur la Scoliose (GES).
• Pediatric Orthoapedic Department, Robert Debre University Hospital, Paris VII University, Paris, France. Emmanuelle.ferrero@aphp.fr.
• Eur Spine J. 2018 Sep 1; 27 (9): 2241-2250.

IntroductionProximal junctional kyphosis (PJK) is a frequent complication, up to 46%, in adolescent idiopathic scoliosis surgical treatment (AIS). Several risk factors have been evoked but remain controversial. The purpose of this study was to analyze the incidence of PJK in a multicenter cohort of AIS patient and to determine risk factor for PJK.Materials And MethodsLenke I and II AIS patients operated between 2011 and 2015 (minimum of 2-years follow-up) were included. On fullspine X-rays, coronal and sagittal radiographic parameters were measured preoperatively, postoperatively and at final follow-up. Occurrence of radiological PJK corresponding to a 10° increase in the sagittal Cobb angle, measured between the upper instrumented vertebra (UIV) and UIV + 2, between postoperative and 2-years follow-up X-rays, was reported.ResultsAmong the 365 patients included, 15.6% (n = 57) developed a PJK and only 10 patients required a revision surgery. Preoperatively, PJK patients had significantly larger pelvic incidence (57° ± 13° vs. 51° ± 12°), larger lumbar lordosis (LL) (63° ± 12° vs. 57° ± 11°) and bigger C7 slope. Postoperatively (3 months), in the non-PJK group, thoracic kyphosis (TK) was increased and LL was not significantly different. However, postoperatively, in the PJK group, no significant change was observed in TK, whereas C7 slope decreased and LL significantly increased. There was also a postoperative change in inflection point which was located at a more proximal level in the PJK group. Between postoperative time and final follow-up, TK and LL significantly increased in the PJK group.ConclusionPJK is a frequent complication in thoracic AIS, occurring 16%, but remains often asymptomatic (less than 3% of revisions in the entire cohort). An interesting finding is that patients with high pelvic incidence and consequently large LL and TK were more at risk of PJK. As demonstrated in ASD, one of the causes of PJK might be postoperative posterior imbalance that can be due to increased LL, insufficient TK or inflection point shift during surgery. These slides can be retrieved under Electronic Supplementary Material.

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