PROXIMAL JUNCTIONAL KYPHOSIS IN ADOLESCENT IDIOPATHIC SCOLIOSIS FOLLOWING SEGMENTAL POSTERIOR SPINAL INSTRUMENTATION an‎d FUSION; MINIMUM 2 YEARS FOLLOW-UP

Background: To evaluate proximal junctional segment changes in Adolescent Idiopathic Scoliosis (AIS) the posterior spinal fusion and also instrumentation also and finding of probable risk factors, were all considered in this study. Methods: We retrospectively reviewed radiographs of 121 consecutive patients who underwent posterior spinal fusion for AIS from T3 or below, with a mean follow-up of 32.8 months (range, 24-83). All coronal and sagittal measurements including the proximal junctional kyphosis (PJK) angle recorded on standing anteroposterior and lateral radiographs preoperative, early postoperative and on follow-up radiographs. The data were analyzed using the Spss 10.0 software. Dependent (paired) samples student t-test was used for analysis between the groups Results: There was PJK angle above normal for the same junctional segment preoperatively in 13 patients (10.7%) and the incidence of the PJK postoperatively was 7.4% (9 patients, 7 female and 2 male), all detected until 2 years postoperation. The mean increase in the PJK angle from pre-operation until 6 weeks postoperation was 5.9o (range, 0-13o) (P=0.02) and until 2 years post operation was 14.3o (range, 2-16o) (p=0.000). The mean proximal junctional angle increased 1.6o until 2 years postoperation in non-PJK group (n=112). Conclusion: The prevalence of Proximal Junctional Kyphosis was low and a silent radiographic problem. In some cases is preventable with perfect pre-operative planning. There is no specific demographic or radiographic variables or instrumentation types associated with developing PJK.