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 Id- iopathic 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 fol- low-up of 32.8 months(range,24-83). All coronal and sagittal measurements includ- ing the proximal junctional kyphosis (PJK)angle recorded on standing anteroposteri- or and lateral radiographs preoperative, early postoperative and on follow-up radi- ographs. 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 pre- operatively 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 5.9° (range,0-13°)(P=0.02) and until 2 years post operation was 14.3° (range, 2- 16°)(p=0.000). The mean proximal junctional angle increased 1.6° until 2 years post- operation 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 instrumenta- tion types associated with developing PJK .