proximal junctional kyphosis in adolescent idiopathic scoliosis following segmental posterior spinal instrumentation and fusion minimum 2 years follow-up

abstract   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 5.9° (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 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 .