BACKGROUND CONTEXT Posterior spinal fusion (PSF) using all-pedicle screw constructs has become the standard surgical treatment for adolescent idiopathic scoliosis (AIS). However, some studies have shown that all-pedicle screw constructs or the use of pedicle screws at the upper instrumented vertebrae (UIV) increases the incidence of proximal junctional kyphosis (PJK). The purpose of this study is to examine the impact of different instrumentation types on the incidence of PJK following PSF for AIS. PURPOSE To determine if all-pedicle screw constructs increase the incidence of PJK following PSF for AIS, as pedicle screw placement at the UIV may violate the supra-adjacent facet capsules. STUDY DESIGN/SETTING Longitudinal cohort study. PATIENT SAMPLE Multicenter database of surgically treated AIS. OUTCOME MEASURES PJA. METHODS A multicenter database of surgically treated AIS was used. A stratified random sampling was done to obtain a representative sample from all curve types. Patients were included if they underwent PSF, and if immediate postoperative and final follow-up radiographs were available. The patients were grouped by instrumentation type: all-pedicle screw (PS), hook at UIV with distal all-pedicle screw (HT), and hybrid (HB). PJA was measured as the angle between UIV and UIV+2 on lateral full-length standing radiographs immediately postoperative and at the final follow-up. PJK was defined as PJA ≥ 10° or PJA progression of ≥ 10° at the final follow-up. RESULTS The PS, HT and HB groups included 128, 111 and 106 patients, respectively. There was no difference in baseline demographic and radiographic characteristics among the groups. Fifteen cases (4.3%) developed PJK at the latest follow-up (average 2.2 years). PJK was more common in the PS group (p CONCLUSIONS The incidence of PJK following PSF for AIS was 4.3% and was more common in an all-pedicle screw constructs compared to hybrid or UIV-hook distal pedicle screw constructs. Using hooks at UIV might be a treatment strategy to limit PJK. FDA DEVICE/DRUG STATUS Unavailable from authors at time of publication.