Incidence and risk factors for proximal junctional kyphosis: a meta-analysis

Purpose To analyse the incidence and risk factors associated with proximal junctional kyphosis (PJK) following spinal fusion, we collect relative statistics from the articles on PJK and perform a meta-analysis. Methods An extensive search of literature was performed in PubMed, Embase, and The Cochrane Library (up to April 2015). The following risk factors were extracted: age at surgery, gender, combined anterior-posterior surgery, use of pedicle screw at top of construct, hybrid instrumentation, thoracoplasty, fusion to sacrum (S1), preoperative thoracic kyphosis angle (T5–T12) >40°, bone mineral density (BMD) and preoperative to postoperative sagittal vertical axis (SVA difference) >5 cm. Data analysis was conducted with RevMan 5.3 and STATA 12.0. Results A total of 14 unique studies including 2215 patients were included in the final analyses. The pooled analysis showed that there were significant difference in age at surgery >55 years old (OR 2.19, 95 % CI 1.36–3.53, p = 0.001), fusion to S1 (OR 2.12, 95 % CI 1.57–2.87, p 40° (OR 2.68, 95 % CI 1.73–4.13, p 55 years, fusion to S1, T5–T12 >40°, low BMD and SVA difference >5 cm are risk factors for PJK. However, gender, combined anterior–posterior surgery, use of pedicle screw at top of construct, hybrid instrumentation and thoracoplasty are not associated with PJK.