Factors Associated With the Development of and Revision for Proximal Junctional Kyphosis in 440 Consecutive Adult Spinal Deformity Patients.

Abstract

Retrospective review of prospectively collected data. The aim of this study was to examine which radiographic parameters and surgical strategies are most closely associated with proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery, the need for revision surgery for PJK, and whether these differ based on the upper instrumented vertebra (UIV). Multiple parameters are considered when planning correction of ASD. Determining which of these factors contribute to the development of and need for revision surgery for PJK presents a challenging problem. Consecutive patients undergoing long fusion to the pelvis with age >18 years, minimum 6-month follow-up, and adequate radiographs for analysis in a single institution between 2003 and 2011 were included. Along with chart review, measurement of proximal junctional angle (PJA), sagittal balance, and pelvic parameters was performed on preoperative, postoperative, and latest follow-up radiographs. Postoperative radiographs were also examined for signs of PJF. A total of 440 patients with a mean follow-up of 34 months met inclusion criteria, 159 of whom developed PJK (36%), with 65 requiring revision surgery (41%). Higher preoperative pelvic tilt (PT) (P = 0.018) and postoperative thoracic kyphosis (TK) (P ≤ 0.001) were predictive for development of PJK, whereas hooks at UIV were protective (odds ratio [OR] 0.049). In patients who developed PJK, revision was more frequent in younger patients (P = 0.005) with greater postoperative sagittal vertical axis and PJA (P = 0.029, P = 0.018). PJF with spondylolisthesis, fracture, or instrumentation failure at the UIV had the highest ORs for proceeding to a revision (5.1, 1.6, and 2.2, respectively). TK and PT are important indicators of overall rigidity and reference the ability of the spine to compensate for sagittal plane deformity. Special attention should be paid to these characteristics and to the choice of proximal instrumentation when attempting to prevent PJK. Prevention of radiographically evident PJF may hold the key to reducing the need for revision surgery. 3.