Preoperative spinal flexibility and proximal junctional kyphosis in adult spinal deformity surgery
Year: 2026
Type: article
Abstract: Proximal junctional kyphosis (PJK) is a common mechanical complication after adult spinal deformity (ASD) surgery. Reported rates range from 17% to 48% and have not declined despite decades of research on static radiographic parameters. Preoperative spinal flexibility has been proposed as a PJK risk factor. This review summarizes current evidence on spinal flexibility parameters, describes how biological factors may modify their relationship to PJK, and identifies research gaps. We searched PubMed, Embase, and Google Scholar for English-language articles published from January 2005 through August 2026 using terms for "spinal flexibility, thoracic flexibility, thoracic compensation, global sagittal flexibility, proximal junctional kyphosis, and adult spinal deformity". Articles were selected by the authors for relevance; formal quality appraisal was not performed. Three flexibility parameters have been studied and linked to PJK: global sagittal flexibility (GSF), thoracic flexibility (TF), and thoracic compensation (TC). Evidence is limited to small retrospective cohorts with heterogeneous measurements, and no flexibility threshold has been externally validated. TF studies have reported conflicting directions of effect. Bone and paraspinal muscle quality may modify junctional vulnerability, but published flexibility thresholds were derived without adjustment for either. Current evidence is insufficient to support routine clinical use of preoperative flexibility assessment, and published thresholds are preliminary. Prospective, multicenter studies with biological covariate adjustment and external validation are needed.
Source: Journal of Spine Surgery
Authors: Jaxon Hopkins, Kari Odland, David Polly Jr
Institution: University of Minnesota
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223970140