Generalized Joint Hypermobility in Adolescent Idiopathic Scoliosis: Greater Curve Flexibility, Larger Thoracic Kyphosis, but Higher Complication Risk

Objectives Generalized joint hypermobility ( GJH ) is prototypical clinical feature of hypermobility spectrum disorders, and emerging studies have found a correlation between GJH and structural spinal changes. This study aims to investigate the preoperative radiographic characteristics and clinical outcomes of patients with GJH and adolescent idiopathic scoliosis (AIS). Methods Patients with AIS were prospectively recruited between July 2023 and August 2024 and divided into GJH (Beighton score ≥ 6) and non‐GJH (Beighton score < 6) groups. The GJH group was matched 1:1 with controls based on age (±1 year), sex, main curve magnitude (±5°), curve type of the Lenke classification, triradiate cartilage status, and Risser stage (±1 grade). Baseline characteristics and surgical data were recorded. Preoperative and immediately postoperative radiographic parameters were measured. The Scoliosis Research Society‐22 revised (SRS‐22r) questionnaire was collected preoperatively and at least 1 year postoperatively. Univariate analysis and multivariable linear regression analysis were used to identify factors associated with main curve flexibility, TK, and T1 tilt angle. Results A total of 136 consecutive patients were included, with 29 patients (21.3%) classified into the GJH group. After mating, the GJH showed greater flexibility of the main curve (60.0% ± 27.7% vs. 45.8% ± 22.1%, p = 0.020) and increased thoracic kyphosis (22.9° ± 11.5° vs. 16.7° ± 11.7°, p = 0.031) compared to the control group. Multivariable linear regression analyses revealed that the GJH was correlated with increased spinal flexibility ( β = 14.09, p = 0.015) and larger thoracic kyphosis ( β = 6.11, p = 0.043). The GJH group demonstrated a relatively higher risk of surgical complications compared to the non‐GJH group (17.2% [5/29] vs. 4.7% [5/107], p = 0.036). However, no significant differences were observed in patient‐reported outcome measures (PROMs) between the two groups. Conclusions In patients with AIS, GJH is associated with increased spinal flexibility and greater thoracic kyphosis and, importantly, a higher risk of surgical complications.