Development and internal validation of a clinical nomogram for predicting vascular complications in patients with Baker’s cysts: A retrospective cohort study

Background Baker’s cysts can cause significant vascular complications including popliteal vein compression and deep vein thrombosis (DVT), yet no validated tool exists to predict which patients are at highest risk. We aimed to develop and internally validate a clinical nomogram for predicting vascular complications in patients with Baker’s cysts. Methods We conducted a retrospective cohort study of 1,364 consecutive patients diagnosed with Baker’s cysts between January 2015 and December 2024 at a single tertiary center. The primary outcome was a composite of vascular complications (symptomatic popliteal vein compression >50%, DVT involving the popliteal vein, pseudothrombophlebitis, or popliteal artery compression). Multivariate logistic regression identified independent predictors, which were incorporated into a nomogram. Internal validation was performed using 1,000 bootstrap resamples and 10-fold cross-validation. Results Vascular complications occurred in 137 patients (10.0%). Of the total cohort, 923 (67.7%) presented with symptomatic cysts, while 441 (32.3%) were incidental findings. Five independent predictors were identified: cyst size >40 mm (adjusted OR 2.78, 95% CI 1.86–4.15), rheumatoid arthritis (aOR 2.24, 1.46–3.43), venous insufficiency (aOR 2.42, 1.52–3.86), anticoagulant therapy (aOR 1.86, 1.19–2.91), and age >65 years (aOR 1.72, 1.16–2.56). The nomogram demonstrated good discrimination (AUC 0.83, 95% CI 0.79–0.87) and calibration (Hosmer-Lemeshow p = .66). Risk stratification identified low-risk (2.6%), intermediate-risk (12.5%), and high-risk (35.7%) groups. The median time to complication was 14.2 months overall, with significantly earlier occurrence in high-risk patients (8.3 months). Conclusions We developed and internally validated a clinical nomogram based on five readily available variables that can stratify patients with Baker’s cysts into risk groups for vascular complications. This tool may help tailor surveillance intensity and timing of intervention. External validation in independent cohorts is required before broad clinical implementation.