Multimodal Deep Learning for Predicting Deep Vein Thrombosis Risk After Total Knee Arthroplasty: A Clinical Study

BACKGROUND: Deep vein thrombosis (DVT) following total knee arthroplasty (TKA) remains a major postoperative complication. Conventional risk assessment tools such as the Caprini score show limited predictive performance (AUC 0.65-0.72). We developed a multimodal deep learning framework that integrates early postoperative radiographs with clinical data to improve DVT risk stratification. METHODS: This single-center retrospective cohort study analyzed 1200 patients undergoing primary unilateral TKA (DVT incidence: 18.0%) from January 2018 to June 2023. A dual-branch architecture was implemented: ViT-B/16 or ResNet50 processed standardized radiographs (metal artifact suppression; 512 × 512 resolution), while Clinical-BERT encoded structured electronic medical record (EMR) representations. A dynamic attention fusion module generated sample-specific modality weights (α) for feature fusion (α·v_img + (1 - α)·v_txt). Performance was evaluated on a stratified test set (n = 180) against the Caprini score, unimodal models, and a nonattention concatenation fusion baseline. AUCs were compared using the DeLong test, and sensitivity/specificity differences were assessed using the McNemar test. RESULTS: The multimodal model achieved an AUC of 0.89 (95% CI: 0.85-0.92; DeLong p < 0.001 vs. all comparators), sensitivity 83% (76%-89%), specificity 88% (82%-93%), and F1-score 0.79. It identified 91.7% (11/12) of DVT cases labeled low-risk by Caprini. The learned attention coefficient α suggested modality reliance patterns associated with specific findings (e.g., higher α in cases with prosthesis-bone lucency > 2 mm; higher text contribution in cases with D-dimer > 1.0 mg/L), but these associations do not establish causality. Anatomical heatmaps consistently localized high-risk regions, particularly the popliteal vein projection area and tibial interface. CONCLUSION: This attention-based multimodal model integrates biomechanical (radiographic) and biochemical/clinical (EMR-derived) signals to improve early postoperative DVT risk prediction while providing interpretable anatomical cues.