Preoperative distal radius CT hounsfield unit and other imaging predictors of postoperative radiocarpal traumatic arthritis after distal radius fracture

Postoperative radiocarpal traumatic arthritis (TA) after distal radius fracture (DRF) may cause persistent pain and functional impairment. Early risk stratification may help identify patients at increased risk. This study aims to identify independent predictors of radiocarpal TA after DRF and develop multifactorial predictive models. We retrospectively analyzed 226 DRF patients grouped by radiocarpal TA status. Variables were screened using univariate and correlation analyses. Logistic regression (LR) and support vector machine (SVM) models were developed using a 70/30 stratified train–test split (seed = 42); 10-fold stratified cross-validation was performed within the training set, and final performance was evaluated on the test set. Independent predictors included preoperative step-off > 2 mm (OR = 6.12, 95% CI: 1.79–20.94), radial shortening > 3 mm (OR = 8.02, 95% CI: 2.55–25.21), low distal radius CT Hounsfield Unit (OR = 0.99, 95% CI: 0.99–1.00). The LR model achieved an AUC of 90.71%, and the SVM model an AUC of 91.34%. Both LR and SVM models showed promising internal performance for predicting radiocarpal TA after DRF. These findings may support preoperative risk stratification, but external validation is required before clinical application.