Postoperative Displacement of the Dorsal Ulnar Fragment After Volar Locking Plate Fixation: Risk Factors and Clinical Prediction Tool.

Abstract

This study aimed to explore the risk factors for postoperative displacement of the dorsal ulnar fragment following volar locking plate fixation in distal radius fractures and to develop a clinical prediction model. A total of 168 cases of AO type C distal radius fracture with a dorsal ulnar fragment treated with volar locking plate fixation were retrospectively included in this study. The patients were grouped into the displaced group (n = 33) and the control group (n = 135) based on the presence of postoperative dorsal ulnar fragment displacement (>2 mm). Univariate analysis was performed to identify potential risk factors for postoperative displacement of the dorsal ulnar fragment, which were then included in a binary multivariate logistic regression model. The predictive performance of the model was evaluated using the area under the receiver operating characteristic curve, calibration curve, and decision curve analysis. Finally, a nomogram was constructed based on the model to facilitate the prediction of outcomes. The univariate and binary logistic regression analysis indicated that preoperative displacement was an independent risk factor, while a greater proportion of radiocarpal articular surface area involvement acted as a protective factor for postoperative displacement of the dorsal ulnar fragment following volar locking plate fixation in distal radius fracture. The binary logistic regression-based dual-marker combined predictive model demonstrated an area under the receiver operating characteristic curve of 0.83. The calibration curve and the Hosmer-Lemeshow test results indicated a good model fit. Preoperative displacement and the proportion of radiocarpal articular surface area involvement are key predictors of postoperative displacement of the dorsal ulnar fragment in distal radius fractures and therefore should be considered in surgical decision-making. This study developed a practical predictive model for postoperative displacement of the dorsal ulnar fragment after volar locking plate fixation in distal radius fractures, offering surgeons a tool for preoperative assessment and surgical planning to help them optimize fixation outcomes.