Although some radiographic evaluations of the risk of flexor tendon injury following fixation of a distal radius fracture are useful, these radiographic measurements are limited because of their inability to obtain three-dimensional measurements. We hypothesized that CT-based measurements would be more sensitive indicators for risk estimation than radiography. We retrospectively evaluated the relationship between plate positioning and the incidence of flexor tendon symptoms based on postoperative radiographic and CT-based measurements in 99 hands that were followed up for more than 12 months. We also compared the reproducibility, diagnostic accuracy, and ability to detect the plate-bone gap between radiographic and CT-based measurements. We also assessed the correlation between the volar prominence and plate-bone gap using CT. Multivariable analysis using stepwise logistic regression was performed to identify factors independently associated with tendon rupture or irritation. In single variable analysis, we found that the volar tilt was significantly smaller and the radiographic plate-to-critical line distance (PCL), CT-PCL, and CT-gap were significantly greater in the group with tendon irritation or rupture. Multivariable logistic regression analysis indicated that the CT-based measurement of the volar prominence is a significantly positive independent predictor of tendon rupture or irritation. CT-based measurement of the volar prominence may be one of the best radiographic predictors of the risk of flexor tendon injury following fixation of a distal radius fracture regardless of the plate type and distal prominence and the extent of rotation. This measurement may assist surgeons when deciding on the need for removal of hardware to decrease the long-term risk of flexor tendon rupture. Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.