Impact of Preoperative CT on Surgical Planning in Posterior Malleolus Involvement of Trimalleolar Ankle Fractures: A Prospective Observational Study

Abstract

Introduction: Posterior malleolar fractures, commonly seen in trimalleolar ankle injuries, pose significant challenges in surgical management due to their complex morphology. While conventional radiographs form the basis of initial planning, computed tomography (CT) offers enhanced visualization that may influence preoperative decision-making.

Objectives: To evaluate the impact of preoperative CT imaging on surgical planning for trimalleolar ankle fractures involving the posterior malleolus.

Methods: This prospective observational study was conducted at the Department of Orthopaedics, SRM Medical College Hospital and Research Centre, Tamil Nadu, between August 2023 and February 2025. A total of 53 adult patients with trimalleolar ankle fractures underwent surgical treatment. Two preoperative surgical plans were formulated per patient: Plan A (based on X-ray) and Plan B (revised after CT review), by a panel of four senior orthopedic surgeons. These were compared with the actual intraoperative decisions regarding fixation method, surgical approach, and patient positioning. The posterior malleolus was classified using the Modified Haraguchi system, and inter-modality agreement was analyzed using Kappa statistics.

Results: CT imaging altered the fixation strategy in a significant number of cases. CC screw fixation increased from 41.5% (X-ray) to 50.9% (CT), while plate fixation increased from 24.5% to 30.2%. Intraoperative decisions showed strong agreement with CT-based plans (Kappa = 0.815 for CC screws; Kappa = 0.859 for plating; p = 0.001). The use of anterior-to-posterior screws increased from 34.0% (X-ray) to 43.4% (CT), and posterior-to-anterior screw plans showed perfect agreement (Kappa = 1.000). CT also influenced patient positioning, with Lazy Prone and Prone-to-Supine conversions employed more frequently post-CT. Type I Haraguchi fractures were most common (62.3%), but Type II and III required more complex fixation approaches

Conclusions: CT imaging significantly improves preoperative surgical planning for posterior malleolus fractures by providing better assessment of fragment morphology, influencing fixation method, approach, and patient positioning. CT-based strategies align more closely with intraoperative requirements than X-ray-based plans, supporting its routine use in managing complex ankle fractures.