Preoperative Computed Tomography in Guiding the Length of Cannulated Screws in Medial Malleolar Fractures

Introduction: Excessive lengths of partially threaded cannulated screws in medial malleolus fractures are often related to failure of fixation and other complications. This study aimed to analyze the distribution and density of cancellous bone in the medial malleolus among healthy individuals and provide a theoretical basis for determining the lengths of cannulated screws based on preoperative computed tomography (CT) to achieve stable fixation of medial malleolus fractures.Methods: Between January 2012 and December 2016, 100 patients (without ankle fractures) who underwent CT of the distal tibia of the lower extremities were included. Specific levels on the CT images were selected to assess the density and length of valid cancellous bone in the medial malleolus for screw fixation. Meanwhile, we followed up 44 patients who underwent open reduction and internal fixation (ORIF) of medial malleolus fractures based on preoperative CT-based measurements.Results: The valid lengths of cancellous bone in the medial malleolus were significantly different between men and women (p < .05). In addition, there was a significant difference among different age groups (p < .05). The median follow-up duration of patients who underwent ORIF was 14 (range, 12–16) months. All patients were followed up to union without displacement, and no screws were observed to have loosened or backed out. Conclusion: Preoperative CT can help determine the length and location of cannulated screws. Age and gender have a considerable impact on the distribution and density of cancellous bone in the medial malleolus. The density and length of valid cancellous bone decrease with age. The shoulder of the tibial plafond in medial malleolus, which is a weak part of cancellous bone, is a common site of fracture. Short screws are recommended for fixation in elderly patients.Level of Evidence: Level IV