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

Abstract

Excessive lengths of partially threaded cannulated screws in medial malleolus fractures are often related to failure of fixation. 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. Between January 2012 and December 2016, 100 patients (without ankle fractures) who underwent computed tomography of the distal tibia were included. Specific levels on the computed tomography images were selected to assess the density and length of valid cancellous bone in the medial malleolus. Meanwhile, we followed up 44 patients who underwent open reduction and internal fixation of medial malleolus fractures based on preoperative computed tomography-based measurements. 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). All patients were followed up to union without displacement. 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. In conclusion, preoperative computed tomography can help determine the length and location of cannulated screws.