A comparative study of degree of the deltoid ligament injury based on X-ray and MRI after lateral malleolus fracture

Objective To investigate the value of X-ray and MRI in judging degree of the deltoid ligament injury after lateral malleolus fracture.Methods The data of X-ray and MRI of 41 patients with acute lateral malleolus fracture,excluding patients combined with medial malleolus fracture,were retrospectively analyzed.The medial clear space (MCS) was measured according to the mortise X-rays.The degree of injury of the superficial deltoid ligament and deep deltoid ligament was graded according to MRIs obtained from PACS (picture archiving and communication system) system.Moreover,the correlation between the width of the MCS and the degree of the deltoid ligament injury were statistically analyzed.The classification results of all patients according to the Lauge-Hansen classification based on X-rays and MRIs were recorded,respectively.Results A positive correlation was found between the width of the MCS and the degree of the deltoid ligament injury,and the optimal critical value of MCS was 7.85 mm for diagnosing complete rupture of the total deltoid ligament or the single rupture of the deep deltoid ligament,while 6.48mm for the complete rupture of the superficial deltoid ligament.Based on the MRIs,the accuracy of the results of Lauge-Hansen classification was 58.5％,and the accuracy for predicting the rupture of the deltoid ligament was 82.9％,however the degree of the deltoid ligament injury cannot be distinguished very well.Conclusion The deltoid ligament injury is common in acute lateral malleolus fracture,even though there is no medial malleolus fracture.The X-ray is still the prefenred choice for the evaluation of the ankle fracture; however the MRI is helpful in judging the degree of the deltoid ligament injury. Key words: Ankle injuries;  Fractures, bone;  Ligaments, articular;  Magnetic resonance imaging