RESUMEN
Objective:To characterize the injury to the ipsilateral ankle joint after low energy spiral fracture of the distal tibia.Methods:A retrospective study was conducted to analyze the 80 patients with distal tibial spiral fracture who had been treated at Department of Traumatic Orthopedics, Affiliated Hospital of Jining Medical University from March 2010 to March 2021. There were 61 males and 19 females with an age of (43.5±12.5) years. Their mean follow-up time was 67.0 (38.5, 90.0) months. All patients underwent preoperative X-ray examination, 64 ones preoperative CT examination, and 30 ones preoperative MRI examination. Of the 80 patients, 3 received conservative treatment with plaster external fixation, 3 closed reduction and intramedullary nail fixation, and 74 plate fixation. Statistically analyzed were incidence of posterior malleolus fracture, characteristics of posterior malleolus fracture lines, normal matching rate of the ipsilateral ankle joint, positive rate of intraoperative Cotton test or stress external rotation test of ipsilateral ankle joint, positive rates of passive pronation-external rotation and supination-external rotation stress tests during follow-up, incidences of short-term ankle pain (≤2 years) and medium-long term pain (>2 years) after operation, injuries to the anterior inferior tibiofibular ligament, the deep medial malleolus deltoid ligament and the posterior malleolus, and incidence of ankle injury.Results:The diagnostic rate for posterior malleolus fracture was 16.3% (13/80) on X-ray film, 60.9% (39/64) on CT and 76.7% (23/30) on MRI. 74.5% (35/47) of the posterior malleolus fracture lines opened on the lateral side. The normal matching rate of the ipsilateral ankle joint was 96.3% (77/80). The positive rates of intraoperative Cotton test and stress external rotation test were 34.8% (8/23) and 7.1% (1/14), respectively. The positive rates of passive pronation-external rotation and supination-external rotation stress tests during follow-up were 46.2% (12/26) and 34.6% (9/26). The incidences of postoperative short term (≤2 years) and medium-long term (>2 years) ankle pain were 37.7% (29/77) and 20.8% (16/77). MRI examination showed that the rates of injury to the anterior inferior tibiofibular ligament, deep medial malleolus deltoid ligament and posterior malleolus were 80.0% (24/30), 80.0% (24/30) and 76.7% (23/30). The incidence of ankle injury was 88.8% (71/80).Conclusions:It is highly probable that spiral fracture of the distal tibia is complicated with ipsilateral ankle injury. The medial malleolus, lateral malleolus, and posterior malleolus are prone to the following hidden injuries while the ankle joint is normally matched in the most cases: injury to the deep deltoid ligament in different degrees, rupture of the inferior tibiofibular anterior ligament and posterior malleolus fracture. Therefore, the ankle injury is likely to be missed in diagnosis. The secondary torsion injuries to the pronation-external rotation and supination-external rotation at the leg are likely to cause ipsilateral ankle injury.