Necessity of Interfragmentary Lag Screws in Precontoured Lateral Locking Plate Fixation for Supination-External Rotation Lateral Malleolar Fractures.

BACKGROUND: Interfragmentary lag screws, protected by a plate, have been applied for many years in the treatment of supination-external rotation (SER) ankle fractures. Recently, similar biomechanical stability was found between fixation completed with a plate and lag screw and a plate alone. The aim of this study was to determine whether interfragmentary lag screws are necessary during precontoured lateral locking plate fixation for SER lateral malleolar fractures. METHODS: A prospective randomized controlled trial of 76 patients with unilateral Lauge-Hansen SER lateral malleolar fractures was conducted. The patients were randomly treated either with or without the use of interfragmentary lag screws with precontoured lateral locking plate fixation. Clinical outcomes were assessed using the Olerud-Molander Ankle Score and a visual analog scale for pain. Radiologic outcomes were assessed based on the Kellgren and Lawrence scale score, incongruity of the ankle joint, and type of fracture healing. Sixty-nine patients completed 12 months of follow-up. RESULTS: There was no significant difference between the 2 groups with regard to clinical outcomes at 3 and 12 months after surgery and radiologic outcomes at 12 months after surgery. All patients in both groups achieved primary bone healing. CONCLUSION: The results of this study suggest that with precontoured lateral locking plate fixation, the use of interfragmentary lag screw is not essential in the treatment SER lateral malleolar fractures. LEVEL OF EVIDENCE: Level I, prospective randomized study.

The predictive value of MRI in the syndesmotic instability of ankle fracture.

OBJECTIVE: Although many types of ankle fracture can be combined with syndesmosis injury, preoperative imaging studies rarely reveal instability of the syndesmosis. This study assessed the use of magnetic resonance imaging (MRI) for syndesmotic instability in patients with unstable ankle fracture. METHODS: A total of 74 patients who were treated for Lauge-Hansen supination external rotation/Weber B type fracture or pronation external rotation/Weber C type fracture and who underwent MRI for preoperative assessment were enrolled. The MRI findings of the syndesmotic ligament and the results of an intraoperative stress test were evaluated. RESULTS: Twenty-six patients had a positive result on the intraoperative stress test for syndesmotic instability. The MRI findings of the syndesmotic ligaments revealed that complete tear of the posterior inferior tibiofibular ligament (PITFL) was the most reliable predictor of syndesmotic instability (sensitivity, 74%; specificity, 78%; positive predictive value, 54%). Interobserver agreement for the intraoperative stress test and MRI assessment was excellent, except for the MRI findings of the interosseous ligament (62% agreement; kappa, 0.3). CONCLUSIONS: Complete tear of the PITFL on MRI has additional diagnostic value for syndesmotic instability in ankle fracture. However, because the sensitivity might not be sufficient to justify the costs associated with MRI, cost-effectiveness should be considered.