POSTOPERATIVE CT AFTER SYNDESMOTIC SCREW IN ANKLE FRACTURES? RADIOLOGIC AND FUNCTIONAL RESULTS OF A PROSPECTIVE STUDY.

Abstract

Objective: 15 patients (male:female= 9:6, mean age 39,5 years) with ankle fractures treated with osteosynthesis including a syndesmotic screw were enrolled in this prospective study. Instability of the distal syndesmosis was proven intraoperatively and then a tricortical syndesmotic screw was placed.

Patients were mobilized with an AirCast®e brace and cranes for six weeks, then the syndesmotic screw was removed and patients started full weight bearing. Follow-Up was 21.7 weeks mean after removal of the syndesmotic screw.

Using the x-rays of the ankle after and the CT of both ankles before removal of the syndesmotic screw we evaluated the radiologic results: the syndesmotic interval in the fontal and axial cuts, the Espace claire de Chaput (total clear space, TCS) und the medial clear space (MCS). The functional results were evaluated by the scores of Phillips, Olerud/Molander and Weber.

Results: The mean frontal interval difference was 0,3 mm und the mean axial interval difference was 0,5 mm, in one case Fall (6,7%) there was a axial interval difference of 2 mm and in one case the interval had been over corrected. There was no subluxation of the talus in any patient. In 3 patients (20%) the syndesmotic screw had been placed in a second operation, after there was suspection of syndesmotic insufficiency in the x-rays which had been verified by CT. After implantation of the screw the CT scan showed regular syndesmotic intervals. Average TCS was 5.3 (range 3.40 – 7,40), mean MCS was 2.2 (range 1.0 – 4.5).

Average functional scores were: Phillips 118.53 (range 53 – 135), Olerud/Molander 93 (range 60 – 100) and Weber 2.33 (range 0 – 12).

Conclusions: Only with CT, the correct placement of the syndesmotic screw can be verified, the syndesmotic interval in the axial cuts can be evaluated and the position of the fibula in the Incisura fibularis can be assesed, therefore CT should be postoperative standard after syndesmotic screw placment. If an ankle fracture has not been treated with a syndesmotic screw, postoperative CT of both ankles should be done in any radiological or clinical suspicion of syndesmotic insufficiency.