Radiographic Change of the Distal Tibiofibular Joint Following Removal of Transfixing Screw Fixation.

BACKGROUND

Syndesmosis disruptions in the ankle joint are typically treated with anatomic reduction followed by transfixing screw and/or suture button fixation. The purpose of our study was to analyze the effects of the removal of transfixing screws on syndesmosis integrity using plain radiographs and computed tomography (CT) scans.

METHODS

Twenty-nine cases (29 patients) who had been treated with transfixing screw fixation for syndesmosis disruptions were studied prospectively. Plain radiographs and CT scans were obtained 1 day before and 3 months after the removal of transfixing screws. The tibiofibular clear space (TCS) and tibiofibular overlap (TFO) were measured on plain radiographs, and the anterior and posterior measurement ratio (A/P ratio) of the syndesmosis was measured on axial CT scans to radiographically analyze the effect of the removal of screws on syndesmosis integrity.

RESULTS

On plain radiographs, syndesmosis diastasis was not observed before or after the removal of transfixing screws. No statistically significant difference was found in the TCS and the TFO between measurements at prescrew removal and at postscrew removal ( P = .761 and .628, respectively). However, the syndesmosis was found malreduced on CT scans in 7 cases (24.1%) before screw removal. All 7 cases showed anterior malreduction of the syndesmosis, 5 (71.4%) of which spontaneously reduced after screw removal. The A/P ratio of the 7 cases decreased from a mean of 1.37 (range, 1.26-1.61) at prescrew removal to a mean of 1.12 (range, 0.96-1.25) at postscrew removal ( P = .016).

CONCLUSION

Syndesmosis malreduction not observed on plain radiographs after performing transfixing screw fixation was identified with CT scans. Of the cases with a malreduced syndesmosis, 71.4% showed spontaneous reduction after screw removal. Therefore, we believe the removal of transfixing screws is recommended after confirming malreduction on CT scans, although plain radiographs demonstrate anatomic reduction.

LEVEL OF EVIDENCE: Level II, prospective prognostic study.