Should the Diastatic Syndesmosis be Stabilized in Advanced Pronation-External Rotation Ankle Injuries? A Retrospective Cohort Comparison

Abstract Background: Ankle injuries with the advanced pronation-external rotation (PE) type are relatively uncommon and the debate about whether the diastatic syndesmosis should be stabilized concomitantly has yet achieved a consensus. Comparison of using (Group 1) or non-using (Group 2) screw stabilization for the diastatic syndesmosis was performed retrospectively. Methods: With the 10-year period, 81 consecutive adult patients with advanced PE ankle injuries (stage 3 or 4 PE type) were treated. After malleolar fractures were internally stabilized with screws and plates, the syndesmotic stability was re-checked by external rotation and hook tests. The necessity of insertion of cortical screws to stabilize diastatic syndesmosis was decided by the individual orthopedic surgeon. The outcomes of both approaches were compared. Results: Seventy-one patients were followed for at least one year (87.7%; average, 2 years; range, 1-11 years). Group 1 had 22 patients and Group 2, 49 patients. The union rate in Group 1 was 100% (22 / 22) and in Group 2, 91.8% (45 / 49; p= 0.30). Syndesmosis re-diastasis occurred in 13.6% (3 / 22) of Group 1 and 30.6% (15 / 49) of Group 2 (p= 0.13). Satisfactory ankle function was noted in 86.4% (19 / 22) of Group 1 and 65.3% (32 / 49) of Group 2 (p= 0.07). Conclusion: Although clinical comparison cannot demonstrate statistical difference, screw stabilization of the diastatic syndesmosis may guarantee safer results. The statistical insignificance may be due to insufficient sample sizes. Clinically and theoretically, insertion of syndesmotic screws to promote ligament healing may be reasonable.