Effect of syndesmosis injury in SER IV (Weber B)-type ankle fractures on function and incidence of osteoarthritis.

BACKGROUND

Syndesmosis fixation of Lauge-Hansen SER IV, Weber B ankle fractures is controversial. This study compared a matched pair of SER IV patients with stress proven syndesmotic injuries with the same number without stress proven syndesmotic injury in terms of functional, pain, and radiologic result.

METHODS

The study was based on a RCT-study comparing syndesmotic transfixation to no fixation in SER IV (Weber B)-type ankle fractures. Twenty-four patients with a syndesmosis injury found on the intraoperative 7.5 Nm standardized external rotation test were compared to 24 patients with a stable syndesmosis. The pairs were matched by fracture morphology, sex, and age. The primary outcome measure was ankle function as assessed by the Olerud-Molander score. Weight-bearing plain radiographs and 3T MRI of the injured ankle were used to assess ankle joint congruity and osteoarthritis, according to Kellgren-Lawrence classification and cartilage defects.

RESULTS

The Olerud-Molander score was 86 in syndesmosis injury patients and 90 in patients with normal syndesmosis (P = .28). The incidence of ankle joint osteoarthritis on plain radiographs was not significantly different between the groups (Grade I 5% vs 21%; Grade II 86% vs 75%; Grade III 9% vs 4%; P = .34). MRI scans showed TC joint cartilage defects in 54% of the patients: 12 (56%) in the syndesmosis injury group vs 13 (54%) in the group without syndesmosis injury (P > .9).

CONCLUSION

After 4 to 6 years of follow-up, clinical and radiologic outcome were not different in patients with syndesmosis injury compared to patients with stable syndesmosis in SER IV (Weber B)-type ankle fractures.

LEVEL OF EVIDENCE: Prognostic Level II, comparative study.