Summary

This is the first study to evaluate the trans-syndesmotic screw frequency after trimalleolar ankle fractures osteosynthesis with a posterior malleolus fracture involving < 25% of the articular surface.

Abstract

Background

Most authors agree that posterior malleolus fragments worsen patient clinical outcomes. There are continuing debates as to whether small posterior malleolus fragments (< 25% of joint surface affected) should be anatomically reduced and fixed. In the past, internal fixation of tibial posterior malleolus fragments was performed in cases wherein > 25% of the articular surface was involved for only 2 reasons: smaller fragments did not alter joint biomechanics and step defects < 2 mm did not affect the functional results. However, many studies have confirmed the role of the posterior malleolus as an important contributor to the alignment and stability of the ankle mortise and syndesmosis.

Objectives: To our knowledge this the first study to evaluate the trans-syndesmotic screw frequency after trimalleolar ankle fractures with a posterior malleolus fracture involving < 25% of the articular surface.

Study Design & Methods: Retrospective comparative study. Patients with trimalleolar ankle fracture who underwent surgery between January 2011 and January 2018 were identified within the department´s fracture database. General demographics, treatment details and fracture specific details (CT-scans) were assessed. Patients were grouped per the posterior malleolus fragment treatment: osteosynthesis (group 1) and non-osteosynthesis (group 2).

Results

64 patients, 58.6 ±17.8 years (range: 23–75), 68.8% female were eligible and follow up time was 43.1 ±22.2 (range 24–96) months. The mean size of the posterior malleolus fragment was 14.7 ±5.3% (range: 5–24). Posterior malleolus fragment treatment distribution: osteosynthesis (group 1) 31.2% and non-osteosynthesis (group 2) 68.8%. Osteosynthesis of the posterior malleolus fragment significantly reduced the frequency of trans- syndesmotic screw (0%) compared to non-osteosynthesis posterior malleolus fragment (15.9%) ( p < 0.05).

Conclusions

Posterior malleolus fragments ( < 25% of the articular surface) have significantly decrease trans-syndesmotic screw need following osteosynthesis.