Biomechanical Effect on Joint Stability of Including Deltoid Ligament Repair in an Ankle Fracture Soft Tissue Injury Model With Deltoid and Syndesmotic Disruption

Abstract

Background: The current operative standard of treatment for bimalleolar equivalent ankle fracture is open reduction and internal fixation (ORIF) of the lateral malleolus followed by syndesmotic stabilization if indicated. There is controversy surrounding the indication and need for deltoid ligament repair in this setting. The purpose of this study was to quantify the biomechanical effect of deltoid ligament repair in an ankle fracture soft tissue injury model.

Methods: Nine fresh-frozen cadaveric specimens were included in this study. Each leg was tested under 5 conditions: intact, syndesmosis and deltoid ligament sectioned, syndesmosis fixed, deltoid repaired, and both the syndesmosis and deltoid ligament repaired. Anterior, posterior, lateral, and medial drawer and rotational stresses were applied to the foot, and the resulting talus displacement was documented.

Results: Isolated deltoid repair significantly reduced anterior displacement to normal levels. Displacement with lateral drawer testing was not significantly corrected until both structures were repaired. Deltoid repair and syndesmosis fixation each reduced internal rotation significantly with further reduction to normal levels when both were repaired. External rotation remained elevated relative to the intact condition regardless of which structures were repaired.

Conclusion: There is existing controversy regarding the importance of deltoid ligament repair in the setting of ankle fractures. The findings of this biomechanical study indicate that deltoid ligament repair enhances ankle stability in ankle fractures with both syndesmotic and deltoid disruption.

Clinical relevance: Concomitant deltoid ligament repair in addition to stabilization of fracture and syndesmosis may improve long-term functioning of the ankle joint and clinical outcomes.

Keywords: ankle fracture; biomechanics; deltoid repair; syndesmosis; trauma.