Biomechanical Effect on Joint Stability of Including Deltoid Ligament Repair in an Ankle Fracture Soft Tissue Injury Model With Deltoid and Syndesmotic Disruption
Pablo Mococain, Lorena Bejarano-Pineda, Richard Glisson, Rishin J. Kadakia, Craig C. Akoh, Jie Chen, James A. Nunley and Mark E. Easley
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.
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.
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.
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.
Concomitant deltoid ligament repair in addition to stabilization of fracture and syndesmosis may improve long-term functioning of the ankle joint and clinical outcomes.
When I was thinking of a project to do during my stay with Duke’s Foot and Ankle team back in 2017, one of my first ideas was to try to understand the role of the deltoid ligament better. I have always wondered why we left the medial side of the ankle unattended when dealing with ankle fractures. We know that the deltoid ligament is the primary ankle stabilizer, but we rarely repaired it. In other joints, such as the knee or the elbow, when a primary ligamentous stabilizer is injured, surgeons perform a primary repair to try to restore joint biomechanics, provide native stability, allow safe early range of motion and avoid later instability which can lead to joint degeneration or malalignment.
Pablo Mococain MD
Department of Orthopaedic Surgery, Clínica Alemana