Cadaveric biomechanical study on purely Lisfranc ligamentous injuries

Abstract

Introduction: The aim of this work is to describe mechanism of Lisfranc injuries acccording to the force applied; and with the use of pre and post-trial MRI, to determine the sequence of the ligament rupture so as to state which structures are injured as the axial force increases (simulating the action mechanism) and regognize which are the most resistant. Methods: Eight (8) fresh cadaveric pieces were studied. The study of Lisfranc ligamentous complex was performed with emphasis on the dorsal, interosseous and plantar ligaments. Pre and Post-trial MRI were performed. The pieces were divided into four groups: 1. Control group (2 feet); 2. A direct force was applied in the second cuneiform bone, simulating a direct mechanism until transverse arch was broken (2 feet); 3. An axial force was applied to the proximal tibia, simulating the mechanism in low energy injuries (midfoot sprain), previous dorsal and Lisfranc ligaments sectioned (2 feet); 4. An axial force was applied to the proximal tibia, simulating the mechanism of low energy, previous plantar ligament sectioned (2 feet). Results: We found a marked difference between the ligamentary resistance to the forces exerted between the direct and indirect mechanism of Lisfranc injuries. In addition, after the trail we confirmed a difference as for the same load between group 3 and 4, thus, obtaining a greater resistance to the force in the Lisfranc ligament, if compared to the dorsal and plantar ligaments. Conclusions: This study allowed us to distinguish the relative resistance of each ligamentary structure to the exerted force. A greater resistance to the exerted forces of the Lisfranc ligament could be demonstrated, compared to the plantar and dorsal ligaments. Besides, in the trials of indirect mechanism injuries, we could demonstrate the rupture sequence. We demonstrate the importance of the MRI to determine possible injuries clinically suspected, and the ligament plantar in stability of Lisfranc injuries.