Comparison of tricortical screw fixation versus a modified suture construct for fixation of ankle syndesmosis injury: A biomechanical study

Objective: To assess the viability of using a modified flexible suture impl ant instead of a tricortical screw for fixation of ankle syndesmosis failur es. Design: Randomized biomechanical study. Setting: Orthopaedic Research Laboratories at the University of North Carol ina at Chapel Hill. Intervention: Formalin-preserved cadaveric legs were used in pairs. Two hol es, 2.5 millimeters in diameter and 7.0 to 10.0 millimeters apart horizonta lly, were drilled through the fibula and tibia 2.0 centimeters above the ti bial plafond. Two strands of Number 5 suture were passed through the holes and tied. Similarly, a 3.5-millimeter tricortical screw was placed on the o pposite leg of each pair at 2.0 centimeters. The ankles were tested to fail ure. This process was repeated at 5.0 centimeters above the tibial plafond. Main Outcome Measurements: Maximum load and displacement at failure of the suture construct at 2.0 centimeters and at 5.0 centimeters were compared wi th a tricortical screw at 2.0 centimeters and at 5.0 centimeters. Results: There was no significant difference in strength or displacement be tween the flexible suture implant and the tricortical screw at either 2.0 c entimeters or 5.0 centimeters. The fixations at 5.0 centimeters had signifi cantly increased holding strength over fixations at 2.0 centimeters, and th e fixations had significantly greater displacement at 2.0 centimeters than at 5.0 centimeters. Conclusion: This study confirms that flexible syndesmosis repair is a viabl e option for internal fixation of ankle mortise instability due to syndesmo sis rupture.