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 implant instead of a tricortical screw for fixation of ankle syndesmosis failures.

DESIGN

Randomized biomechanical study.

SETTING

Orthopaedic Research Laboratories at the University of North Carolina at Chapel Hill.

INTERVENTION

Formalin-preserved cadaveric legs were used in pairs. Two holes, 2.5 millimeters in diameter and 7.0 to 10.0 millimeters apart horizontally, were drilled through the fibula and tibia 2.0 centimeters above the tibial 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 opposite leg of each pair at 2.0 centimeters. The ankles were tested to failure. 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 with a tricortical screw at 2.0 centimeters and at 5.0 centimeters.

RESULTS

There was no significant difference in strength or displacement between the flexible suture implant and the tricortical screw at either 2.0 centimeters or 5.0 centimeters. The fixations at 5.0 centimeters had significantly increased holding strength over fixations at 2.0 centimeters, and the fixations had significantly greater displacement at 2.0 centimeters than at 5.0 centimeters.

CONCLUSION

This study confirms that flexible syndesmosis repair is a viable option for internal fixation of ankle mortise instability due to syndesmosis rupture.