Strength of Syndesmosis Fixation: Two TightRope versus One TightRope with Plate-and-Screw Construct

Injuries involving the distal tibiofibular syndesmosis can lead to critical destabilization of the ankle mortise. Although specific indications for operative fixation remain unclear, accurate reduction of the syndesmosis has been correlated with the best functional outcomes. The purpose of this study was to evaluate the maximum torque and rotation to failure after fixation with a novel construct. Seven pairs (14 ankles) of embalmed cadaveric lower legs, disarticulated at the knee, were obtained. Each pair was randomly assigned to receive either two TightRopes (Arthrex) or a plate-and-screw construct with one TightRope. All samples were mechanically tested in torsion to determine peak torque, torsional stiffness, and the maximum rotation angle at which failure occurred. Differences between the groups were compared using paired Student's t test. The maximum torque to failure after fixation was not significantly different between the two TightRopes (28.8 N*m; range, 7.3-49.7 N*m) and the one TightRope group (29.5 N*m; range, 9.2-44.9 N*m; p = 0.92). The maximum rotation to fracture after fixation was not significantly different between the two TightRopes (33.3 degrees; range, 21.6-57.0 degrees) and one TightRope group (38.6 degrees; range, 23.0-73.9 degrees). All specimens failed with the fracture of the fibula at the level of the inferior syndesmotic screw. The similar load to failure of the two TightRope and the one TightRope and plate-and-screw plate suggested similar stiffness between the two constructs. The addition of the plate may improve distribution of forces at the level of syndesmosis, reducing stress risers and decreasing the risk of failure, as demonstrated by a lower rotation to failure of the one TightRope with plate-and-screw construct. In addition, this construct is not likely to not be associated with any substantial cost increase. Further clinical studies may further elucidate the role of plate and/or TightRope augmentation to syndesmosis fixation.