Comparison of Several Combinations of Suture Tape Reinforcement and Suture Button Constructs for Fixation of Unstable Syndesmosis.

INTRODUCTION:The purpose of this study was to arthroscopically evaluate syndesmotic stability after fixation with several combinations of suture buttons (SBs) and suture tape reinforcement in a completely unstable cadaver model. METHODS:Fifteen cadaver above-knee specimens underwent sequential ligament transection and fixation to create six experimental models: (1) intact model, (2) after complete disruption of the syndesmotic ligaments, and after repair with either suture tape reinforcement (3), suture tape reinforcement with a single SB (4), suture tape reinforcement with two diverging SBs (5), or two diverging SBs alone (6). Instability measurements included anterior and posterior tibiofibular spaces measured arthroscopically under 100 N coronal stress, tibiofibular anteroposterior and posteroanterior translation in sagittal plane measured arthroscopically under sagittal stress of 100 N, and anterior tibiofibular space measured directly with a caliper under external rotation torque of 7.5 N·m. Instability measurements taken after each fixation method were compared with the uninjured model and with the complete unstable model using the Wilcoxon signed-rank test. RESULTS:Fixation using a combination of one SB and singular suture tape reinforcement augmentation provided stability similar to the intact stage (coronal anterior space 1.24 versus 1.15, P = 0.887; coronal posterior space 1.63 versus 1.64, P = 0.8421; anteroposterior translation 0.91 versus 0.46, P = 0.003; posteroanterior translation 0.51 versus 0.57, P = 0.051; external rotation anterior tibiofibular space 1.08 versus 0.55, P = 0.069). Moreover, adding a second SB led to further gains in fixation stability. DISCUSSION:This study suggests that although a destabilizing syndesmotic injury that includes the anterior inferior tibiofibular ligament, interosseous ligament, and posterior inferior tibiofibular ligament is not adequately stabilized by either one or two SBs, the addition of a suture tape reinforcement to even one SB restores syndesmotic stability to the preinjury level.