Strength of Bone Tunnel Versus Suture Anchor and Push-Lock Construct in Brostrom Repair

Background: Operative treatment of mechanical ankle instability is indicated for patients who have had multiple sprains and have continued episodes of instability despite bracing and rehabilitation. Anatomic reconstruction has been shown to have improved outcomes and return to sport as compared with nonanatomic reconstruction. Hypothesis: The use of 2 suture anchors and a push-lock anchor is equal to 2 bone tunnels in strength to failure for anatomic Brostrom repair. Study Design: Controlled laboratory study. Methods: In 7 matched pairs of human cadaver ankles, the calcaneofibular ligament (CFL) and anterior talofibular ligament (ATFL) were incised from their origin on the fibula. A No. 2 Fiberwire suture was placed into the CFL and a separate suture into the ATFL in a running Krackow fashion with a total of 4 locking loops. In 1 ankle of the matched pair, the ligaments were repaired to their anatomic insertion with bone tunnels. In the other, 2 suture anchors were used to reattach the ligaments to their anatomic origins, and a push-lock was used proximally to reinforce these suture anchors. The ligaments were cyclically loaded 20 times and then tested to failure. Torque to failure, degrees to failure, and stiffness were measured. The authors performed a matched pair analysis. An a priori power analysis of 0.8 demonstrated 6 pairs were needed to show a difference of 30% with a 15% standard error at a significance level of .05. Results: There was no difference in the degrees to failure, torque to failure, and stiffness. A post hoc power analysis of torque to failure showed a power of .89 with 7 samples. Power for initial stiffness was .97 with 7 samples. Eleven of 14 specimens failed at either the suture anchor or the bone tunnel. Conclusion: There is no statistical difference in strength or stiffness for a suture anchor and push-lock construct as compared with a bone tunnel construct for an anatomic repair of the lateral ligaments of the ankle. Clinical Relevance: The use of suture anchors in lateral ligament stabilization allows for a smaller incision, less surgical dissection, and improved surgical efficiency. It is up to the discretion of the performing surgeon based on preference, ease of use, operative time, and cost profile to choose either of these constructs for anatomic repair of the lateral ligaments of the ankle. The suture repair at the ligament was significantly strong enough such that the majority of ankles failed at the bone interface.