Sternoclavicular Joint Reconstruction Fracture Risk Is Reduced With Straight Drill Tunnels and Optimized With Tendon Graft Suture Augmentation

BACKGROUND: Despite the rare entity of sternoclavicular joint (SCJ) instability, a variety of different reconstruction techniques for SCJ dislocations have been described. A technique with oblique drilling has been proposed to reduce intraoperative risks. PURPOSE: To biomechanically investigate different cerclage reconstruction techniques and the benefit of additional reinforcement using suture tape. STUDY DESIGN: Controlled laboratory study. METHODS: Reconstructed artificial bone specimens were mounted on a mechanical testing machine. They were subjected to anterior and posterior translation, analyzing ultimate strength, displacement, stiffness, and elongation. For stage 1, different angulations of the drill tunnels through the sternum and clavicle were compared. Straight drill tunnels from anterior to posterior were compared with 45° oblique drill tunnels. For stage 2, three different materials for cerclage reconstruction were compared: (1) suture tape alone (FT group), (2) tendon graft alone (tendon group), and (3) tendon graft with suture tape augmentation (tendon+FT group). RESULTS: For the FT group, in the anterior and posterior directions, straight drill holes resulted in a significantly higher load to failure (936.9 ± 122.5 N) compared with oblique ones (434.5 ± 20.2 N) (P < .0001). During cyclic testing, all specimens with straight drill holes survived the 5- to 550-N step, while all specimens with oblique ones failed during the 5- to 450-N step. Analyzing the graft material choice, the mean load to failure was 556.6 ± 174.3 N for the tendon group, 936.9 ± 122.5 N for the FT group, and 767.0 ± 110.7 N for the tendon+FT group (P = .089). The stiffness of the tendon+FT group was significantly lower than that of the FT group and significantly higher than that of the tendon group. CONCLUSION: Oblique tunnel placement during SCJ reconstruction, while reducing the intraoperative risk, results in decreased primary stability of the construct. Tendon graft reconstruction with suture tape augmentation leads to enhanced stability and optimizes biomechanical properties of the construct. CLINICAL RELEVANCE: The surgical technique with straight drill holes has superior initial biomechanical properties and may likewise produce superior clinical outcomes in the treatment of SCJ instability. Suture tape augmentation can provide additional stability to reconstruction procedures.