Design and Mechanical Evaluation of Sutureless Implants for the Surgery Treatment of Rotator Cuff Tears

Rotator cuff (RC) tears cause pain and functional disability of the shoulder. Despite advances in suture anchors, there are still reports about the incidence of surgical-related injuries to RC mainly associated with sutures. The purpose of this study was to design and evaluate the mechanical behavior of sutureless implants to repair RC tears. We hypothesized that the implants present mechanical characteristics suitable for the surgical treatment of RC tears as suture anchors. Three different implants (T1, T2, T3) were designed and fabricated with titanium: T1 has two rods and rectangular head; T2 has two rods with a small opening and enlarged rectangular head; and T3 has three rods and a circular head. The implants were fixed in rigid polyurethane foam blocks by a series of blows, and the applied mechanical loads along with the number of blows were quantified. Pullout tests using tapes fixed between the implant head and testing machine grip were conducted until implant failure. The maximum pullout strength and displacement of the implant relative to the rigid foam block were computed. Statistical significance was set at p < 0.05. Owing to its geometric configuration, implant T2 presented the best characteristics related to stability, strength, and ease of insertion. Implant T2 confirms our hypothesis that its mechanical behavior is compatible with that of suture anchors, which could lead to the reduction of RC repair failures and simplify the arthroscopic procedure.