Avaliação de implantes sem fios de sutura para o reparo alternativo de tendões do manguito rotador

Abstract

Rotator cuff tears are pathological disorders that generate shoulder pain and disability. The repair is made by arthroscopic surgery using suture anchors. However, the suture anchors have disadvantages like guiding sutures through tendon and tying knots. To solve those problems, the aim of this study is developing and optimizing sutureless implants. The mechanical behavior of implants was evaluated using experimental testing and finite element analysis. As result, two three staple-shaped implants was proposed. The implants were manufactured in titanium alloy by additive manufacturing and named of implant type 1 (two legs and rectangular head), type 2 (two legs and enlarged rectangular head) and type 3 (three legs and circular head). Experimental testing was performed with a polyester ribbon passed through the head of implants to pull them out and a rigid polyurethane foam block with close related biomechanical properties to the trabecular bone. The insertion average load of each implant was estimated by using a device building for that procedure and connected to a data acquisition system. The mechanical strength and displacement of implants was evaluated using pull out testing at a constant rate. The analysis of implant fixation was performed by using tridimensional finite element models. The results of experimental testing showed that two implants had failed during the insertion procedure: one of type 1 and one of type 3. The implant type 3 required a higher average load to be inserted than the others. In the pullout test, the fixation strength of implant type 2 was higher than type 1 and 3. And the displacement until the failure of the implant type 2 was lower than the other implants. In the finite element analysis, the rotator cuff repair model of implant type 2 showed lower levels of displacement and von Mises stress. From these results it was concluded that the type 2 implant showed geometrical characteristics that can contribue to a better fixation resistance and stability of bone tendon in rotator cuff repairs.