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Ultimate Failure Load of Plate-Based Fixation and a Suture Anchor for Rotator Cuff Repair Across Polyurethane Bone Densities

Authors :

Parviz Ahangar¹ Solmaz Mojadam Mofrad² Amir Nourani³ Amirhasan Amini⁴ Erfan Ahmadpour Joeini⁵ Mohammad nasir Naderi⁶

1- کلینیک شمس تبریزی 2- دانشگاه صنعتی شریف 3- دانشگاه صنعتی شریف 4- دانشگاه صنعتی شریف 5- دانشگاه صنعتی شریف 6- بیمارستان کسری

Keywords :

Rotator cuff repair،Suture anchor،Plate-based fixation،Synthetic cancellous bone،Ultimate failure load

Abstract :

Abstract—Background— Early after rotator cuff repair, the tendon–bone interface is weak; robust time-zero fixation is therefore required to resist oblique loading. Objective— To evaluate the time-zero fixation strength of a plate-based approach versus a commercial suture anchor across synthetic cancellous bone densities. Methods— Twenty-four tests (four for each combination of method and density) were performed on rigid polyurethane foam blocks with densities of 10, 12, and 15 pcf according to ASTM F1839. The investigational plate-based fixation (AP) and a 4-mm suture anchor (SA) were set up on a custom fixture and pulled to failure at an oblique angle of one hundred twenty degrees under displacement control at one millimeter per second. The primary outcome was the ultimate failure load, defined as the first peak followed by an abrupt drop in load. Independent t-tests were used to compare methods within each density. Results— Mean ultimate failure load for SA was 160 N at 10 pcf, 225 N at 12 pcf, and 400 N at 15 pcf. Mean ultimate failure load for AP was 392 N at 10 pcf, 449 N at 12 pcf, and 455 N at 15 pcf. AP exceeded SA within each density (10 pcf: p less than 0.0001; 12 pcf: p equal to 0.0003; 15 pcf: p equal to 0.0217). Within AP, increasing density from 10 to 12 pcf raised the mean ultimate failure load by about 56 N (p equal to 0.0240); increasing from 12 to 15 pcf did not produce a notable change (p equal to 0.7569). Failures were predominantly anchor pull-out for SA and tape rupture at plate holes for AP; surface indentation beneath the plate was most apparent at 10 pcf. Conclusion— Under a conservative oblique pull of one hundred twenty degrees, the plate-based method provided higher time-zero strength than a suture anchor across 10, 12, and 15 pcf, with the greatest margin at lower density. These density-resolved data may help guide fixation choice when bone quality is limited, pending confirmation under cyclic loading and in cadaveric and clinical studies.