Does the Anchor Eye Alignment Affect the Performance of the Rotator Cuff Repair? A Biomechanical Study

Lara Locatelli,Cesar A.Q Martins,Arthur P.G Santos,Patricia O Cubillos,Carlos R.M Roesler

doi:10.1016/j.asmr.2020.10.005

Abstract

PurposeTo investigate the metal screw-in anchor failure mode and load to failure for 2 different eyelet alignments after anchor insertion in ovine humeri.MethodsSixteen ovine humeri were dissected, and a 5-mm metal anchor with 2 nonabsorbable polyblend polyethylene sutures was inserted into them in the proximal position of the greater tuberosity. The alignment of the anchors after insertion was adjusted to make 2 test groups, each with 8 specimens: In group 1, the anchor eyelets were malpositioned, whereas in group 2, the anchor eyelets were aligned according to the manufacturer's instructions. After insertion, cyclic tests from 10 N to 180 N were performed with a frequency of 1 Hz for 200 cycles; specimens were then loaded to failure to evaluate the maximum load of the system and observe the associated failure mode.ResultsThe mean ultimate failure load in group 2 was not significantly different from that in group 1 (P = .472).ConclusionsFor metallic screw-in suture anchors, the alignment of the eyelet does not change the failure mode and the load to failure after cyclic loading of the bone-anchor-suture system in ovine humeri.Clinical RelevanceOur results indicate that on the basis of this anchor model, the position of the eyelet in the greater tuberosity does not interfere directly with the biomechanical performance of the system.

Highlights

The use of implants in rotator cuff repair has changed dramatically in the past few decades, and the use of anchors was the most important innovation after the advent of arthroscopic shoulder surgery.[1]
When eyeleted anchor designs are used, the plane containing the hole of the anchor eyelet may be positioned parallel to the sagittal plane of the humerus or lie perpendicular the sagittal plane of the humerus
The mean ultimate failure load of the system, displacement after the first cycle and after the 200th cycle, and failure modes are reported in Table 1, together with the standard deviations

Summary

Introduction

The use of implants in rotator cuff repair has changed dramatically in the past few decades, and the use of anchors was the most important innovation after the advent of arthroscopic shoulder surgery.[1]. When eyeleted anchor designs are used, the plane containing the hole of the anchor eyelet may be positioned parallel to the sagittal plane of the humerus or lie perpendicular the sagittal plane of the humerus. Most implant manufacturers provide an insertion guide so that the plane containing the hole of the eyelet lies perpendicular to the sagittal plane of the humerus.[2] In this position, the suture wire tension is supported by the rounded edge of the eyelet. The purpose of this study was to investigate the metal screw-in anchor failure mode and load to failure for 2 different eyelet alignments after anchor insertion in ovine humeri. There would be a difference in the ultimate failure load and associated failure mode between the 2 alignments because the contact of the suture with the inner surface of the eyelet is not the same

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Conclusion