Effect of suture anchor type, eyelet configuration, and loading condition on suture failure: An in vitro study

To determine the effect of suture anchor type, eyelet configuration (raised or embedded), and loading condition (without or with cyclic loading) on failure load and failure mode of sutures in anchors with embedded and raised eyelets.

Controlled laboratory study.

A total of 4 unique clinical anchor+suture combinations (n = 40 total); eyebolt screw reference samples (n = 30 total).

A total of 10 samples of each anchor+suture combination were either (a) loaded to failure (n = 5) or (b) loaded from 0 N to 60 N for 1000 cycles then loaded to failure (n = 5). As a "best-case" reference, an eyebolt screw with a smooth, round cross-section was tested under the same two loading conditions and the same sutures (n = 10 per suture) used with the clinical anchors. The percent difference in the maximum load at failure ( $\%∆F_{\max }$ ) between each anchor and suture-matched eyebolt screw was used to quantify the effect of each anchor on suture strength.

There was no effect of loading condition (i.e., without or with cyclic loading) on F_max. The Anika anchor had a significantly lower $\%∆F_{\max }$ than the Arthrex anchor (p = .015), IMEX anchor (p = .004) and Jorvet anchor (p < .001). A total of 14 out of 20 samples of anchors with raised eyelets failed at the suture mid-section, whereas all 20 samples of anchors with embedded eyelets failed at the suture knot.

Anchors with raised eyelets had more failures at the suture mid-section indicative of wear and/or cutting of the suture against the eyelet.

Eyelet geometry and surface finish of metallic screw-type anchors have effects on suture strength.