Cyclic load testing and ultimate failure strength of biodegradable glenoid anchors

Purpose: The purpose of this study was to compare biodegradable glenoid suture anchors by cyclic loading and load to failure testing. Methods: Seven different suture anchors (BioKnotless and Lupine Loop [DePuy-Mitek, Norwood, MA]; BioPushLock, BioSutureTak, and BioFasTak [Arthrex Corp, Naples, FL]; BioAnchor [Conmed Linvatec, Largo FL]; and BioRaptor [Smith & Nephew, Andover, MA]) were tested in 8 matched pairs of human cadaver fresh-frozen glenoids. The anchors were inserted in rotation into different glenoid rim positions. Sutures attached to the anchors were fixed to an Instron 8871 machine (Instron, Canton, MA) and cyclic loading and destructive testing were performed. The cyclic displacement at 100 and 500 cycles, stiffness, ultimate failure strength, and mode of failure were determined. Results: No statistical difference was found in the ultimate failure load for any of these anchors. The Lupine Loop and BioAnchor had greater 100 cycle and 500 cycle mean displacements than the BioPushLock and BioSutureTak. The Lupine Loop also had greater 100 cycle and 500 cycle mean displacement than the BioFasTak (P < .05). The BioAnchor had greater mean 500 cyclic displacement than the BioFasTak (P < .05). Mean BioSutureTak stiffness was greater than the Lupine Loop, BioAnchor, BioKnotless, and BioRaptor (P < .05). Conclusions: No differences in ultimate failure strength after cyclic loading were found in these seven biodegradable glenoid anchors (BioKnotless, Lupine Loop, BioPushLock, BioSutureTak, BioFasTak, BioAnchor, and BioRaptor). Most displacement occurred in the first 100 cycles. Displacement at 500 cycles was greater for the Lupine Loop and the BioAnchor than the BioPushLock, BioSutureTak, and BioFasTak. Failure was principally by the anchor pulling out of bone except for the BioSutureTak, which also failed by the suture loop eyelet pulling out of the anchor body, and the BioPushLock which failed by the suture slipping past anchor. Clinical Relevance: Biodegradable glenoid anchors did not show statistical difference in ultimate failure load after cyclic loading.