THE BIOMECHANICAL STABILITY OF A NOVEL BIOABSORBABLE MAGNESIUM ALLOY (ZX00:Mg–Zn–Ca) BONE ANCHOR FOR ROTATOR CUFF REPAIRS: A HUMAN EX VIVO STUDY

Introduction: The purpose of this study was to ascertain the primary ex vivo biomechanical stability of a novel bioabsorbable magnesium alloy (ZX00: Mg–Zn–Ca) bone anchor in human cadaveric proximal humeri, indicated in the reconstruction of the rotator cuff. Methods: Twenty human Thiel-embalmed cadaveric humeri were prepared and freed from soft tissue. One ∅5.7 × 20.5-mm ZX00 anchor and one ∅5.5 mm × 16.3 mm Arthrex Titanium FT Corkscrew (ATC) control anchor were inserted into the footprint of the supraspinatus tendon, 15 mm apart. The humeri were mounted onto a material testing machine and following a 40 N preload, cyclic loading was performed over 400 cycles. If the construct remained intact, ultimate load to failure (ULTF) was measured using an increasing axial load of 1 mm/s, ULTF and mode of failure were recorded. Results: No difference was found in the ability to withstand cyclic loading, mode or load-to-failure strengths between ZX00 and control anchors. The maximum tractional force loaded for the ZX00 anchors had a median of 257.4 N (range 165.3–328.2). The corresponding value for the ATC anchors averaged 239.9 N (range 118.9–306.7). Conclusion: ZX00 alloy anchors appear to provide adequate initial biomechanical stability when compared to an industry-standard control in a cadaveric rotator cuff repair model.