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Maik-Benjamin Bockmann, E. Jaeger, Lukas Dankl, Wolfgang Nebelung, Sören Frey, Werner Schmölz, Tobias Schulte

• \(\bf Introduction\) The fixation of the coracoid process onto the glenoid is an important step of the Latarjet procedure, and implant-associated complications are a relevant and severe problem. This study compares the fixation strength and failure mode of two biodegradable materials with stainless-steel screws. \(\bf Methods\) 24 Fresh-frozen cadaveric scapulae were divided into three groups of equal size and received a coracoid transfer. Cadavers were matched according to their bone mineral density (BMD). In group 1, small-fragment screws made of stainless steel were used. In the second group, magnesium screws were used, and in the third group, screws consisted of polylactic acid (PLLA). A continuously increasing sinusoidal cyclic compression force was applied until failure occurred, which was defined as graft displacement relative to its initial position of more than 5 mm. \(\bf Results\) At 5-mm displacement, the axial force values showed a mean of 374 \(\pm\) 92 N (range 219–479 N) in group 1 (steel). The force values in group 2 (magnesium) had a mean of 299 \(\pm\) 57 N (range 190–357 N). In group 3 (PLLA), failure occurred at 231 \(\pm\) 83 N (range 109–355 N). The difference between group 1 (steel) and group 2 (magnesium) was not statistically significant (\(\it P\) = 0.212), while the difference between group 1 (steel) and group 3 (PLLA) was significant (\(\it P\) = 0.005). \(\bf Conclusion\) Stainless-Steel screws showed the highest stability. However, all three screw types showed axial force values of more than 200 N. Stainless steel screws and PLLA screws showed screw cut-out as the most common failure mode, while magnesium screws showed screw breakage in the majority of cases. \(\bf Evidence\) Controlled laboratory study.