Comparable biomechanical performance of magnesium-based and titanium screws for the Latarjet procedure in a cadaveric...

Nonbiodegradable metal screws used for fixation in the Latarjet procedure can cause complications, including irritation from prominent hardware and the need for revision surgery. Magnesium-based, bioabsorbable screws may address these concerns. This study compared the biomechanical performance of magnesium screws to titanium screws with the hypothesis that there is no statistically significant difference between both groups.

Fourteen fresh-frozen cadaveric shoulders were matched by age and sex. Seven shoulders underwent a standard Latarjet procedure using two 5 mm cannulated partially threaded magnesium screws (average age 70.6 ± 9.4 years). The other 7 were fixed with two 4.5 mm cannulated partially threaded titanium screws (average age 71.4 ± 14). All shoulders underwent biomechanical testing with direct pressure on the graft: cyclic loading (100 cycles 10 N- 100 N) was performed to assess displacement, stiffness and load-to-failure. Those were measured using force-displacement data obtained through a mechanical testing system.

Maximum cyclic displacement was 1.2 ± 0.6 mm for magnesium and 1.4 ± 1.1 mm for titanium screws (P = .643). Cyclical stiffness was 329 ± 147 N/mm (magnesium) vs. 402 ± 220 N/mm (titanium, P = .489). Construct stiffness was 327 ± 141 N/mm vs. 408 ± 207 N/mm (P = .425), and ultimate load to failure was 414 ± 128 N vs. 475 ± 271 N (P = .605). Bone block failure with screw bending was the most common failure mode in both groups.

No statistically significant differences in biomechanical performance were found between magnesium and titanium screws in this time-zero biomechanical study. Magnesium screws may offer a viable bioabsorbable alternative that reduces complications from permanent hardware.