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Background: Titanium plantar plates have proven successful in the fixation of the first tarsometatarsal arthrodesis (TMT). However, a second surgery is typically needed for implant removal, and potential adverse effects, carried by the conventional implantations, are not uncommon. The purpose of this study was to determine whether a novel magnesium-based plantar plate system provides similar fusion stability to a titanium-based plantar plate system under various loading conditions. Methods: Six matched-pair human cadaveric specimens underwent TMT fusions using either a magnesium plantar plate system prototype or a titanium plantar plate system. Specimens were cyclically loaded with a force ranging from 5 N to 50 N for 5,000 cycles, and displacement was recorded. Axial stiffness (N/mm) was calculated from load-displacement curves. Each specimen was loaded to failure at a rate of 5 mm/min, and the ultimate load was recorded. Results: No significant difference was found in the vertical displacement between Ti group and Mg group after 100 cycles (2.4 ± 1.0 mm vs. 1.3 ± 1.4 mm, p = 0.196), 500 cycles (3.3 ± 1.3 mm vs. 1.7 ± 1.7 mm, p = 0.142), 1,000 cycles (3.7 ± 1.5 mm vs. 1.9 ± 1.9 mm, p = 0.128), 2,500 cycles (4.2 ± 1.7 mm vs. 2.3 ± 2.2 mm, p = 0.172) and 5,000 cycles (4.5 ± 1.8 mm vs. 2.3 ± 3.3 mm, p = 0.125), Additionally, no significant differences were observed in initial stiffness (53.1 ± 19.2 N/mm vs. 82.2 ± 53.9 N/mm, p = 0.257), final stiffness (90.6 ± 48.9 N/mm vs. 120.0 ± 48.3 N/mm, p = 0.319), or maximum load-to-failure (259.8 ± 98.2 N vs. 323.9 ± 134.9 N, p = 0.369). Conclusions: Based on the performed biomechanical testing, the magnesium plantar plate system provides mechanical stability equivalent to the titanium plantar plate system in fixation for the first TMT joint fusion. [ABSTRACT FROM AUTHOR]

Tibial shaft fractures are common injuries in the pediatric and adolescent populations. Elastic stable intramedullary nailing (ESIN) is the treatment of choice for cases that require surgical stabilization. A new intramedullary device, BoneHelix® (BH), may be an alternative for use with fractures that cannot be satisfactorily stabilized with ESIN. This study aimed to assess the biomechanical performance of BH compared with ESIN in a porcine tibia fracture model, observing cyclic fatigue and load to failure. Computed tomography was used to monitor the implant position and to rule out unintended damage. No implant or bone failure occurred during the fatigue testing. An increase in the cumulative plastic displacement was observed in both test groups over the loading cycles applied. Both implant–bone constructs displayed a trend toward closure of the osteotomy gap. During the load-to-failure test, the average loads at failure in specimens instrumented with ESIN and BH were 5364 N (±723) and 4350 N (±893), respectively, which were not statistically significant (p = 0.11). The values of both groups were two to three times higher than the estimated maximal load (2000 N) during physiological weight bearing. The biomechanical results thus indicate equivalent performance and stability by the implants tested. [ABSTRACT FROM AUTHOR]