Transfer of post-trial feedback on impacts during drop landings in female athletes.

Increased vertical ground reaction force (vGRF) and dynamic knee valgus contribute to non-contact anterior cruciate ligament (ACL) injuries. We examined feedback's influence during landing and transfer to a game-specific drill, measured by deceleration. Thirty-one female athletes performed 30 drop landings with augmented feedback and dual-task conditions, with a game-specific drill before and after. Differences were shown across time (baseline, feedback, post-feedback) and between conditions (with or without dual-task) in peak vGRF and knee to ankle ratio (K:A ratio). K:A ratio is the ratio of the frontal plane distance between the knees relative to the frontal plane distance between the ankles. This measure serves as a surrogate for knee valgus where a ratio closer to 1 indicates less knee valgus. There were reductions in peak vGRF (p < 0.05) and improvements in K:A ratio (p < 0.05) across time, improvements in K:A ratio across time and by condition (p < 0.05), and reduction in deceleration during landing in a game-specific drill (p < 0.05). Feedback may improve landing mechanics and transfer to a game-specific drill that can influence ACL injury in sport.

FIB-TEM Study of Magnesium Corrosion Products after 14 Days in the Murine Artery.

After a decade of intensive research on magnesium biodegradation, the composition and structure of corrosion products formed during in vivo corrosion are still not precisely known. Focused ion beam (FIB) micromilling and transmission electron microscopy (TEM) were used to elucidate the nanostructure and crystallography of the corrosion products that form at or near the interface between the corrosion products and metallic magnesium. This study built upon previously reported scanning electron microscopy, infrared spectroscopy, and energy dispersive X-ray spectroscopy data. These prior results revealed a duplex corrosion layer comprising a calcium- and phosphorus-containing outer product (near the tissue interface) and a magnesium- and oxygen-containing inner product (near the metallic interface). A specimen that had resided in the murine arterial wall for 14 days was selected for FIB-TEM analysis. Highly oriented, nanocrystalline magnesium oxide was identified near the metallic magnesium, apparently without the co-occurrence of magnesium hydroxide or carbonates. The calcium- and phosphorus-containing surface layer was also examined, and shown to be nearly amorphous.