Biodegradable Magnesium Screw Implants Decrease Inflammatory Response and Enhance Osteogenesis in Orthopedic Traumas
Introduction: There is a high national burden of orthopedic trauma, which often leads to the use of fixation devices in orthopedic surgical procedures1-2. Previous treatment options for femoral fractures included inserting stainless steel, titanium alloys or cobalt-chromium alloy screws into the bone at the site of the fracture, but this yielded significant stress shielding effects and a potential need to perform secondary surgeries3. After metals, synthetic polymers, such as polylactic acid (PLA), were used, but these implants have show limitations in their mechanical capabilities, and impaired abilities to induce osteogenesis4-5. This review will seek to understand how a new approach of using Magnesium-based biodegradable screws may be a suitable alternative treatment options due to their ability to decrease inflammatory response and increase osteogenesis. Methods: Four discs were seeded with macrophages, introduced to LPS, and the effects were investigated using ELISA and qPCR6. TRPM7 knockouts osteoblast cells were compared to unmodified osteoblast cells, and each sample was exposed to various concentrations of MgSO47. A Zn-Mg-Ag implant was surgically implanted into the distal femur of rats and histological evaluation of the tissue was evaluated at 12 and 24 weeks8. A clinical trial was conducted to establish if biodegradable magnesium screws employed better clinical results and decreased risk of complications9. Results: Seeded discs containing magnesium (JDBM, extract, MgCl2) had lower levels of TNF-a and IL-6 expression at both the protein expression and mRNA expression levels6. In the TRPM7 knockouts, the 5-, 10-, and 20-mM Mg ions did provide mineralization of Ca2+ and PO4 and an increased presence of alkaline phosphatase, but higher concentrations of Mg (40 mM) inhibited Ca2+ formation and showed a decreased presence of alkaline phosphatase7. Additionally, in the cells lacking TRPM7, osteogenesis was inhibited and there was decreased formation of Ca2+ and PO4 complexes7. Knockdown of the TRMP7 pathway inhibited ALP production7. More continuous bone fractions and better osteointegration was seen in the mice with the MgSO4 implants8. Employment of biodegradable Mg-screws provided better clinical results and decreased the risk of avascular necrosis of femoral head in human patients9. Conclusions: Mg screws can decrease the inflammatory response by decreasing the production of TNF-a and IL-6 production via down regulation of the TLR-4/TNF-KB/MAPK signaling pathways6. Mg ions can also help increase osteogenesis by stimulating the PI3k-AKT pathway7. During in-vivo biocompatibility assessments, it was seen that the Mg-based implant proved no toxicity and good osseointegration of implant, and in clinical testing Mg screws displayed better clinical results and fewer complications8,9. This suggests that biodegradable Mg screws can prove as a plausible solution for orthopedic trauma patients and should continue to be explored as a viable treatment option for patients.
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