Evolution toward new bioabsorbable material for osteosynthesis implants used in foot and ankle surgery

摘要

Bioabsorbable osteosynthesis material is a new solution in the ankle and foot fracture surgery, being wide spread and in continuous expansion. Surgical fixation of these fractures requires small materials. Also, postoperative cast immobilization and mobilization without bearing limits the requirements for strength of materials.Thus, bioabsorbable polymers were optimal solution for a long period, in the form of pins, screws, plates made of poly-Llactide, polyglycolide, polydioxanone or copolymers of polylactide and polyglycolide. In time, these materials have shown a number of complications, such as low strength, exudate and macrophage granuloma in the implant site. In order to eliminate these drawbacks, new bioabsorbable materials have been studied. These are made from magnesium, which is a natural element of the body. This paper evaluates the different Mg alloys, pointing out their advantages: high biocompatibility, high mechanical strength, density similar to that of bone.At the same time it evaluates the disadvantages of magnesium: increased rate of degradation emission of gas bubbles H+, rapid loss of initial mechanical strength. Several solutions have been proposed: combining with other compounds (alloys of Ca, Mn, Zn, rare earth as Y), grain refining and alloys coatings. These solutions have increased corrosion resistance up to coefficients sufficient to support callus formation, at the moment osteosynthesis material made from Mg alloys being marketed.