Experimental study on the application of a novel degradable calcium-phosphate coated magnesium alloy encircling bone plate in the internal fixation of rib fractures

Severe rib fractures often require surgical plate fixation, but non-biodegradable implants typically necessitate a second surgery for removal. Although AZ31 magnesium alloy is a biodegradable medical material, its excessively rapid in vivo degradation makes it difficult to meet the requirements for fracture fixation in high-load, dynamic environments such as the ribs. To address this issue, we used surface modification technology to apply a calcium-phosphate coating onto a biodegradable AZ31 magnesium alloy rib plate and evaluated its degradation rate, fracture fixation effectiveness, and potential adverse effects through in vitro and in vivo experiments. The results showed that the degradation rate of the coated plate was significantly slower than that of the uncoated plate in both settings (p < 0.05). In animal models of rib fracture, the coated plate achieved better fracture alignment and healing morphology, with no significant adverse reactions observed during the 6-month postoperative follow-up. Surface modification with a calcium-phosphate coating effectively mitigated the problem of premature fixation failure caused by the overly rapid in vivo degradation of AZ31 magnesium alloy. The findings of this study provide a new perspective for the development of biodegradable internal fixation implants for rib fractures.