Due to good biocompatibility and mechanical properties, magnesium (Mg) and its alloys are considered promising degradable materials for orthopedic applications. In this work, a Mg metal matrix composite (MMC) was fabricated using Mg-2.9Zn-0.7Zr alloy as the matrix and 1 wt% nano-hydroxyapatite (n-HA) particles as reinforcements. In vitro corrosion behavior and cytocompatibility of a Mg–Zn–Zr/n-HA composite and a Mg–Zn–Zr alloy were investigated. In contrast with the Mg–Zn–Zr alloy, the MMC has better properties. The average corrosion rate of MMC is 0.75 mm/yr after immersion in simulated body fluid (SBF) for 20 days, and the surface of MMC is covered with white Ca–P precipitates. The electrochemical test results show that the corrosion potential (Ecorr) of MMC increases to −1.615 V and its polarization resistance (Rp) is 2.56 KΩ with the addition of n-HA particles. The co-cultivation of MMC with osteoblasts results in the adhesion and proliferation of cells on the surface of the composite. The maximum cell density is calculated to be (1.85±0.15) × 104/l after 5 days of co-culture with osteoblasts. The average cell numbers for two groups after culturing for 3 and 5 days (P<0.05) are significantly different. All the results demonstrate that the Mg–Zn–Zr/n-HA composite can be potentially used as biodegradable bone fixation material.
