[An experimental study of the process of bony ingrowth into inorganic bone-particle impregnated bone cement]

A composite of inorganic bone particles formed with bone cement in certain proportion was implanted in the proximal femora of 15 New Zealand rabbits. The animals were sacrificed in batches at different intervals after implantation and specimens were sectioned for scanning electron microscopic (SEM) observation and push-out test. SEM showed that the bone particles in the composite were in contact with each other and forming bony pathways. The gaps between inorganic bone particle bone cement and cortical bone were filled at first with collagen fibrils which were interwoven to form collagen fiber bundles and then mineralized to assume woven bone. The bone particles became smaller in size and were enveloped, absorbed and replaced by new bone structure gradually reaching the depth of bone cement along the pathways formed by bone particles. The shear strength of the cement-bone interface was increased subsequently.