We implanted nails made of titanium (Ti6Al4V) and of two types of glass ceramic material (RKKP and AP40) into healthy and osteopenic rats. After two months, a histomorphometric analysis was performed and the affinity index calculated. In addition, osteoblasts from normal and osteopenic bone were cultured and the biomaterials were evaluated in vitro.

In normal bone the rate of osseointegration was similar for all materials tested (p > 0.5) while in osteopenic bone AP40 did not osseointegrate (p > 0.0005).

In vitro, no differences were observed for all biomaterials when cultured in normal bone-derived cells whereas in osteopenic-bone-derived cells there was a significant difference in some of the tested parameters when using AP40.

Our findings suggest that osteopenic models may be used in vivo in the preclinical evaluation of orthopaedic biomaterials. We suggest that primary cell cultures from pathological models could be used as an experimental model in vitro.

The anterior cruciate ligament was replaced in rabbits, using implants of carbon or polyester filaments with known mechanical properties. The biocompatibility of the implants was assessed in detail using light microscopy, and scanning and transmission electron microscopy. Mechanical tests were made of stability, in comparison with normal joints and controls after excision of the ligament. Some carbon fibre implants broke down in vivo, allowing instability; the fragments caused chronic inflammation. Intact carbon implants did not induce the formation of neoligaments; they were covered by tissue, but there was no ingrowth. Polyester did not degrade mechanically and supported early collagenous ingrowth within the implant, even in the mid-joint space. It was concluded that there was no justification for the use of carbon fibres as anterior cruciate replacements; polyester appeared to be suitable.