Histological evaluation of bone—cement interface affected by polyethylene particles in rabbit knee

To investigate the biological process of aseptic component loosening caused by polyethylene wear debris, nine rabbits were implanted with acrylic cement into the non-weight-bearing intercondylar notch of distal femur. Six animals were administrated the particles of polyethylene into the knee joint repeatedly for 12 weeks. At the bone-cement interface, thin connective tissue was observed, while bone sometimes existed directly next to the acrylic cement. The percentage of the length of interposed fibrous tissue against the total length of bone-cement interface was measured. The percentage was 15.8±10.3 in the polyethylene-injected group and 8.3±7.7 in the control group (no significance). While not significant, the amount was greater in the polyethylene-injected group. Thus it is proposed that the polyethylene particles played a role in bone resorption and fibrous tissue formation at the bone—cement interface. In some specimens, macrophages and foreign body giant cells that surrounded the particles near the articular surface were seen to cause resorption of bone. It is supposed that this phenomenon is similar to the focal osteolysis that is sometimes observed around a prosthetic component.