The influence of wear particles in the expression of osteoclastogenesis factors by osteoblasts.

Orthopedic implant failures are often associated with peri-implant osteolysis. Particles generated from the wear process have been suspected to play an important role in this situation. Indeed, the peri-implant osteolysis could be due to the presence of particles stimulating the osteoclastogenesis process. We hypothesize then that the presence of a low particle concentration positively influences osteoblasts to produce osteoclastogenesis factors. If true, this hypothesis would then support the idea that the particles could be at the origin of the process leading to implant loosening. To check the validity of this hypothesis, we quantified in vitro the production of different genes involved in the osteoclastogenesis process using primary isolated human osteoblasts treated or not with particles. Results showed that low concentrations of particles might have a stimulating effect on osteoblasts to produce osteoclastogenesis factors as demonstrated by the increase of RANKL and CSF-1 gene expression in the particle group.