A Study Of Bisphosphonates On The Aseptic Loosening Of Prosthesis

Along with the popularization of artificial joints replacement and the improving of operation technique, a lot of patients who have suffered from joints diseases were cured effectively, the curative effect of total joints replacement is satisfied in the near future, but the long-term complication aseptic loosening of prosthesis have not been controlled and it has become the major causes of prosthesis failure. The causes of aseptic loosening of prosthesis have been investigated profoundly, now people consistent with the concept of "paticle diseases". Macrophages around prosthesis were activated by the particles produced largely by the wearing of prosthesis and the activated macrophages could release resorption factors, then the bone resorption of osteoclasts was enhanced severely, interspace between bone and prosthesis appeared and at last prosthesis became loosed because of lacking bone surpport.Can we effectively prevent and treat aseptic loosening of prosthesis in order to prolong the use of prosthesis? Therefor we studied the influence of pamidronate on the resorption activity of osteoclasts.To observe the effects of pamidronate and polyethylene particles on the osteoclasts' resorption activity, the osteoclasts were isolated from the long bones of neonatal New Zealand's rabbits and cocultured with bone slices.Our study consists of three parts:First, we observed the influence that polyethylene particles of different dosage on the osteoclasts' resorption activity, we found that three kinds of polyethylene particles (103/ml, 10 6ml 109/ml) all can stimulate theosteoclasts' bone resorption when they were cocultured, but the resorption activity was not the direct ratio with particle consistency, particles of 103/ml had the strongest stimulation and particles of 106/mK 109/ml were weaker.Secondly we analysed influence that pamidronate of different dosage on the osteoclasts' resorption activity, we found that pamidronate of 1 u g/ml and 10 u g/ml can markedly inhibit the osteoclasts' resorption activity, whereas pamidronate of 0.1 u g/ml havn't obvious influence on the osteoclasts.Finally we observed the influence of polyethylene particles associated with pamidronate on the osteoclasts' resorption activity, wo found that pamidronate of lOug/ml can inhibit the stimulation that polyethylene particles on the osteoclasts.From our experiments it is indicated polyethylene particles can remarkably enhance osteoclasts' bone resorption activity, this may contribute to the aseptic loosening of prosthesis. Pamidronate directly inhibit not only normal osteoclasts but also osteoclasts stimulated by the polyethylene particles, which provide the experimental basis that bisphosphonates were used clinicaly to prevent and treat aseptic loosening of prosthesis.