Abstract
Purpose of the study: Oestrogen depletion leads to osteoclastic hyperactivity and subsequent postmenopausal osteoporosis. Little is known about interactions with bone absorption induced by wear particles from joint bearings. The purpose of this study was to evaluate bone response to polyethylene (PE) particles in a mouse model of oestrogen deficiency.
Material and methods: Particles of PE were implanted in the calvaria of seven non-ovariectomised mice and in seven ovariectomised mice (OVX). Fourteen mice were operated on without implantation of the particles (7 non-OVX and 7 OVX, control groups). The mice were sacrificed at two weeks. The crania were studied under a microscanner and histologically without decalcification.
Results: The microscanner showed that particles of PE induced a significant decrease in bone thickness in non-OVX mice (p=0.04), while the thickness remained unchanged in OVX mice who had received the particles (p=0.40). After implantation of the PE particles, the number of osteoclasts per mm of bone perimeter was 2.84±1.6 in the non-OVX mice and 1.74±1.3 in OVX mice (p=0.004). Compared with controls, the mean loss of bone was 12±10% in the non-OVX mice versus 4.7±0.9%in the OVX mice (p=0.004).
Discussion: The volume of osteolysis induced by PE particles was smaller in OVX mice compared with non-OVX mice.
Conclusion: These results suggest that a deficit in oestrogens has a protective effect against bone adsorption induced by PE particles.
Correspondence should be addressed to Ghislaine Patte at sofcot@sofcot.fr
