The following abstract should have been included in the European Calcified Tissue Society (ECTS) abstracts supplement, Calcified Tissue International Volume 78 Supplement 1 2006. The Society apologizes to the authors for this omission. The paper was presented at the ECTS meeting in Prague, Czech Republic, 10–14 May 2006.

P168 EFFECTS OF CALCITONIN ON THE EXPERIMENTAL OSTEOARTHRITIS DEVELOPMENT IN DOGS. MICROSCOPIC ANALYSIS OF THE TIBIAL SUBCHONDRAL BONE

A. Berners1, D. H. Manicourt2, J. Devogelaer2, C. Nyssen-Behets*1

1Experimental Morphology Unit, 2Rheumatology department, Université catholique de Louvain, Brussels, Belgium

Aim: To elucidate the role of subchondral bone remodeling in osteoarthritic (OA) cartilage breakdown by studying the effects of calcitonin (CT) on epiphyseal bone changes in the early stages of canine experimental osteoarthritis. Materials and methods: Twelve dogs underwent anterior cruciate ligament transection (ACLT) in the right knee. Thereafter each of them received a daily nasal spray delivering either 400 U of CT (CT group, n = 6) or a placebo (placebo group, n = 6). The animals were killed 84 days after surgery. Both proximal tibiae of each dog were embedded in methylmethacrylate and cut into undecalcified 80-μm-thick coronal sections which were microradiographed. The microradiographs were observed under ordinary light microscope in order to assess the thickness of the subchondral bone plate and the qualitative aspect of the epiphyseal trabecular bone. The quantitative data were analysed with a two-tailed paired test. A p value < 0.05 was considered statistically significant. Results: Macroscopic signs of OA were visible in all operated knees, though less numerous and less developed in the tibiae of the CT group than in the placebo one. Neither ACLT nor CT treatment had a significant effect on the thickness of the subchondral bone plate. However, the microradiographic aspect of this latter was characterized by higher porosity and increased mineral heterogeneity in the ACLT knees. These signs of increased remodelling were less extensive in the CT-treated dogs than in the placebo group. In the same way, epiphyseal trabecular bone in the operated knees showed eroded and disrupted trabeculae. This bone loss was also less pronounced in the CT-treated animals than in the placebo group. Conclusions: Increased subchondral epiphyseal bone remodelling, leading to bone loss, is suggested to contribute to the osteoarthritic cartilage deterioration. By reducing the bone loss correlated to increased turnover, CT can attenuate the OA lesions in this experimental model.