Effect of implanted bisphosphonate-enriched cement on the trabecular microarchitecture of bone in a rat model using micro-computed tomography

PURPOSE: Bisphosphonates (BPs) are antiresorptive drugs typically used to inhibit bone resorption. The latest reports show that BPs play an important role in not only achieving better bone mineral density but also in improving bone microarchitecture. The mechanism of action of the BPs is complex and multifactorial. We tried to determine whether there are any changes in the microarchitectural bone structure during local use of BP (Pamifos 60). The aim of this study was to see if BP-enriched cement used in rat models had positive effects on bone formation. METHODS: Research was performed on 40 adult male Wistar rats that were divided into four groups: two control groups and two experimental groups. Rats in the experimental groups were implanted with BP-enriched cement into the bone, while the control group rats were implanted with clean bone cement (without BP). Micro-computed tomography was applied for the investigation of trabecular microarchitecture of the proximal physis of the tibial bone in all animals three and six weeks after surgery. In all microCT images variables such as bone volume density (BV/TV), trabecular thickness (TbTh), trabecular separation (TbSp) and trabecular number (TbN) were used to describe trabecular bone morphometry. RESULTS: The major finding of this study is that using BP-enriched cement results in distinct changes in bone microarchitecture. We showed that local use of pamidronate (Pamifos 60) in orthopaedic cement had a positive effect on bone formation. It significantly changed three variables. We noticed increasing bone volume fraction and trabecular thickness together with decreasing trabecular separation. CONCLUSION: In this paper we demonstrate the efficacy of using BP-enriched cement in vitro in the tibiae of rats. Our most significant finding based on micro-CT picture analysis allows us to start further work on more suitable applications of BP-enriched cement in humans. We believe that future successful experiments will facilitate potential use of BP-enriched cement in clinical applications.