Abstract
Background, Context and Motivation
“Increases in reconstructive orthopaedic surgery, resulting from advances in surgical practice and the ageing population, have lead to a demand for bone graft that far exceeds supply.”…Traditional bone grafting methods have been linked with a number of negative issues including increased morbidity due to secondary operation site and action as a vector for spread of disease. (Hing 2004). A solution to these insufficiencies would be the creation of a synthetic osteoinductive bone graft material. This would vastly improve bone graft surgery success rates and expedite post-op recovery times. The aim of this study was to classify then explore the dissolution rates of three experimental hydroxyapatite/silicate apatite synthetic bonegrafts in physiological solutions, (phosphate buffered saline, (PBS) +/− serum proteins, (PBS +FCS). The overall objective being to identify whether there is an explainable significant difference in ion exchange that could be behind the osteoinductive phenomena.
Methods Used
Classification of the apatite samples, (HA, SA1 and SA2), was conducted via X-Ray diffraction, FTIR-PAS Spectroscopy and SEM with EDS analysis. A dissolution experiment of the experimental apatites was conducted in PBS and PBS + FCS solutions, over time periods of 1, 2 and 4 hours, and at 1, 2, 4 and 8 days, with repeat measures.
Results and Conclusions
Silicon both free in solution and at the apatite surface was found to be key for osteoinduction and its presence at both these sites increases the rates of bone apposition around a synthetic graft. Experimental Samples HA, SA1 and SA2 share the same crystalline structure as Hydroxyapatite and are phase pure. Sample SA1 showed a %wt of silicon of 0.9%wt and SA2 showed a %wt of silicon of 0.6% wt. Review of the literature indicates that samples SA1 and SA2 are within an osteoinductive range for %wt of silicon. All three samples exhibit porosity within the most bioactive levels (150-500μm). Dissolution reactions for silicon are present and faster than experienced in the literature, this leads us to hypothesise that bone apposition rates would be high in all samples as silicon is available both free in solution and at the apatite surface, indicating all experimental samples possess an osteoinductive effect. Further work would involve exposing these samples to solutions containing osteoblast like cells and comparing the levels of activity found to those of traditional bone grafts currently used.
