Microstructural investigations of strain-related collagen mineralization

Distraction osteogenesis in rabbit mandibles after osteotomy can be used as an experimental model to study the microstructural features of mineralizat ion of callus under defined mechanical loads. Our aim was to study the rela tion between the micromotions in the gap and the resulting features of mine ralization of the matrix. We found that assembly of collagen and formation of crystals depended on the magnitude of the mechanical stress applied. At physiological bone strains (2000 mu strains), the callus had collagen type I in a mature bone-like extracellular arrangement, whereas at 20 000 mu str ains bundles were orientated predominantly towards the tension vector. Maxi mum loads (200 000 mu strains) resulted in disorganized assembly of the col lagen. Quantitative energy-dispersive analysis by X-rays confirmed that hig h strains were associated with substantially lower concentrations of calciu m and phosphate. In contrast to bone-like apatitic formation of crystals at physiological strains, significantly fewer but larger crystals were detect ed by electron diffraction analysis in samples exposed to high strains. liv e suggest that mechanical stress regulates the assembly and mineralization of collagen during distraction osteogenesis. (C) 2001 The British Associati on of Oral and Maxillofacial Surgeons.