Solvent dehydrated bone transplants to bridge segmental bone defects: histomorphological and biomechanical investigations in an animal model

Cancellous bone is routinely used in human surgery to fill skeletal defects . The availabilty of autogenous and allogenous grafts is limited, however. The aim of this in vivo study was therefore to determine the ingrowth behav iour and biomechanical properties of solvent dehydrated human bone as an al ternative to the use of autografts. In a weight-bearing experimental model, solvent dehydrated bone transplants were implanted subchondrally in the me dial proximal tibia of merino sheep. After 9 months, explants as well as co ntrols from the contralateral leg were, harvested and prepared for histomor phological, histomorphometrical and biomechanical examination. A smaller, b ut statistically insignificant difference was found for the yield strength after 9 months for harvested specimens in comparison with untreated control s. Regarding the histomorphological results, we found a homogenous ingrowth of new bone trabeculae throughout the transplants. The degradation of the solvent dehydrated bone was not complete within the study period as shown b y persistent bone remodelling. The bone per tissue volume of remaining solv ent dehydrated graft particles together with newly formed bone was signific antly higher than for controls. Our observation period was not long enough to document complete remodelling, but good osteointegration and reasonable biomechanical properties in this weight-bearing large animal model support the application of solvent dehydrated bone in cancellous defects of clinica l relevance.