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 in-growth behaviour and biomechanical properties of solvent dehydrated human bone as an alternative to the use of autografts. In a weight-bearing experimental model, solvent dehydrated bone transplants were implanted subchondrally in the medial proximal tibia of merino sheep. After 9 months, explants as well as controls from the contralateral leg were harvested and prepared for histomorphological, histomorphometrical and biomechanical examination. A smaller, but statistically insignificant difference was found for the yield strength after 9 months for harvested specimens in comparison with untreated controls. 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 by persistent bone remodelling. The bone per tissue volume of remaining solvent dehydrated graft particles together with newly formed bone was significantly 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 clinical relevance.