PubMed · 14765885
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J P M Frölke, G C Reeling Brouwer. 2004. Friction burns within the tibia during reaming.. https://pubmed.ncbi.nlm.nih.gov/14765885/
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The demand for organ transplantations greatly exceeds the number of organ donors (OD) and it is likely that this discrepancy will continue. There is a continuously growing demand for biostatic allogenic bone transplantation mostly for orthopedic reconstructions. The bone material is predominantly harvested during postmortem examinations in forensic medicine departments. The collected amounts are not enough so the material need to be acquired from other sources. Bone collecting from OD seems to be the optimal solution. Between January 2000 and December 2005, 1,883 out of 2,601 organ donors fulfilled the criteria for bone donation, but only 42 bone harvesting (BH) were performed being only 2.22% of all suitable cases. The main reasons for so few bone procurements were: lack of acceptance of bone procurement by relevant part of donors' families, insufficient cooperation between tissue banks and transplantation teams, lack of equipment for BH, and no experience in bone procurement.
Although extensive efforts have been put into the development of porous scaffolds for bone regeneration, with encouraging results, all porous materials have a common limitation: the inherent lack of strength associated with porosity. Hence, the development of porous hydroxyapatite scaffolds has been hindered to non-load bearing applications. We report here how freeze casting can be applied to synthesize porous scaffolds exhibiting unusually high compressive strength, e.g. up to 145 MPa for 47% porosity and 65 MPa for 56% porosity. The materials are characterized by well-defined pore connectivity along with directional and completely open porosity. Various parameters affecting the porosity and compressive strength have been investigated, including initial slurry concentration, freezing rate, and sintering conditions. The implications and potential application as bone substitute are discussed. These results might open the way for hydroxyapatite-based materials designed for load-bearing applications. The biological response of these materials is yet to be tested.
Determining how to apply an appropriately mechanical environment which can improve the quality and function of bone-like construct in vitro is a required problem to be solved for the current development of bone tissue engineering. A specific mechanical force may be a key determinant of tissue development in vitro in bone tissue engineering. From the standpoint of bionics, the mechanical environments applied on bone tissue engineering should work in three aspects: providing adequately mechanical stimuli to the cells seeded in 3-D scaffold; ensuring the efficient mass-transport of the nutrients and waste products of the cells; promoting the development of functionally extracellular matrix in 3-D scaffold. After the analysis of several differently mechanical environments comparing with that in vivo, the directly dynamical compression environment, instead of hydrostatic pressure or microgravity or direct perfusion, can recreate the in vivo mechanisms of mechanosensation, mechanotransduction and mass-transport during engineered bone-like tissue culturing process in vitro. Therefore, it is hypothesized that the directly dynamic compression will be a specific mechanical environment to bone tissue reconstruction in vitro.