PROCESS FOR PRODUCING OSTEOINDUCTIVE BONE; OSTEOINDUCTIVE BONE PRODUCED THEREBY; AND CONTROLLED-FLOW APPARATUS FOR USE THEREWITH

The invention produces osteoinductive bone using a controlled-flow apparatus. The apparatus allows for the controlled extraction of undesirable constituents from a body tissue. The invention provides for the demineralization of ground bone particles or pieces of cancellous or cortical bone which permits the controlled and reproducible demineralization of bone to produce bone which is maximally osteoinductive. It has been demonstrated that ground cadaveric bone which is demineralized to a residual calcium level approximating 2% by dry weight of bone is optimally osteoinductive as assayed using in vivo and in vitro assays of osteoinductivity. The controlled-flow apparatus includes one or more solution containers which supply solutions to be pumped into one or more vessels filled with tissue samples to be extracted. Solvent outflowing from the vessels can be monitored for pH, calcium ion concentration or conductivity as a basis for determining when extraction is complete. Using the invention, a linear relationship has been shown to exist between eluent pH and percent residual calcium in the bone being demineralized. Thus, the invention permits the reproducible demineralization of bone which is optimally osteoinductive. The invention also corrects the percent residual calcium in bone which is overly demineralized, returning it to a state of being optimally osteoinductive.