Injectable bone graft substitutes

Designing ceramics for injectable bone graft substitutes 29... 

Key words putty, cement, bone graft substitute, calcium phosphate, injectable. 

Stmctural load-bearing applications of bone grafts cannot be performed by injection but in situ setting bone graft substitutes can be injected to provide structural support or fixation for metaphyseal and epiphyseal fractures. 

Hak, D.J. 2007, The use of osteoconductive bone graft substitutes in orthopaedic trauma. Journal of the American Academy of Orthopaedic Surgeons 15(9), 525. Halloran, D.O., Grad, S., Stoddart, M., Dockery, P., Alini, M., Pandit, A.S. 2008. An injectable cross-linked scaffold for nucleus pulposus regeneration. Biomaterials 29(4), 438-447. 

Horstmann, W.G., Verheyen, C.C.P.M., Leemans, R. 2003. An injectable calcium phosphate cement as a bone-graft substitute in the treatment of displaced lateral tibial plateau fractures. Injury 34(2), 141-144. 

Kim CW, Talac R, Lu L, Moore MJ, Currier BL, Yaszemski MJ. Characterization of porous injectable poly-(propylene fumarate)-based bone graft substitute. J Biomed Mater Res A 2008 85(4) 1114-1119. 

One of the major classes of synthetic bioresorbable polymers is that of aliphatic polyesters or poly(a-hydroxy acids). Poly(a-hydroxy acids) such as PGA, poly(lactic acid) (PLA) stereoisomers poly(L-lactic acid) (PLLA) and poly(D-lactic acid), and pol-y(lactic-co-glycolic acid) (PLGA) copolymers are the most widely used and most popular bioresorbable polymers since they received Food and Drug Administration (FDA) approval for clinical use in humans in different forms (eg, fibers for sutures, injectable forms) (Nair and Laurencin, 2007). These polymers are commonly used in regenerative medicine applications. An example is the InQu Bone Graft Extender Substitute (ISTO Technologies), an osteoconductive biosynthetic product used as bone graft substitute in the skeletal system to support new bone formation. The resorption rate of... 

Difficulties with the clinical applicability of preformed ceramic blocks and granules have led to the development of injectable ceramic bone graft substitutes. In the early eighties, Brown and Chow were... 

The lack of effective treatments for the identified clinical needs motivates the current trend in the development of synthetic graft substitutes. Numerous synthetic bone substitutes (SBSs) are commercially available and are presented in block or particulate form, with relatively few nonsetting BGSs being injected to a defect and shaped in situ (Bhandari, 2012). A BGSs should be osteoinductive (promote the differentiation of primitive, undifferentiated, and pluripotent cells to an... 

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