Bone grafts characteristics

Based on observed tissue response, synthetic bone-graft substitutes can be classified into inert (e.g., alumina, zirconia), bioactive (e.g., hydroxyapatite, bioactive glass), and resorbable substitutes (e.g., tricalcium phosphate, calcium sulfate). Of these, resorbable bone-graft substitutes are preferred for bone defect filling because they can be replaced by new natural bone after implantation, p-tricalcium phosphate (Ca3(PO )2, p-TCP) is one of the most widely used bone substitute material, due to its faster dissolution characteristics. Preparation of magnesium-substituted tricalcium phosphate ((Ca, Mg)3(PO )2, p-TCMP) has been reported by precipitation or hydrolysis method in solution. These results indicate that the presence of Mg stabilizes the p-TCP structure (LeGeros et al., 2004). The incorporation of Mg also increases the transition temperature from p-TCP to a-TCP and decreases the solubility of p-TCP (Elliott, 1994 Ando, 1958). 

Posterior lumbar interbody fusion (PLIF) cage has been used after disc removal to provide the neural elements decompression, anterior column reconstruction, spine segmental stabilize, prevent bone graft collapse or displacement [8,9,10]. Biomechanical characteristics of numerous commercial cages under different design were investigated through some researches [8,11-19]. 

Table 13.2 Basic characteristics of an ideal bone graft.

Yanke AB et al (2013) Central-third bone-patellar tendon-bone allografts demonstrate superior biomechanical failure characteristics compared with hemi-patellar tendon grafts. Am J Sports Med 41(ll) 2521-2526... 

The surface eroding characteristics of POE has led to the research of this polymer for bone reconstruction [8,73 ]. Surface degradation allows a scaffold to sustain mechanical support for the surrounding tissue since the bulk of the material remains structurally intact. In other studies, hepatocytes were grafted onto polyorthoesters and adhered to the surface of the synthetic scaffold [74]. 

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