Materials


BIOSORB

Biosorb is a material made of high-purity, absorbable, synthetic β-Tricalcium Phosphate (β-TCP).

Safety

β-TCP (β-Ca3(PO4)2) is a synthetic, completely inorganic compound. The absence of any organic phase eliminates the risk of contamination of human or animal origin (AIDS, hepatitis, bovine or ovine spongiform encephalopathies).

Similarity and biocompatibility

Biosorb is comprised of pure β-TCP. This composition makes it very similar to the inorganic bone phase, and thus well tolerated by the body. This compound is in compliance with ASTM F1088-04a, regarding standard specifications for the surgical implantation of β-TCP, which guarantees its biocompatibility.

Porosity and resistance

Biosorb is available in a wide range of pore volumes, from 5% to 70% (± 5%). These pores can increase the heat-exchange surface vis-a-vis the environment, and can promote colonization by osteoblasts and angiogenic cells. The presence of pores affects the mechanical strength of the material. The wide range of porosities allows a selection of the best compromise between mechanical resistance and bone colonization in light of the indications (Fig. 1). The physicochemical characteristics can be optimized thanks to the various porosities available (2).

Figure 1: Mechanical resistance of Biosorb as a function of its pore volume.

Osteoconduction and osseointegration

Biosorb guides bone growth, facilitating the colonization of the implant surface by osteoblasts, which will proliferate and then synthesize the extracellular matrix in direct contact with the material (Fig. 2). Thus the implant pores are gradually filled by newly formed bone (Fig. 3) (31).

  

Figure 2: Radiographic study of the implantation of β-TCP cement in rabbit femurs.

Microradiographs (x500) after implantation of β-TCP cement.
A - At 1 week, bone growth mainly occurs circumferentially, in a close contact with the old cortical bone. The newly formed bone gradually envelops the β-TCP particles.
B - At 3 weeks, advanced resorption of the β-TCP can be seen, accompanied by bone growth in very close contact with the β-TCP particles.

Figure 3: Bone growth within 45% β-TCP implants as a function of time.

Resorption

In parallel with bone formation, the β-TCP undergoes resorption under the influence of osteoclasts that break down its structure. Finally, the implant is replaced by newly formed healthy bone tissue identical to the peri-implant bone. Studies have shown that porosity also has an influence on resorption. The greater the porosity, the faster the absorption (31). Thus a wedge made of β-TCP (30% porosity) will still be visible five years after the operation, but as for granules (45% porosity), absorption is almost complete after 12 months (26).

Indications

Compounds derived from Biosorb (BIO 1, BIO 1-S, BIO 1-KITOTIS, BIO-TECMA) but differing in terms of size, dimensions, or porosity have been designed by SBM in order to suit a greater number of surgical indications, primarily in the fields of traumatology, orthopedics, and dental or maxillo-facial surgery. The BIO 1-KIT allows Biosorb to be mixed with autologous cancellous bone or bone marrow to accelerate engraftment.

  

Bibliography

2 - Influence of porosity on the mechanical resistance of Hydroxyapatite under compressive stress
LE HUEC J-C, T. SCHAEVERBEKE T., CLEMENT D., FABER J., LE REBELLER A.: Biomaterials, 16, 113-118, 1995.

26 - Bone ingrowth into two porous ceramics with different pore sizes: An experimental study
GALOIS L., MAINARD D.: Acta Orthopaedica Belgica, 70, 598-603, 2004.

31 - Resorbability of rigid beta-tricalcium phosphate wedges in open-wedge high tibial osteotomy: A retrospective radiological study.
KRAAL T., MULLENDER M., DE BRUINE JHD., REINHARD R., DE GAST A., KUIK DJ., VAN ROYEN BJ.: The Knee, 15, 201-15, 2008.

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SBM France | Science & BioMaterials 1991-2015
Solutions for BioSurgery since 1991