Biological performance of a new β‐TCP/PLLA composite material for applications in spine surgery: In vitro and in vivo studies

Abstract

The objective of this research was to carry out an in vitro and in vivo study of the biological performance of PLLA/beta-TCP composite materials, to estimate the scope of their potential applications in bone surgery. Samples with increasing beta-TCP (0-60% w/w) contents were processed by injection molding. The in vitro study consisted of an evaluation of inflammatory potential by assaying the IL-1alpha secreted by monocytes, and then cell proliferation (counting) and phenotype expression (PAL and I collagen) in human osteogenous cells. The in vivo study was carried out using cylindrical implants of composite materials composed of composite materials containing 0 or 60% beta-TCP and pure beta-TCP, respectively. The implants were inserted in femoral sites in rabbits, using the Kathagen protocol. Each animal received a 60% implant, with either a 0 or a 100% implant in the contralateral femur, so that the materials could be compared with one another. Five animals were examined for each material and implantation period, giving a total of 30 animals. This study showed that adding increasing percentages of beta-TCP to a lactic acid polymer matrix stimulated the proliferation of human osteogenous cells and synthesis of the extracellular bone matrix in a dose-dependent manner. In vivo results indicate that, in comparison with pure PLA, tricalcium phosphate-containing composite materials had faster degradation kinetics, caused less inflammatory reaction, and promoted contact osteogenesis. The composite material containing 60% beta-TCP demonstrated a similar performance to pure tricalcium phosphate bone grafts in terms of osteogenesis, and is apparently compatible with the production of intra-osseous implants for situations representing high levels of mechanical strain.

Augmentation of bone defect healing using a new biocomposite scaffold: An in vivo study in sheep

“…The initial fibrous tissue formation observed in this study has been previously reported with PLA implants inserted into rabbits [20]. However, this fibrous tissue does not always disappear and may be present after more than 6 months [20,23,24]. The absence of fibrous tissue at 12 months in our study may be related to the presence of the b-TCP particles, as b-TCP has been shown to decrease the inflammatory reaction when composite PLA/b-TCP scaffolds were implanted [20].…”

“…It is the accumulation of this acid which becomes toxic [22]. The initial fibrous tissue formation observed in this study has been previously reported with PLA implants inserted into rabbits [20]. However, this fibrous tissue does not always disappear and may be present after more than 6 months [20,23,24].…”

“…The effect of the b-TCP particles has been specifically highlighted in a rabbit study, in which a clear correlation between the percentage of b-TCP particles incorporated in a PLA scaffold and bone healing was established [20]. A 40/60 wt.% PLA/b-TCP ratio showed the best results.…”

“…However, this fibrous tissue does not always disappear and may be present after more than 6 months [20,23,24]. The absence of fibrous tissue at 12 months in our study may be related to the presence of the b-TCP particles, as b-TCP has been shown to decrease the inflammatory reaction when composite PLA/b-TCP scaffolds were implanted [20]. Indeed, in the present study most of the b-TCP particles were embedded in the PLA trabecula of the biocomposite scaffold, as was seen in a previous study [10].…”

Anterior cervical fusion with a bio-resorbable composite cage (beta TCP–PLLA): clinical and radiological results from a prospective study on 20 patients

“…The addition to beta-TCP particles of a plastic material, such as resorbable lactic acid polymer (PLLA), increases breaking strength and provides real capacity to withstand plastic and elastic strain [1]. Such composite materials can retain high strength over time.…”