The project concerns the development of a new form of processing for resorbable osteosynthesis devices, using continuous fibre-reinforced polymeric materials. Taking the main degradable polymers known as a basis, a material has to be chosen which meets the requirements regarding processability, mechanical behaviour and degradation kinetics. After fibre processing, the embedding of the fibres in the matrix has to be performed with good fibre-matrix adhesion and a high alignment to prevent the diffusion of tissue fluids at the fibre-matrix interface, and to obtain maximum strength of the device over an accountable period of time.
Poly-L-lactide and poly-L/DL-lactides have been synthesised for reinforcement fibres and matrix material respectively. Melt-spun P-L-LA fibres of a strength of 800 Mpa have been embedded in an amorphous P-L-DI 70:30 matrix by compression moulding. Ethyleneoxide sterilized samples have been tested in vitro and in vivo. Satisfying bending modulus has been reached (6 Gpa). Yet with 50 % strength retention after 10 weeks a fast degradation occurred which could be related to residual monomers. By this fast degradation 70 % resorption after 1 year could be observed in the non-functional animal studies in rabbits. Only mild inflammatory reaction confirmed a good biocompatibility of the materials even during the resorption period. Further effort has to concentrate on the reduction of initial monomer content. The high advantage of the processing method to orient the fibres in the device will be utilized in prototype samples like osteosynthesis plate with fixation holes.