Biomedical Engineering Reference
In-Depth Information
(a)
(b)
(c) (d)
9.2
Examples of continuous fibre reinforced polymers for biomedical
applications: ligament (a), intervertebral disc (b), spinal cage (c) and
hip prostheses (d).
excellent mechanical stability but critical processing conditions owing to its
temperature-sensitive semi-crystalline structure. Polysulphone has shown a
reduction of mechanical properties following saturation in Ringer's solution.
In vitro
and
in vivo
studies (merolli
et al
., 1999) have shown that PEI is
an excellent substrate for cell spreading and growth, eliciting no cytotoxic
response or haemolysis, coupled with both easy processability and resistance
to sterilization capability (g rays and autoclave). Using PEI reinforced with
drop-off plies of carbon and glass fibres a composite hip prosthesis has
been developed in order to provide an adequate stress transfer between the
prosthesis and bone (De Santis
et al
., 2000).
Material-structural designs for advanced prostheses requiring a stem fitting
into a canal (i.e. long bone or dental root canals) may differ, although a
common challenge is to make a stem more flexible than those made of metal
in order to improve proximal stress transfer and to avoid stress-shielding
effects (Svensson
et al
., 1977; Wilke
et al
., 1994; Chang and Perez, 1990).
by tailoring the stiffness of the prosthesis, both along its length and through
its thickness, it is possible to change the pattern of load transfer between
