Abstract
Polylactides are commonly praised for their excellent mechanical properties (e.g. a high
modulus and yield strength). In combination with their bioresorbability and biocompatibility,
they are considered prime candidates for application in load-bearing biomedical implants.
Unfoliunately, however, their long-term performance under static load is far from impressive. In a previous in vivo study on degradable polylactide spinal cages in a goat model it was observed that, although short-term mechanical and real-time degradation experiments predicted otherwise, the implants failed prematurely under the specified loads. In this chapter we demonstrate that this premature failure is attributed to the time-dependent character of the
material used . The phenomenon is common to all polymers, and finds its origin in stressactivated segmental molecular mobility leading to a steady rate of plastic flow. The main
conclusion is that knowledge of the instantaneous strength of a polymeric material is
insufficient to predict its long-term performance.
Original language | English |
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Title of host publication | Degradable polymers for skeletal implants |
Editors | P.I.J.M. Wuisman, T.M. Smit |
Place of Publication | New York |
Publisher | Nova Publishers |
Pages | 21-39 |
Number of pages | 19 |
ISBN (Print) | 978-1-60692-426-6 |
Publication status | Published - 2009 |