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Evaluation of hydroxylapatite/poly(L-lactide) composites: mechanical behavior
C C Verheyen1, J R de Wijn, C A van Blitterswijk
1Department of Biomaterials, School of Medicine, University of Leiden, The Netherlands.
Journal of Biomedical Materials Research
|October 1, 1992
Summary
Hydroxylapatite/poly(L-lactide) composites show improved strength and hardness but degrade rapidly in vivo. These materials are suitable for non-loadbearing orthopedic applications.
Area of Science:
- Biomaterials Science
- Polymer Science
- Materials Engineering
Background:
- Poly(L-lactide) (PLLA) is a biodegradable polymer with potential for medical implants.
- Hydroxylapatite (HA) is a bioceramic known for its osteoconductive properties.
- Combining HA with PLLA can enhance mechanical properties and biocompatibility.
Purpose of the Study:
- To investigate the mechanical properties of hydroxylapatite-filled poly(L-lactide) (HA/PLLA) composites.
- To compare the performance of HA/PLLA composites with unfilled PLLA.
- To evaluate the effect of sterilization and in vivo degradation on HA/PLLA composite properties.
Main Methods:
- HA/PLLA composites were synthesized by polymerizing L(-)-dilactide monomer with HA filler.
- Mechanical testing included compressive strength, tensile strength, stiffness, and Vickers hardness.
- Sterilization effects (ethylene oxide) and in vivo degradation (subcutis of goats, phosphate-buffered saline) were assessed.
Main Results:
- A 30 wt% HA/PLLA composite exhibited superior compressive and tensile strengths, stiffness, and hardness compared to PLLA.
- Ethylene oxide sterilization significantly reduced molecular weight and flexural strength.
- Implantation studies showed a 50% loss in flexural strength within 3 weeks, with faster degradation in phosphate-buffered saline.
Conclusions:
- HA/PLLA composites offer enhanced mechanical properties over PLLA.
- Sterilization and in vivo degradation significantly impact mechanical integrity.
- Current HA/PLLA composites are not suitable for load-bearing implants but may be useful in non-loadbearing orthopedic and maxillofacial applications.