Advances in ultra high molecular weight polyethylene/hydroxyapatite composites for biomedical applications: A brief review

- UHMWPE/HA composite show excellent mechanical properties and bioactivity;
- The use of paraffin oil or decaline as swelling agent increase the mobility of UHMWPE chain;
- The paraffin make better the processability of composites;
- Ball milling, sol-gel, extrusion and others techniques of UHMWPE composites are carefully discussed;
- Wear, toughness and creep properties of UHMWPE/HA composites was carefully discussed;
- In vitro and in vivo tests of UHMWPE/HA are discussed.

Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been applied, as a bearing surface in total human joint replacements and artificial bones. UHMWPE has a superior wear resistance, low-friction surface, biological inertness, high levels of strength, creep resistance and low friction coefficient. However, the wear debris generated during the joint motions could cause problem in human implant, such as osteolysis and loosening. For this, several attempts was been made to improve UHMWPE properties and increases safety and biocompatibility in human implants. One of them, include the use of hydroxyapatite (HA), as reinforcement agent to modify the UHMWPE properties and facilitate biological fixation between the implant and the human cells. Recent studies showed that the addition of HA in polymer matrix result in enhancement of mechanical and tribological properties. In addition, it also improves the formation of the actual bond between the material and the living organism since the hydroxyapatite is the major component of the mineral part of the human bone. In this brief review the some properties and characteristic of UHMWPE and HA are described and main processing methods of UHMWPE/HA composites and biocompatibility studies were also reviewed.