Devices for use as an artificial articular surface in joint prostheses or in the repair of osteochondral defects

The covering of ultra high molecular weight polyethylene (UHMWPE) and calcium hydroxyapatite (HA)/tricalcium phosphate (TCP) porous solid substrate with polyHEMA hydrogel has been studied aiming at the development of devices to be used as artificial articular surfaces in joint prosthesis or osteochondral repair grafts. Commercial porous UHMWPE was used. Ceramic porous substrate was prepared by load compaction of an HA and TCP powder mixture obtained by aqueous precipitation technique. Two different compaction loads and grain size distribution was used. Polymer particles were added to the powder mixture in order to increase the substrate porosity after the sintering process. The porous substrate was covered with polyHEMA hydrogel by in situ polymerization. Morphological analysis (SEM) showed that a hydrogel layer formed in the porous solid top surface was fixed to the substrate by mechanical interlocking because the porous surface was filled by the hydrogel. After hydrogel covering, the resultant devices showed a decrease in the compressive elastic modulus that was influenced by the porous substrate material.