2.1. The Humeral Head Implant

The titanium alloy Ti6Al₄V humeral implant was straight-stemmed and proportional from 44–56 mm in diameter. Its undersurface was porous-coated with commercially pure titanium plasma spray/beads to give an average pore size of 350 µm and a volume porosity of 30%. The articulating surface was made of titanium alloy coated with a polished 10 µm-thick layer of titanium nitride ceramic (TiN). This polishing was to 0.03 µ before and to 0.04 µ after the TiN coating. The TiN coating was applied using the Physical Vapor Deposition process [18]. When a glenoid component was used, it was Ethylene Oxide sterilized GUR 1020 polyethylene.