Data relating to Figure 4: Number of studies using either particle method or scratching the implant surfaces directly and the bearing material combinations used Metal-on-Polyethylene Ceramic-on-Polyethylene Ceramic-on-Metal Ceramic-on-Ceramic Metal-on-Metal Other Particle method Hip 13 4 1 2 3 Knee 5 1 Pin-on-Plate/Disc 10 1 1 Scratching counterfaces directly Hip 12 1 1 Knee 6 2 Pin-on-Plate/Disc 10 3 1