Various surgeons devised many types of components, for instance ring using a long screw Wilson and Scales using three divergent spikes. Charnby introduced socket of high density polyethylene and femoral component ball of 22 mm diameter. Muller used same pattern with ball of 32 mm diameter. At present there are many types of piosthesiS; the most popular one is Charnbys low friction arthroplasty.