As a result of histological studies, there have been new developments in the field of modular acetabular cup design. Osteolysis has been isolated as one of the major causes of aseptic loosening of the femoral component in total hip arthroplasty (THA). Histological studies of retrieved tissue during revision THA have revealed a high content of polyethylene (PE) particles which are submicron in size in the surrounding tissue of the loose femoral component. The source of the polyethylene can be easily traced to the liner in the acetabular component. Great efforts have been made in reducing PE wear at the femoral head/liner interface through the use of ceramics, better CoCr polishing techniques, and improved processing of polyethylene. Until recently, however, not much attention has been given to the liner outside diameter/shell inside diameter interface, sometimes known as the “second articulating surface”. The first aspect of this paper provides background on various studies which examined metal shell/polyethylene liner interfaces of several commercially available acetabular components. Movement of the liner was confirmed and measured. Various types of surface abrasion were noted on the liners. The second aspect of this paper examines two modular adjunctive fixation methods for debris generation potential. Recommendations for design improvements are included.