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Modularity is being diversified in total hip prostheses to increase surgical latitude in optimizing implant fixation and adjusting hip biomechanics. However, several problems have been clearly identified with implant modularity. First generation metal-backed acetabular components have shown deficiencies in the locking mechanism, the congruency and extent of polyethylene liner support, and polyethylene thickness, all of which have been implicated in accelerated polyethylene wear and failure. Evidence of screw motion against the metal backing, release of particulate material, and focal osteolysis have also been observed. At the head/neck junction evidence of corrosion and fretting has been documented with both similar-metal and mixed-metal taper combinations. Femoral prostheses with other sites of modularity present additional concerns with regard to mechanical integrity and generation of particulate debris …