The rationale and performance of modularity in total hip arthroplasty.

Modularity in total hip arthroplasty design is an evolving concept that continues to receive citation in the clinical literature. The advantages of these systems include off-the-shelf flexibility for customizing proximal and distal canal filling, as well as accommodation of difficult situations of femoral deformity and bone loss. Clinical concerns in the application of modular femoral stem hip designs include the maintenance of anatomical stability within the femoral canal component dissociation, structural compromise at metal-metal interconnections due to cyclic microdisplacements (fretting), and the increased potential for metallic-wear debris generation. This article reviews the rationale and performance of typical modular systems.