Femoral neck modularity in total hip arthroplasty design is receiving increased citation in the clinical literature. The advantages of these systems include a potential reduction in the occurrence of femoro-acetabular impingement and its consequences as well as an ability to optimize leg length, version and offset. While modular femoral neck systems have been successfully employed for a variety of patient skeletal pathology, they are not without clinical concerns. Their structural compromise at metal-metal interconnections due to cyclic microdisplacements, component disassociation in vivo, and increased potential for metallic wear debris generation and corrosion have all been reported along with tissue reactivity surrounding the tapers. Whether the cited benefits of deformity and biomechanical correction, tissue preservation and revision options outweigh these risks is a consideration in their selection. This handout describes a laboratory basis for the evaluation of modular femoral neck designs and suggests a thought process for the joint arthroplasty surgeon when considering their employ.