Modular revision stems in total hip arthroplasty.

Many different clinical circumstances are seen in revision total hip arthroplasty. Modular stems provide significant flexibility in choices to ensure distal and/or proximal unitary construct of implant and host bone. There are two basic types of modular stems. Designs that incorporate a metaphyseal sleeve taper fit with a splined, slotted distal body of varying lengths and neck offsets and also provide infinite choices for version of the components. Designs incorporate a distal stem with various proximal stems and Morse tapers. These designs also may vary the distal stem configuration from extensively porous-coated, to tapered and with corundum, to splined and slotted. Although there have been no clinical studies that document improved outcomes with modular stems over one-piece stems, the intraoperative flexibility provided by choices of diameter, stem length, fixation type, and proximal stem size and orientation enable establishment of a stable hip center. I will review the clinical indications for modular stems, outline their advantages, discuss the applicable operative techniques, the reported results, and the limitations of the current literature.