A Review of the Variations in Design Features in Diaphyseal Engaging Tapered Fluted Titanium Femoral Stems in Revision Total Hip Arthroplasty

For femoral reconstruction in revision total hip arthroplasty (rTHA), cementless, diaphyseal engaging femoral components are the most commonly-used implants. At present, there are no reviews that directly compare the design features of these implants. We performed a manual review of the designs of commercially available diaphyseal engaging femoral stems. We compiled and compared the design features of these implants. Clinical outcomes of modular and monoblock stems were also compared. We identified five modular and four monoblock stems in the manual review of commercial companies manufacturing these stems. Distal stem taper varied from 2° to 3.5°, and the number of splines varied from 8 to 16. The stems varied in their stem lengths, offsets, and surface finish. Although there are no clinically significant differences in the restoration of leg length between monoblock compared to modular stems. The modular stems appear to perform slightly better with respect to subsidence and restoration of leg length. A source of concern for modular stems are mechanical implant failures that occur almost exclusively at modular junctions. Current evidence does not support any difference in dislocation rate, intraoperative or postoperative fracture, aseptic loosening, re-revision rates, or clinical outcomes between monoblock and modular stems. With the knowledge of the distinct features of implants, surgeons must make choices associated with specific design characteristics that could be pivotal to the success of the operation. Our understanding of design differences will help us minimize chances of failure and choose patient-specific implants that will lead to a high rate of success.