Cementless Femoral Stems in Primary Total Hip Arthroplasty

Cementless stem design in total hip arthroplasty (THA) has evolved significantly, with numerous advancements aimed at improving long-term fixation, reducing complications, and optimizing functional outcomes. The primary focus of cementless fixation is achieving biological integration of the femoral stem through bone growth and remodeling, which is influenced by factors such as stem geometry, surface coating, and the fixation philosophy employed. Various stem designs including flat taper (type A); quadrangular tapers (types B1-B2-B3); fit-and-fill (types C1-C2-C3); conical (type D); cylindrical (type E); and calcar-guided short stems (type F). offer different biomechanical advantages in terms of stability and load distribution. Furthermore, surface coatings, such as porous coatings or titanium plasma spray, are designed to enhance osseointegration and reduce the risk of loosening. This paper reviews the current philosophies behind cementless stem fixation, evaluates the biomechanics of different stem designs, and introduces an updated classification system that categorizes stems based on their design, fixation mechanism, and clinical outcomes. Understanding these aspects allows surgeons to tailor implant choices based on patient anatomy, bone quality, and activity level, ultimately improving the longevity and success of THA.