Stem modularity: rarely necessary in primary total hip arthroplasty.

A retrospective review of two consecutive series of cementless primary THA performed simultaneously from November 1987 to February 1994 within a single orthopedic practice by three surgeons was conducted. A series using non-modular Mallory-Head Porous (Biomet Inc, Warsaw, Ind) femoral components was compared to a series using modular Sivash Range of Motion (DePuy, Warsaw, Ind) femoral components to evaluate whether modularity of the femoral stem body is necessary in cementless primary THA. Clinically and radiographically, both components performed at comparable levels with equally satisfactory results. Both series demonstrated effective femoral fixation as evidenced by excellent Engh fixation scores. However, this study has shown the importance of circumferential proximal porous-coating to form an effective seal, preventing the propagation of particulate debris. Modular systems were associated with a higher degree of technical difficulty, operative time, and blood loss.