TITANIUM AS THE MATERIAL OF CHOICE FOR CEMENTLESS FEMORAL COMPONENTS IN TOTAL HIP-ARTHROPLASTY

Modern total hip arthroplasty has been performed using femoral stems m anufactured from stainless steel, cobalt-chrome molybdenum alloy (CoCr Mb), titanium aluminum vanadium alloy (TiAlV), and, on a limited basis , low-elastic modulus composites. Today, only CoCrMb and TiAlV are use d in significant numbers. There is ample theoretical, experimental, an d clinical evidence to support TiAlV as the material of choice for cem entless femoral stems, based on superior mechanical compatibility and biocompatibility. The primary advantage of TiAlV over CoCrMb is a lowe r modulus of elasticity. This results in decreased stress shielding an d subsequent favorable femoral remodeling. This effect is more signifi cant with the smaller stem sizes used in primary surgery but persists even with larger stem sizes used in revision. surgery. The second adva ntage of TiAlV is its biocompatibility. Titanium aluminum vanadium aho y is of relatively tow toxicity in concentrations found clinically, an d TiAlV is inert in the physiologic environment. With regard to fixati on in cementless total hip arthroplasty, TiAlV has been shown to achie ve excellent bone ingrowth into porous surfaces. In addition, there is evidence of superior bony ingrowth into TiAlV as compared with CoCrMb . Titanium aluminum vanadium alloy is presently the material of choice to be used in conjunction with hydroxyapatite coating. Prosthetic des ign, stem diameter, and porous-coating applications play significant r oles in bony response regardless of metal composition.