Biology of alkali- and heat-treated XXXX implants.

@entity702 @entity3798 @entity95 @entity7159
In cementless fixation systems, surface character is an important factor. Alkali and heat treatments of @entity702 metal have been shown to produce strong bonding to bone and a higher ongrowth rate. In this study we examined the effect of alkali and heat treatments on @entity702 rods in an intramedullary @entity95 femur model, in regard to the cementless hip stem. The implant rods were 5 mm in diameter and 25 mm in length. Half of the implants were immersed in 5 mol/L @entity7159 solution and heated at 600 degrees C for 1 h ( @entity3798 implants), and the other half were untreated (CL implants). The rods were implanted into the distal femur of the @entity95 ; @entity3798 implants into the left femur and CL implants into the right. The bone-implant interfaces were evaluated at 3, 6, and 12 weeks after implantation. Pull-out tests showed that the @entity3798 implants had a significantly higher bonding strength to bone than the CL implants at each time point. As postoperative time elapsed, histological examination revealed that new bone formed on the surface of both types of implants, but significantly more bone made direct contact with the surface of the @entity3798 implants. At 12 weeks, approximately 56% of the whole surface of the @entity3798 implants was covered with the bone. In conclusion, alkali- and heat-treated @entity702 offers strong bone bonding and a high affinity to bone as opposed to a conventional mechanical interlocking mechanism. Alkali and heat treatments of @entity702 may be suitable surface treatments for cementless joint replacement implants.
