Alkali- and heat-treated porous titanium for orthopedic implants

This study was carried out to investigate the effects of the alkali and hea t treatments on the bone-bonding behavior of porous titanium implants. Poro us titanium im plants had a 4.6 mm solid core and a 0.7 mm thick porous out er layer using pure titanium plasma-spray technique. Three types of porous implants were prepared from these pieces: 1. control implant (CL implant) as manufactured 2. AW-glass ceramic bottom-coated implant (AW implant) in which AW-glass ce ramic was coated on only the bottom of the pore of the implant 3. alkali- and heat-treated implant (AH implant), where implants were immer sed in 5 mol/L NaOH solution at 60 degreesC for 24 h and subsequently heate d at 600 degreesC for 1 h. The implants were inserted into bilateral femora of six dogs hemi-transcort ically in a randomized manner. At 4 weeks, push-out tests revealed that the mean shear strengths of the CL, AW, and AH implants were about 10.8, 12.7, and 15.0 MPa, respectively. At 12 weeks there was no significant differenc e between the bonding strengths of the three types of the porous implants ( 16.0-16.7 MPa). Histologically and histomorphologically, direct bone contac t with the implant surface was significantly higher in the AH implants than the CT, and AW implants both at 4 and 12 weeks. Thus, the higher bonding s trength between bone and alkali- and heat-treated titanium implants was att ributed to the direct bonding between bone and titanium surface. In conclus ion, alkali and heat treatments can provide porous titanium implants with e arlier stable fixation. (C) 2000 John Wiley & Sons, Inc.