In cementless fixation system, surface character becomes important factor. Alkali and heat treatments on titanium metal has been proved to show strong bonding to bone and higher ongrowth rate. In this study we examined the effect of alkali and heat treatments on titanium rod in rabbit femur intramedurally model, in consideration of cementless hip stem. The implant had a 5mm in diameter and 25 mm in length. The implants were and half of them were immersed in 5 mol/L sodium hydroxide solution and heated at 600 åé for one hour (AH implant), and the other half were untreated (CL implant). The implants were implanted into the distal femur of the rabbits, AH implant into left femur and CL implants into right. The bone-implant interfaces were evaluated at 3, 6, and 12 weeks after implantations.

Pull-out tests showed that AH implants significantly higher bonding strength to bone than CL implants at each week after operations. At 12 weeks mean pull-out load of AH implants was 411.7 N and that of CL implants 72.2 N. As postoperative time elapsed, histological examination revealed that new bone form on the surface of the both types of the implants, but significantly more bone contacted directly on the surface of AH implants. At 12 weeks AH implant was covered by the newly formed bone about 56% of the whole surface of the implants and CL implants was about 19%.

In conclusion, alkali- and heat-treated titanium offers strong bone-bonding and high affinity to bone instead of conventional mechanical interlocking mechanism. Alkali and heat treatments on titanium may be applicable to the surface treatment for cementless joint replacement implant.

The results of 278 consecutive primary total hip arthroplasties performed with bone grafting for ace-tabular bone deficiencies were reviewed at an average of 9.0 years (range, 5–23) after surgery. All patients had underlying developmental dysplasia of the hip. For all hips, the grafts used were from the patients’ own resected femoral heads. All but three grafts were screwed to the supero-lateral aspect of the acetabular roof, the exceptions being grafts without internal fixation. Kaplan-Meier survivorship analysis predicted a rate of survival of the acetabular component at 10 years of 97% (95% confidence interval (CI), 94–100%) with revision for aseptic loosening as the endpoint, and of 82% (95% CI, 76–89%), when radiological loosening was used. Trabecular reorientation, as an indicator of graft incorporation, was seen in 89% of the joints between 1.5 and 5 years (mean 3 years), and delayed up to 7 years. Parametric survivorship analysis using the Cox proportional-hazards model indicated that trochanteric non-union, lateral placement of the socket, and delayed trabecular re-orientation of the bone graft, were risk factors for loosening of the acetabular component. Autogenous acetabular bone grafting will be of value for long-term success and has good potential for additional improvement of the results, provided these three risk factors are reduced. In order to promote the trabecular reorientation, we have gradually improved the surgical technique including sizing of bone graft and adaptation technique. By these alterations of the surgical technique, trabecular reorientation of the 51 joints operated after 1993 was completed by 4 years after surgery.