Aims

We previously reported the long-term results of the cementless Duraloc-Profile total hip arthroplasty (THA) system in a 12- to 15-year follow-up study. In this paper, we provide an update on the clinical and radiological results of a previously reported cohort of patients at 23 to 26 years´ follow-up.

We reviewed 111 hemispherical Duraloc series-500 acetabular components with a minimum follow-up of 12 years. The mean clinical and radiological follow-up was 13.4 years (12 to 15). A Profile hydroxyapatite-coated anatomical femoral component was used in each case. Six patients had a late dislocation, for whom the polyethylene liner was exchanged. Each acetabular component was well fixed and all femoral components showed signs of bone ingrowth. The mean rate of femoral head penetration was 0.10 mm/year (0.021 to 0.481). The probability of not developing femoral cortical hypertrophy and proximal osteopenia by 12 years was 80.2% (95% confidence interval, 72.7 to 87.6) and 77.5% (95% confidence interval, 69.7 to 85.2), respectively. Despite these good clinical results, further follow-up is needed to determine whether these prostheses will loosen with time.

We have analysedin the results of 24 femoral lengthenings in 23 patients operated on between 1993 and 2000, using a gradual elongation intramedullary nail (Albizzia). Of the 23 patients, 22 had femoral deficiency and one was of short stature. Their mean age was 16.9 years. Technical difficulties encountered during the procedure were mild or moderate in 18 femora and severe in six femora. Distraction was obtained by 15 ratchetings per day (1 mm/day).

There were 18 excellent results although in two patients this was achieved after the development of a pseudarthrosis which required further surgery. There were four good and two fair results in which the lengthening obtained was at least 3 cm less than had been projected. The consolidation index was 35.2 days/cm. No patient had associated long-term stiffness of the knee.

Femoral lengthening using an elongation nail gives good results and is a comfortable procedure.

We implanted cylinders of cobalt-chrome or titanium, with smooth or porous surfaces, into rabbit bones which had been inoculated with suspensions of Staphylococcus aureus in various doses. The bacterial concentration required to produce infection of porous-coated titanium implants was 2.5 times smaller than that necessary to infect implants with polished surfaces. Porous-coated cobalt-chromium implants required bacterial concentrations that were 40 times smaller than those needed to infect implants with polished surfaces, and 15 times smaller than those required to infect porous-coated titanium implants. The other advantages and disadvantages of the various implants, such as improved osseointegration, larger ion-release surfaces, surface wear and relative stiffness, must be weighed against the higher infection rates in the porous-coated implants, and particularly in the cobalt-chromium implants.