Purpose: During revision of alumina-on-alumina prostheses, reimplantation of a ceramic head on the former stem raises the risk of head fracture. Furthermore, serious deformation of the metal head has been reported after failure of ceramic-on-ceramic prostheses. The purpose of this retrospective study was to evaluate the incidence of these complications and analyse clinical and radiological results of revision for alumina-on-alumina total hip arthroplasties.

Material and methods: This consectutive series included 107 patients (74 women and 33 men, mean age 65 years, age range 32–91 years) who underwent 118 revision arthroplasties from 1976 to 1997. The cause in the majority of the cases was isolated non-infected cup loosening (80%) or ceramic implant fracture (4%). There were 72 cemented alumina cups, 38 screwed cups, six press-fit metal-backed cups, and two massive alumina impacted cups. Cavitary acetabular osteolysis was present in 67% of the cases. The cup was replaced alone in 94 cases (80%). The implanted cup was a polyethylene cup in 93 cases and an alumina cup in 25. When the femoral stem was left in place, a new ceramic head was implanted in 49 cases (39 alumina, 10 zircone). The alumina head was replaced by a metal head in 18 cases.

Results: Four early dislocations and two infections were noted. Mean follow-up after revision surgery was 67 months. Fourteen patients were lost to follow-up. Sixteen patients required revision surgery, ten of them for repeated cup loosening. At last follow-up (mean 61 months), there were no failures among the 49 ceramic heads implanted on a stem left in place. No revisions were required for polyethylene cup wear or metal head wear. In all, 72 hips were evaluated at a minimum two years follow-up. The functional score at last follow-up was 15.2±3.5. Seven-year actuarial survival was 95.5% taking revision of non-infected revision as the endpoint.

Discussion and conclusion: Analysis of the results shows that acetabular loosening is the main cause of revision of alumina-on-alumina total hip arthroplasties. The femoral stem was loosened in only nine cases and could be preserved in 80% of the cases. Replacement of an alumina-on-alumina couple with a metal-on-polyethylene couple does not appear to be a contraindication in this series.

In order to avoid the consequences of polyethylene wear in a high-risk population, 128 alumina-alumina total hip arthroplasty were implanted in 116 consecutive patients of 40 years old or less. Osteonecrosis and sequellae of congenital hip dislocation were the main etiologies representing 71% of the hips. The same titanium alloy cemented stem was implanted in all hips. Four alumina acetabular component fixations were used: cemented plain alumina socket (41 hips), screw-in ring with an alumina insert (22 hips), a press-fit plain alumina socket (32 hips) and a press-fit titanium metal back with an alumina insert (33 hips).

Eight patients (11 hips) died during the follow-up period. Sixteen revisions were documented, 12 for ace-tabular aseptic loosening, 3 for bipolar loosening (2 were septic), and 1 for unexplained pain. Eighty-nine hips were followed radiologically for two to twenty years. No femoral nor acetabular osteolysis were observed with an average follow-up of 8.4 years. Wear was unmeasurable. Four additional sockets showed definite migration. The respective survival rate at 7 years were 91.4% for the cemented cup, 88.8% for the screw-in ring, 95.1% for cementless press-fit plain alumina socket and 94.3% for the metal-back press-fit component.

The ten-year survival rate was 88.0% for the cemented socket and 88.8% for the screw-in ring. The fifteen-year survival rate was 76.7% for the cemented socket. The occurrence of a graft was the only prognostic factor with a 62.6% survival rate at ten years for the grafted hips and a 90.1% for the non-grafted hips (p=0.004).

The alumina-alumina bearing surfaces for young patients appeared as a valuable alternative to standard metal-polyethylene system. There is a need to improve socket fixation if we want to have a survival of the arthroplasty as long as the life expectancy of this increasing and demanding population. The last design with a fully coated HA titanium shell and an alumina liner seems to fulfill the requirements.

Introduction: The achievement of a well aligned limb is one of the main factor that probably affect the long term survival of total knee arthroplasty. Despite many improvements in ancillary device design, a significant number of total knee arthroplasty remain in excessive varus or valgus. Computer assisted systems may improve the control on implant positioning. The goal of this paper is to present the rationale and the early experience with a recently developed system (Navitrack®).

Material and methods: A CT-scan allows acquisition of patient anatomy. The 3D reconstruction is obtained with specially developed software. Location of the instruments and bone during surgery is obtained either with a magnetic or an optical system. After captor placement, navigation allows real-time control of the ancillary device in order to perform the necessary cuts. The main landmarks given by the system during surgery are the femoral and tibial mechanical axis, cuts location, rotational positioning of the femoral implant can also be controlled using the transepicondylar axis, the posterior aspects of the femoral condyles, or the patellar groove. Rotational positioning of the tibial component can also be evaluated in order to allow a adequate orientation of the tibial slope.

Results: Four implantations failed for technical reasons including failure of captor fixation on bone during surgery, and failure of the electronic control of the captors. However, most attempted implantations were successful with an accurate placement of the implants evaluated on long leg radiographs.

Discussion: Implantation of a TKA with an anatomic-based system is possible. But, this first encouraging experience needs to be confirmed and improvements are in progress.