Un couple de frottement métal-métal peut-il améliorer la longévité des prothèses totales de hanche ?

Metal Ion release with large-diameter metal-on-metal hip arthroplasty

Preoperative and postoperative ion concentrations were measured in 29 metal-on-metal, large-diameter head total hip arthroplasty (LDH-THA) patients. Mean chromium, cobalt (Co), and titanium levels from LDH-THA were 1.3, 2.2, and 2.7 μg/L at 12 months. The open femoral head design showed significantly higher Co concentrations than the closed design (3.0 vs 1.8 μg/L, P = .037). Compared with previously published ion levels from a hip resurfacing system presenting the same bearing characteristics, Co levels were significantly higher in LDH-THA (2.2 vs 0.7 μg/L, P < .001). This study has demonstrated that the addition of a sleeve with modular junctions and an open femoral head design of LDH-THA causes more Co release than bearing surface wear (157% and 67%, respectively). Even if no pathologic metal ion threshold level has been determined, efforts should be made to minimize its release. We recommend modification or abandonment of the modular junction and femoral head open design for this specific LDH-THA system.

Eleven-year follow-up of second-generation metal-on-metal total hip arthroplasty

PURPOSE

To investigate the cause of failure in matte-surface cemented stems in second-generation metal-on- metal total hip arthroplasty (THA).

METHODS

Records of 26 men and 11 women (39 hips) aged 29 to 72 years who underwent primary cementless THAs by a single surgeon using second-generation metal-on-metal prostheses and were followed up for a mean of 122 (range, 120-141) months were reviewed. Two types of femoral stems were used: a cementless Ti-alloy stem (n=21) and a matte-surface, iron-based alloy, cemented stem (n=18). Clinical outcomes were measured using the Harris hip score. Radiographs were assessed for stem loosening and osteolysis. Patient activity levels were graded. Surfaces of the retrieved femoral stems and periprosthetic tissue samples were examined. Metallic and cement particles were studied. Hypersensitivity to metal was tested.

RESULTS

None of the cementless stems were revised; no osteolysis or stem loosening occurred. In contrast, 7 of 18 matte-surface cemented stems were revised owing to stem loosening or osteolysis. Periprosthetic tissues revealed abundant cement-related particles; 90% were zirconium oxides but a few were iron particles. Histological examination of periprosthetic tissues showed perivascular infiltration of lymphocytes and macrophages containing tiny foreign materials. Metal hypersensitivity was not associated with aseptic loosening.

CONCLUSION

Metal-on-metal THA with cementless components could be recommended for young, active patients to prevent wear and osteolysis. The matte-surface cemented stem is more likely to fail owing to friction during the earlier stage and cement-related biological processes during the later stage.

Two- to 9-year clinical results of alumina ceramic-on-ceramic THA

From June 1997 to June 2003 we performed 194 total hip arthroplasties on 173 patients using alumina ceramic-on-ceramic bearings as part of a prospective United States Food and Drug Administration/Investigational Device Exemption study. The average patient age at surgery was 49.9 years. Minimum followup time was 2 years (mean 4.3 years, range 2-9 years). We evaluated survival rate, implant- and nonimplant-related complications. Clinical outcomes included the Merle d'Aubigné score. We assessed radiographs for signs of osteolysis, component loosening, and implant wear. No patients had osteolysis and there were no hip dislocations. Implant survivorship for all hips with aseptic revision of any component was 96% (CI, 91-100) at 9 year; survivorship for hips without prior surgery was 99.3%, (CI, 98-100). There was a 1.7% incidence of implant-related complications. Our data help confirm two United States FDA/IDE studies on alumina ceramic-on-ceramic total hip arthroplasty that reported low aseptic revision rates and low revision rates for instability. Total hip arthroplasty using alumina ceramic-on-ceramic implants is a safe and reliable procedure in the comparably young and active patient.