[Early femoral osteolysis following Charnley-Kerboull total hip arthroplasty combining a 22-mm zirconia head on polyethylene].
OBJECTIVE
New bearings have been developed to reduce polyethylene wear. Zirconia ceramic is one proposal with attractive tribologic properties. The purpose of this prospective study was to evaluate the clinical and radiological results at least two years after implantation in a continuous series of total hip arthroplasties combining a zirconia head with polyethylene socket.


METHODS
The series included 56total hip arthroplasties performed in 51 patients (30 females and 21 males), mean age 52.2 +/- 12 years (25-76 years). Prostheses were implanted for primary degenerative disease (43%) and dysplasia (27%). The femoral component was a stainless steel stem with a Morse cone measuring 11degrees 25' for 27 hips and 5 degrees 40' for 28 hips. A 22-mm stabilized yttrium tetragonal polycrystalline zirconia head (Y-TZP) was used. The transtrochanteric approach was used for all arthroplaties with implantation of a cemented Charnley-Kerboull prosthesis. Clinical outcome was assessed with the Postel-Merle-d'Aubligné (PMA) score. Acetabular cup wear and periprosthetic osteolysis were measured on successive AP x-rays of the pelvis.


RESULTS
Mean follow-up was 32 months (24-48). None of the patients were lost to follow-up. Mean function score at last follow-up was 17.8 +/- 0.2 (16-18) versus 12.2 +/- 2.6 preoperatively (Wilcoxon, p < 0.0001). There were no cases of implant migration (femoral or acetabular). An endosteal defect by femoral osteolysis in the calcar femoral was observed in 19 of 55 cases. It appeared early between first and second post-operative year and did not progress later. Its surface remained less than 1 cm2 in all cases. We were unable to identify any factor predictive of these osteolytic lesions.


CONCLUSIONS
The short-term clinical results with this type of arthroplasty was comparable with earlier results described with classical Charnely-Kerboull implants using a metal-polyethylene bearing. The Merkel osteolysis observed in this series occurred early for one-third of the hips with no measurable polyethylene wear. We suggest surgeons should be cautious about using the zirconia head. We are continuing our surveillance of these patients.
Hamadouche
M
M
Service A de Chirurgie Orthopédique et Reconstructrice de l'Appareil Locomoteur, CHU Cochin Port-Royal (AP-HP), 27, rue du Faubourg-Saint-Jacques, 75014 Paris.
Madi
F
F
Kerboull
L
L
Courpied
J P
JP
Kerboull
M
M
D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D003776:Dental Porcelain; D005260:Female; D005269:Femur; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000209:etiology*; D020959:Polyethylene; D011446:Prospective Studies; D011474:Prosthesis Design; D013997:Time Factors; D015019:Yttrium; D015040:Zirconium
C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D020959:Polyethylene; D015040:Zirconium