[Five-year follow-up of a hydroxyapatite coated stem].
OBJECTIVE
We studied a cementless anatomic stem combination with a cementless press-fit cup. The purpose of this work was to assess prospectively in a homogeneous consecutive series of patients, the clinical and radiological outcome of this prosthesis at five years follow-up.


METHODS
The series included 176 hips with a total hip arthroplasty implanted between September 1997 and December 1998 by the same surgeon through an antero-lateral approach (Watson-Jones). We retained for study first intention implantations for primary or secondary joint degeneration. Fractures and revisions were excluded from the analysis. At last follow-up the survival was 93.2%. Patients were revised clinically (satisfaction Harris score). An independent surgeon unaware of the clinical results performed the radiological analysis (Engh and Ara score, Brooker classification). The Kaplan-Meier method was used for the survival curve expressed with 95% confidence interval and considering revision for all causes as failure.


RESULTS
The five-year survival of the prosthesis was 98.8%. Clinically, the Harris score varied significantly (p<0.0001) from 32.9+/-1.2 preoperatively to 93.1+/-0.8 at last follow-up. Among the score items, pain exhibited the greatest improvement since at five years only, 10.2% of patients complained of mild pain. Thigh pain, often associated with cementless stems, was very low, 1.3%. Radiologically, the femoral implant was very stable with excellent bone remodelling as illustrated by the high Engh and Ara scores, 20.7+/-0.5 and 5+/-0.2 respectively. Polyethylene wear, 0.075mm/year, was below the usually observed levels. We noted a high rate of heterotopic ossifications, 65.1%, most Brooker I.


CONCLUSIONS
The SPS stem has shown good results at five years, both clinically and radiographically. The objectives of a stable fixation over time and harmonious remodelling appear to be achieved. These promising results should be reexamined in a series with a longer follow-up.
Mouttet
A
A
Clinique Saint-Roch, Chemin du Mas-Anglade, Cabestany, France. a.mouttet@wanadoo.fr
Philippot
R
R
Farizon
F
F
Vallotton
P-H
PH
Ibnou-Zekri
N
N
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017886:Durapatite; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011474:Prosthesis Design; D013997:Time Factors
D017886:Durapatite