[Clinical and radiographic results of a continuous series of 124 type Ceraver-Osteal hip prostheses with a 9-year survival analysis].

INTRODUCTION

Since 1979, we have been using a model of cemented total hip arthroplasty (THA) with a titanium femoral stem, a 32 mm femoral head, and for some cases an alumina on alumina browing combination. We tried to appreciate the results of these different modifications with a sufficient follow-up.

MATERIALS AND METHODS

Among the 124 THA, 63 sockets were made of alumina, 61 of polyethylen, 22 patients had deceased and 23 were lost for follow-up before seven years, we studied 72 THA followed between 7 and 9 years up. The cementing technique was not modified. The clinical evaluation was done using the Merle d'Aubigné-Postel hip rating scale the radiographic analysis was conducted for 79 hips.

RESULTS

After 9 years 8 cups had been removed for loosening, 2 hips were operated for infection, the global survivorship without a new operation was then 88.73 per cent. Among all hips, 80 per cent were clinically rated as "fair" or better. We noticed 8 migrations among the alumina cups and 6 among those made of polyethylene. Among the 31 polyethylene cups, there were 25 lucencies between bone and cement (18 < 1 mm). Among the 48 alumina cups there were 22 lucencies just between bone and cement and 21 between cup and cement and also between bone and cement (double lucencie). The lucencies between cup and cement were more often in the lower third of the cup and 7 of the 8 migrations had double lucencies. Forty-nine percent of the femoral stems had lucencies, 40 per cent in the proximal zones. But there was just one femoral subsidence associated with the lowest distal femoral filling. So just considering the femoral subsidence the survivorship was 98.79 per cent.

DISCUSSION

The clinical results of this series were as good as the more recent series. Because of the difference of radiographical aspect between the polyethylene and alumina cups, the high rate of lucencies and migration could have been interpreted as two different mechanisms. For polyethylene cups, the 32 mm femoral head is frequently associated with this complication, as it was already described in other series. For the alumina, the difference of elasticity between bone and cement should have been the principal responsible. As we considered just the migration of the stem, and although the cementing technique was simple, our rate of femoral loosening was as low as in the more recent series. The frequent proximal lucencies should may be not be considered as loosening but as consequence of the elasticity of titanium. The distal fixation obtained by a good distal femoral filling seemed to be the more important point.

CONCLUSION

To reduce the acetabular loosening rate we use now a head of 28 mm for the metal on polyethylene combination, the alumina cup has been abandoned and the alumina on polyethylene combination should still be assessed. The encouraging femoral results, due to the good femoral filling and to the titanium elasticity needs to be confirmed after a longer follow-up.