RESULTS OF A HYDROXYAPATITE COATED MODULAR FEMORAL STEM IN PRIMARY TOTAL HIP ARTHROPLASTY. A MINIMUM FIVE-YEAR FOLLOW-UP.

Abstract

Introduction: Modular metaphyseal-diaphyseal femoral stems are infrequent in primary total hip arthroplasty. We analyse the results of a proximally hydroxyapatite coated anatomic two-piece modular femoral stem over a minimum five years follow-up.

Material and Methods. 94 ESOP (Fournitures Hospitalieres, France) stems are analysed. The mean follow–up was 70.45 + 8.6 months. Patients’ mean age was 65.8 + 9.6 years. Proximal osteopenia and radiographic stem fixation are assessed according to Engh et al.

Results: There were 2 aseptic femoral stem loosenings. There were no cases with thigh pain. Three stems presented subsidence. Mean femoral canal filling was 89% and was related to stem subsidence (p< 0.05). Stable bone fixation was obtained in 83 hips and was related to fluted femora (p< 0.0001). The cumulative probability of not having radiographic loosening was 97.8% (94.8% to 100%). The cumulative probability of not having proximal femoral osteolysis was 86.0% (78.9% to 93.1%), cortical widening 88.1% (81.5% to 94.7%), and proximal osteopenia 94.5% (89.8% to 99.2%).

Conclusions: A cementless two-piece modular hydroxyapatite coated femoral stem provides good clinical results with an absence of pain and excellent radiographic results when there is good adaptation between the metaphyseal part of the stem and the femoral anatomy. This design is an option in femora with good bone quality and especially in tunnel-shaped cases. Femoral osteopenia and cortical widening were infrequent in this series. The modular metaphyseal-diaphyseal junction is not an in vivo problem, contrary to previous reports. A longer follow-up is needed to assess the results of this design.