We followed 66 total hip arthroplasties using a cement-less Omniflex femoral component with different surface morphology in 51 patients for a mean of 98 months (72 to 138). There were 57 women and nine men, and the mean age of the patient at the time of operation was 55.4 years (39 to 70). Preoperative diagnosis was osteoarthritis secondary to congenital hip dislocation and dysplasia in 64 hips, rheumatoid arthritis in two hips. This series was divided into three groups according to the extent of surface treatment in the proximal part of the femoral component. A circumferential Hydroxyapatite or titanium plasma-spray coated Omniflex stem was used in 33 hips (Group A). A patchy titanium-beads coated stem and a smooth surfaced stem of the same design were used in 25 hips (Group B) and eight hips (Group C), respectively.

Clinically, the mean Harris Hip Score was 54 points preoperatively, which improved to 89 points at the latest follow-up. Incidence of thigh pain was the lowest in Group A ( 6%) in comparison with in Group B (28%) and Group C (25%). Radiographically, the aseptic loosening rate of the femoral component was none in Group A, 16% in Group B and 75% in Group C. Incidence of femoral osteolysis was almost the same rate among the three groups; 38% in Group A, 40% in Group B, and 50% in Group C. However only in Group A, no Osteolysis was found distal to the lesser trochanter level. The femoral revision was performed in two hips of Group C. This study elucidated that the extent of surface treatment would be one of the important factors to influence the stem stability and the occurence of femoral osteolysis.