Comparison of collared and collarless femoral components in primary uncemented total hip arthroplasty.

Two hundred three consecutive primary uncemented total hip arthroplasties were prospectively randomized using collared and collarless versions of an identical titanium stem. Identical 28-mm titanium heads were implanted in all cases. One hundred three collared hips were compared with 100 collarless hips. Follow-up periods averaged 45.7 months in both groups. Intraoperative, early, and late complications were similar. Hip scores, including thigh pain, at final follow-up visit were also similar. No significant differences were noted in acetabular or femoral radiolucencies, subsidence, osteolysis, or proximal femoral remodeling. At 5 years, more collarless stems revealed pedestal formation (57.1% vs 33.9%). The presence of a collar had no effect on the adequacy of fixation, proximal femoral osteopenia, or clinical scores at 5 years.