100 patients who underwent primary total hip replacement were randomized to receive a large-head metal-on-metal bearing on a stem for primary hip replacement or a 28 mm diameter conventional metal-on polyethylene bearing. The results from 2 year follow-up indicated that both groups displayed significant improvements in regards to function, pain, and hip scores. However, it was found that patients who received the metal-on-metal bearing displayed significantly better patient satisfaction. Lastly, it was found that the metal ion levels were above safety thresholds in 20% of patients in the metal-on-metal group.