Read Study Here – August 2017 Forsthoefel CW , Brown NM , Barba MLMechanical wear at the articular surface and corrosive processes at modular junctions, such as the trunnion, are responsible for metal ions production. We retrospectively reviewed 64 patients who underwent THA with a metal on metal bearing surface and 34 patients with hip Resurfacing. Metal ion measurements, six-week post-op radiographs, and functional scores were included in the analysis. Cobalt ion levels were significantly elevated in THA patients, 2.95 μg/L as compared to resurfacing patients, (2.95 versus 1.30 μg/L, p < 0.0005). Chromium levels were not significantly different between THA patients and resurfacing patients (1.05 versus 1.00 μg/L, p = 0.529).