Purpose: The purpose of this study was to monitor serum cobalt (Co) and chromium (Cr) levels in patients after metal-on-metal resurfacing hip arthroplasty with the Cormet 2000® prosthesis, and to evaluate the effect of patient characteristics, prosthesis characteristics, clinical and radiographic measures on metal levels.

Methods: Serum Co and Cr levels were determined in 32 patients with Cormet resurfacing prostheses at 0.5, 1 and 2 years postoperatively using ICP-MS and are reported as & #61549;g/L. Control levels were measured in 20 patients without implants.

Results: Medium Co and Cr were 0.21 and 0.16 in controls without implants. Medium Co at 6 months (2.65), 1 year (3.62) and 2 years (2.80), and Cr at 6 months (3.74), 1 year (4.73) and 2 years (4.68) were signifi-cantly increased in the Cormet group when compared to control levels (p < .0001). Metal levels did not correlate with cup inclination, component position, head size, age, weight, sex or Harris Hip scores. Markedly elevated Co (35, 63) and Cr (13, 70) levels were found in two patients with excessive cup abduction. In addition, one patient with a loose implant that required revision had markedly elevated Co (19) and Cr (44) levels.

Conclusions: Significantly increased levels of cobalt and chromium were released from Cormet 2000 articulations at all time points. Excessive cup abduction was associated with markedly elevated ion levels indicating that accurate cup placement is an important consideration in resurfacing arthroplasty. The significantly increased trace metal levels following resurfacing with the Cormet prosthesis is a concern and warrants further monitoring.

Purpose: The purpose of our study was to compare serum titanium levels in patients with the three-piece modular AcuMatch® and one-piece nonmodular Versys® titanium femoral components.

Methods: Blood samples were obtained at multiple time points for four years after the surgery in patients with the Versys® one-piece (47 patients) or AcuMatch® three-piece (70 patients) femoral stems. Control levels were measured in 20 patients without titanium implants. Titanium (Ti) levels were measured using high resolution inductively coupled-plasma mass spectroscopy by a technician blinded to the patient groups.

Results: Medium Ti was significantly lower in the control group (.21 & #61549;g/L), when compared to patients with one- and three-part stems at all follow-up periods (p < .02). At 1 and 2 years post-operatively, medium Ti levels in the three-part group (3.1 and 3.4 & #61549;g/L) were significantly higher than levels in the one-part group (1.7 and 1.6 & #61549;g/L) (p < .004). At 3 and 4 years, medium titanium levels were not significantly different in the one-part group (2.5 and 2.7 & #61549;g/L) when compared to the three-part group (3.5 and 3.1 & #61549;g/L) (p > .05).

Conclusions: The intraoperative flexibility provided by modular femoral stems may be offset by increased wear at modular junctions. Ti levels were significantly higher in patients with a highly modular three-part femoral stems at 1 and 2 years but no significant difference was found at 3 and 4 years postoperatively. Continued monitoring of these patients is warranted to determine if metal levels can be used to evaluate stem performance.