Echocardiographic Changes in the Context of Metal-on-Metal versus non-Metal-on-Metal Total Hip Arthroplasty

Abstract Aims The purpose of this study is to determine if there is a difference in echocardiographic results between patients with metal-on-metal (MoM) versus non-MoM total hip arthroplasty (THA) and to determine if a correlation exists between serum metal levels and echocardiographic outcomes. Methods Seventy-five patients with the same modular THA enrolled in this prospective cohort study, and 49 had MoM bearings. All patients had serum cobalt, chromium, and titanium levels drawn at two study visits with a transthoracic echocardiogram at the second visit. Serum metal concentrations and echocardiographic parameters were compared with two-way t-tests. Multiple linear regression analyses identified any significant predictors of echocardiographic outcomes. Results Mean serum cobalt and chromium levels were significantly greater in the MoM group at both time-points (p 0.05). MoM patients had significantly lower global longitudinal strain compared to the non-MoM group (18.4% vs. 20.2%; p = 0.026). Serum cobalt concentration was found to be an independent predictor of tricuspid annular plane systolic excursion (p=0.02). Conclusion MoM THA bearings are associated with increased serum cobalt and chromium levels. Patients with MoM THAs had decreased global longitudinal strain, a measure of left ventricular function, but both groups remained within normal range. The clinical impact of the positive association between serum cobalt concentration and tricuspid annular plane systolic excursion, a marker of right ventricular function, deserves further study. These findings can reassure physicians and patients that metal-induced cardiomyopathy is not typical in the setting of MoM total hip arthroplasty. Level of Evidence Level II, Prospective Cohort Study