Relationship between Pelvic Incidence Angle and Blood Concentration of Chromium and Cobalt Ions after Metal-on-Metal Hip Replacement: A Brief Report.

Background And Aims: The wear of metal-on-metal hip implants may increase chromium or cobalt ion blood level. This phenomenon may depend among other things on the particularity of spinopelvic anatomy. The effect of pelvic incidence angle on the wear of metal-on-metal hip implants is not known. The objective of the study was to investigate whether such effect does exist.

Material And Methods: The pelvic incidence and inclination of acetabular component angles of 89 patients after unilateral metal-on-metal hip replacement were compared with blood level of chromium and cobalt ions using Pearson correlation coefficient.

Results: No significant correlations between pelvic incidence angle and the metal ion blood levels were observed. The correlation coefficients varied from -0.02 to 0.2 and all p values were >0.05.

Conclusion: No evidence was found on the effect of pelvic incidence angle on metal wear after metal-on-metal hip replacement when measured by the blood levels of chromium and cobalt ions. It is reasonable to assume that other factors than pelvic tilt may affect the rate of implant wear.