Determinación de los niveles en suero de cobalto y cromo en 17 pacientes tras el implante de una prótesis total de cadera con par metal-metal / Determination of serum levels of cobalt and chromium in 17 patients undergoing metal-on-metal THR

ABSTRACT

Purpose. To assess cobalt and chromium concentrations in serum and urine in 17 patients that underwent total hip replacement (THR) with a metal-on-metal bearing and to determine their correlation with radiographical findings. Materials and methods. Cobalt and chromium concentrations were measured in 17 patients by means of atomic absorption spectrophotometry before implantation of a metal-on-metal THR, between the first and second year post-op and between the third and fourth year post-op. Cobalt and chromium concentrations in urine were also determined at the end of follow-up. The post-op radiological study was compared with that carried out at the end of follow-up. Mean patient age was 57 ± 6 years and mean follow-up was 31 ± 9 months. Results. Mean cobalt concentration did not rise during the first and second year post-op with respect to the mean pre-op concentration, but it did increase between the third and fourth year. Mean chromium concentration rose between the first and second year and they went on to drop slightly between the third and fourth year post-op. No relationship was found between the appearance of radiolucent lines or a varus or valgus position of the stem and the cobalt and chromium levels in serum and urine. Eighty-five percent of cups with an inclination > 56° showed cobalt and chromium concentrations in serum in excess of the mean pre-op value. Conclusions. The increase in mean serum cobalt and chromium concentrations detected in our study was lower than that shown by other authors. This increase occurred mainly between the first and second year post-op. The series under study shows that the more vertically the cup is placed the higher the cobalt and chromium levels present (AU)