Validation of ion level analysis as method to assess in vitro total hip replacement wear

Currently in vitro hip simulator wear of metal on metal hip replacements is carried out by gravimetric means. However, this is time consuming and cannot be used to assess wear between measurement intervals. Measuring ion levels (Co and Cr) by inductively coupled plasma mass spectroscopy has been proposed as an alternative method. A standard hip simulator test was conducted using clinically available parts and wear assessed by gravimetric means; additionally, the serum lubricant was assessed for Co and Cr ion levels. A strong correlation in the ion levels and gravimetric was observed, indicating that this method would provide an appropriate alternative wear measurement technique in hip simulator testing.