Retrieval Analysis of a Cementless Modular Total Hip Arthroplasty Prosthesis

This paper reports the analysis of a modular S-ROM hip implant, which was retrieved at revision, secondary to aseptic loosening approximately after 24 months of implantation. Light microscopy and scanning electron microscopy confirmed the presence of pitting, fretting corrosion, plastic deformation, and stress induced corrosion cracking. Energy dispersive X-ray microanalysis of the stem surface revealed the release of metal ions secondary to environmental interaction. High resolution inductively coupled plasma mass spectroscopy performed on the blood serum sample confirmed the elevated titanium ion levels (4.66 ppb). Finite element analysis of the implant showed that the micromotion and stress levels were the maximum at the proximal lateral region of the taper junction, in congruence with the observation. This case shows that taper performance is influenced by implant´s metallurgy and geometry. Patient weight, activity level, and effect of the local microenvironment also play a significant role.