Crevice Corrosion of Implants Recovered After Tibial Plateau Leveling Osteotomy in Dogs

Abstract

To describe corrosion discovered on implants recovered from dogs after tibial plateau leveling osteotomy (TPLO). Descriptive. Dogs (n=4) that had TPLO (n=7) approximately 3 years earlier. Implants were recovered surgically and lightly cleaned before visual inspection, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). Multiple corrosion sites were found on the recesses of each plate; invariably, there was a corroded area present on that part of the bone screw which had been in contact with a corrosion site on a plate. Most corroded regions featured attached, nonmetallic material believed to be a precipitate arising from interaction with the local environment during electrochemical corrosion. SEM examination of TPLO plates revealed surface porosity, particularly visible in the screw hole recesses. Surface irregularities and porosity of TPLO plates--a consequence of the casting process--are initiation sites for corrosion which, in concert with the crevice geometry between the plate and screw, result in the observed corrosion defects. Implants used for TPLO, a commonly performed veterinary orthopedic procedures may corrode generating a number of chemical species that have the potential to cause disease.