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

OBJECTIVE: To describe corrosion discovered on implants recovered from dogs after tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: Descriptive. ANIMALS: Dogs (n=4) that had TPLO (n=7) approximately 3 years earlier. METHODS: Implants were recovered surgically and lightly cleaned before visual inspection, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). RESULTS: 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. CONCLUSIONS: 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. CLINICAL RELEVANCE: 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.