Should the galvanic combination of titanium and stainless steel surgical implants be avoided?

It is recommended that one should not combine different metals in orthopaedic devices. The least noble metal in such a galvanic coupling is more likely to corrode. However, some studies have failed to show increased corrosion when titanium and stainless steel are combined. The aim of this study was to determine the fretting corrosion of the contact areas between screws and plates made of these dissimilar metals used for internal fixation of bone fractures. The plates were fixed to a bone-simulating material and subjected to tensile and compressive forces in both human serum and Hank's solution. The outcome variables included in the analyses were weight loss, and release of Ti, Cr, Ni and Mo to the different media. Results from the multiple combinations were subjected to multivariate statistics. Principal component analysis visualised our findings and allowed classification of similar samples and separation of discrepant groups of samples. We found a significant effect of the test medium, but no dramatic effect due to mixing of metals. The titanium screws and plates corroded more in serum than in saline, while the opposite was true for stainless steel. Combination of dissimilar screws and plates did not cause higher weight loss or metal release than the single-material constructions, indicating comparable clinical safety.