How should modular neck components be evaluated for corrosion and fracture risk in hip arthroplasty?

• A. Inspect trunnion interfaces for discoloration, fretting, and corrosion; assess micromotion and mechanical failure; avoid excessive modularity when possible.
• B. Visual inspection only; ignore micromotion.
• C. Assume modular necks are immune to corrosion.
• D. Replace modular components routinely every year.

Answer: (B)

Corrosion and fracture risk in modular neck hip implants come from wear at the interfaces where modular pieces meet, driven by small but ongoing micromotion. The most informative evaluation starts with inspecting the trunnion interfaces for signs of wear: discoloration, fretting patterns, and corrosion deposits indicate tribocorrosion is occurring and can precede failure. However, looking alone isn’t enough—assessing micromotion and overall mechanical stability is essential, because even tiny motions at the junction can accelerate wear and lead to fracture over time. Since modularity adds more contact surfaces that can corrode, minimizing modularity when feasible helps reduce risk. Purely visual checks can miss hidden wear, and assuming modular necks are immune is incorrect; routinely replacing components on a set schedule isn’t evidence-based. In practice, use a combination of interface inspection and evaluation of mechanical stability, with further imaging or analysis as needed to guide decisions.