A 58-year-old woman with proven severe type IV hypersensitivity to nickel requires total hip arthroplasty. Which femoral head material is the MOST appropriate choice to minimise allergen exposure?

• A Oxidised zirconium (ceramicised metal) ✓
• B Stainless steel
• C Cobalt-chromium-molybdenum alloy
• D Titanium alloy (Ti-6Al-4V)

Explanation

Oxidised zirconium consists of a zirconium-niobium alloy whose surface is transformed into zirconia ceramic; it contains negligible nickel and releases far fewer metal ions than cobalt-chrome. Stainless steel contains about 10 percent nickel and cobalt-chrome also carries substantial nickel, so both are unsuitable. Titanium alloy is nickel free but is too soft for use as a bearing surface against polyethylene because abrasive wear produces copious debris.

Reference: Miller's Review of Orthopaedics, 8th ed.

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