Question

Metal on metal articulation should be avoided in:

• A. Osteonecrosis
• B. Young female
• C. Inflammatory arthritis
• D. Revision surgery

Hint:

Think about cobalt and chromium ions crossing the placenta and decades of exposure.

Answer 1

The Correct Option is B

Step 1: Metal on metal bearings in hip arthroplasty release metal wear debris, mainly cobalt and chromium ions, into the local tissue and the bloodstream. The concern is the systemic effect of these ions.

Step 2: A young woman of childbearing potential is the group where this matters most, because circulating cobalt and chromium ions can cross the placenta. The possible effect on a developing fetus, together with the long expected implant life and high cumulative ion exposure in a young patient, makes metal on metal articulation best avoided in this group.

Step 3: The same metal ions are also linked to adverse local tissue reactions such as pseudotumours and metallosis, and these reactions appear to be more frequent in women, which adds to the caution in a young female.

Step 4: The other choices are not specific reasons to avoid metal on metal on this ion exposure basis. Osteonecrosis, inflammatory arthritis and the need for revision are about implant selection and bone stock rather than the fetal and ion concerns that single out the young woman.

Answer: B. Young female.