Waterman1,
A few things...Ultimately mine was not an "allergic" reaction. I am not
allergic to either of the metals, or the corrosion by-product. Mine and others are categorized as an "adverse local tissue reaction".
The issue is that these modular hips are designed with flexible titanium in the stem to bend with the bone, and a much stronger chromium cobalt in the neck where more strength is warranted.
Where the 2 metals connect, touch and rub there is a potential for corrosion (read up on galvanic corrosion or bimetallic corrosion). So any non-modular hip will avoid this corrosion issue. Any
SINGLE metal modular hip will avoid the bimetallic corrosion (but will have potential other issues).
My hip, the Wright Profemur Renaissance is not normally distributed in the US with a Titanium Neck Option, but they received clearance and got me one. Studies I've seen have not shown a high incidence (or ANY occurrences) of titanium neck fractures in folks under 170 pounds like me.
I have dozens of articles on the topic in folders but here are a few for your perusal.
broken link removed: https://www.healio.com/orthopedics/journals/ortho/%7B903f2596-c0dd-4712-aee7-222d416c8eb4%7D/failure-of-a-modular-hip-implant-at-the-stem-sleeve-interface
https://www.biomedcentral.com/1471-2474/11/3/
broken link removed: https://www.bjjprocs.boneandjoint.org.uk/content/95-B/SUPP_22/52.short
broken link removed: https://www.bjjprocs.boneandjoint.org.uk/content/95-B/SUPP_15/42.abstract
Many of the reports I read require access to medical libraries or charge fees per view. With 2 kids in sciences in college and my wife working at a hospital I had plenty of ways to get them...
I hope that helps.
Z