Was there any indication that the rash/hives were from the titanium in the hip? My husband had a titanium hip replacement last fall and suddenly is covered with a rash and hives.
Allergic reaction to titanium is possible although rare. Titanium which is a bioactive metal is capable of tricking the body into believing that the implant is a bone. Because of this the bone bonds to the implant. When the implant moves after it is placed, the body recognizes it as a foreign object and rejects it. This causes an allergic reaction to the implant.
Diagnosis is done by skin patch test or blood tests for allergy. MELISA (Memory Lymphocyte Immunostimulation Assay) test is a blood test that is confirmatory for metal allergy.
I feel that you should consult your doctor and talk about this allergy and the option of changing the implant as avoidance is the only treatment for metal allergies. Desensitization techniques, such as allergy shots, also are not effective for metal allergies.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.