4 months ago i had total knee replacements(both) and i still have swelling, burning, sharp needle like pains is this normal? what are the signs if one is allergic to the metal in the knee replacement (both)

Can be normal: Some pain and swelling can be normal at this stage. May take close to 1 full year for complete resolution with good therapy. Signs of metal allergy include persistent pain and swelling, skin rashes, including hives , and x-ray findings of component loosening. A sample of the metal, provided by the implant company, can be taped to your arm to confirm. Ask your surgeon.