Big toe fracture with toenail torn off. how long should swelling and pain persist? xray was normal 6 months later but still swollen and painful.

There's more there.: Apparently, there was more damage to the toe than just the nail being torn off and a fracture. There may have been some soft tissue damage that has not fully resolved, and may not if further treatment is started soon. You need a referral to a physical or rehab therapy. Sometimes a second opinion does wonders.

Consider an MRI: to rule out a bone infection (with and without contrast.)

OPEN FRACTURE: My question is: When the nail became torn off, was the nail bed cut open exposing the toe bones. If so, this is called an open fracture, with a chance of bone infection. If you were my patient, I would get a CBC, ESR, and MRI, checking for osteomyelitis. The MRI can also detect a non-healing fracture. Good luck. Dr. Latva