Pelvis inflammation: Introduction. Pelvis inflammation: Inflammation of the pelvic bones. See detailed information below for a list of 2 causes of Pelvis inflammation, including diseases and drug side effect causes. Causes of Pelvis inflammation: The following medical conditions are some of the possible causes of Pelvis inflammation. There are likely to be other possible causes, so ask your doctor about your symptoms. 1  Osteomyelitis.  Septic arthritis (see Joint pain)