Final answer:
The likely diagnosis for a post-operative total arthroplasty patient presenting with severe throbbing pain, fever, and malaise is septic arthritis, which can arise from various underlying conditions and the introduction of bacteria during surgery.
Step-by-step explanation:
A post-operative total arthroplasty patient presenting to the ER with severe throbbing pain, fever, and malaise is likely experiencing septic arthritis. This condition is a form of acute infectious arthritis that can occur after invasive procedures like total joint replacements. Factors contributing to this infection may include underlying conditions such as HIV infection, previous bacterial or fungal infections, prosthetic joints, rheumatoid arthritis (RA), and immunosuppressive treatments such as chemotherapy. The onset of septic arthritis is normally in a single joint and can be indicated by a combination of symptoms including fever, acute pain, swelling, and mobility limitations.
Pathogens responsible for septic arthritis often enter the body via surgery, such as a total arthroplasty, direct trauma, or spread from another infected area through the bloodstream. A prompt diagnosis and treatment are crucial, as the condition can quickly lead to joint destruction and other severe complications. For diagnosis, joint fluid aspiration and cultures, along with blood tests, are typically performed to identify the responsible bacterium and tailor antibiotic treatment.