Differential Diagnosis for Recent Knee Arthroplasty with Joint Effusion and Soft Tissue Swelling on X-Ray

• Single Most Likely Diagnosis
  • Postoperative hemorrhage or hematoma: This is a common complication following knee arthroplasty, which can lead to joint effusion and soft tissue swelling due to blood accumulation in the joint and surrounding tissues.
• Other Likely Diagnoses
  • Infection (e.g., prosthetic joint infection): Early signs of infection can include joint effusion and soft tissue swelling, making it a critical consideration in the postoperative period.
  • Loosening of the prosthesis: Mechanical issues with the prosthesis can lead to inflammation and fluid accumulation.
  • Reactive synovitis: An inflammatory response to the surgical procedure or the presence of the prosthesis can cause joint effusion.
• Do Not Miss Diagnoses
  • Deep vein thrombosis (DVT): Although DVT might not directly cause joint effusion, it is a critical and potentially life-threatening condition that can occur postoperatively, especially in patients who are immobile.
  • Septic arthritis or osteomyelitis: These infections can have severe consequences if not promptly treated and can present with similar symptoms.
  • Nerve injury: Direct trauma to nerves during surgery can lead to significant morbidity if not recognized and addressed.
• Rare Diagnoses
  • Metallosis: A condition caused by the release of metal debris from the prosthesis, leading to an inflammatory response.
  • Systemic inflammatory response syndrome (SIRS) due to another cause: While less directly related to the knee arthroplasty, SIRS can occur due to infection or other systemic issues and might present with similar symptoms.
  • Complex regional pain syndrome (CRPS): A rare condition characterized by chronic pain, inflammation, and hypersensitivity following trauma or surgery.