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Last updated: July 19, 2025View editorial policy

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Differential Diagnosis for Knee Stiffness and Swelling

Single Most Likely Diagnosis

  • Osteoarthritis (OA): This is the most common cause of knee stiffness and swelling, especially after physical activity or standing. OA is a degenerative joint disease characterized by cartilage breakdown, leading to joint pain, stiffness, and swelling.

Other Likely Diagnoses

  • Meniscal Tear: A tear in the meniscus, which is the cartilage that cushions the knee joint, can cause knee stiffness, swelling, and pain, especially after physical activity.
  • Ligament Sprain: A sprain in one of the knee ligaments can cause knee stiffness, swelling, and pain, particularly after physical activity or standing.
  • Tendinitis: Inflammation of the tendons surrounding the knee joint can cause knee stiffness, swelling, and pain, especially after physical activity.
  • Bursitis: Inflammation of the fluid-filled sacs (bursae) that cushion the knee joint can cause knee stiffness, swelling, and pain, especially after physical activity or standing.

Do Not Miss Diagnoses

  • Septic Arthritis: A bacterial infection in the knee joint can cause severe knee stiffness, swelling, and pain, and can lead to serious complications if not promptly treated.
  • Deep Vein Thrombosis (DVT): A blood clot in the deep veins of the leg can cause knee stiffness, swelling, and pain, and can lead to life-threatening complications if not promptly treated.
  • Osteonecrosis: A condition where the bone tissue dies due to lack of blood supply can cause knee stiffness, swelling, and pain, and can lead to serious complications if not promptly treated.

Rare Diagnoses

  • Rheumatoid Arthritis (RA): An autoimmune disease that causes inflammation and pain in the joints, including the knee, can cause knee stiffness, swelling, and pain.
  • Gout: A type of arthritis caused by the buildup of uric acid crystals in the joints can cause knee stiffness, swelling, and pain, especially after physical activity or standing.
  • Pseudogout: A type of arthritis caused by the buildup of calcium pyrophosphate dihydrate crystals in the joints can cause knee stiffness, swelling, and pain, especially after physical activity or standing.
  • Hemophilia: A genetic disorder that affects the blood's ability to clot can cause knee stiffness, swelling, and pain, especially after physical activity or trauma.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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