Pseudogout (Chondrocalcinosis):

• In this condition, there is deposition of calcium pyrophosphate crystals in the joints. The wrist, knee and great toe are most commonly affected.
• The condition is called pseudogout, because symptoms are very similar to true gout. The difference is in the nature of crystals deposited.
• Examination of fluid shows rhomboid shaped crystals of calcium pyrophosphate and x-ray shows soft tissue swelling.

Septic Arthritis:

• When bacterial infection of the joint results in arthritis, the condition is called septic arthritis.
• Knee joint is the most commonly involved joint in septic arthritis.
• Symptoms include sudden onset of joint pain with redness and swelling and acute increase in pain on movement.

Rheumatoid Arthritis:

• Rheumatoid Arthritis is an autoimmune disease that results in a chronic, systemic inflammatory disorder that principally attacks flexible (synovial) joints.
• It is more common in women than in men.
• The symptoms include pain, redness, swelling, warmth and tenderness with damage to the protective cushion called synovium present between the joints.