Joint effusion

Abnormal accumulation of intra-articular fluid within a synovial joint cavity, producing joint swelling, pain, stiffness, and restricted range of motion.

Causes

• Traumatic causes

  • Joint injury

  • Ligament sprain or tear

  • Meniscal injury

  • Fracture involving the joint surface

  • Hemarthrosis due to trauma

• Inflammatory causes

  • Rheumatoid arthritis

  • Systemic lupus erythematosus (SLE)

  • Psoriatic arthritis

  • Reactive arthritis

  • Postoperative joint inflammation

• Crystal-induced causes

  • Gout due to monosodium urate crystal deposition

  • Calcium pyrophosphate deposition disease (pseudogout)

• Infectious causes

  • Septic arthritis

  • Bacterial joint infection

  • Viral arthritis

  • Fungal or mycobacterial joint infection (rare)

• Degenerative causes

  • Osteoarthritis

  • Degenerative arthropathy

  • Cartilage breakdown with secondary synovitis

• Synovial tumors or proliferative disorders