What are the characteristics of septic arthritis on plain film radiography?

Early findings: few if any bony changes, although soft tissue swelling and joint effusions may be present.
Late findings: juxta-articular cortical destruction (osteomyelitis) or osteopenia and secondary degenerative changes.
1. Destruction of articular cartilage and bone
2. Joint effusion
3. Soft tissue swelling
4. Osteoporosis