Septic arthritis is a painful infection of a joint that can be caused by germs entering your bloodstream from another part of your body. Septic arthritis can also occur when a sting injury, such as an animal bite or trauma, releases germs directly into the joint.
Infants and older adults are more likely to develop septic arthritis. People with artificial joints are also at risk for septic arthritis. The knees are most commonly affected, but septic arthritis can affect the hips, shoulders, and other joints as well. The infection can damage the cartilage and bone in the joint quickly and severely. Therefore, immediate treatment is essential.
Septic arthritis usually causes extreme discomfort and difficulty in using the affected joint. The joint may be swollen, red, and hot, and you may have a fever.
If septic arthritis (infection of the prosthetic joint) develops in an artificial joint, signs and symptoms such as mild pain and swelling may appear months and years after knee or hip replacement surgery. In addition, there may be some loosening of the joint causing pain when moving the joint or when applying it to the joint. Usually the pain goes away with rest. In extreme cases, the joint can shift.
Septic arthritis can be caused by bacterial, viral, or fungal infections. Staphylococcus aureus (Staphylococcus) bacterial infection is the most common cause. Staphylococci also usually live on healthy skin.
Septic arthritis can develop when an infection, such as a skin infection or a urinary tract infection, spreads to a joint through your bloodstream. More rarely, a stab wound, drug injection, or surgery in or near a joint – including joint replacement surgery – can cause germs to enter the joint space.
The risk factors for septic arthritis are:
Existing joint problems. Chronic conditions that affect your joints, such as osteoarthritis, gout, rheumatoid arthritis, or lupus, can increase your risk of septic arthritis, as can previous joint surgeries and joint injuries.
Do you have an artificial joint? Bacteria can be introduced during joint replacement surgery, or an artificial joint can become infected if the germs travel to the joint from another area of the body through the bloodstream.
Take medication for rheumatoid arthritis. People with rheumatoid arthritis are at increased risk of suppressing the immune system and making infections more likely because of the drugs they take. Diagnosing septic arthritis in people with rheumatoid arthritis is difficult because many signs and symptoms are similar.
If treatment is delayed, septic arthritis can lead to joint degeneration and permanent damage. When septic arthritis affects an artificial joint, complications can include loosening or dislocation of the joint.