Hopkins ABX Guide

Septic Arthritis

What is Septic Arthritis?

Septic arthritis is an inflammation of a joint or multiple joints due to an infection. Acute or less commonly chronic, the condition occurs when bacteria or other pathogens enter the joint either through bloodstream or directly (for example through an injury or surgery). The most common causes of septic arthritis are bacteria such as Streptococcus and Staphylococcus but it can also be caused by fungi such as Coccidiomyces, Candida and Histoplasma as well as viruses such as Hepatitis, Herpes viruses and Adenovirus, to mention only a few. The infection can also be developed in a prosthetic joint.

Who is at Risk of Septic Arthritis?

Some groups of people are more likely to develop septic arthritis. Factors that increase the risk of joint infection include certain underlying medical conditions such as rheumatoid arthritis, diabetes and immunocompromising conditions (cancer, HIV/AIDS), recent joint surgery or injury, joint prosthesis, open wounds, medications that suppress the immune system and age. Septic arthritis can be developed at any age including infancy but it most often affects older adults.

Symptoms of Septic Arthritis

If it is caused by a bacterial infection (and it most often is), symptoms of septic arthritis develop quickly. The infected joint is typically swollen and painful, while most patients also have a fever. Knee is the most commonly infected joint (approximately one half of all cases), followed by hip (every 1 in 5 patients). Other commonly affected joints are wrist, shoulder and ankle. Multiple joints can be infected but in most cases, only one joint is affected. If the infection is in prosthesis, signs and symptoms can be less apparent until a drainage occurs. The infection can be accompanied by abscess on the site of the joint.

Treatment of Septic Arthritis

Treatment of septic arthritis depends on the underlying cause. If it’s caused by a bacterial infection, it is treated with antibiotics up to about 6 weeks, depending on the bacteria causing the infection and the severity. It may also require drainage of the synovial (joint) fluid, while severe cases may require surgery. Most people recover without any lasting consequences but only under condition that they receive prompt treatment unless they may sustain permanent damage to the joint.