Definition

Septic arthritis is a serious infection of the joints caused by bacteria. This infection causes the joint to be filled with pus cells. These pus cells release substances directed against the bacteria. However, this action can damage the joint structures, bone, and surrounding cartilage.

Causes

Septic arthritis develops when bacteria spreads from the source of infection through the bloodstream to a joint. It can result from:

• Infection due to an injection
• Surgery
• Other infections

Septic arthritis can also be caused from injury or trauma. It can result from:

• A penetration wound
• An injury that affects the joint
• Joint surgery/replacement

Septic arthritis can strike at any age. However, it occurs most often in children aged 3 and younger. In infants, the hip is a frequent site of infection. In toddlers, it is the shoulders, knees, and hips.

Septic arthritis rarely occurs from early childhood through adolescence. After that, it occurs more often. In adults, it most commonly affects weight-bearing joints, such as the knees.

Risk Factors

Factors that may increase your chance of developing septic arthritis include:

• Diseases that weaken the immune system, such as HIV or taking drugs that suppress immunity
• A history of joint problems or having other types of arthritis, gout, or lupus
• A history of IV drug use
• Chronic illnesses, such as anemia, diabetes, sickle cell, and kidney failure
• Joint replacement or organ transplant surgery
• Recent joint

  injections, such as cortisone or hyaluronic acid

• Alcoholism
• Skin conditions, such as psoriasis and eczema

Symptoms

Symptoms may include:

• Newborn or infants
  • Crying when a joint is moved, such as during a diaper change
  • Inability to move the limb of a joint
  • Swelling and redness
  • Irritability
  • Fever
  • Persistent crying for any reason
• Children and adults
  • Intense joint pain
  • Joint swelling and redness
  • Fever
  • Chills
  • Inability to move a joint or its limb
  • Limping

Diagnosis

You will be asked about you or your child’s symptoms and medical history. A physical exam will be done. Your doctor may refer you to a specialist.

Bodily fluids may need to be tested. This can be done with:

• Testing joint fluids
• Blood tests

Images may be taken of your bodily structures. This can be done with:

• X-rays
• MRI scan

Treatment

Antibiotic therapy is started as soon as a diagnosis is made. In the beginning, antibiotics are given by IV. This is to ensure that the infected joint receives medication to kill the bacteria. The specific medications used depend on the type of bacteria that is causing the infection. The remaining course of antibiotics may be given by mouth.

Fluid may be removed from the joint to reduce the likelihood of joint damage. This may be done either by placing a needle in the joint or through surgery.

Rest, preventing the joint from moving, and warm compresses may be used to manage pain. Physical therapy or exercises may also speed recovery.

Prevention

To help reduce your chance of getting septic arthritis, get prompt treatment of infections that could lead to septic arthritis.

National Institute of Arthritis and Musculoskeletal and Skin Disease http://www.niams.nih.gov

Health Canada http://www.hc-sc.gc.ca

Howard A, Wilson M. Septic arthritis in children. BMJ. 2010;341:c4407.

Ma L, Cranney A, et al. Acute monoarthritis: what is the cause of my patient’s painful swollen joint? CMAJ. 2009;180(1):59-65.

Septic arthritis. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated April 11, 2013. Accessed June 29, 2015.

Septic arthritis. Patient UK website. Available at
http://www.patient.co.uk/health/septic-arthritis-leaflet
Updated August 30, 2013. Accessed June 29, 2015.