Septic arthritis presents with a joint that is painful, hot, swollen, and restricted.
Diagnosis is based on the opinion of the clinician experienced in the management of musculoskeletal disease.
In all cases of suspected native joint sepsis, the joint should be aspirated.
In all cases of suspected septic arthritis, empirical antibiotic therapy should be commenced once appropriate cultures have been taken.
Septic arthritis is defined as the infection of 1 or more joints caused by pathogenic inoculation of microbes. It occurs either by direct inoculation or via hematogenous spread.
History and exam
Key diagnostic factors
- hot, swollen, tender, restricted joint
Other diagnostic factors
- low socioeconomic status
- history of intravenous drug abuse
- history of diabetes
- history of cutaneous ulcers
- prosthetic joint
- history of rheumatoid arthritis or osteoarthritis
- short history of symptoms
- history of alcohol use disorder
- history of previous corticosteroid injection
- underlying joint disease
- joint prostheses
- contiguous spread (presence of cutaneous ulcers or skin infection)
- previous intra-articular corticosteroid injection
- recent joint surgery
1st investigations to order
- synovial fluid Gram stain and culture
- synovial fluid white cell count
- blood culture
- white cell count
- erythrocyte sedimentation rate
- plain radiograph
Investigations to consider
suspected gram-positive infection or negative Gram stain
suspected gram-negative infection
confirmed MSSA or streptococcal infection
confirmed MRSA infection
confirmed gram-negative rods infection
confirmed gonococcal or meningococcal infection
infection with fungi/tuberculosis/other organisms
Gerald Coakley, PhD, FRCP
Queen Elizabeth Hospital
GC is an author of a reference cited in this topic.
Catherine J. Mathews, MSc, FRCP
Queen Elizabeth Hospital
CJM is an author of a reference cited in this topic.
Andrew Keat, MBBS
Consultant Physician and Rheumatologist
Northwick Park Hospital
AK declares that he has no competing interests.
Cheryl Main, MD, FRCPC
Infectious Disease Consultant
Hamilton Regional Laboratory Medicine Program
Hamilton Health Sciences
CM declares that she has no competing interests.
John Ross, MD
Brigham and Women’s Hospital
JR declares that he has no competing interests.
- Psoriatic arthritis
- Rheumatoid arthritis
- Hot joint guideline update
- ACR appropriateness criteria: suspected osteomyelitis, septic arthritis, or soft tissue infection (excluding spine and diabetic foot)
Aspiration and injection of the knee: animated demonstration
Venepuncture and phlebotomy: animated demonstrationMore videos
- Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer