Septic arthritis
Updates to Article Attributes
Septic arthritis is a destructive arthropathy caused by intra-articular infection.
Clinical presentation
The diagnosis of joint sepsis is often considered straightforward. Patients often present with a painful joint, fever, and purulent synovial fluid.
Pathogenesis
Risk factors for septic arthritis include bacteraemia, advanced age, an immunocompromised state, rheumatoid arthritis, intra-articular injections, and prosthetic joints.
In the absence of trauma or recent instrumentation of the joint, septic arthritis is usually secondary to haematogenous seeding. S aureus is the most commonly isolated agent (31.3% of casesref).
Location
Large joints with abundant blood supply to the metaphyses are most prone to bacterial infection, with the most commonly affected joints theoretically being the shoulder, hip, and knee.
In intravenous drug abusers, the sternoclavicular joint is more frequently affected.
Radiographic features
Imaging generally plays an adjunct role to arthrocentesis in the diagnosis of joint sepsis. If synovial fluid cannot be retrieved, however, radiologic studies become of the utmost importance.
Plain film
- destruction of subchondral bone on both sides of a joint
- juxta-articular osteoporosis
- joint effusion may be seen
CT
- CT features of septic arthritis include a joint effusion and bone erosions around the joint
- a fat-fluid level can be a specific sign in the absence of trauma
MRI
- sensitive for early cartilaginous damage
- synovial enhancement
- perisynovial oedema
Treatment and prognosis
If unrecognised and left untreated, septic arthritis can result in irreversible joint damage within 48 hours of the onset of infection due to the proteolytic enzymes of the white blood cells that flood the infected synovial space.
Conversely, approximately 90% of patients with septic arthritis will recover with appropriate antibiotic treatment.Therefore, timely diagnosis and treatment are critical.
See also
-<li><a href="/articles/differential-diagnosis-of-erosive-arthritis">differential diagnosis of erosive arthritis</a></li>-<li><a href="/articles/monoarticular-arthropathy">monoarticular arthropathy</a></li>