Septic arthritis is an infection of one of the joints which can quickly lead to joint destruction if left untreated.

Involvement may mono- or poly-articular. Contamination of the joint can occur by several mechanisms including hematogenous or contiguous spread, and postoperative infectious. Direct implantation of organisms can also occur from a hand injury during a brawl, or penetration from a nail, knife, etc. The metacarpophalangeal joints are key target sites of involvement during fist fights.

Radiographic Appearance:
Early findings include soft tissue swelling and effusions. With progression of the infectious process, destruction of articular cartilage and bone can lead to radiographic findings of poorly defined articular erosions and joint space narrowing. Juxtaarticular osteoporosis and central erosions can also be noted and ankylosis of the joint may eventually result in the most severe cases.

Differential Diagnosis:

Although other disorders such as rheumatoid arthritis or PVNS may be the actual underlying cause, an infectious etiology must be considered when the radiographic findings of a mono-articular destructive process are present. Superimposed septic arthritis on a chronic arthropathy such as rheumatoid arthritis may be difficult to differentiate from the preexisting articular disorder.



Rheumatoid Arthritis
Psoriatic Arthritis
Calcium Pyrophosphate Deposition Disease
Multicentric Reticulohistiocytosis
Septic Arthritis