Acute hematogenous osteomyelitis progressing to septic synovitis and eventual pyarthrosis. The vascular pathway.

A case suggesting sequential infection of bone, synovial membranes, and finally synovial fluid is presented. Hematogenous osteomyelitis manifests itself differently in children than in adults. In children, the avascular epiphyseal cartilage in the growing long bone is an effective barrier to the spread of bone infection to the joint. After obliteration of the growth plate, vascular anastomoses form between metaphysis and epiphysis, and at maturity the entire bone shares a common blood supply with the capsule and synovium of the adjacent joint. In the adult with acute osteomyelitis, contiguous joint infection should be anticipated. In septic arthritis, unless caused by penetrating trauma, the synovium must be infected before the joint fluid. Even when bacterial joint infection is present, repeated arthrocenteses may be required over several days to confirm the diagnosis.