Pediatric emergency medicine trisk 1165 1165

that there are regional variations in virulence factors or causative organisms in
septic arthritis of which clinicians should be aware.
Often, based on clinical findings, a physician can make a diagnosis of transient
synovitis without the need for laboratory testing or arthrocentesis. In more
equivocal cases, inflammatory markers may be helpful and Lyme testing should
be considered.
Inflammatory markers are usually elevated in patients with osteomyelitis, as
well. In contrast to those with septic arthritis, children with osteomyelitis have a
more subacute onset of pain, are less likely to be febrile, have focal bony
tenderness, will have greater range of motion at the joint, and may not have signs
of joint inflammation.
Legg–Calvé–Perthes disease, a condition of uncertain cause, occurs
overwhelmingly in boys, with an onset between 4 and 8 years of age. The pain,
which may be localized to the hip or referred to the thigh or knee, is insidious in
onset. The aseptic or avascular necrosis of the femoral head will be manifest on
plain radiographs as a small, osteopenic femoral head with a widened joint space
although films obtained early in the clinical course may be normal.

Polyarthritis
Historical and physical examination findings help narrow the choices among the
many causes of polyarthritis and fever ( Tables 60.4 and 60.5 ). The ill-appearing
adolescent with migratory arthritis, tenosynovitis involving the extensor tendons
of the wrist or ankle, and scattered crops of vesiculopustules should be strongly
suspected for gonococcal arthritis. This occurs three to five times more often in
girls, often during menstruation. Of note, patients may report lower abdominal
pain or vaginal discharge concurrently, and cultures of blood and synovial fluid
are typically negative. The highest yield for establishing the diagnosis is by Gram
stain of the skin lesions or by recovering the organism from the cervix, rectum, or
throat.