In addition to the examination of clinical signs, several laboratory markers have been measured for diagnostics and monitoring of pediatric septic bone and joint infections. Traditionally erythrocyte sedimentation rate (ESR) and leukocyte cell count have been used, whereas C-reactive protein (CRP) has gained in popularity. We monitored 265 children at ages 3 months to 15 years with culture-positive osteoarticular infections with a predetermined series of ESR, CRP, and leukocyte count measurements. On admission, ESR exceeded 20 mm/hour in 94% and CRP exceeded 20 mg/L in 95% of the cases, the mean (± standard error of the mean) being 51 ± 2 mm/hour and 87 ± 4 mg/L, respectively. ESR normalized in 24 days and CRP in 10 days. Elevated CRP gave a slightly better sensitivity in diagnostics than ESR, but best sensitivity was gained with the combined use of ESR and CRP (98%). Elevated ESR or CRP was seen in all cases during the first 3 days. Measuring ESR and CRP on admission can help the clinician rule out an acute osteoarticular infection. CRP normalizes faster than ESR, providing a clear advantage in monitoring recovery. Level of Evidence: Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Acute septic arthritis in children is usually hematogenous. It is more common in boys, and it most often affects the large joints of the lower limb. Diagnosis is based on cultures obtained from the infected joint and is supported by C-reactive protein blood test or ultrasound imaging. Staphylococcus aureus is the most common causative agent and is the primary target for empiric treatment. First-generation cephalosporins and clindamycin are suitable antibiotics. Vancomycin is utilized in areas with high rates of clindamycin- and methicillin-resistant S. aureus. After a short intravenous administration of 2–4 days, a total course of 2 weeks is sufficient in uncomplicated cases. Early antibiotic treatment has significantly improved the prognosis in high-income settings, but uncomplicated recovery is compromised if the treatment is delayed. Complications such as symptomatic osteoarthritis or avascular necrosis of the femoral head develop slowly. A long follow-up of 1–2 years is required to detect all possible sequelae.

In our multicenter treatment study on pediatric nonneonatal osteoarticular infections we had 62 septic hip arthritides. All had confirmed joint effusion, were culture-positive, and Staphylococcus aureus was isolated in 71% of the cases. Sixty-one of the 62 had a diagnostic joint aspiration. Following protocol, arthrotomy was to be performed only if the response to antimicrobial treatment was slow. The course of illness was monitored by preset criteria. Analysis of 95% of the patients who attended the last checkup ≥1 year posthospitalization showed that invasive surgery had been avoided in 81% of the patients. All patients recovered completely. Routine arthrotomy in nonneonatal hip arthritis warrants reconsideration.

Acute septic arthritis of childhood is a potentially devastating disease that causes permanent disability and can result in death. Traditional treatment consists of a prolonged course of intravenous antibiotics combined with aggressive surgery. However, this approach is challenged by trials showing satisfactory outcomes with shorter treatment and less invasive surgery. Diagnostic arthrocentesis alone and an antibiotic for a fortnight, including initial intravenous administration for 2–4 days, suffice in most non-neonatal cases. A good penetrating agent, such as clindamycin or a first-generation cephalosporin, exceptionally high doses, and administration four times a day are probably key factors. If the symptoms and signs subside within a few days, and the serum C-reactive protein level drops below 20 mg/l, the antibiotic can usually be safely discontinued. Methicillin-resistant Staphylococcus aureus is a concern, but fortunately, most strains have retained susceptibility to clindamycin. The above guidance is not applicable to neonates and immunocompromised patients who may require a different approach.

Acute septic arthritis is a rare, but potentially devastating disease. The treatment is initiated intravenously, but can be safely switched to oral after 2-4 days providing large doses of a well-absorbing antibiotic and, for time-dependent antibiotics, 4 times-a-day administration are used. Empiric treatment should always cover Staphylococcus aureus and common respiratory pathogens, whereas Kingella kingae and Salmonella are important only regionally. Studies conducted by our group have shown that a total course of 10 days may suffice for previously healthy children in a Western setting. Treatment of neonates, patients with immunodeficiency or cases caused by methicillin-resistant S. aureus, may deserve a different approach.