Clinical characteristics of and risk factors for poor outcomes in children with bacterial culture-negative septic arthritis of the hip

Background

Septic arthritis of the hip is a serious infection in children. However, blood and joint fluid cultures are often negative, which makes the diagnosis and treatment challenging. We analyzed the clinical features of children with septic arthritis of the hip with negative bacterial cultures and identified the risk factors for poor outcomes.

Methods

The clinical data of children with septic arthritis of the hip with negative bacterial cultures who were treated at our hospital from January 2010 to December 2020 were retrospectively analyzed. The clinical characteristics and outcomes of the culture-negative cohort were compared with those of children with positive bacterial cultures treated during the same period. Culture-negative patients were divided into a group with good outcomes and a group with poor outcomes. The differences between the two groups were compared.

Results

Thirty-nine children with culture-negative septic arthritis of the hip were compared with 37 children with culture-positive sepsis. Compared with the culture-positive group, the culture-negative group had a significantly younger mean age and a significantly lower mean serum C-reactive protein concentration. Logistic regression analysis of culture-negative patients with good versus poor outcomes revealed that the independent risk factors for poor outcomes were an increased serum C-reactive protein concentration and prolonged time from onset to surgery. The cut-off values for predicting a poor outcome in the culture-negative group were a time from onset to surgery of greater than 21 days and a C-reactive protein concentration of greater than 23 mg/L.

Conclusions

Culture-negative septic arthritis of the hip has similar clinical features to culture-positive septic arthritis of the hip and can result in sequelae of varying severity. Therefore, active anti-infective and hip drainage therapy should be performed when children present with clinical symptoms, inflammatory marker concentrations, and imaging findings that are clinically diagnostic for septic arthritis of the hip.

Level of evidence

Level II, retrospective study.