Risk of repeated drainage in pediatric septic arthritis: patient or method?

How drainage of septic arthritis should be performed remains controversial. The aim of the present study was to compare arthrocentesis (Ac) using double intra-articular needle lavage to arthrotomy (At) as first-line drainage treatment for pediatric hip and knee septic arthritis. The secondary objective was to identify risk factors of second articular drainage. A retrospective review of medical records of children with knee and hip septic arthritis was conducted. Inclusion criteria were: children treated for septic arthritis between 2014 and 2020 with a positive culture of joint fluid. Clinical, biological, radiographical and ultrasound data were recorded at presentation and during follow-up. Patients were divided into 2 groups according to the type of drainage performed: Ac or At. 25 hips and 44 knees were included, 42 treated by Ac (15 hips, 27 knees) and 27 by At (10 hips, 17 knees). There is no significant difference between Ac and At regarding the need for repeated drainage and Ac nor At was reported as risk factor for repeated drainage. The presence of associated musculoskeletal infection (MSI) was a significant risk factor of repeated drainage [odds ratio = 11.8; 95% confidence interval = 1.2-114.2; P < 0.001]. Significantly more associated MSI (P < 0.001), level I virulence germs (P < 0.001) and positive blood culture (<0.001) were found in patients who underwent repeated drainage. There was no significant difference between Ac and At regarding rate of repeated drainage. The risk factors for repeated drainage were: associated with MSI, virulent germs and positive blood culture.