Sonication findings do not support routine removal of paediatric orthopaedic implants.

Purpose: The risk of implant-associated infection (IAI) is occasionally cited as an indication for routine removal of orthopaedic implants in children, but evidence is lacking. This study aimed at exploring the frequency of microbial colonization of paediatric orthopaedic implants by sonication, a gold standard for diagnosing IAI. Methods: Data of all patients aged <18 years at index implantation who underwent implant removal over a 34-month period at a single institution were retrospectively reviewed. Sonication culture results were classified according to microbial growth as negative (no/non-significant growth) or positive (significant growth/colonization). Descriptive statistics were performed, correlations were analysed via crosstabs and univariate ANOVA (p < 0.05). Results: One hundred and twenty-nine sonicated devices from 63 patients were included. Mean patient age at implantation was 9.8 years (standard deviation (SD) 3.4; range 3.0-15.6), mean implant in situ time was 2.2 years (SD 1.5; range 0.6-8.8). In all, 63 tension band plates, 35 locking screw plates, 26 cannulated screws, 3 intramedullary nails and 2 K-wires were evaluated. In total, 128/129 (99%) of implant sites were asymptomatic. Sonication fluid cultures of 24/128 (19%) implants from 21 asymptomatic patients showed non-significant growth of pathogens mainly related to the human skin microbiome, suggesting contamination. Conclusions: Sonication of implants removed from asymptomatic implant sites showed no significant microbial growth. Thus, the risk of IAI should be irrelevant for scheduling implant removal in children without signs and symptoms of infection. Significance of study: This study investigates for the first time the role of sonication in non-spinal paediatric orthopaedics and provides important insights into the question of routine implant removal in children, providing a foundation for future research.