Acute haematogenous osteomyelitis in Lisbon: an unexpectedly high association with myositis and arthritis

Despite the current trend toward less aggressive therapeutic approaches, acute haematogenous osteomyelitis (AHO) continues to be a challenge and is associated with significant morbidity worldwide. Our aim was to assess whether compliance with the current protocol was achieved in 80% of cases, to identify complications and the associated risk factors, and to analyse trends in the aetiology and management of AHO in the paediatric population.We conducted a longitudinal, observational, single-centre study in patients with AHO aged less than 18 years admitted to a paediatric hospital between 2008 and 2018 divided in 2 cohorts (before and after 2014). We analysed data concerning demographic and clinical characteristics and outcomes.The study included 71 children with AHO, 56% male, with a median age of 3 years (interquartile range, 1-11). We found a 1.8-fold increase of cases in the last 5 years. The causative agent was identified in 37% of cases: MSSA (54%), MRSA (4%), S. pyogenes (19%), K. kingae (12%), S. pneumoniae (8%), and N. meningitidis (4%). Complications were identified in 45% of patients and sequelae in 3.6%. In recent years, there was an increase in myositis (30% vs 7%; P=.02), septic arthritis (68 vs 37.2%; p=0.012) and in the proportion of patients treated for less than 4 weeks (37 vs 3.5%; p=0.012), with a similar sequelae rates. The risk factors associated with complications were age 3 or more years, C-reactive protein levels of 20mg/L or higher, time elapsed between onset and admission of 5 or more days and positive culture, although the only factor that continued to be significantly associated in the multivariate analysis was positive culture. The presence of complications was a risk factor for sequelae at 6 months.Our study confirms that AHO can be aggressive. The identification of risk factors for complications is essential for management.