Epidemiology of childhood bone and joint disease during the COVID-19 pandemic in New Zealand.

Purpose: It is unknown whether social distancing impacts frequency of presentation and severity of childhood bone and joint infection (BJI). In New Zealand, the COVID-19 disease elimination strategy involved strict social isolation policies spanning March 2020-September 2022. Examination of this period may provide insight around risk factors for BJI.

Methods: A retrospective review of all patients < 16 years with presumed acute haematogenous osteomyelitis (AHO) or septic arthritis (SA) treated in the Auckland region was performed between 2018 and 2023. Frequency and severity of presentations has been examined before, during, and after periods of social restriction. Severe cases included those with intensive care admission, recurrent infection, or multiple surgeries. Pre-hospital experience, length of stay, and disease outcomes have also been assessed.

Results: A total of 563 cases met inclusion criteria. Compared to the pre-pandemic period, monthly case averages reduced between April 2020 to September 2022 (10.1 vs. 7.9 cases/month, p = 0.008). Separating cases by causative microbiology shows a statistically significant drop in culture negative and Kingella kingae mediated BJI cases (4.2 vs. 2.9 cases/month, p = 0.006) but not for cases secondary to Staphylococcus aureus and Streptococcus pyogenes (4.2 vs. 3.9 cases/month, p = 0.6). The frequency of severe disease reduced during this period (5.6 vs. 4.1 cases/month, p = 0.01) together with lower rates of recurrent infection (9% vs. 4%, p = 0.03).

Conclusion: The COVID-19 management strategy in New Zealand utilised strict social isolation, mask wearing, and hand hygiene measures to control disease spread between 2020 and 2022. These measures coincided with reduction in frequency and severity of presentations for childhood BJI.