You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

Purpose: Developmental dysplasia of the hip (DDH) ultrasound screening (USS), which is usually performed in Italy as an outpatient, was halted for an indefinite period in most centres during lockdown. The aim of this study was to analyze the effect of COVID-19 on DDH-USS, in two paediatric orthopaedic centres in one of the most critical areas of the western World. Methods: An academic teaching hospital and paediatric trauma centre (T) and a University hospital and DDH referral centre (H), classified as national COVID-19 hubs, were involved. Graf's method was applied in both centres. In T, paediatricians directly referred only patients with delayed DDH-USS or suspicious unstable hips; in H, paediatricians or parents could directly refer to the screening service. Results: The mean age of the 95 patients (190 hips) who were referred for DDH-USS in T, was 3.85 months (0.1 to 7.4); 175 were type I, nine were type IIa (+ and -), five type D and one type IV. In H, the screened patients in 2020 were only 78% of the same period in 2019. A total of 28 patients with 32 hips (8 IIb, 5 IIc, 8 D, 11 III) had late diagnosis at a mean age of 114 days (96 to 146). In the same period in 2019 only eight patients with 11 hips (8 IIb, 1 D, 1 III, 1 IV) at a mean age of 142 days (92 to 305) had late diagnosis. Conclusion: DDH-USS was the only screening in newborns which halted during lockdown. Few centres, which still performed diagnosis and treatment, were overloaded causing a delay in DDH management. Level of evidence: IV.
["Prevention"]