Age- and gender-specific magnetic resonance imaging findings in paediatric ankle trauma with negative radiographs

The objective of this study is to investigate the age- and gender-specific frequencies of different pathologies after ankle trauma with negative radiographs in children and adolescents. We retrospectively analysed the MRIs of 100 patients ≤ 18 years within 30 days after acute primary ankle trauma with negative radiographs. Patients were classified into three age groups: 0–11 years, 12–15 years, and 16–18 years. MRI detected pathological findings in 96 cases (96%): Lateral collateral ligament (n = 62), deltoid ligament injury (n = 10), syndesmosis injury (n = 12), Salter-Harris Type 1 fracture of the distal fibula (n = 2), bone bruise and marrow oedema (n = 32), soft tissue oedema and hematoma (n = 13), joint effusion and hematoma (n = 8), fracture (n = 12), osteochondral lesion of the talus (n = 2). Among LCL injuries, 21 cases (33.9%) affected the ATFL alone, 34 cases (54.8%) involved both the ATFL and CFL, 2 cases (3.2%) affected only the CFL, and 5 cases (8.1%) involved all three ligaments (ATFL, CFL and PTFL).The percentages of lateral collateral ligament and syndesmotic injuries both increased significantly with age (0–11 years: 43%, 12–15 years: 57%, and 16–18 years: 78%, p = 0.019; 0–11 years: 5%, 12–15 years: 5%, and 16–18 years: 24%, p = 0.015). There were no significant differences between the genders for any of the injuries (p≥ 0.539). In 24% of cases, injuries detected by MRI resulted in a modification of the clinical management. There is a high rate of injuries missed by radiographs but detected by MRI, with LCL injuries being the most common. The older the patient, the more likely it is that a syndesmotic injury will be detected with an MRI.