Abstract

Introduction There is uncertainty around the pathogenesis and prevalence of distal femoral cortical irregularities (DFCI). We aimed to assess the prevalence of DFCI in a cohort of adolescents that underwent MRI and identify and assess associated risk factors. Methods A historical cohort study of adolescents (age 10 - <20 years) undergoing MRI scans was conducted. Data was collected for a period of five years using the Picture Archive and Communication System database at a large tertiary hospital. Data collected included sex, age, mechanism of injury and other pathology present in the original MRI report. Binary logistic regression was used to investigate potential risk factors for DFCI. Results 897 scans (mean age, 15.3 (SD 2.59) years; 499 (55.6 %) male) were analysed. Prevalence of DFCI among adolescents who had a MRI scan was 9.1 % (95 % CI: 7.3 %–11.2 %). Patients that had experienced DFCI were younger than those that had not (mean age 14.5 vs 15.3 years, P = 0.002). The mechanism of injury differed between patient groups (P = 0.015); Patients with DFCI were more likely to have had a patella instability/dislocation (22.8 % vs 16.1 %), and less likely to have had a pivotal knee injury (12.7 % vs 29.0 %). When compared to patients aged 10–13 years, older children had reduced odds of a DFCI: 13–16 years had an adjusted odds ratio (aOR) of 0.79 (95 % CI: 0.45 to 1.39); 16–20 years (aOR = 0.36; 95 % CI: 0.18 to 0.71). Males had reduced odds of a DFCI (aOR = 0.38; 95 % CI: 0.22 to 0.66). Conclusions Female sex and younger age were risk factors for development of DFCI. There was no statistically significant association between mechanism of injury and developing a DFCI. Further research is required to establish its prevalence in those who are asymptomatic and why younger adolescent females are more likely to experience DFCI.