Anterior tibiotalar fat pad morphology and signal intensity on magnetic resonance imaging are correlated with patient characteristics and joint pathology

Purpose: In this study, we tried to investigate the innovative concept of the ATFP as missing link in the pathogenesis of persistent complaints after ankle sprain and potential source driving inflammation in the development of ankle osteoarthritis. Methods: The present study is a secondary analysis of an observational case control study by Van Ochten et al. We included 106 patients with a Kellgren & Lawrence score of 0 in the tibiotalar joint on x-ray. T1 MRI scans were assessed for the signal intensity and area of the ATFP by mapping the fat pad in ‘Mimics 18.0’. After importing those mapped scans in the program ‘MATLAB’, quantitative values of intensity and area were generated. Those values were statistically tested for correlations with patient characteristics and structural abnormalities by univariate and multivariate linear regression. Results: MRI signal intensity of the ATFP is associated with BMI (p= 0.03), sex (p<0.01) and age (p= 0.01). ATFP area is correlated with sex (p<0.01) and presence of pre-OA signs in the subtalar joint (p= 0.01). After multivariate analysis, correcting for sex, subtalar pre-OA signs and BMI, persistent complaints were associated with ATFP area (p= 0.04). Conclusions: This study demonstrates the involvement of the ATFP in hindfoot joint pathology. ATFP MRI characteristics were also influenced by patient characteristics. Further research should confirm these findings in a more elaborate population including OA patients, focus on histological validation and determine underlying pathogenic processes that may explain the observed correlations.