Prevalence of bone marrow edema in a study population with foot and/or ankle pain.

Bone marrow edema (BME) is an imaging diagnosis defined by an abnormal accumulation of intraosseous interstitial fluid within a bone on magnetic resonance imaging (MRI) investigation. The aim of this study was to determine the prevalence of BME in patients with foot and/or ankle pain studied using MRI. This was a retrospective observational work on patient cases and controls studied through MRI of the foot and/or ankle at our Foot and Ankle Unit (FAU). An analytical statistical analysis and a multivariate analysis were performed to eliminate possible confounding factors. 1950 foot and/or ankle MRI cases were reviewed, of which 451 presented bone edema (23% prevalence). The average patient age was 51.8 (range, 7-87); the talus bone was most frequently affected: post-traumatic in 43.5% of cases, degenerative in 34.7% and there was no specific cause identified in 6.3% (these cases were termed 'idiopathic'). With regards to risk factors, in the case of gender, the odds ratio (OR) of men suffering bone oedema was 1.5 times higher than that of women (P = 0.003); for immunosuppression the OR was 3.4 times higher (P = 0.001); while among those with a smoking habit it was 0.59 (P = 0.001), meaning that after ruling smoking out as a possible confounding factor, it was, in fact, revealed to be a protective factor. The prevalence of bone edema in MRI in patients with foot and/or ankle pain was 23%. The average patient was male, aged approximately 50, with traumatic or degenerative origin talus bone oedema. Level of Evidence: Level IV, revision observational study.