Magnetic Resonance Imaging: Marrow Edema Patterns in Chronic Foot Pain

Objectives: The objective of the study was to determine whether there are specific magnetic resonance (MR) marrow edema patterns in patients with chronic foot pain and whether the individual small bones contribute significantly to pain. Material and Methods: A total of 153 symptomatic consecutive MR studies of patients with chronic foot pain and altered bone marrow signals of the foot and ankle were included in the study. Patients were placed into subgroups based on medial, central, or lateral marrow edema patterns. All cases with a clinical history or MR features of trauma, infection, inflammatory diseases, and tumors were excluded from the study. Statistical analysis was conducted to determine whether the marrow edema in each small bone of the subgroup was significant for the contribution of pain. Results: There were 84, 41, and 28 cases (153 patients) for the medial, central, and lateral marrow edema subgroups, respectively. The medial talus and medial and lateral sesamoid bones achieved statistical significance for an association between pain and marrow edema on MR images. Of the central group, sinus tarsi was statistically significant as a contributor of pain. None of the lateral bones were statistically significant as contributors of pain. Conclusion: Abnormal bone marrow edema patterns of the foot including the ankle on MRI fall into specific patterns of the medial, central, and lateral foot. This could be attributed to altered mechanical weight-bearing axis. The normal mechanical weight-bearing axis for the purpose of this study was along the long axis of the 2nd metatarsal, akin to the underlying seen in March fractures. The medial bone marrow edema was deemed to be a result of medial deviation of the normal mechanical weight-bearing axis, resulting in the marrow edema from the abnormal stress forces. The bone marrow edema pattern along the 2nd metatarsal was considered on the basis of excessive mechanical stress forces. The marrow edema pattern along the lateral foot, 4th and 5th metatarsals, and the lateral talus, calcaneus, and cuboid, was considered as a lateral deviation of the normal axis resulting in the abnormal stress and marrow edema pattern within these bones. By defining bone marrow edema patterns, we can assist orthopedic surgeons, physiatrists, and physiotherapists to provide appropriate corrective treatment including orthotics and physiotherapy. These MR features can also provide a baseline to monitor interval improvement after the application of the corrective measures.