Bone marrow edema in the foot—MRI findings after conservative therapy

Abstract

Bone marrow edema (BME) is a rare cause of pain in the foot. We reviewed 23 patients with unilateral idiopathic bone marrow edema located in the foot. The patients' mean age was 59.1 years (32–73). Bone marrow edema was located 12 times in the talus, four times in the cuneiform bones, four times in the metatarsal bones, two times in the calcaneus, and once in the navicular bone. Edema secondary to an activated osteoarthritis, to mechanic stress, to a chronic regional pain syndrome or to trauma were excluded. The size of BME was categorized large in nine cases (50–100% of the bone involved), in nine cases medium (25–50%) and in five cases small (<25%).

Conservative therapy consisted of infusions with the vasoactive substance iloprost and limited weight-bearing for a period of three weeks. After 3 months, in 15 patients BME showed total regression on MRI scan. In three there was subtotal regression and in three no change in the size of the BME (p<0.0001).

No correlation between the primary size of BME and outcome was seen (p=0.453). No progression to AVN occurred in our patients. In two patients BME appeared to migrate to neighbouring bones and in one patient to a femoral head.

Conclusions. Bone marrow edema syndrome is rarely seen in the foot. Progress to avascular necrosis is unlikely. Conservative therapy can be recommended.

Introduction

Bone marrow edema (BME) can be found as a primarily ischemic disease, mainly of the femoral head, with a lower incidence in other localizations. Only a few cases of BME in the foot have been published in the literature [1], [2], [3], [4], [5], [6], [7], [8]. Different treatment options have been reported, mainly for the femoral head and the knee. These include symptomatic non-operative treatment (reduction of weight bearing, analgesic and anti-inflammatory medication, physical therapy) and surgical treatment such as decompression (alone or in combination with electromagnetic stimulation or bone grafting). Several authors have reported a relationship between transient bone marrow edema to avascular necrosis [9], [10], but the incidence of progress from bone marrow edema to avascular necrosis is still unclear. There is still controversy as to whether ischemic bone marrow edema syndrome (BMES) reflects a distinct self-limiting disease, a kind of reflex sympathetic dystrophy [11], [12], or a diffuse but reversible early phase of avascular necrosis [9], [13]. Although there is consensus about different vascular factors contributing to bone marrow edema syndrome and avascular necrosis, the exact pathogenesis remains unclear. Current theories include thromboemboli, obstruction of arteriolar inflow or venous outflow, injury to the vessel wall caused by vasculitis, altered lipid metabolism and decreased fibrinolysis [14], [15], [16].

The aim of this prospective MRI study was to assess the course of bone marrow edema after conservative therapy with the vasoactive drug iloprost and partial weight-bearing.