Clinical images: Bone marrow edema syndrome

Abstract

The patient, a 55-year-old male farmer who had been in good health, presented 1 month after acute onset of sharp pain in the left groin, which was subsequently progressive and exacerbated with weight bearing. He denied having radicular or constitutional symptoms or antecedent trauma, and had no history of corticosteroid treatment. Passive hip range of motion reproduced the pain. Radiography of the left hip yielded normal results. Magnetic resonance imaging (MRI), with T1 weighting (A) and T2 weighting (B) revealed diffusely increased T2 signal with partial loss of T1 signal, consistent with bone marrow edema involving the femoral neck and head. There was moderate soft tissue edema in the adjacent fat, vastus intermedius, and adductor muscles. No evidence of fracture, mass, or avascular necrosis was present. These findings are consistent with bone marrow edema syndrome (BMES) of the hip, a condition first described in pregnant women. Men in the fourth to seventh decade of life, however, account for >66% of cases (1). Idiopathic transient osteoporosis of the hip is perhaps the term most commonly used to identify this disease. The term BMES has recently been introduced, based on the characteristic MRI findings. Patients present with progressive, ill-defined, unilateral hip pain which is described as a deep ache that localizes to the medial or anterior thigh without radiation below the knee. Symptoms present acutely without inciting trauma and are often quite disabling. Pain worsens primarily with weight-bearing activity, which may lead to impaired function (2). Pain at rest, back pain, and neurologic dysfunction are not characteristic of BMES and would suggest an alternative diagnosis. Physical examination findings include an antalgic or compensated Trendelenburg's sign. The most common finding is guarding during hip range of motion, especially with abduction or rotation of the hip. Tenderness over the greater trochanter and adjacent adductor and hip flexor muscle groups may be present. Provocative tests with flexion in abduction and external rotation, resisted straight-leg raise, or hip joint compression or rotation loads may result in reproduction of pain. Results of spine and knee examination as well as neurologic examination will be normal. MRI demonstrates diffuse, ill-defined signal change of the affected region. There is increased T2-weighted signal with a corresponding low signal on T1-weighted images, and the edema is often best recognized on coronal plane sections. The bone cortex may appear thinned but is always intact, and, unlike findings in avascular necrosis, there should be no evidence of subchondral defects (3). After 3 months of conservative therapy, the patient's symptoms were improving. BMES has distinct clinical and radiologic features and should be considered in active middle-aged adults with acute spontaneous hip pain.