Repeated Low Back Pain Caused by Regional Migratory Osteoporosis of the Sacroiliac Joint

INTRODUCTION: Regional migratory osteoporosis (RMO) is a rare, self-limiting disorder characterized by migratory arthralgia that mainly occurs in the weight-bearing joints of the lower extremities. RMO is most commonly observed in middle-aged men, and its etiology is unknown. We report the case of a middle-aged man who experienced repeated low back pain that was caused by RMO of the sacroiliac joint (SIJ). CASE REPORT: In this case, the patient initially complained of left low back pain; however, there were no specific findings in plain radiography of the lumbar spine and pelvis. In addition, blood chemistry test findings were normal. Magnetic resonance imaging (MRI)revealed a diffuse bone marrow edema in the left SIJ. Conservative treatment was effective, and the pain was relieved within 3 months. However, 2 months later, a similar pain developed on the right side. MRI showed bone marrow edema in the right SIJ and the left-sided lesion had disappeared. The symptom was relieved by conservative treatment. After 5 months, the pain disappeared and the MRI findings became normal. During the next 2 years of follow-up, there is no recurrence of the illness. CONCLUSIONS: To the best of our knowledge, this is the first report of RMO with a lesion that moved to the SIJ of both sides. We believe that knowledge of this disorder can prevent invasive procedures, particularly, in treating a patient with low back pain.