Sacral Stress Fracture Complicated by L5 Radiculopathy in a Patient with Rheumatoid Arthritis.

A 60-year-old Japanese woman with severe osteoporosis presented with a history of right buttock pain and right lateral lower leg pain in an L5 distribution. She had been treated with methotrexate and methylprednisolone for rheumatoid arthritis (RA) and interstitial pneumonia. Computed tomography demonstrated a sacral stress fracture in the right sacral ala. The right L5 nerve root was compressed by the fracture site. This case is rare in that L5 radiculopathy was complicated by a sacral stress fracture. Clinicians should suspect sacral stress fractures when RA or osteoporosis is present in women who experiences lumbar pain and lumbar radiculopathy.