Vertebroplasty for osteoporotic thoracolumbar vertebral compression fractures usually results in complete and immediate cessation of pain symptoms. Occasionally the procedure does not relieve pain and further intervention is required. We herein report the case of a 62-year-old female with L2 and L3 vertebral compression fractures treated with vertebroplasty. Her symptoms did not improve and subsequent magnetic resonance imaging showed focal changes in the S1 and S2 vertebral bodies; bone scintigraphy showed the characteristic Honda sign of a sacral insufficiency fracture. Sacroplasty at S1 and S2 completely relieved the patient's back pain. If a vertebroplasty fails to relieve back pain immediately after the procedure as expected, surgeons should be aware of the possibility of a concomitant sacral insufficiency fracture.