The authors report a patient with recurrent lumbosacral myxopapillary ependymoma, followed for more than 20 years, who presented with severe axial pain resulting from osteolytic destruction at the lumbosacral junction. Because the patient had a long history of paraplegia despite three previous incomplete tumor resections, we chose not to attempt a fourth resection. Moreover, because viable fixation points were not present within the sacrum and most of the lumbar spine, instrumented fusion was extended from T7 to the ilia using a modified Galveston L-rod technique, which we believe to be unique in its application to this problem. This case demonstrates the long-term potential for instability from locally destructive myxopapillary ependymoma that is incompletely excised. We are not aware of any previous reports of lumbopelvic instability in association with myxopapillary ependymomas.