Introduction:

Spinal fractures related to diffuse idiopathic skeletal hyperostosis (DISH) are almost always caused by a long lever arm, so treatment of the fractures requires stabilization of long segments of the spine. Treatment of unstable sacral fractures in DISH patients with ankylosis of the sacroiliac joints requires a treatment strategy that includes a consideration of the condition of the spine. This article is the first report of an unstable sacral fracture in a patient with DISH.

Case report:

A 95-year-old male fell and presented with severe low back pain. An X-ray and computed tomography showed unstable pelvic fracture (AO type C2) and ankylosis of the lumbar spine due to DISH. We performed minimally invasive spinopelvic posterior fixation and internal anterior fixation (INFIX) for stabilization of the pelvic fracture. Initially, due to the long lever arm created from the lumbar spine to the pelvis, we performed L2-iliac posterior stabilization while the patient was in a prone position. After that, we performed INFIX to stabilize the anterior pelvis while the patient was positioned supine. The postoperative clinical course of the patient was uneventful and bony fusion was achieved as seen on X-ray obtained 1 year postoperatively.

Conclusion:

This patient was ankylosed from spine to pelvis due to DISH and sacroiliac joint ankylosis and sustained bilateral sacral fractures which dissociated the sacrum from the rest of the pelvis. Therefore, this fracture required spinopelvic fixation from the ankylosing spine to the pelvis. Because this patient was so elderly and in poor general health, we performed minimally invasive spinopelvic posterior fixation using percutaneous pedicle screws. We considered that many screw insertions that would equivalently stabilize the spine several segments above and below the fracture would be needed to stabilize the sacral fractures in this patient with DISH. In this case, we stabilized the unstable right pelvis, in a patient with a stable left side, using INFIX. Although osteoporosis is frequently associated with DISH, bony fusion was achieved in this case. This demonstrates that this procedure is sufficient fixation for an unstable sacral fracture in patients with DISH.