Thurs., 10/16/08 Spine, Paper #5, 2:54 pm OTA-2008
Sacral Kyphosis As a Cause of Sacral Nerve Impingement in Lumbosacral Dissociations
Melvin D. Helgeson, MD (n); Ronald A. Lehman, Jr., MD (n); F. Marshall Moore, MD (n);
LTC Romney C. Andersen, MD (n); H. Michael Frisch, MD (n);
Walter Reed Army Medical Center, Washington, District of Columbia, USA
Introduction: Lumbosacral dissociation is a relatively uncommon injury pattern recently described in several small case series. With our current conflicts in Iraq and Afghanistan, the high energy associated with improvised explosive devices and helicopter crashes have caused an increased incidence of lumbosacral dissociations. With this fracture pattern, the most common deformity is sacral kyphosis, and the purpose of this study is to review complications of this deformity.
Methods: We performed a retrospective review of inpatient/outpatient medical records and radiographs for all patients treated at our institution with combat-related lumbosacral dissociations. Included were all patients with radiographic evidence of an H- or U- type zone III sacral fracture, in addition to associated lumbar fractures indicating loss of the iliolumbar ligamentous complex integrity.
Results: 15 patients met our inclusion criteria and had at least 1-year follow-up. At the time of presentation, 11 (73.3%) had evidence of kyphosis, measured on sagittal reconstructions of the CT scans. The mean kyphosis was 12.0°, with a range of 0° to 30° on the initial scan. Patients were treated initially as follows: posterior spinal fusion, 4; sacroiliac screw fixation, 7; and nonoperative, 4. At most recent follow-up, two patients (both with >20° kyphosis initially) treated nonoperatively had progression of sacral kyphosis. One required sacral decompression for associated sacral nerve root impingement while the other has residual pain without any sacral nerve root symptoms. At greater than 1-year follow-up, six patients still reported pain, with a mean visual analog score of 4. Additionally, 12 patients had no evidence of sacral nerve root symptoms, while 3 had persistent bowel or bladder dysfunction.
Conclusion: High-energy lumbopelvic dissociations must be evaluated for sacral kyphosis with consideration given for operative fixation. In our case series, two patients treated nonoperatively with greater than 20° of kyphosis progressed, while no patients treated with sacroiliac screw fixation or posterior spinal fusion progressed.
Summary: Lumbopelvic dissociations, while relatively uncommon, have a high incidence of posttraumatic sacral kyphosis. This posttraumatic deformity must be properly recognized and evaluated, and operative fixation considered to prevent progressive sacral kyphosis.
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