Image Quiz

Severe Neurologic Deficit Below L3 in a Fifteen-Year-Old Struck from Behind by a Motor Vehicle1 (continued)

Answer: Fracture through the inferior portion of the L5 vertebral body and complete posterior displacement with respect to the superior portion of the sacrum.


Fig. 1		 Fig. 1 Lateral radiograph demonstrating the posterior sagittal translation of the L5 vertebral body and the complete loss of contact with the sacrum inferiorly.

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Fig. 2		 Fig. 2 Sagittal magnetic resonance image demonstrating a fracture through the inferior portion of the L5 vertebral body and complete posterior displacement with respect to the superior portion of the sacrum.

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Fig. 3-A
Fig. 3-B		 Figs. 3-A and 3-B Axial computed tomography demonstrating the sagittal fracture involving the posterior cortex of the L5 vertebral body (Fig. 3-A) as well as separation and displacement of the posterior lamina with the superior end plate of the sacrum anterior to the L5 vertebral body (Fig. 3-B).

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On arrival at the trauma unit, the patient had a positive result of diagnostic peritoneal lavage. She became hypotensive, and an exploratory laparotomy was done; it revealed unremarkable findings. The patient's condition was stabilized in the trauma intensive care unit. Approximately six days after injury, reduction of the posterior L5-S1 spondyloptosis, posterior decompression, and spinal arthrodesis with instrumentation was performed. The findings of the neurologic examination remained unchanged during the stabilization period prior to the operation.

Details of the operative procedure and postoperative course are available with the original case report1.

The patient eventually regained some neurologic function, including partial bowel and bladder function with pharmacological assistance. At the five-year follow-up evaluation, the patient had incomplete paraplegia at the L4 level and walked independently with a right ankle-foot orthosis. Full quadriceps muscle strength was evident bilaterally, and grade 4 of 5 anterior tibialis muscle strength and grade 3 of 5 ankle inversion strength was evident on the left side. The patient had loss of sensation below the L4 level on the right and below the L5 level on the left. She experienced occasional, mild low-back pain, which resolved with short-term use of nonsteroidal anti-inflammatory medication.

Discussion

Previous case reports of posterior lumbosacral fracture-dislocation demonstrated that most of these injuries occur in young patients as a result of high-energy trauma and that these fracture-dislocations are usually accompanied by neurologic injury. Despite the frequent association with neurologic injury, nerve-root avulsion injuries in the lumbosacral region have been rare, and most have been associated with pelvic fractures and injuries to the lower extremities.

The posterior fracture-dislocation at the lumbosacral junction in our patient, as well as in the cases we reviewed, demonstrates many features consistent with a mechanism of injury resulting from combined hyperextension and shear forces. These features include a lack of compression injuries to the anterior column and frequent fractures of posterior-column structures. Additionally, the posterior sagittal translation, the avulsion of the intervertebral disc, and the fractures of the posterior column are evidence of a shear-force component of the mechanism of injury.

Treatment of fracture-dislocations involving the lumbosacral spine has evolved from traction and immobilization to operative reduction and internal fixation with instrumentation. Many authors have advocated open reduction and stabilization to facilitate early mobilization and functional rehabilitation. The high-energy nature of these injuries necessitates a careful evaluation of the soft-tissue injury. We believe that, despite the severe neurologic deficits that accompany these high-energy injuries, if the spine is properly stabilized, the patient will have a reasonable chance of avoiding neurologic deterioration after the operation and may even recover some degree of function. Additionally, we believe that it is reasonable to expect some relief of pain after surgical stabilization, as demonstrated by the case of our patient and all but one of the case reports that we reviewed.

Reference

1. Meneghini RM, DeWald CJ. Traumatic posterior spondyloptosis at the lumbosacral junction: a case report. J Bone Joint Surg Am. 2003;85:346-50.