Thoracic Fracture through a Prior Instrumented Arthrodesis in a Patient with Ankylosing Spondylitis without Hardware Loosening: A Case Report

Abstract

The objective of this article is to report a case of a patient with ankylosing spondylitis who sustained a fracture through a prior solid arthrodesis without loosening or changing posterior instrumentation. There have been few cases reported of a patient with ankylosing spondylitis suffering a fracture through a prior instrumented arthrodesis. None have noted the instrumentation remaining intact with the fracture through the middle of the construct. The surgeon must be aware of this possibility to avoid spinal instability that may lead to a neurological deficit. We retrospectively reviewed the case. A review of the literature was performed through a PubMed search. A patient was found to have a fracture within a prior construct despite the presence of a posterior instrumentation. The mechanism of failure was a three-column spine fracture with "bending" of the rods. This patient was treated with a revision posterior/anterior instrumentation and fusion with placement of larger-diameter rods for added stiffness. Fractures through a prior instrumented arthrodesis are rare but still can occur in the ankylosing spondylitis patient. Given the higher risk of epidural hematoma and neurological compromise in this patient population, the surgeon must keep this on the differential diagnosis when treating patients with a prior instrumented arthrodesis.

Keywords: ankylosing spondylitis; postoperative complication; spinal arthrodesis.

Figure 1

Lateral radiograph showing T10 fracture with significant local kyphosis.

Figure 2

Sagittal reformat of a computed tomography myelogram showing T10 fracture with spinal canal stenosis.

Figure 3

Postoperative lateral radiograph after T9–11 laminectomy and T6–L3 posterior fusion. Overall kyphosis at this time measured 61 degrees.

Figure 4

Sagittal reformat of computed tomography scan in 2009 after fall resulted in refracture through fusion mass and extension-bending of the rods. Overall kyphosis at this time measured 45 degrees. Sagittal plane bending of the rods in an extension direction will result in a decrease in overall kyphosis angle.

Figure 5

Postoperative lateral plain film from index surgery prior to reinjury showing overall kyphosis of 68 degrees.

Figure 6

Postoperative computed tomography scan after revision posterior fusion and anterior corpectomy with placement of iliac crest allograft.