Lumbar unifacet dislocation without an associated fracture – A case report and literature review

Introduction: Lumbar unifacet dislocations, without an associated facet fracture, are rare. Even in cases where they do occur, the lumbosacral junction is the most common site described, with their occurrence in the higher lumbar levels being infrequently seen. Case description: We describe an adult male patient who presented to our unit complaining of severe axial lumbar pain after being assaulted with a hammer, whereby a focal force was applied to the right side of the midline of his mid-lumbar spine. Our radiological investigations revealed a right sided L3/L4 unifacet dislocation without an associated facet fracture. He was taken to the operating room where after thoroughly removing the L3/L4 facet capsule, and using the pedicle screws to facilitate distraction, the right L3/L4 unifacet dislocation was reduced without the need to perform a partial facetectomy. Post reduction a posterolateral single level L3/L4 instrumented fusion was performed. Discussion: Pure unifacet/bifacet dislocations of the lumbar spine commonly occur in the context of high-speed motor vehicle accidents where the seatbelt acts as a fulcrum and the lumbar spine incurs a hyperflexion distraction injury. While a lumbar unifacet dislocation without an associated facet fracture is infrequently associated with a neurological deficit, most spinal surgeons recognize these injuries as unstable with an inherently increased risk of progression of the spondylolisthesis and secondary neurological deterioration. For these reasons, these injuries are best managed operatively, with reduction of the dislocation, and subsequent posterolateral instrumented fusion, being the technique of choice. Despite seemingly straight-forward, significant controversy exists surrounding the issue of whether a partial facetectomy is necessary to reduce the dislocation, as well as the role of a laminectomy. Conclusion: We advocate that by thoroughly removing the facet capsule, followed by pedicle screw distraction, and posterolateral instrumented fusion, these injuries can be successfully reduced and stabilized.