Abstract

Background: Although rare, traumatic lumbosacral (L/S) Grade I spondylolisthesis (i.e., Lumbar locked facet syndrome) is characterized by unilateral or bilateral facet dislocations.

Case Description: A 25-year-old male presented following a high velocity road traffic accident with back pain and tenderness at the L/S junction. His radiologic images showed bilateral locked facets at the L5/S1 level with Grade 1 spondylolisthesis, bilateral pars fractures, acute traumatic L5/S1 disc herniation, and disruption of the anterior and posterior longitudinal ligaments. After undergoing a L4-S1 laminectomy with pedicle screw fixation, he became asymptomatic and remained neurologically stable.

Conclusion: L5/S1 facet dislocation whether unilateral or bilateral needs to be diagnosed early and treated with realignment and instrumented stabilization.

Keywords: L5-S1, Lumbosacral (LS), Pars fracture, Road traffic accident (RTA), Traumatic lumbar locked facet

INTRODUCTION

Traumatic L5S1 unilateral or bilateral facet dislocations with resultant Grade I spondylolisthesis need to be recognized early and appropriately decompressed and stabilized.[ 7 ] Mostly facet dislocations tend to be bilateral with only few cases of unilateral facet dislocations being reported in the literature.[ 2 , 5 , 10 ] Here, we present a 25-year-old male who sustained a road traffic accident resulting in low back pain secondary to bilateral L5/S1 locked facets and a L5/S1 disc herniation that warranted surgical decompression and stabilization.

CASE REPORT

Following a high velocity traffic accident, a 25-year-old male presented with back pain and tenderness at lumbosacral (L/S) junction but remained neurologically intact. The computed tomography (CT) scan showed bilateral locked facets at the L5/S1 level with Grade 1 spondylolisthesis, bilateral pars fractures, L5/S1 herniated disc, and disruption of the anterior/ posterior longitudinal ligament [ Figures 1 and 2 ]. The patient underwent L4-S1 decompressive laminectomy with L4-S1 pedicle screw fixation. At surgery, there was a sub-fascial hematoma, significant L5/S1disc fragment, and dural tear that required primary repair. The post-operative period was uneventful, and subsequent plain X-rays showed maintained normal realignment.

Figure 1:

(a) Computed tomography (CT) scan LS spine axial cuts at L5/S1 level. (b) CT scan LS spine sagittal cut at the level of left pars. (c) CT scan LS spine sagittal cut at the level of right pars. (d) CT scan LS spine – Mid sagittal cut.

Figure 2:

(a) Magnetic resonance imaging (MRI) T2 – Axial cut at L5/S1 level. (b) MRI T2 – Sagittal cut.

DISCUSSION

Fracture dislocations of the L/S spine are rare, with L5/S1 involvement being even less reported than L4/L5.[ 4 ] However, most authors are of the view that significant traumatic forces, including hyperflexion, combined with some degree of distraction and rotation may cause these facets to dislocate.[ 1 , 3 , 10 ] Multiplanar and 3D reconstruction of L/S CT aids in diagnosing vertebral locked facets at the L5/S1 level along with plain radiographs.[ 12 ] Accompanying magnetic resonance imaging (MRI) studies look for simultaneous musculoligamentous injuries, dural tears, root injuries, and traumatic disc herniation.[ 8 , 10 ]

As bilateral facet dislocations result in an unstable 3-column injury, they need to be quickly reduced, decompressed, and fused to avoid the progression or the onset of new neurological dysfunction.[ 9 , 11 ] Posterior reduction typically involves drilling off the locked facets (facetectomy), or manual manipulation of the posterior elements (levering the spinous process of L5 and S1), followed by fixation of fracture with pedicle screws.[ 1 ] If there is an accompanying L5S1 disc herniation (i.e., on the MRI), interbody fusion may also be necessary.[ 1 , 6 , 10 ]

CONCLUSION

Traumatic bilateral facet fractures/dislocations, Grade I spondylolisthesis, and disc herniations at the L5S1 level, documented with X-rays and CT studies, should be decompressed and stabilized early in the clinical course to avoid the onset of new or the progression of neurologic deficits.[ 1 ]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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