Thoracolumbar Spine Fracture-Dislocation without Neurological Deficit: A Case Report and Review of the Literature

Background: Thoracolumbar spine fracture-dislocations are very unstable and usually secondary to high energy trauma. Due to disruption of the entire vertebrae columns, the absence of neurological deficit is exceptional. Aim: The purpose of this work is to report our experience in the management of this entity in a context of limited resources and to make a review of the literature. Case presentation: A 30-year-old man was admitted with a severe low back pain after a traffic accident. Neurological functions were intact after examination. Ra-diological assessments revealed a complete L3-L4 fracture-dislocation. The patient underwent an open posterior reduction and internal long segment fixation. The post-operative was marked by a surgical site infection treated with surgical debridement and targeted antibiotic therapy. The neurological functions were preserved. Conclusion: Fracture-dislocations of the thoracolumbar spine are caused by high energy trauma and are remarkably unstable le-sions. When they are associated with intact neurorological functions, reduction and stabilization of these fractures are a challenge.


Introduction
Fracture-dislocation of the thoracic and lumbar vertebral column comprised 3% of the injuries related to the vertebral column [1]. Common injuries resulting in fractures of the thoracolumbar spine include fall from a height, motor vehicle and pedestrian accidents, and penetrating trauma (gunshot wounds and stabbings) [2] [3]. Fracture-dislocation is defined as failure of all three columns of the spine with gross displacement [4] [5] [6]. There is a typically complete disruption of the stabilizing ligaments, facet joint capsules and the paraspinal musculature resulting in the translation of the spinal column and the transfer of shearing forces leading to disruption of the spinal cord. Considering the significant violence necessary to produce fracture-dislocations, these injuries are often associated with major neural deficit and since the spinal column is grossly unstable because of the column disruption, there are significant risks of further instability and neurological deficit during transfer, positioning on the operating table, and surgical intervention. The management is usually straightforward, the injuries are managed surgically and surgical fixation enables early mobilization and rehabilitation. Preservation of neurological function following complete fracture-dislocation is a quite rare entity. There are a few neurologically intact cases in the literature [7]- [23] (Table 1) and none has been reported from Senegal. Here, we report our experience in the management of this entity in a context of limited resources and we make a review of the literature.

Case Presentation
A 30-year-old man was admitted with severe low back pain after a traffic accident. He was a passenger on a motorcycle that collided with a truck. On examination, his vital signs were normal. His Glasgow coma scale score was 15/15, the sensation and muscle strenght were preserved, no pathological reflex was noted, bladder and bowel functions were normal. He had a severe tenderness on his lower back and pain when moving the left knee.
The X-ray and the Computed tomography (CT) of the lumbar spine revealed a rotational-dislocation of the L3 to L4 vertebrae with fractured bilateral inferior facets of L3 and corporeal split fracture and compression of L3 ( Figure 1). The X-ray of the left knee was normal. The laboratory tests prior to surgery were normal (Table 2).   Surgery was performed 7 days after initial injury. The patient was placed in the prone position under general anesthesia on a non X-ray transparent operating table. Sensory evoked potential responses (SSEP) monitoring was not available. A posterior middle incision was made from T12 to L5 revealing a contusion of paravertebral muscles, rupture of the supraspinous and interspinous ligaments at the L3-L4 level and a fracture of both inferior facets of L3. Laminectomy of L3-L4 and inferior facetectomy of L3 were performed. Bilateral transpedicular 45mm screws were inserted in the L1, L2, L4 and L5 vertebrae under intraoperative lateral fluoroscopic imaging. The realignment was made with reduction forceps applied on spinous process of L2 and L4; stabilization was achieved with rods and tightened nuts. Posterolateral grafting was performed with autologous bone harvest from the resected posterior arc. The operating site was then irrigated with 0.9% saline solution and a drain was placed and secured with a suture before wound closure.
On day 1 after surgery, neurological functions were intact. On day 2, the drain was removed and the lumbar spine control x-ray showed good spinal alignment ( Figure 2). The patient was allowed to walk with a brace on day 3 after surgery ( Figure 3). The patient presented, 6 days after surgery, fever, wound dehiscence and purulent drainage from the wound. An open surgical debridement was done the same day and the exploration of the wound established a superficial infection. Cultures of the surgical site were obtained and broad spectrum antibiotics were initiated and then the antibiotics were tailored to culture's results 4 days after ( Table 3). The evolution was satisfactory and the patient was discharged on day 29 after surgery with preserved neurological functions. The brace was removed 3 months later and the patient remained neurologically asymptomatic at 2 years follow-up. Due to his financial limitation neither a CT nor an X-ray could be done to assess the bony fusion.

Discussion
Fracture-dislocation of the thoracolumbar spine is rare. It requires a very high energy trauma and a direct application to the spine, most often, of shearing forces [24]. This injury mechanism shows the importance of displacement and the highly unstable nature of this injury due to the rupture of the three columns.
The neurological prognosis is usually severe resulting in permanent paraplegia.
Neurological trauma is very often related to the rupture of nerve structures during the translational displacement of the spine or the sudden and extreme tension of these structures without rupture [20].  [23]. Junfeng et al. [21] reported a case of complete fracture-dislocation of the L1 to L2 vertebrae with a normal neurological examination. He claimed that the mechanism of neural preservation was spontaneous decompression from fractured bilateral pedicles of L2 and bilateral facet joints between L1 and L2. Rahimizadeh et al. [19] also reported such a case and specu- As a result, the nerve injury may be minimal, because the nerve roots in this region are accommodated in a larger area, with less content [27]. Due to high energy trauma, fracture-dislocations of the thoracolumbar spine may be associated with various organ injuries which can delay the diagnosis [19]. Having an accurate and early diagnosis is critically important before any improper maneuver can be applied to patients. Some authors have recommended a spinal computed tomography for patients involved in severe high velocity trauma [9] [12].
Surgery is recommended for fracture-dislocations of the thoracolumbar spine and should be performed at the earliest possible opportunity for neurologic protection [6] [21] [28] [29] [30]. The physical condition of the patient, as well as the potential existence of associated lesions, should always be taken into account before attempting the procedure. It is also important for patients to be stabilized before surgery, and for the right personnel to be available at the time of decompression and reduction of these injuries [13]. The objectives of the surgery are reduction of dislocated vertebrae, decompression of nerve structures, spinal stabilization and an early mobilization and rehabilitation [28] [31]. In our case, through a posterior approach, we performed laminectomy and facetectomy at the involved level of compression; a long transpedicular fixation and posterolateral fusion were performed. The optimal surgical approach for decompression and stabilization is controversial. A posterior approach with long instrumentation (2 levels above and 2 levels below) is recommended due to the severe instability of the injured spine. In addition, short bony fusion, that is, posterolateral or interbody fusion, should be applied [9] [11] [12] [29]. Junfeng Z et al. [21], for a complete fracture-dislocation in 38-year-old patient, performed a long instrumentation and long posterolateral fusion for fixation to avoid implant failure. He obtained a solid fusion and a satisfactory outcome at the 23-month follow-up.
Anterior approach for fracture-dislocation injury may not be applicable as the  [32]. Circumferential anterior and posterior fusion often plays a role in these severely injured cases. Xia et al. [33] advocated this combined surgery for thoracolumbar fracture-dislocations and he conclued that simultaneously combined anterior and posterior surgery was a reliable method that can achieve a sufficient decompression, reduction and reconstruction. Xiao-Bin W et al. [32] performed a posterior TLIF approach with a single stage pedicle screw fixation and interbody bone graft to achieve reduction, decompression and reconstruction for the treatment of thoracic and lumbar fracture-dislocations. He claimed that it is a safe procedure because working zone can be acquired without retrac- As only spinous processes are manually distracted, theoretically lesser risk of neurological insult is there. Disadvantages are higher risk of cut-out of the towel clips through spinous processes, particularly in osteoporosis cases, and hence failure to achieve reduction [37]. Rishi MK et al. [38] insisted on critical steps to ensure safe surgical reduction of the spine: Unilateral exposure and temporary fixation, use of high-speed burr and drill to create screw track, avoid torque forces while inserting the screws, perform a laminectomy before reducing the dislocation, use of gentle reduction maneuvers with persuaders and rod rotation under direct visualization of the spinal cord. Overall, experience and expertise of the operating surgeon is also important, as unintended neural injury can happen if appropriate care is not taken.

Informed Consent
Informed consent was obtained from the patient for publication of this manuscript and any accompanying images.

Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this paper.