Introduction: Lumbosacral dislocation revealing cauda equina syndrome is relatively uncommon. Although various treatment strategies have been reported, no consensus has been reached regarding the best surgical approach.Case Presentation: We report the case of a 35-year-old patient with no previous history, admitted for lumbosacral trauma with acute urine retention and neurological deficits in both legs. The CT scan revealed an anterolisthesis of the 5th lumbar vertebra (L5) on the 1st sacral vertebra (S1). The patient was operated on with a posterior approach followed by ALIF. The patient’s neurological recovery was almost complete. Conclusions: Lumbosacral dislocation is a rare cause of compression of the cauda equina. This case report presents our first experience with a posterior approach followed by an anterior ALIF approach between L5 and S1.

Posttraumatic lumbosacral dislocation is a rare, high-energy injury characterized by displacement of the 5th lumbar vertebra in relation to the sacrum [1,2]. Lumbosacral dislocation is generally the result of high-energy trauma and is often associated with a fracture of the isthmus [1]. The lumbosacral region is surrounded by important bone and ligament structures that protect important neural elements controlling lower limb function, as well as bladder and sexual functions [3]. Patients typically present with complicated injuries with wide-ranging neurological deficits below the level of trauma [4]. Most published reports and clinical series have shown that these injuries are commonly associated with motor vehicle accidents and are more prevalent in men than in women [2,3,5]. The surgical treatment strategy for traumatic lumbosacral joint dislocation remains controversial, no consensus has been reached regarding the best surgical approach [1,6]. We report a rare case of lumbosacral dislocation, revealing cauda equina syndrome, and our first experience with a posterior approach followed by an anterior approach of the ALIF type to reduce, stabilize and fuse this lesion.

M.D 35-year-old patient without any medical or surgical history was admitted for lumbosacral trauma following an accident on the public road. He was a passenger in a car that had rolled over.

The patient's history revealed no signs of head trauma (initial loss of consciousness, headache, vomiting or posttraumatic convulsive seizure). The patient complained of severe low back pain, rated at 7 on the Graphical Rating Scale (GRS) ref associated with paresthesia and cramps of the lower limbs. The physical examination revealed hypoesthesia in the buttock, paralysis of both lower limbs, diminished osteotendinous reflexes in the lower limbs and a negative Babinski sign. Elsewhere, a bladder globe was present, and rectal tone was normal.

Urinary retention required indwelling catheter drainage. Hemodynamic and respiratory functions were stable.

A CT scan of the lumbar spine revealed anterolisthesis of L5 on S1, which was classified as Meyerding grade III with bilateral isthmic lysis of L5 (Figure 1). An angioscan of the iliac vessels was performed to assess the level of bifurcation of the iliac vessels (Figure 2).

Figure 1: CT-Scan of lumbosacral spine in bone window, sagittal reconstruction showing L5 listhesis on S1

Figure 2: Angioscan of the iliac vessels

Double-approach arthrodesis was indicated. The patient underwent surgery 12 days after the trauma. Initially, a posterior approach was used to perform hemi-laminectomy of L5 and S1, followed by the placement of 4 monoaxial pedicle screws in L5 and S1 and two rods secured with nuts. Second, we performed anterior lumbar interbody fusion (ALIF): our patient was placed in a supine position with the head on a log and the log under the iliac crest and popliteal fossa. A horizontal subumbilical incision was made, the fascia and muscles of the anterior abdominal wall were opened, and the peritoneum was identified. We performed a retroperitoneal approach down to the prevertebral fascia while identifying the iliac vessels and the lumbar spine. After scoping the L5-S1 disc, we performed an L5-S1 discectomy. An iliac graft was placed in the L5–S1 

interbody and secured with a screw plate (Figure. 3). A reduction was observed after the combination of these two techniques. Our patient's immediate postoperative course was straightforward. The results of the follow-up CT scan were satisfactory (Figure. 4), and the patient was exeated on the 7th postoperative day, with a lumbosacral corset prescribed.

The urinary catheter was renewed every 7 days and removed at 1 month postop. The patient recovered from his bladder independence and deficit after several sessions of physiotherapy.

In consultation at M1 postop, we noted an improvement in pain symptoms and almost complete neurological recovery. He is still followed up in consultation.

Figure 3: Intraoperative iconography of the “ALIF” with visualization of the screwed plate

Under our working conditions, L5-S1 lumbosacral dislocation is a rare cause of compression of the cauda equina roots. This posterior approach followed by an anterior ALIF approach is our first experience in Senegal, but it has several limitations. This is a unique case, so it will be difficult for us to draw any conclusions.

There are few cases of lumbosacral fracture-luxation, which usually clinically manifests as cauda equina syndrome, as in our case [7,8]. They were first described by Watson-Jones in 1940, and the mechanism of injury is considered to be correlated with high hyperextension forces [9]. In our case, the patient probably suffered a violent impact on the lumbosacral region during vehicle rollover, which may have resulted in severe hyperflexion in this region and led to fracture-luxation of the bilateral inferior articular processes of L5 anterior to the S1 vertebra.

The main surgical treatment for lumbosacral dislocation is posterior instrumentation, decompression of the cauda equina roots and interbody fusion. Anatomical reduction of the L5 vertebra and repair of the dural sac in cases of dural breach are very important, and reliable fusion of the vertebrae is crucial for stabilization of the spine after surgery [10,11]. In our patient, decompression was performed. Reduction and fusion were 

achieved via a dual approach (posterior arthrodesis followed by anterior arthrodesis, hence anterior lumbar interbody fusion (ALIF)). The main advantage of the anterior approach to spinal fusion is that it allows access to the entire intervertebral disc. The main risks associated with ALIF are related to damage to vascular or neural structures encountered during the approach [12].

Hence, preoperative angioscanning of the iliac vessels was important in our case. When L5-S1 is approached via the bifurcation of the great vessels, we can cross the middle sacral artery and vein. These can be very difficult to visualize and must be carefully sought out and ligated to avoid hemorrhage [13]. In our case, the vessels were identified and preserved, and the approach was cautious to avoid damaging the vessels. A discectomy was performed. We harvested an iliac graft that was incarcerated intersomatically and then fixed it with a screw plate. Identification of the sympathetic chain was also necessary to avoid damage to it.

The most feared complication of this approach is sexual dysfunction (14), which was not found in our patient at the M1 postoperative follow-up. Caution and informed consent of adult males are recommended, as in our case.

Some reports suggest that the time to decompression, the degree of slippage and the extent of neurological deficits prior to surgery are the main factors influencing the recovery of neurological function [2,15]. In our case, the patient underwent surgery at 12 days after the trauma, given that the preparation for surgery was considerably onerous in psychological, physical and financial terms for the patient and given the challenge of the operation for the surgical team. The patient nevertheless recovered from his bladder independence, and an almost complete recovery of his motor deficit at L5 was observed 1 month later. This is our first experience with the double approach to the lumbosacral spine. The patient is satisfied with the treatment since he has had a recovery of motor functions. But the cost of the treatment was expensive for him, since he did not have medical insurance.

L5-S1 lumbosacral dislocation is a rare cause of compression of the cauda equina roots and usually results from high-energy trauma. Surgery consisted of a posterior approach followed by an anterior ALIF approach to reduce, stabilize and fuse this rare pathology.

List of abbreviations

ALIF: anterior lumbar interbody fusion

L5: 5th lumbar vertebra

S1: 1st sacral vertebra