A distraction technique using reduction multi-axial screws for open reduction of high-grade lumbar posterior dislocation:a case report and literature review

Lumbar burst fracture with dislocation is usually caused by high-energy trauma. It often occurs in high-activity and high-stress vertebral body parts of the spine, such as the junction of thoracolumbar vertebrae and lumbosacral vertebrae [1, 2]. There are several directions of lumbar dislocation, and posterior dislocation is rare and can lead to serious nerve injury [3‐5]. After we carefully searched and consulted the literature, six similar cases were reported in the past 10 years [6‐11] (Table 1). This study represents a case of L3 vertebral burst fracture with posterior dislocation, and the technique of reduction using reduction multi-axial screw with long tail is rarely reported for fracture with dislocation.

Studies have shown that traumatic thoracolumbar fractures with dislocation account for 3% of spine-related injuries. Because many patients died on the spot due to severe trauma, there were fewer patients with high-grade posterior lumbar dislocation [12]. Therefore, the treatment of lumbar fracture with high posterior dislocation is rarely reported. We report a case of L3 burst fracture and posterior dislocation with neurological impairment. According to the description of the patient and his family, the patient fell from a high altitude and fell to wood. We inferred the mechanism of this injury: hyperflexion and an upward shear force resulted in fracture and posterior dislocation of L3.

Computed tomography (CT) scan showed that L3 vertebral burst fracture with posterior dislocation and the pedicle screw insertion points of L4 vertebral were under L3 vertebral plate. Baron et al. reported a case of L4 vertebral fracture with posterior dislocation. The reduction was achieved by initial lengthening [9]. In severe fractures and dislocations, even with articular process interlocking, it is difficult to achieve perfect vertebral reduction by simply horizontal lengthening, and vertical pull-reduction of the dislocated vertebral body is necessary. Francis et al. reported a case of fracture with dislocation of the reduction site attempted by extracorporeal traction before operation [13]. This method has uncontrollable reduction direction and strength, as well as the risk of damage to blood vessels and nerves, so we did not attempt traction reduction, but direct surgery. Reduction with gradual lengthening (first L3-L5 and then L3-L4), has the advantages of gentle operation and less injury. Hadgaonkar et al. reported a case of manual reduction through short segment fixation of upper and lower vertebral bodies [14]. Because the operation is a direct manual reduction, there is a risk of nerve injury and the possibility that patients with strangulation cannot be unlocked. In this case, the key of fracture reduction is to lengthen and pull. Because of the long segmental fixation, with the help of professional instruments, the rods could be applied into the pedicle screws with long tails easily. Our method that the reduction multi-axial screws with long tails were locked slowly after lengthening achieved the satisfactory effect of pulling. In this case, if the L3-L5 vertebral body was fixed by a short rod in the first, there may be a high risk of pedicle destruction, even if the CT showed that the fractured L3 vertebral pedicle was intact. At the same time, the L3-L5 short rod maintained less strength than the long rod between L1-L3 and L5. In the operation, gap between L1-L3 and L5 was lengthened and pulled, and the insertion point of the pedicle screw at the L4 vertebrae level was exposed. Then, gap between L1-L3 and L4 was lengthened and pulled again after pedicle screws with long tails were inserted into the L4 vertebrae. Finally, the perfect reduction was achieved. The mechanical forces of lengthening and pulling is safe, effective, accurate, sustainable and controllable during the reduction process. The disadvantage of the technique is that it can not be used in patients with osteoporosis or pedicle destruction. In order to restore the stability of the spine, the anterior column of the spine should be fixed subsequently. However, in view of the patient’s condition, we did not adopt anterior column fixation: (1) The patient has achieved good reduction; (2) The paraplegia state before operation and the inability to get out of bed early after operation; (3) Avoid reoperation bleeding and prevent abdominal aorta injury; (4) Reduce costs.

Domenicucci et al. reported a case of lumbar fracture with dislocation and lumbar artery injury. Satisfactory results were achieved through endovascular embolization [15]. Therefore, CT angiography (CTA) was necessary for the patient who understand the condition of vascular injury. CTA results showed that the left third lumbar artery was interrupted continuously, but no pulsatile hemorrhage occurred. Combined with the vital signs of patient and no progressive bleeding, the indications for lumbar vertebral artery embolization were inadequate.

Since L3 vertebral fractures with posterior dislocation are rare, it is difficult to compare different surgical approaches using large-scale or clinical controlled trials. Preoperative blood vessel evaluation is very important to avoid bleeding during the surgery. Long instrumentation with bony fusion is the recommended surgical method while the reduction is the key point. This standard technique which can achieve good reduction is easy to understand, perform, and is reproducible.