A 33-year-old man was involved in an automobile accident and was brought to our hospital by ambulance. He had been in the front passenger seat and had been wearing a three-point seatbelt. He reported severe back pain, but showed no neurological deficit.
Anteroposterior and lateral radiographs of the spine showed an increased gap between the 1st and 2nd lumbar spinous processes and 2nd lumbar vertebral fracture (figures not shown). Magnetic resonance imaging (MRI) of the spine also demonstrated an L2 vertebral fracture and disruptions of the posterior ligamentous complex between L1 and L2, in combination with extensive subcutaneous hematoma (Figure 1).
Computed tomography (CT) of the spine in the sagittal orientation and 3-dimensional (3D) CT further revealed the involvement of the superior end plate of the L2 vertebra, comprising horizontal splitting from the left pedicle, through the left transverse process, and reaching the center of the neural arch (Figure 2). The right-sided L2 pedicle was intact.
After checking the general condition of the patient and excluding intra-abdominal injury by enhanced CT and ultrasonography, the patient underwent L1-L2 single-level instrumented fusion using a posterior approach. Initially, monoaxial pedicle screws with conventional trajectory were placed at L1 and L2 pedicles on the right side (intact pedicle side). A rod slightly bent in lordosis was then introduced and connected with these pedicle screws with a compression force applied between screws. This procedure achieved reduction and the fracture gap at the left L2 pedicle and lamina was completely closed. Polyaxial pedicle screws were used on the left side. A pedicle screw with a conventional trajectory was placed at the left L1 pedicle. A CBT pedicle screw was then inserted through the fractured L2 pedicle under fluoroscopy. This CBT screw was used as an alternative to an osteosynthesis screw. A rod was introduced on the left side, bilateral facet fusion with local bones obtained from the lower one-third of the L1 spinous process was performed, and the wound was closed. Although the merits of cross connectors for CBT screws remain unclear, we applied the connector in this case because connecting bilateral pedicle screws along conventional trajectories has been reported to increase the pullout strength of these screws. Postoperative X-rays showed good reduction by this single-level fixation (Figure 3).
The postoperative period was uneventful. Although rigid fixation was obtained with this procedure, a thoracolumbosacral orthosis (TLSO) was applied for 6 weeks, since this case was our first experience. Physical activities were not restricted with the TLSO. Sagittal CT and 3D-CT obtained at 6 months and 1 year postoperatively showed proper trajectory of the CBT pedicle screw and complete bone union (Figure 4).