A chronic flexion-distraction injury with a “fistulous wither” on the split spinous process of the L1 vertebra—a case report of a modified transpedicle wedge osteotomy
A 59-year-old man, a retired worker, presented chronic pain in his lower back. There was no history of definitive trauma, but he mentioned that he had experienced a mild motor vehicle crash while wearing a three-point seat belt 6 months earlier and the swelling in his back had been deteriorating for 3 months. The pain was dull in character, and confined to the thoracolumbar spine. He also described that standing, walking, and especially lying in a supine position aggravated the pain.\nPhysical examination revealed that he was poorly nourished. His body mass index was 19.7 (body height, 173 cm; body weight, 59 kg). A visible thoracolumbar gibbus was present. A subcutaneous fluctuation, which seemed to be the size of a large egg, was palpable at the tip of the deformity (Fig. ). Tenderness was also present at the affected spinous process. Five milliliter of bloody serum was aspirated from the fluctuation (Fig. ). Bacterial culture of the fluid was negative. A lateral plain X-ray demonstrated a kyphosis of 35° at T12/L1 (Fig. ). No instability of the fracture site was found in flexion and extension X-rays. MRI was not performed because he had a stainless steel clip in his cranium. Reconstructed CATs in the sagittal plane demonstrated a fracture line through the spinous process, the pedicle, and the upper vertebral body in L1. A lesion containing gas was also seen at the T12/L1 intervertebral disc and the upper vertebral body of the L1 vertebra, whereas no bony protrusion was present in the spinal canal at the affected level (Fig. ). These investigations suggested a diagnosis of a chronic FDI with a bursitis or hematoma on the split spinous process in L1. In spite of a thoracolumbar brace, NSAIDs, and repeated aspiration, no recovery from the symptoms were observed. Corrective surgery for the gibbus and resection of the bursa or hematoma was indicated 6 weeks after his initial visit.\nAt operation, a posterior approach was chosen. The patient was positioned prone on a Hall-Relton spine frame. Thereafter, a midline incision was made, a subcutaneous fibrous cystic lesion, which was connected with the split L1 spinous process, was demarcated and radically excised. It was elliptical in shape and approximately 40 × 50 mm in size. Pathological diagnosis was a bursitis (Fig. ). The supraspinous process on the spinous ligament in L1 was completely torn. Secondarily, the T11 to L2 laminae was exposed subperiosteally. A fracture line of the L1 spinous process was identified. No instability or bleeding was identified. The cephalad portion of the split spinous process and the lamina was resected. Then, the facet joints of T12/L1 were bilaterally removed. Discectomy of T12/L1 and osteotomy of the posterior wall of L1 was then performed. The bilateral L1 pedicles were also subtracted from their base. Anterior soft tissue was released as much as possible with a great care. Resected local bone and two titanium spacers (8° angled, 7 mm in height, 25 mm in length) were placed at the T12/L1 space. Pedicle screws were bilaterally inserted in T11, T12, and L2. Correction was done via compression of the pedicle screws and rods assembly using two titanium spacers as a fulcrum. Postoperatively, the patient was placed in a soft thoracolumbar brace for 3 months. At 1.5-year follow-up, he reported no backache. Recurrence of the bursitis at the spinous process in L1 was not observed. Plain radiograms and reconstructed CAT demonstrated a solid boney fusion with a minimal kyphosis of 5° at T12/L1 (Fig. ).