At the Neurosurgery Department in Sohag Faculty of Medicine, between August 2014 and August 2017, 26 patients with single dorsolumbar metastatic spinal lesions with vertebral body collapse underwent a single-stage, circumferential corpectomy and anterior spinal reconstruction with a pyramesh titanium cage via a midline, posterior, and lateral approach.
We included in our study patients with retropulsed fragment inside the canal that causes spinal cord compression with neurological manifestation in patients with expected life span of more than 1 year. Metastatic workup was done for our cases. Exclusion criteria include patients with more than one spinal metastasis or extra-spinal metastasis, patients with other comorbidities as cardiac ill patients, patients with chronic renal failure, and patients who received radiotherapy or chemotherapy within 1 year before surgery. In a preoperative neurological assessment, full laboratory investigations were done. We used the Quebec scale to assess the patients’ improvement regarding pain, and muscle power scale to evaluate the motor power improvement.
Operative technique
Under general anesthesia with hypotensive anesthesia technique, our patients were placed prone in radiolucent spine frame that allows for intraoperative AP (anteroposterior) and lateral imaging by C-arm. A standard midline posterior skin incision is done with subperiosteal dissection above and below the affected level. Cauterization was done for the bleeding points.
In the majority of our cases, transpedicular screws were placed bilaterally two levels above and two levels below the involved vertebra. However, in one case, we noticed a high level of wedged vertebrae with osteoporotic bone, so we lengthened the fixation levels in this patient. A rod is placed unilaterally contralateral to the side planed for pediculectomy and corpectomy, and gentle distraction is applied for stabilization of the spine during the manipulation for corpectomy.
At the affected vertebrae, laminectomy is carried out with the removal of the facet and then skeletonizing pedicle. Only laminectomy with facetectomies can be done in one level above and below the affected vertebra to maximize the cephalic caudal working space between the nerve roots, which becomes critical during the pyramesh cage placement. At the dorsal spine lesions, we can sacrifice with the nerve root by ligation and bipolar cauterization to decrease the possibility of CSF leak.
At the aimed level, the transverse process is resected using a Kerrison rongeur and then exposed the lateral edge of the vertebral body. In the dorsal spine, disarticulation of the transverse process from the ribs should be done first. Subperiosteal dissection was performed using the Cobb. Packing sponge was applied very gently and slowly around the vertebral body to avoid the potential vascular, pleural, or peritoneal injury. A high-speed burr was then used cautiously to drill the pedicle and the vertebral body away from the exiting nerve root and the spinal cord.
Curettes were used to perform the discectomy above and below the involved vertebrae. If the vertebral body was completely destructed, we went for bilateral corpectomy, but if the lesion was unilateral, we performed a unilateral pediculectomy, discectomies, and corpectomy till the creation of an eggshell hole leaving the other side that augments the posterolateral fusion bed. Dorsal cortex should be preserved to minimize the epidural bleeding and protection of the spinal cord. Once the discectomies are completed, the vertebral body is hollowed using the high-speed burr and curved curettes.
The most challenging part of the procedure occurs with the pyramesh cage placement. Firstly, we measure the length of the suitable cage and filled with iliac crest bone graft.
Placement of the cage should be parallel to the nerve root with gentle retraction of the root. Once we entered the cage inside the corpectomy hole, we rotate it 90° until it is perpendicular to the adjacent vertebral endplates (Fig. 1).
Distraction was then performed under direct fluoroscopy with very gentle modulation of the cage to reach its appropriate position against the vertebral endplates without tilting (Fig. 2).
Finally, we placed the second rod with loosening of the first rod screws to make bilateral compression across the affected segments. All of the set screws were tightened and additional bone graft was then packed around the posterolateral contralateral side.
Statistical analysis
Data was analyzed using Microsoft Excel 2016 (Microsoft corporation, USA) and SPSS version 24 (May 2016, IBM corporation, USA). Qualitative data was presented as numbers and percentages, while quantitative data were presented as mean and standard deviation. Comparison between pre- and postoperative data regarding the Quebec scale and motor power was done using a paired t test. P value of less than 0.05 was considered significant.