Comparison of the Posterior Vertebral Column Resection With the Expandable Cage Versus the Nonexpandable Cage in Thoracolumbar Angular Kyphosis.

STUDY DESIGN: This was a retrospective study.

OBJECTIVE: To compare the radiographic and clinical results of anterior support with nonexpandable cage with those of expandable cage.

SUMMARY OF BACKGROUND DATA: The goals of surgical treatment in patients with thoracolumbar angular kyphosis are to improve the neurological deficit through neural decompression, to restore the normal alignment by correction of deformity, and to stabilize the spinal column by arthrodesis. Mesh cages have been traditionally used for reconstruction after corpectomy. However, expandable cages are gaining popularity due to some advantages over mesh cages, structural autograft or allograft, and poly-ether-ether-ketone/carbon fiber.

MATERIALS AND METHODS: We performed a retrospective study in a consecutive series of 42 subjects with a male-to-female ratio of 15:27, a mean age of 65.3±10.9 years, and a mean follow-up period of 36.4±7.1 months, who underwent posterior vertebral column resection at our medical institutions between 2006 and 2011. They consist of 32 patients with posttraumatic kyphosis with a mean kyphotic angle of 33.1 degrees (range, 12.2-58.1 degrees) and 10 patients with tuberculous kyphosis with a mean kyphotic angle of 53.9 degrees (range, 22.6-126.0 degrees). The mean follow-up period was 36.4 months (range, 28-54 mo). We compared the clinical outcomes between the 2 groups based on radiographic findings, neurological status, and complications. Intervertebral heights and kyphosis at the level of vertebral column resection were used to measure the radiographic outcomes. Neurological outcome was evaluated using the modified Frankel grading system.

RESULTS: Postoperatively, the mean kyphosis angle was 3.0±10.8 and 6.7±7.2 degrees (P=0.094). At a final follow-up, these values were 4.7±10.1 and 12.3±18.9 degrees in the corresponding order (P=0.099). There were 19 (80.0%) and 21 (86.4%) patients with solid arthrodesis of grade 1. On modified Frankel grading system, all the patients but one achieved improvement. But there was no significant difference in the grade between the 2 groups (P>0.05). Also in our series, there were 12 patients with cage subsidence and 6 with screw loosening.

CONCLUSIONS: Nonexpandable cage and expandable cage are viable options for anterior support; both cages allow for correction of kyphosis with good fusion rate with similar neurological outcomes. Expandable cage is effective for the anterior support of posterior vertebral column resection.