Comparison of thoracoscopic and open thoracic discectomy in a live ovine model for anterior spinal fusion

Study Design. The authors undertook a randomized comparison of 30 thoracoscopic and 30 open thoracic discectomies for anterior spinal fusion in a live sheep model. Objectives. To compare in a live sheep model discectomies performed using a thoracoscopic technique with those using an open thoracotomy technique to validate the efficacy of thoracoscopic disc and end plate removal for potential fusion. Summary of Background Data. In 1993, Mack and Regan described a technique for video-assisted thoracic surgery that resulted in less morbidity than open techniques. Subsequent reports support the finding that thoracoscopic spinal surgery results in less morbidity. Methods. Sixty discectomies were performed in 10 live sheep. In each sheep, three randomly selected discectomies were performed thoracoscopically, and, subsequently, three open discectomies were performed. The animal then was killed, and the spine was sectioned and analyzed by computer imaging. Results. Statistical analysis found no significant difference in the amount of disc resected (t' = 1.9639, t_0.025,60 = 2.000, α = 0.05). The mean percentage of disc resected was 67.8% (range, 0-92.2%) in the thoracoscopic group and 76.1% (range, 44.9-95.4%) in the open group. More than 50% of the disc was excised in 27 of 30 spines (90%) in the thoracoscopic group and in 29 of 30 (96.7%) in the open group. This difference was not statistically significant (Θ²(_0.05,1) = 3.84, Θ²' = 1.07). Conclusion. The findings in this study indicate that the thoracoscopic discectomy technique is equivalent to the open technique in the amount of disc and end plate resected. In addition, these findings suggest that thoracoscopic discectomies provide adequate disc resection to provide for an acceptable fusion rate according to the criteria demonstrated by Bunnell in 1982 and therefore support the efficacy of a thoracoscopic technique for anterior spinal fusion.