Study Design.Two surgical techniques for anterior discectomy were compared biomechanically. The surgical procedures were performed in live, anesthetized, skeletally immature pigs. Spine flexibility was measuredin vitro.Objective.To determine whether endoscopic techniques for discectomy are as effective as open procedures in increasing spine flexibility.Summary of Background Data.Although studies have verified that discectomy increases spine flexibility, no study has confirmed whether endoscopic techniques increase flexibility as effectively as standard thoracotomy, which is a substantially different procedure.Methods.The intervertebral disc between vertebrae T8 and T9 was resected from 30 live, anesthetized, adolescent pigs. In 15 pigs, the chest was opened via thoracotomy of the eighth rib, and the disc was excised. In the other 15 pigs, the disc was removed endoscopically. These motion segments and six intact controls were tested mechanically in side bending, flexion-extension, and axial rotation.Results.No statistically significant differences in flexibility were found between open and endoscopic groups in any loading direction. The statistical power to detect a 20% difference between surgical groups was ≥ 95%.Conclusions.Endoscopic and open techniques were equally effective in increasing spine flexibility. Because endoscopy may reduce surgical morbidity compared with open discectomy, these results support the use of endoscopy for the surgical correction of scoliosis before instrumentation.