ENDOSCOPIC DISKECTOMY INCREASES THORACIC SPINE FLEXIBILITY AS EFFECTIVELY AS OPEN DISKECTOMY - A MECHANICAL STUDY IN A PORCINE MODEL

Study Design. Two surgical techniques for anterior discectomy were com pared biomechanically. the surgical procedures were performed in live, anesthetized, skeletally immature pigs. Spine flexibility was measure d in vitro. Objective. To determine whether endoscopic techniques for discectomy are as effective as open procedures in increasing spine fle xibility. Summary of Background Data. Although studies have verified t hat discectomy increases spine flexibility, no study has confirmed whe ther endoscopic techniques increase flexibility as effectively as stan dard thoracotomy, which is a substantially different procedure. Method s. The intervertebral disc between vertebrae T8 and T9 was resected fr om 30 live, anesthetized, adolescent pigs. In 15 pigs, the chest was o pened via thoracotomy of the eighth rib, and the disc was excised. In the other 15 pigs, the disc was removed endoscopically. These motion s egments and six intact controls were tested mechanically in side bendi ng, flexion-extension, and axial rotation. Results. No statistically s ignificant differences in flexibility were found between open and endo scopic groups in any loading direction. The statistical power to detec t a 20% difference between surgical groups was greater than or equal t o 95%. Conclusions. Endoscopic and open techniques were equally effect ive in increasing spine flexibility. Because endoscopy may reduce surg ical morbidity compared with open discectomy, these results support th e use of endoscopy for the surgical correction of scoliosis before ins trumentation.