A BIOMECHANICAL COMPARISON OF OPEN AND THORACOSCOPIC ANTERIOR SPINAL RELEASE IN A GOAT MODEL

Study Design. A biomechanical assessment of anterior release and disce ctomy in the thoracic spine was performed on an animal model using tho racoscopic and open thoracotomy techniques. Objectives. To compare the relative efficacy of these two techniques of release in achieving inc reased spinal mobility. Background Data. The clinical use of video-ass isted thoracoscopy in the correction of spinal deformity is increasing . The effectiveness of thoracoscopic anterior spinal release with disc ectomy has not been evaluated biomechanically. Methods. Anterior relea se with discectomy was performed on six midthoracic motion segments in five mature goats. The thoracoscopic technique was used for three lev els on one side, and an open thoracotomy was used for the alternating three levels of the contralateral side. The duration of surgery for di sc excision and the amount of blood loss for each technique were recor ded. The intact cranial and caudal motion segments served as controls. The motion segments were individually subjected to nondestructive bio mechanical testing. Torsional, sagittal, and coronal bending torques w ere applied, and the resulting angular displacement was measured. Resu lts. The duration of surgery to remove a disc thoracoscopically decrea sed as experience was gained by the surgeon. The amount of intraoperat ive blood loss was comparable using the two methods. There was signifi cantly increased flexibility in the released segments with both techni ques, compared with the flexibility in the intact levels for all three loading directions. There was no difference in the motion obtained af ter release between the two techniques. Conclusion. Open and thoracosc opic anterior release and discectomy have been demonstrated, through b iomechanical in vitro testing, to increase the flexibility of the spin e to a similar extent.