Experimental laparoscopic and thoracoscopic discectomy and instrumented spinal fusion. A feasibility study using a porcine model.

To explore the safety and the effectiveness of laparoscopic and thoracoscopic spinal surgery, an acute/non-survival animal trial was performed in 5 pigs using rigid and flexible endoscopes, flouroscopy, a holmium-YAG laser, and prototype instruments and implants. Our study aimed to approach the intervertebral disc space and spinal canal using laparoscopic and thoracoscopic techniques and to explore the potential and limits for endoscopic anterior spinal decompression and fusion. In a lateral recumbency access was provided to the anterolateral aspect of the lumbar spine from L1/2 to L7/S1, the thoracic spine was accessible from T2/3 to the diaphragmatic insertion. Complete disc space emptying with penetration into the spinal canal could be performed, epidural bleeding could be controlled by a hemostatic sponge, however bleeding restricted visualization for further endoscopic manipulation in the spinal canal. Intervertebral fusion was accomplished at T6/7, L4/5 and L7/S1 using small fragment plates with 3.5 mm screws and iliac bone grafts or prototype carbon fiber cages. On post mortem examination we found no dural tears and no nerve root damage, all animals had stabilized fusion sites and good implant position. We conclude that minimally invasive thoracoscopic and laparoscopic approaches to the spine are feasible and safe to perform disc decompression and implant placement for spinal fusion. In addition to currently performed laparoscopic interbody fusion, also plate fixation to reestablish lordosis of the lumbar spine is feasible at least in the porcine model. Careful disc decompression must be performed prior to implant introduction to prevent iatrogenic disc protrusion and spinal cord or nerve root compression. However, further surgical exploration of the spinal canal using these techniques does not provide adequate visualization of epidural spaces and therefore must be regarded as unsafe.