Experimental development and validation of a technique for lumboendoscopicanterior fusion of lumbar spine fractures - Comparison of endoscopic and open surgery in a live porcine model

Background: Using a porcine model, this study describes the feasibility of a lumboendoscopically guided approach to the lumbar spine for anterior inte rbody fusion, and compares the results with that of the open procedure. The objectives of this study were to develop a minimally invasive approach to the lumbar spine for anterior fusion in pigs, and to test the validity and safety of the procedure in this porcine model. Besides posterior stabilizat ion, considerable number of thoracolumbar spine (Th12-L5) fractures require intervention for anterior fusion to prevent loss of height of the injured segment and kyphotic deformation. Because anterior fusion needs major surge ry (thoracophrenolumbotomy for Th12-L1), which is associated with high morb idity, this study aimed to develop a less traumatic minimally invasive appr oach. Methods: Six pigs under balanced anesthesia were used to study the feasibil ity of the lumboendoscopic approach for bisegmental fusion (iliac crest bon e block and dynamic compression plate) from Th15 to L6. In an additional si x animals, lumboendoscopic fusion was performed at the level of diaphragm i nsertion (Th14-Th16), representing Th12-L1 in patients. For comparative ana lysis, six animals undergoing open thoracophrenolumbotomy and anterior Th14 -Th16 fusion served as control subjects. Results: Endoscopic anterior fusion could be successfully performed at all levels of the thoracolumbar spine without major complications. In three cas es, unintended opening of the peritoneal cavity was observed, however, with out the operative procedure being affected. Comparative analysis revealed a significantly longer p < 0.01 operation time (126 +/- 6.5 min) and increas ed femoral vein pressure (11.3 +/- 0.7 mmHg) in animals undergoing endoscop ic surgery (open procedure, 76.0 +/- 11.6 min and 5.2 +/- 0.5 mmHg). Howeve r, the microvascular blood supply (perfusion) to the distal extremities, as assessed by laser Doppler flowmetry, was not affected. Conclusions: Our study demonstrates that lumboendoscopic anterior spine fus ion in pigs is feasible at all levels from Th14 to L6, and can be performed in an acceptable operation time without major complications.