Experimental development and validation of a technique for lumboendoscopic anterior 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 interbody 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 stabilization, 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 surgery (thoracophrenolumbotomy for Th12-L1), which is associated with high morbidity, this study aimed to develop a less traumatic minimally invasive approach.

METHODS

Six pigs under balanced anesthesia were used to study the feasibility of the lumboendoscopic approach for bisegmental fusion (iliac crest bone block and dynamic compression plate) from Th15 to L6. In an additional six animals, lumboendoscopic fusion was performed at the level of diaphragm insertion (Th14-Th16), representing Th12-L1 in patients. For comparative analysis, 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 cases, unintended opening of the peritoneal cavity was observed, however, without the operative procedure being affected. Comparative analysis revealed a significantly longer p < 0.01 operation time (126 +/- 6.5 min) and increased femoral vein pressure (11.3 +/- 0.7 mmHg) in animals undergoing endoscopic surgery (open procedure, 76.0 +/- 11.6 min and 5.2 +/- 0.5 mmHg). However, 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 fusion in pigs is feasible at all levels from Th14 to L6, and can be performed in an acceptable operation time without major complications.