Research

The cantilever TLIF (c-TLIF) uses structural allograft placed midline in the anterior column followed by local autologous graft placed in the middle column. Compression across pedicle screw instrumentation using the structural allograft as a fulcrum creates restoration of lordosis and places the autologous bone graft under compression. Advances in technology allow for the same technique to be performed in a less invasive fashion maintaining the advantages of the c-TLIF concept.

The MedRx™ cannula system (Medtronic) is used unilaterally though a 26mm working cannula for exposure of the facet joint. Facetectomy follows to expose the disc space through the foramen. Sub-total discectomy allows for the structural allograft to be placed midline and dorsal against the anterior annular fibers. Local autologous bone is packed into the middle column. The contralateral facet and posterior elements are packed with bone graft through a second cannula. Bilateral percutaneous pedicle screw placement is accomplished with the Sextant™ pedicle screw system (Medtronic). Incision closure consisted of two 2.5 centimeters paramedian incisions that were used for the working cannulas and screw insertion and two stab incisions where the rods were inserted.

The results of the first seven patients using this technique were analyzed. There were no intra-operative complications and EMG monitoring was used in all cases. Pedicle screws were placed bilaterally in all cases without incident. Operative time averaged 250 minutes (range 220-310). Estimated blood loss averaged 75 cc (range 50 to 150). Two patients were discharged the day after surgery and the remaining five on the second day after surgery (average 1.7 days). All five patients presenting with pre-operative radiculopathy had resolution of symptoms immediately post-operatively. Narcotic use was discontinued between two and four weeks postoperatively. Outcomes and radiographic data are being collected. No early failures or complications have been documented.

Minimally invasive transforaminal lumbar interbody fusion is a technically feasible method that allows for neural decompression and interbody bone grafting. Although technically demanding, this technique offers several advantages to traditional open techniques, including minimized soft tissue trauma, blood loss, hospital stays, and the potential for earlier return to function. Further analysis will be required to determine rate of fusion and outcomes.