Neurology Minimally Invasive Transforaminal Lumbar Interbody Fusion

18 Minimally Invasive Transforaminal Lumbar Interbody Fusion Tips and Pearls Before You Begin Visualization of the disk space is essential Complete resection of the facet joint with removal of all overlying bone from the superior articular process of the inferior vertebra should be performed Disk space preparation is the key to an increased likelihood of a successful arthrodesis A combination of currettes and Kerrison rongeurs should be used to prepare the end plate Fluorscopy may be used to ensure that the anterior longitudinal ligament is not violated Care should be taken with paddle distractors and shavers, as these devices may compromise the end plates, which can result in subsidence of the implant midline L5 spinous process dura ligam en flavu tum m L5 pedicle ex ner iting ve L5 roo t L5–S1 facet joint pars interarticularis gL rsinroot e v tra erve n L4–L5 facet joint L4–L5 disk space e ne xitin rv g e r L4 oo t L5 lamina L4 lamina L4 pedicle • With the working portal appropriately docked on the level of pathology, an initial exposure can be performed • Often there are residual paraspinal muscle fibers that must be removed from the lamina 99 100 IV Lumbar Spine midline L5 spinous process ligam en flavu tum m L5 lamina L4 dura gL sin t ver e roo a r t er v n lam ina pars interarticularis L5 pedicle L4–L5 facet joint L5–S1 facet joint L4–L5 disk space exiting L4 nerve root L4 pedicle • Once the lamina is exposed, a high-speed burr is used to perform a laminectomy Bone is removed until only the flavum is visualized – The laminectomy is extended laterally through the pars interarticularis – Bone is saved in a bone trap 18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion midline L5 spinous process ligam en flavu tum m dura L4 lamina L5 ing t ers roo v a e tr erv n L5 lamina e ne xiti rv ng e r L4 oo t L5 pedicle L5–S1 facet joint L4–L5 disk space L4 pedicle • The laminectomy is extended cranially until the end of the flavum insertion is identified – Epidural fat or dura is often seen • This marks the cranial extent of the laminectomy • The burr is then directed directly laterally through the pars interarticularis 101 102 IV Lumbar Spine midline L5 spinous process dura ligam en flavu tum m L5 rsing trave e root ner v L5 lamina L4 lamina L5 pedicle L5–S1 facet joint L5 superior facet L4–L5 disk space exiting L4 nerve root • Once the burr is through the pars, the inferior articular process can be removed, completing the facetectomy and exposing the involved disk space midline L5 spinous process dura ligamentum flavum L4 lamina L5 lamina L5–S1 facet joint L5 superior facet L4–L5 disk space exiting L4 nerve root L4 pedicle • The ligamentum flavum can now be resected • Care is taken to preserve the flavum initially, as it protects the dura while the decompression is being performed 18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion midline L5 spinous process dura ligamentum flavum gL rsinroot e v tra erve n L5 lamina L4–L5 disk space L4 lamina L5 pedicle L5–S1 facet joint L5 superior facet exiting L4 nerve root • Bipolar cautery is used to coagulate the veins that overlie the disk space superficial midline L5 spinous process dura deep midline L4 lamina L5 lamina ng L ersi ot trav rve ro ne L5 pedicle L5–S1 facet joint L5 superior facet cage in L4–L5 disk space exiting L4 nerve root • Once the veins have been coagulated, the inferior pedicle (L5) and disk space (L4–L5) can be visualized – The traversing nerve root (L5) is just medial to the pedicle – The exiting nerve root (L4) is above the disk space It is not typically exposed 103 104 IV Lumbar Spine • The working space in the TLIF is lateral to the exiting root in the neuroforamen – Lateral fluoroscopic imaging is used when preparing the disk space 18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion • The disk space is prepared using a combination of paddle distractors and end plate shavers to remove the disk material 105 106 IV Lumbar Spine • Once the disk material has been removed and the end plates prepared, a bone funnel is passed into the disk space – The bone collected during the laminectomy can then be placed into the disk space • The interbody cage is then impacted into place – Care is taken to protect the nerve root during cage placement 18 Minimally Invasive Tranforaminal Lumbar Interbody Fusion deep midline dura L5 traversing nerve root suction on TLIF working zone L4 exiting nerve root • The interbody cage has been placed into the prepared disk space – The cage is directed obliquely toward the midline – The tube can be directed medially to perform a contralateral decompression Potential Pitfalls Inadequate resection of the facet joint will lead to decreased visualization of the disk space As a result, the transforaminal working zone will be narrowed and an undersized implant will be placed, increasing the likelihood of cage migration and pseudarthrosis 107