Extraforaminal (“Outside In”) Approach
The extraforaminal, or “outside-in” technique, also uses a posterolateral approach, but differs from the transforaminal (“inside-out”) technique in that the needle and dilator are targeted to a bony structure outside of the foramen. Rather than passing through the foramen and entering the disc, the working sleeve is docked onto the pedicle, superior articular process, or other bony landmark. This access can be attained using the same instrument set as is used for the transforaminal (“inside out”) approach.
With the tip of the endoscope positioned just outside of the foramen, instruments can access the bony structures and extraforaminal pathology. The facet and/or pedicle can be resected to provide better access through the foramen or to decompress the exiting nerve. This bony resection is performed under direct visualization with the endoscope, while the neural structures are carefully retracted under visualization to ensure they are protected from the burr or reamer. The extraforaminal approach also allows extruded fragments to be addressed without the additional step of entering the disc.
- Target the pedicle caudal to the foramen with a needle and guide wire
- Advance the dilator while maintaining contact of the guide wire on the pedicle
- Place the working sleeve over the dilator
- Insert the endoscope and dissect the structures of the foramen under direct visualization
- Identify and remove herniated disc material
- Resect the bony structures of the foramen with the burr under direct visualization as necessary to decompress the nerve and/or provide access to the epidural space without compromising the nerve root