Transforaminal (“Inside Out”) Approach

The transforaminal approach, with direct access to the interior of the disc, was refined and popularized by Dr. Anthony Yeung, and represents the first major implementation of endoscopic discectomy. The inside-out technique is one of the easier endoscopic surgeries for surgeons to learn. This posterolateral approach uses the natural opening of the intervertebral foramen to minimize trauma during access. The working sleeve passes between muscle planes, through the foramen and between the exiting and traversing nerves (Kambin’s triangle) to insert directly into the disc. No cutting of muscles and, typically, no resection of bone or ligament is required to gain this access.

This approach provides direct access to the interior of the disc for nuclear decompression, and to the annulus fibrosis for annuloplasty. By withdrawing the working sleeve from the disc slightly, structures outside the disc can then be accessed. For example, a foraminoplasty can be performed or a sequestered nucleus fragment can be retrieved. Further, by adjusting the skin entry point and the angle of approach, different regions of the spine can be accessed. A more lateral, shallower approach permits access to the epidural space, while a more posterior, steeper approach allows access to far lateral herniations.

Technique Summary:

  • Using fluoroscopy, target the posterior portion of the disc with a spinal needle and guide wire
  • Make a skin incision and insert the dilator over the guide wire down to the annulus
  • With a mallet, advance the dilator through the annulus and into the disc
  • Place a working sleeve over the dilator, and then insert the spine endoscope
  • Use rongeurs and the RF probe to resect nucleus material inside the disc
  • Withdraw the tip of the working sleeve slightly to the exterior of the disc to visually confirm the decompression of neural structures and to address any extradiscal pathology
  • Perform any required additional steps (foraminoplasty, extruded or sequestered fragment removal, annuloplasty, etc.)
  • Remove the endoscope and working sleeve and close the incision with a suture or bandage