An Effect and Safety Investigation on Percutaneous Endoscopic Lumbar Discectomy Technique to Remove Extraforaminal Disc Herniation at L5/S1 Segment Through 5th Transverse Process-facet Joint-sacrum Space

30 cases diagnosed as extraforaminal disc herniation at the segment of Lumbar 5 / sacrum 1 (L5/S1) will be recruited in this investigation. All the patients will receive PELD operation following the strict procedure that penetrating through the TFS space. The pain score (VAS), physical ability (ODI score) and life quality (SF-36） will be evaluated one day before surgery and 2 days, 1 month and 3 months after the surgery. Any side effects such as infection, nerve damage, main blood vessel injury will be recorded.

The operation procedure must follow the following steps:

1. The patient was positioned prone.
2. The skin entry point was determined using axial MRI or CT images
3. During operation, with anterior posterior view of fluoroscopy, the longitudinal midline of lumbar spine on the skin (Line C), the line right across L5/S1 space (Line A) was marked on the skin. With lateral view, the line right across L5/S1 space was also marked on skin (Line B). The line A and B should be crossed. The final entry point on skin was on the Line A and away from midline with the distance measured on axial MRI or CT images as described above.
4. Local infiltration with 1% Lidocaine was applied to skin and deep fascia on the penetration path. The introduction of long 20G needles could be performed with continuous or intermittent fluoroscopy. The needle traveled through TFS space. Generally, the position just above S1 superior endplate has enough safe space from the existing nerve root that might be pushed downward by the protruded discs, so it is usually the target for needle puncture.

Discography was strongly recommended to confirm diagnosis and distinguish the protruded disc from the surrounding soft tissue. 5. The following steps were performed as usual: the needle was replaced by a guide wire; a 9 mm incision was made in the skin at the entry site; a tapered cannulated dilator was inserted along the guide wire; and finally a beveled round working cannula of 8.0 mm in outer diameter was inserted, with the beveled tip touching the endplate of S1 and leaning against superior articular process of S1. If the TFS space is not big enough for working cannula, manual bone drills with blunt tip could be used to enlarge it.

Soft tissue including fat tissue, muscle and fibers of ligaments were pushed cephalad until the blue stained herniated disc was visible. Then the disc was removed. An absorbable gelatin sponge was impacted via the working cannula for hemostasis. A sterile dressing was applied with a one-point suture.