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REVIEW
A novel surgical concept of transforaminal full-endoscopic
lumbar undercutting laminectomy (TE-LUL) for central canalstenosis of the lumbar spine with local anesthesia :A case report and literature review
Koichi Sairyo, Kazuta Yamashita, Hiroaki Manabe, Yoshihiro Ishihama, Kosuke Sugiura, Fumitake Tezuka,
Yoichiro Takata, Toshinori Sakai, Yasuyuki Omichi, Nobutoshi Takamatsu, Ayaka Hashimoto, and Toru Maeda
Department of Orthopedics, Tokushima University, Tokushima, Japan

Abstract : Full-endoscopic spinal surgery was first developed for the lumbar herniated nucleus pulposus. Mainly,
there are two types in the full-endoscopic lumbar surgery : i.e., transforaminal (TF) and interlaminar approach.
The surgery can be done under the local anesthesia for the TF approach ; therefore, we need to further develop
the TF approach to variety of the spinal disorders. Recently, the TF full-endoscopic surgery has been applied forthe spinal canal stenosis. First, transforaminal full-endoscopic lumbar foraminoplasty for the foraminal stenosis ; then, transforaminal lumbar lateral recess decompression for the lateral recess stenosis has been developed.
Finally, we have developed the surgical technique to decompress the central stenosis via TF approach under
the local anesthesia. Prior to initiate the clinical case, we have attempted the lumbar undercutting laminectomy
using a fresh cadaveric spine. After we technically confirmed that the transforaminal full-endoscopic lumbar
undercutting laminectomy (TE-LUL) is possible, we applied the technique to the patient whose lung capacity did
not allow general anesthesia. The 72 years old female patient with central canal stenosis could be improved herleft leg pain and muscle weakness after TE-LUL under the local anesthesia. In this paper, we introduce the surgical technique of the TE-LUL and discuss of the efficacy of the TE-LUL. J. Med. Invest. 66 : 224-229, August, 2019
Keywords : transforaminal full-endoscopic lumbar decompression, central stenosis, undercutting laminectomy

INTRODUCTION
Full-endoscopic lumbar spine surgery was initially developed
using transforaminal (TF) approach. Several frontiers attempted to use an endoscope with a cannula (1, 2, 3, 4) using Hijikata’s percutaneous discectomy technique (5). Finally, Dr. Yeung
successfully established the current single-portal endoscopic
discectomy (3, 4, 6). The Full-endoscopic surgery requires only
8 mm skin incision, minimum damage to the back muscles andbeing able to conduct under local anesthesia (7, 8). Thus, it isunderstood the least invasive disc surgery, so far.
There is another way in the full-endoscopic surgery : i.e., interlaminar (IL) approach (9,10). It is called Interlaminar full-endoscopic lumbar discectomy (IELD). This is further minimallyinvasive surgery of microendoscopic discectomy (11). Recently,
the IL technique has been applied for the decompression of thelumbar spinal canal stenosis (12, 13). Although we use same endoscopic system both for TF and IL approach, there is the biggest
difference between them. The IL approach basically necessitates
general anesthesia, on the other hand, the TF approach can bedone under the local anesthesia with aware and awake condition.
The TF approach has been also applied for the decompressionof the lumbar spinal canal stenosis. Once again, the TF approachis possible with the local anesthesia ; thus, it should be the great
benefit especially for the elderly cases with poor general condition. First, the foraminal stenosis was decompressed with TF
Received for publication June 3, 2019 ; accepted July 4, 2019.
Address correspondence and reprint requests to Koichi Sairyo, MD,
PhD, Professor and Chairman Department of Orthopedics, Tokushima University Graduate School, 3-18-15 Kuramoto, Tokushima 7708503, Japan and Fax: +81-88-633-0178.

full-endoscopic system (14, 15). Now, it is called Transforaminal
endoscopic lumbar foraminotomy (TELF). Second, very recently,
lateral recess stenosis can be decompressed with TF approach(16, 17, 18).
There is one more type of the lumbar spinal canal stenosis : i.e.,
central stenosis. We have developed the TF full-endoscopic decompression technique for the disorder. First, we established theendoscopic technique with a fresh cadaver ; then, we applied thesurgery to one female case whose general condition was reallypoor. We name the technique as transforaminal full-endoscopic
lumbar undercutting laminectomy (TE-LUL). In this paper, we
describe the technique and introduce the first case. Finally, we
discussed some issues on this procedure.

A SCHEMATIC PRESENTATION OF THE SURGICALTECHNIQUE
Figure 1 demonstrates the surgical procedure of the TE-LUL.
The 8 mm cannula is first installed on the superior articular
process (SAP). Total removal of the SAP is performed at thestep 1 ; then, articular surface of the inferior articular process(IAP) is exposed. Next, undercutting laminectomy is conductedwith ventral half resection of the IAP as the step II. After that,the dorsal surface of ligamentum flavum is seen. Almost of theligamentum flavum at the area is removed as the step III, anddecompression of the central stenosis is completed. As shown in
the final panel on Figure 1, the compression of the dural tube isenlarged after the TE-LUL surgery.

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The Journal of Medical Investigation Vol. 66 August 2019

Step I  :  Total removal of SAP

Step Ⅱ :Partial removal of IAP

Pre-OP

Post-OP

Figure 2．The comparative axial MRI before and after the surgery.
Decompression is obtained with TE-LUL on the axial image.

Step Ⅲ :Partial removal of LF

L3

L4

L4

Step Ⅳ :Final view of TF-LUL

Figure 1．Surgical procedure of the TE-LUL.
The 8 mm cannula is first installed on the superior articular process(SAP). Total removal of the SAP (color in red) is performed at the step
1. Undercutting laminectomy (color in red) is conducted with ventral
half resection of the IAP as the step II. The ligamentum flavum at thearea (color in red) is partially removed as the step III. As shown in the
final panel on, the compression of the dural tube is enlarged after the
TE-LUL surgery.

A CASE REPORT

L3

Pre-OP

Post-OP

Figure 3．The comparative right para-sagittal MRI before and after
the surgery.
Although slight compression of the dural tube is still existed, complete
compression before the surgery was recovered after the surgery.

L3 L3
L3 L3
A 72 years old female visited us with complaining of both legs
pain and left leg weakness. Standing upright posture caused
severe legs pain ; thus, she was using whirl chair with lumbar
flexed position to move. Any of conservative treatment was not
L4 L4
L4 L4
effective to reduce her symptom for 2 months ; then, she wasreferred to us for the purpose of surgical intervention.
On her first visit, we examined motor manual testing andfound muscle weakness on the left side as follows : quadriceps(4/5), tibialis anterior (2/5), and extensor halluscis longus (2/5),
whereas the right side showed all normal. Figure 2,3, and 4
demonstrates MRIs before and after the surgery. Most severe
stenosis is found at L3/4, and at the other levels stenosis was
Pre-OP
Post-OPvery moderate. Thus, we diagnosed that her symptoms were due
to cauda equina syndrome due to the central canal stenosis at Figure 4．The comparative left para-sagittal MRI before and afterL3/4. We planned posterior decompression with laminectomy the surgery.
Although slight compression of the dural tube is still existed, complete
and flavectomy under the general anesthesia.
Before surgery, an anesthesiologist examined her general compression before the surgery was recovered after the surgery.
condition. The physician pointed that her lung capacity was so
weak : i.e. one second volume being 0.71 (l), that she could not
tolerate the general anesthesia. Thus, the anesthesiologist recommended her to avoid the general anesthesia and to undergo was present at the left. Local anesthesia was conducted to skin,
any kinds of surgery that can be done under the local anesthesia. subcutaneous tissue, muscle, capsule, facet joint and the surface
Under the guidance of the anesthesiologist, we decided to con- of the disc with 15 ml of 1% lidocaine. Following skin incision in 8mm, a cannula was installed just on the SAP joint. TE-LUL wasduct the TE-LUL for L3/4 bilaterally.
First, we performed to the left side, since muscle weakness conducted with the technique as shown in Figure 1. After the226

K. Sairyo, et al. TE-LUL for lumbar central canal stenosis

confirmation of the decompression of L4 traversing nerve rootand dura matter, TE-LUL for the left side was over. The rightside was also decompressed with TE-LUL maneuver. During thesurgery, we did not experience any complications. One hour after
the surgery, she stood and walked with a walker. She noticed
no leg pain any more, and rehabilitation started for her muscle
weakness. One week later, the weakness partially improved toquadriceps (5/5), tibialis anterior (4/5), and extensor halluscis
longus (3/5). She returned to her job as a president of a local company two weeks after the surgery, since low back and leg pain
disappeared. Two months later, strength of the tibialis anterior
and extensor halluscis longus completely became normal.
Figure 2,3, and 4 demonstrates the comparative MRI before
and after the surgery. Decompression is obtained with TE-LUL
on the axial image as shown in Figure 2. On the right (Figure 3)
and the left (Figure 4) sagittal images, slight compression of thedural tube is still existed. However, complete compression before
the surgery was recovered after the surgery.
CT scans before and after the surgery were exhibited on Figure 5 (3-dimensional CT), Figure 6 (sagittal CT) and Figure 7

Pre-OP(axial CT). On posterior view of the 3-dimensional CT, it is very
difficult to understand the decompression area, since during thesurgery posterior construct was mostly preserved (Figure 5). On
the sagittal view, it is obvious that entire SAP and partial IAP isresected at L3-4 level bilaterally (Figure 6). Even though entire
SAP is removed, facet contact is about 50% remained. On axial
scans, one can easily understand that entire SAP and partial
IAP is resected (Figure 7).

DISCUSSION
In the literature, there are many reports to conduct full-endoscopic decompression of the central stenosis under the generalanesthesia via interlaminar approach (12, 13). In this paper, wehave first introduced the transforaminal full-endoscopic surgical
technique to decompress the central canal stenosis under the
local anesthesia as shown in Figure 1. We have named thistechnique transforaminal full-endoscopic lumbar undercutting
laminectomy (TE-LUL).

Post-OP

Figure 5．Posterior view of the three dimensional CTs before and after the surgery.
It is very difficult to understand the decompression area, since during the surgery
posterior construct was mostly preserved

Right

Pre-OP

Left

Post-OP

Pre-OP

Post-OP

Figure 6．The sagittal reconstructive CTs before and after the surgery.
It is obvious that entire SAP and partial IAP is resected at L3-4 level bilaterally. Even though entire SAP isremoved, facet contact is about 50% remained.

The Journal of Medical Investigation Vol. 66 August 2019

Pre-OP

Post-OP

Figure 7．The axial reconstructive CTs before and after the surgery.
On axial scans, one can easily understand that entire SAP and partial
IAP is resected.

The great benefit of the TE-LUL surgery should be what one
can perform this procedure under the local anesthesia withjust 8mm skin incision. The lumbar spinal canal stenosis is thedisorder for the elderly patients. As comparing to the younger
generation, elderly patients has poor tolerance for the generalanesthesia. For example, they may frequently have disorders in
cardiovascular, pulmonary, hepatic, renal, and/or cognitive function. Among them, pulmonary dysfunction would be extremely
important like the current case.
Chung et al. (19) reviewed 404 elderly cases who underwent
surgery under the general anesthesia and evaluated post-operative complications. They found that 26.4% of patients developed
one or more postoperative complications, and the in-hospitalmortality rate was 6.7%. Respiratory complication was the mostcommon postoperative complication (12.9%). They also evaluatedthe effectiveness of the anesthesia method on the post-operative
pulmonary complication and found that the regional anesthesia
could reduce the complication as comparing to the general anesthesia. Rock and Rich (20) reviewed post-operative pulmonary
complications (POPC) and concluded that POPC is a significant
source of morbidity and mortality, and regarding the risk factors
they stated that cigarette smoking, chronic respiratory disease,age greater than 70 years, and others. Thus, the elderly patientswith pulmonary dysfunction like the current case has a greatrisk for the post-operative pulmonary complication.
Urwin et al. (21) reviewed 2162 cases from 15 trials who underwent hip surgery under regional or general anesthesia. They
concluded that there are advantages for regional anaesthesia
compared to general anaesthesia in terms of early mortality.
Rasmussen et al. (22) reviewed 438 elderly patients who had
major non-cardiac surgery. The 217 cases surgeries under thegeneral anesthesia, and the remaining 211 underwent surgeries
under the regional anesthesia. They found that the mortality
after the general anesthesia was significantly higher. Chou etal. (23) reviewed 2,407 registered cases of femoral fracture in
the aged (over 65 y.o.). They found 42 mortal patients, and foundthe patients in mortality group had a significantly higher rateof pneumonia, respiratory failure, sepsis, and pulmonary embolism than those in the survival groups. Regarding the mortality
after the surgery for elderly patients, especially for poor pulmo-

227

nary condition, spine surgeons need to develop the spinal decompression surgery that can be done under the local anesthesia.
Thanks to many frontiers on the endoscopic spine surgeries,
recently, single portal full-endoscopic spine surgery has been developed and established (1, 2, 3, 4, 6). At first, the full-endoscopic
surgery was limited only for the disc surgery (3, 4, 6, 7, 8, 9, 10) ;however, the technique has been applied for the lumbar spinal
canal stenosis (LSS). There are two maneuver in the full-endoscopic surgery : i.e. interlaminar (IL) and tansforaminal (TF).
Indeed, the decompression for the LSS with IL full-endoscopic
technique would be minimally invasive (12, 13). Although thetrial of IL surgery under the local anesthesia (24) has been reported, majority of the IL surgery requires general anesthesia(12, 13).
The TF full-endoscopic surgery is possible to conduct under
the local anesthesia ; thus, one needs to expand the surgicalindication from the disc surgery to the LSS decompression surgery. First, the foraminal stenosis has be overcome with the TF
technique (14, 15, 25). Yeung et al. (25) reported the long-termclinical results and more than 80% would be excellent and good.
Next, TF full-endoscopic lateral recess decompression (TE-LRD)
was started (16, 17, 18, 26, 27, 28). Ahn et al. (26) followed 45 patients who had the TE-LRD for years and reported satisfactory
clinical results more than 80%. Thus, for the foraminal and lateral recess stenosis, technique and skill of the TF full-endoscopic
surgery would be now established.
There is one more type of the LSS : i.e. central canal stenosis.
There has been no report in the literature on the TF full-endoscopic technique of the decompression of the central canal stenosis. This time, we have developed such technique and namedtransforaminal full-endoscopic lumbar undercutting laminectomy (TE-LUL). Finally, all three types of the LSS is possible tobe decompressed with transforaminal full-endoscopic surgery
under the local anesthesia.

LIMITATIONSThere are possible limitations in the TE-LUL surgery.
1) indication of the surgery
By the TE-LUL surgery, it is very difficult to remove entire
ligamentum flavum (LF). As shown in Figure 3 and 4, partial
LF still exists after the surgery. Thus, the first indication shouldbe the traditional interlaminar laminectomy with the generalanestheisa. This time, the case was not combined with the spondylolisthesis. Thus, the surgical outcome for the LSS patientswith spondylolisthesis is still unclear.
2) post-operative complication
The possible concern after the total removal of SAP would
be instability following TE-LUL. However, as shown in Figure
6, after the total SAP resection, about 50% of the facet contact
could be preserved. Moreover, the cases that is in a good indication should be not active and poor general condition. Post-surgical instability may not be occurred. The biggest concern would befatigue fracture of the thinner SAP after the surgery. We warned
this patient not to perform the repetitive extension exercise.

CONCLUSION
In this paper, we have proposed a novel surgical concept oftransforaminal full-endoscopic lumbar undercutting laminectomy (TE-LUL) for central canal stenosis of the lumbar spine
under local anesthesia, and reported the clinical results in theinitial case. There are three types of the lumbar spinal canal stenosis. TELF for the foraminal stenosis, TE-LRD for the lateral

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K. Sairyo, et al. TE-LUL for lumbar central canal stenosis

recess stenosis, and TE-LUL for the central stenosis. Now, forthe standard three type of the stenosis, transforaminal full-endoscopic decompression under the local anesthesia is finallydeveloped.

ACKNOWLEDGMENT
The authors wish to thank to the following people and companies for their support to develop this new endoscopic technique.
Daido Nakahara, Yasuo Araki, Akihito Kobayashi, Takeshi
Fujiwara, Eitaro Tanaka, Shigeki Tenma, Yozo Takehisa,
Kazue Kobayashi, Sei-Ichi Mima, Keiko Shimada, Takahiko
Makino, Shigeru Ueda, Yoshiyuki Kato, Fujio Ito, Michio Ueda,
Yuiji Ogawa, Masao Marumoto, Nobuaki Mima, Tomoni Mima,
Tatsuo Kosugi, Ken Noguchi, Sumiko Suzuki, Hachioji Sports
Clinic, and Nihon Flush Co., Ltd.

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