UMIN-CTR Clinical Trial

Public title

A Comparative Study of Working Portal Placement in AFESS Surgery for Lumbar Spinal Stenosis

Acronym

AFESS trial

Scientific Title

A prospective randomized controlled trial comparing working portal placement in assisted full-endoscopic spine surgery (AFESS) unilateral laminotomy with bilateral decompression for lumbar spinal stenosis, using the ipsilateral inferior articular process preservation rate as the primary endpoint

Scientific Title:Acronym

AFESS portal trial

Region

Japan

Condition

Lumbar spinal canal stenosis

Classification by specialty

Orthopedics

Classification by malignancy

Others

Genomic information

NO

Narrative objectives1

Primary objective:
To compare the preservation rate of the ipsilateral inferior articular process on CT obtained within 4 days after surgery between patients undergoing left-sided unilateral laminotomy with bilateral decompression using assisted full-endoscopic spine surgery (AFESS) with the working portal placed 4 mm lateral to the midline and those with the working portal placed 10 mm lateral to the midline.

Secondary objectives:
To compare between the two groups the extent of additional bone resection at the base of the ipsilateral spinous process on CT within 4 days after surgery, adverse events and reoperation from intraoperatively to 12 months postoperatively, patient-reported outcomes (VAS for low back pain, VAS for leg pain, ODI, and EQ-5D) at 3, 6, and 12 months postoperatively, and radiographic instability on plain radiographs at 12 months postoperatively.

Basic objectives2

Safety,Efficacy

Basic objectives -Others

Trial characteristics_1

Confirmatory

Trial characteristics_2

Explanatory

Developmental phase

Not applicable

Primary outcomes

Postoperative CT-based preservation rate (%) of the ipsilateral inferior articular process within 4 days after surgery

Key secondary outcomes

Operative time (from skin incision to completion of skin closure), Amount of additional bone resection at the base of the ipsilateral spinous process, VAS for low back pain, VAS for leg pain, ODI, and EQ-5D at 3, 6, and 12 months postoperatively, Perioperative complications (including dural injury, neurologic injury, hematoma, infection, and reoperation), Presence or absence of radiographic instability on plain radiographs at 12 months postoperatively

Study type

Interventional

Basic design

Parallel

Randomization

Randomized

Randomization unit

Individual

Blinding

Open -but assessor(s) are blinded

Control

Active

Stratification

NO

Dynamic allocation

NO

Institution consideration

Institution is not considered as adjustment factor.

Blocking

YES

Concealment

Numbered container method

No. of arms

2

Purpose of intervention

Treatment

Type of intervention

Maneuver

Interventions/Control_1

Group A (lateral group): Left-sided unilateral laminotomy with bilateral decompression using AFESS. The skin incision center of the working portal is placed 10 mm lateral to the midline on the left side (allowable range, 6-14 mm). The fascia is opened longitudinally. The camera portal position, endoscope, instruments, decompression range, and perioperative management are standardized according to the institutional AFESS protocol. For safety reasons, portal relocation is allowed intraoperatively if continuation is judged difficult or unsafe.

Interventions/Control_2

Group B (medial group): Left-sided unilateral laminotomy with bilateral decompression using AFESS. The skin incision center of the working portal is placed 4 mm lateral to the midline on the left side (allowable range, 0-8 mm). The fascia is opened transversely. The camera portal position, endoscope, instruments, decompression range, and perioperative management are standardized according to the institutional AFESS protocol. For safety reasons, portal relocation is allowed intraoperatively if continuation is judged difficult or unsafe.

Interventions/Control_3

Interventions/Control_4

Interventions/Control_5

Interventions/Control_6

Interventions/Control_7

Interventions/Control_8

Interventions/Control_9

Interventions/Control_10

Age-lower limit

20

years-old

<=

Age-upper limit

Not applicable

Gender

Male and Female

Key inclusion criteria

･ Patients scheduled to undergo elective left-sided unilateral laminotomy with bilateral decompression using AFESS for lumbar spinal stenosis at our institution
･ Age 20 years or older
･Lumbar spinal stenosis involving 1 to 3 levels at L2/3, L3/4, L4/5, or L5/S1 (central canal stenosis and/or lateral recess stenosis), with concordance between imaging findings and symptoms and judged to require surgery
･ Insufficient improvement after conservative treatment, including medication, nerve block, and/or physical therapy
･ Able to undergo preoperative CT and MRI and routine postoperative CT evaluation within 4 days after surgery
･ Written informed consent obtained

Key exclusion criteria

･ Reoperation at the same level
･ Cases judged to require concomitant fusion surgery
･ Cases with obvious instability (posterior opening angle >10 degrees) or degenerative spondylolisthesis of Meyerding grade II or higher
･ Cases with severe ossification of the ligamentum flavum
･ Cases in which the main pathology is not degenerative disease, such as infection, tumor, trauma, or cystic lesions
･ Cases with marked degenerative scoliosis (Cobb angle >20 degrees), congenital or acquired bony deformity, or severe ossified lesions, in which standardized portal placement is expected to be difficult
･ Cases judged inappropriate by the principal investigator

Target sample size

60

Name of lead principal investigator

1st name	Shota
Middle name
Last name	Takenaka

Organization

Japan Community Healthcare Organization Osaka Hospital

Division name

Department of Orthopaedic Surgery

Zip code

553-0003

Address

4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka, Japan

TEL

06-6441-5451

Email

show710216@gmail.com

Name of contact person

1st name	Sadaaki
Middle name
Last name	Kanayama

Organization

Japan Community Healthcare Organization Osaka Hospital

Division name

Department of Orthopaedic Surgery

Zip code

553-0003

Address

4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka, Japan

TEL

06-6441-5451

Homepage URL

Email

drsada@jewel.ocn.ne.jp

Institute

Japan Community Health Care Organization Osaka Hospital

Institute

Department

Personal name

Shota Takenaka

Organization

Japan Community Health Care Organization Osaka Hospital

Organization

Division

Category of Funding Organization

Self funding

Nationality of Funding Organization

Co-sponsor

Name of secondary funder(s)

Organization

Japan Community Health Care Organization Osaka Hospital

Address

4-2-78 Fukushima, Fukushima-ku, Osaka City, Osaka, Japan

Tel

06-6441-5451

Email

drsada@jewel.ocn.ne.jp

Secondary IDs

NO

Study ID_1

Org. issuing International ID_1

Study ID_2

Org. issuing International ID_2

IND to MHLW

Institutions

独立行政法人地域医療機能推進機構大阪病院

Date of disclosure of the study information

2026

Year

04

Month

19

Day

URL releasing protocol

Publication of results

Unpublished

URL related to results and publications

Number of participants that the trial has enrolled

Results

Results date posted

Results Delayed

Results Delay Reason

Date of the first journal publication of results

Baseline Characteristics

Participant flow

Adverse events

Outcome measures

Plan to share IPD

IPD sharing Plan description

Recruitment status

Preinitiation

Date of protocol fixation

2026

Year

04

Month

14

Day

Date of IRB

2026

Year

04

Month

15

Day

Anticipated trial start date

2026

Year

04

Month

15

Day

Last follow-up date

2028

Year

12

Month

31

Day

Date of closure to data entry

2028

Year

12

Month

31

Day

Date trial data considered complete

Date analysis concluded

Other related information

Registered date

2026

Year

04

Month

15

Day

Last modified on

2026

Year

04

Month

15

Day

Link to view the page

Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000070071