Using Percutaneous Endoscopic Outside-In
Technique to Treat Selected Patients with
Refractory Discogenic Low Back Pain
Authors: Chen Shih-Hao 
Published: February 2021

Background: Controversy is not uncommon in the diagnosis of discogenic low back pain (DLBP)
and in the identification of the location of the pain source for the symptomatic disc in patients
with DLBP. Various techniques, from minimally invasive procedures to fusion surgery, are used to
treat chronic DLBP, but the clinical outcomes are variable. Percutaneous endoscopic discectomy by
transforaminal or interlaminar approach is considered to be an effective method to treat DLBP, but
the evidence is limited; the lack of clear evidence may be associated with patient selection and
surgical technique.
Objectives: The purpose of this study is to evaluate the clinical results of percutaneous endoscopic
treatment for annular tear in selected patients with DLBP by using the outside-in technique.
Study Design: A prospective study and retrospective observations were performed on 24
consecutive patients with a minimum 2 years of follow-up. This study was approved by the
Institutional Review Board (IRB) of Buddhist Dalin Tzu-Chi General Hospital Foundation (IRB number:
10504004) and written informed consent was obtained from all patients.
Setting: This research took place within an interventional pain management and spine practice.
Methods: Twenty-four consecutive patients with single-level DLBP diagnosed by positive highintensity zone on magnetic resonance imaging, positive provocative discography, and block test
underwent a percutaneous endoscopic procedure from January 2014 to December 2015. The
transforaminal approach or interlaminar approach was selected according to the location of the
annular tear. The torn lesions were visualized directly and treated by puncture and debridement of
the inflammatory tissues from the outer annulus fibrosus to the inner nucleus using the outsidein technique. The Visual Analog Scale (VAS) score and Oswestry Disability Index (ODI) score were
evaluated before and after surgery. The clinical global outcomes were assessed on the basis of
modified MacNab criteria.
Results: These patients included 13 men and 11 women with a mean age of 43.8 years (range,
32-55 yrs). There were 15 lesion levels at L4/L5 and 9 lesion levels at L5/S1. Among them, 15
levels were accessed by transforaminal approach and 9 levels by interlaminar approach. No serious
complications were observed during the follow-up periods. All except 2 patients experienced
significant symptomatic and functional improvements at the 2-year follow-up with a success rate
of 91.7%.
Limitations: Significant limitations include nonrandom format and small sample size. Future
research may focus on controlled prospective studies with larger sample sizes and long-term followup to examine the validity of this protocol.
Conclusions: The percutaneous endoscopic procedure provides a safe and effective treatment for
selected patients with DLBP. The outside-in technique allows the surgeons to visualize and treat the
torn or inflammatory lesions directly, and the success rate is high at 2 years follow-up.
Key words: Transforaminal, interlaminar, outside-in technique, endoscopic discectomy, discogenic
low back pain