====== 🧠 Unilateral Biportal Endoscopy (UBE) ======

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===== 📌 Definition =====
> **Unilateral Biportal Endoscopy (UBE)** is a minimally invasive spinal surgery technique that uses two small incisions (portals) on the same side: one for an endoscope and one for surgical instruments.

It allows for excellent visualization and effective decompression with minimal tissue damage.

===== ⚙️ Indications =====
  * Lumbar disc herniation
  * Spinal canal stenosis
  * Foraminal stenosis
  * Bilateral decompression via unilateral approach

===== 🛠️ Technique Overview =====
<WRAP box>
**Portal Placement:**  
  * Two small incisions (~1 cm) on the same side of the spine  
  * One for endoscopic camera (viewing)  
  * One for surgical tools (working)  

**Irrigation:** Continuous saline flow to maintain a clear field.

**Steps:**
  - Patient prone
  - Fluoroscopic marking
  - Serial dilation
  - Endoscopic visualization
  - Decompression (laminotomy, flavectomy, discectomy, etc.)
</WRAP>

===== ✅ Advantages =====
  * Less muscle trauma
  * Better visualization than microscopy
  * Faster recovery and less postoperative pain
  * Can be performed under epidural or general anesthesia

===== 📚 Comparison Table =====
^ Technique ^ Ports ^ Visualization ^ Working Channel ^ Invasiveness ^
| Microscopic Surgery | 1 | Microscope | Same | Moderate |
| Uniportal Endoscopy | 1 | Endoscope  | Same | Minimally invasive |
| **UBE**             | **2** | **Endoscope** | **Separate** | **Minimally invasive** |

===== 🧾 Coding (ICD-10-PCS) =====
<WRAP tip>
**Note:** UBE is often coded as a **percutaneous endoscopic** procedure in ICD-10-PCS, even though it uses two portals.
</WRAP>

Example (lumbar discectomy):
  * **0SB64ZZ** – Excision of lumbar disc, percutaneous endoscopic approach


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Park et al. described the unilateral biportal endoscopic (UBE) technique for decompression of [[extraforaminal stenosis]] at L5-S1 and evaluate 1-year clinical outcomes. Especially, we evaluated compression factors of extraforaminal stenosis at L5-S1 and described the surgical technique for decompression in detail.

Thirty-five patients who underwent UBE decompression for extraforaminal stenosis at L5-S1 between March 2018 and February 2019 were enrolled. Clinical results were analyzed using the MacNab criteria, the visual analogue scale (VAS) for back and leg pain, and the Oswestry Disability Index (ODI). Compression factors evaluated pseudoarthrosis within the transverse process of L5 and ala of sacrum, disc bulging with or without osteophytes, and the thickened lumbosacral and extraforaminal ligament.

The mean back VAS was 3.7 ± 1.8 before surgery, which dropped to 2.3 ± 0.8 at 1-year postoperative follow-up (p < 0.001). There was a significant drop in postoperative mean VAS for leg pain from 7.2 ± 1.1 to 2.3 ± 1.2 at 1 year (p < 0.001). The ODI was 61.5 before surgery and 28.6 (p < 0.001). Pseudoarthrosis between the transverse process and the ala was noted in all cases (35 of 35, 100%). Pure disc bulging was seen in 12 patients (34.3%), and disc bulging with osteophytes was demonstrated in 23 patients. The thickened lumbosacral and extraforaminal ligament were identified in 19 cases (51.4%). No complications occurred in any of the patients.

In the current study, good surgical outcomes without complications were achieved after UBE decompression for extra[[foraminal stenosis]] at L5-S1
((Park MK, Son SK, Park WW, Choi SH, Jung DY, Kim DH. Unilateral Biportal
Endoscopy for Decompression of Extraforaminal Stenosis at the [[Lumbosacral
Junction]]: Surgical Techniques and Clinical Outcomes. Neurospine. 2021
Dec;18(4):871-879. doi: 10.14245/ns.2142146.073. Epub 2021 Dec 31. PMID:
35000343.))
((Lee CK, Kim I. Commentary on "Unilateral Biportal Endoscopy for Decompression
of Extraforaminal Stenosis at the Lumbosacral Junction: Surgical Techniques and
Clinical Outcomes". Neurospine. 2021 Dec;18(4):880-881. doi:
10.14245/ns.2143268.634. Epub 2021 Dec 31. PMID: 35000344.))


===== Narrative reviews =====


A [[narrative_review]] presents a structured 10-tier progression model for mastering [[unilateral biportal endoscopy]] (UBE), a technique gaining momentum in [[minimally_invasive_spine_surgery]]. The framework serves as a training roadmap, beginning with basic [[lumbar decompression]] procedures and progressing toward advanced interventions such as [[transforaminal_lumbar_interbody_fusion]] (TLIF) and thoracic decompressions.

The authors suggest that surgeons must acquire competency in lumbar UBE before attempting cervical and thoracic levels, highlighting the anatomical and technical demands of more complex procedures. Each tier includes specific surgical targets and emphasizes core skills like safe [[nerve_root_mobilization]], minimal [[spinal_cord]] manipulation, and effective [[foraminal_decompression]].

The framework is informed by evidence from [[learning_curve]] analysis using cumulative sum (CUSUM) methodologies, aiming to enhance safety, reduce complications, and support adoption of UBE worldwide
((Espinoza XAS, Pérez EG, Choi DJ. The unilateral biportal endoscopy journey: proposing a 10-tier difficulty progression framework for unilateral biportal endoscopy. Asian Spine J. 2025 Apr 7. doi: 10.31616/asj.2025.0064. Epub ahead of print. PMID: 40195633.)).

===== 🔍 Critical Review =====

**✅ Strengths:**
  * The **10-tier structure** is logically designed, covering increasing complexity across spinal regions.
  * Grounded in **realistic training needs** for novice and intermediate surgeons.
  * Incorporates modern **[[learning curve analytics]]**, such as [[cusum analysis]], to support its recommendations.
  * Bridges the gap between **technical skill acquisition** and **clinical outcome improvement**.

**⚠️ Weaknesses:**
  * As a [[narrative_review]], it **lacks empirical validation** through clinical trials or prospective cohort data.
  * It doesn’t provide **quantitative data** on how many cases are required to master each tier.
  * The framework, while comprehensive, may be **challenging to implement** in low-resource settings with limited access to advanced endoscopic tools or simulation labs.

**🧠 Implications for Practice:**
This tiered model can serve as a **template for UBE training programs**, particularly in academic centers aiming to structure minimally invasive spine fellowships. It promotes **progressive learning**, aligns well with surgical simulation, and could potentially reduce early complications associated with the steep UBE learning curve.

**📌 Recommendation:**
Further studies are needed to validate this model through **multicenter trials**, **feedback from trainees**, and **long-term surgical outcomes**. If validated, it could become a **cornerstone of UBE education**.