Endoscopic spine surgery has advanced greatly, providing minimally invasive solutions for various spinal conditions. Minimally invasive spine surgery (MISS) techniques have transformed spinal surgery by offering alternatives to traditional open surgeries. Among these advancements, large working channel (LWC) uniportal endoscopy and unilateral biportal endoscopy (UBE) stand out. Both techniques aim to reduce tissue damage, speed up recovery, and lower complications. LWC uniportal endoscopy is an advanced technique that allows surgeons to perform decompressions and other spinal procedures through a larger working channel. This method is particularly useful for treating conditions like lumbar disc herniations and spinal stenosis. The procedure involves a small incision, which reduces tissue damage and postoperative pain, and offers enhanced visualization for precise targeting of problematic tissues, leading to quicker recovery compared to open surgery. Studies have shown that patients undergoing LWC uniportal endoscopy often report significant pain relief, improved function, and high satisfaction rates. For instance, Heo et al. [1] demonstrated that this technique leads to favourable clinical outcomes with minimal complications. Moreover, Lee et al. [2] found that this approach effectively treats lumbar disc herniations, providing long-term benefits and high patient satisfaction.

UBE is a minimally invasive technique using 2 separate portals: one for the endoscope and another for surgical instruments. This method enhances flexibility and visualization during procedures, making it effective for treating lumbar disc herniations and spinal stenosis. UBE allows for greater flexibility and instrument manipulation compared to single-portal techniques, and it provides better visualization of the surgical field, which can facilitate more complex interventions. Clinical outcomes for UBE are positive, with studies reporting effective pain relief, improved functional recovery, and high patient satisfaction. Choi et al. [3] noted that UBE provides effective decompression with low complication rates, while Choi et al. [4] highlighted its benefits in treating recurrent lumbar disc herniations. Additionally, Kang et al. [5] reported significant improvements in patient-reported outcomes and reduced recovery times for those undergoing UBE for lumbar spinal stenosis. Choosing the appropriate endoscopic technique is crucial, especially in obese patients, where anatomical challenges can complicate surgical procedures. This article aims to describe why the uniportal (LWC) endoscope is superior to the UBE at the lower lumbar level (L4–5 and L5–S1) in obese patients. Obese patients present unique challenges, such as increased tissue thickness, especially in the subcutaneous fat layer, altered anatomical landmarks, and deeper visualization requirements, which can complicate endoscopic procedures, particularly at the lower lumbar levels (L4–L5 and L5–S1). Heo et al. [1] emphasised that the enhanced visualization and manipulation provided by the LWC are particularly beneficial in the anatomically challenging region of L5–S1, ensuring precise decompression and reducing the likelihood of complications. The working channel for the LWC uniportal endoscope generally measures between 7 and 10 mm (usually more than 5.5 mm in diameter) (Figure 1). This larger diameter facilitates the use of various surgical instruments, such as endoscopes, Kerrison punches, and discectomy tools, enhancing the overall efficiency of the procedure [6-8]. These advantages make the LWC endoscope a preferable choice over UBE for obese patients undergoing spinal interventions at these lower lumbar levels, as it effectively addresses the unique difficulties posed by their anatomy, instrument handling, water outflow leading to debris removal, and clear visualization. A study comparing biportal and uniportal techniques in unilateral laminectomy for bilateral decompression suggests that while both methods offer effective decompression, the uniportal approach may offer superior outcomes in terms of reduced operative time and lower complication rates [9].

Obesity is determined by calculating the body mass index (BMI), which is the ratio of a person's weight in kilograms to the square of their height in meters. Individuals with a BMI of 30 kg/m² or above were categorized as obese, whereas those with a BMI ranging from 18.5 to 22.9 kg/m² were classified as having a normal weight [10]. Addressing these challenges requires a technique that maximises efficiency, precision, and safety without significantly damaging soft tissue, bone, and facet joints. This approach preserves the normal posterior anatomical structures, promoting early functional and cosmetic healing.

This article explores the unique benefits of using LWC uniportal endoscopy in obese patients at lower lumbar levels, focusing on innovations not previously published. It highlights how keyhole techniques effectively decompress levels affected by disc herniations and contrasts the differences in working mechanisms between LWC uniportal and UBE endoscopy. By examining these distinctions, the article aims to demonstrate the advantages of LWC uniportal endoscopy in addressing the specific challenges posed by obese patients.

The comparative analysis between the LWC endoscope and UBE underscores the LWC endoscope's numerous advantages, particularly when addressing the unique challenges presented by obese patients undergoing spinal surgery at the lower lumbar levels (L4–5 and L5–S1). The LWC endoscope's design is tailored to optimize surgical outcomes in this patient population, where increased tissue depth and altered anatomical landmarks can complicate procedures.

One of the most compelling advantages of the LWC endoscope is its superior access to the surgical site. The single, LWC allows for a more direct and efficient approach, minimizing the need for multiple incisions and extensive tissue dissection. This is particularly important in obese patients, where the thickness of subcutaneous adipose tissue can make navigation and visualization more challenging. The LWC endoscope's design simplifies these complexities, providing a streamlined pathway to the target area.

Enhanced visualization is another critical benefit offered by the LWC endoscope mainly due to proper water outflow. The wider field of view afforded by its larger working channel ensures that surgeons can clearly see the surgical site, which is crucial for precise targeting of problematic tissues. In contrast, the UBE system, with its dual-channel approach, may struggle to provide the same level of clarity in patients with significant tissue thickness in obese patients at lower lumbar region. The challenge of maintaining clear visualization is further exacerbated by the potential difficulties in managing proper irrigation flow during UBE, particularly in obese patients. The LWC endoscope's ability to maintain a continuous and controlled flow of irrigation fluids through its single channel effectively addresses this issue, flushing out blood, debris, and other obstructions that could otherwise hinder visibility.

This efficient water outflow mechanism is particularly beneficial in obese patients, where the increased depth of tissue can impede clear visualization. By ensuring a consistently clear surgical field, the LWC endoscope enhances the surgeon's ability to perform precise movements, reducing the risk of complications associated with poor visualization of surgical field. The capacity to maintain such clarity throughout the procedure is a significant advantage, as it directly contributes to the overall efficiency and success of the surgery.

The working portal design of the LWC endoscope further enhances its efficiency and precision. The dual-portal system may also require more extensive dissection to create sufficient working space, which could increase the risk of complications and prolong the operation time. The LWC endoscope's streamlined design, by contrast, allows for a more straightforward approach, reducing both the duration of the surgery and the associated risks.

The cumulative effect of these advantages is evident in the improved patient outcomes associated with the LWC endoscope. The reduced need for multiple incisions and the minimized tissue disruption lead to faster recovery times and lower complication rates. This is especially relevant for obese patients, who are at a higher risk for postoperative complications such as wound dehiscence. By minimizing the extent of tissue damage and preserving key anatomical structures like the posterior osseous and ligamentous elements, the LWC endoscope promotes better healing both functionally and cosmetically. This is a crucial factor in ensuring early recovery, particularly in obese patients who may otherwise face more challenging postoperative courses.

Despite these clear advantages, it is important to recognize that the choice of surgical technique is not one-size-fits-all. Individual patient anatomy and the surgeon's experience play significant roles in determining the most appropriate approach. While our experience with the LWC endoscope has demonstrated its superiority in many cases, it is essential to remain open to further advancements and alternative perspectives. More extensive comparative studies are needed to definitively establish the superiority of the LWC endoscope over other techniques like UBE. Additionally, ongoing research into endoscopic technology and its applications in spinal surgery will likely yield new innovations that could further refine these procedures.

We also acknowledge that different endoscopic surgeons may have varying opinions on the efficacy and practicality of these techniques. Surgical preferences often depend on personal experience, training, and familiarity with specific tools and methods. Therefore, while the evidence supports the LWC endoscope as a highly effective option for obese patients at the lower lumbar level, it is important to consider these findings within the broader context of evolving surgical practices. We encourage continued dialogue and collaboration within the surgical community to explore the full potential of endoscopic spine surgery and to ensure that patients receive the best possible care tailored to their individual needs.

In conclusion, LWC uniportal endoscope proves to be a superior choice for endoscopic spine surgery at the lower lumbar level in obese patients. Its design and functionality address the unique challenges presented by this patient population, leading to more efficient procedures and better patient outcomes. As endoscopic technology continues to advance, ongoing research and innovation will further enhance the effectiveness of MISS techniques.