In this study, Endo-P/TLIF achieved satisfactory clinical results in patients with single-segment LSS. In a specific subset of patients, spinal fusion showed good clinical results as a management method in the treatment of degenerative spinal conditions . Although traditional PLIF techniques have been widely used, they are associated with paraspinal muscle atrophy and long-term low back pain. It was found that multifidus muscle atrophy is commonly associated with postoperative low back pain . Therefore, several scholars sought for an alternative minimally invasive surgery. Foley et al.  first introduced MIS-TLIF technology and used the natural muscle space in the spine to insert channels for surgery. This technique has a similar efficacy as traditional open surgery, but avoids the destruction of complex posterior muscle-ligament structures, causing less tissue damage and less intraoperative bleeding .
Nevertheless, MIS-TLIF is limited by a narrow operating space and poor field visibility. This can cause nerve root injury, which is a serious complication of endoscopic surgery, especially injury to the exiting nerve roots . Moreover, MIS-TLIF exposes patients and surgeons to radiation. Therefore, an alternative minimally invasive technique was required to overcome these limitations of lumbar fusion surgery.
This study demonstrates that Endo-P/TLIF technology achieved clinical efficacy similar to MIS-TLIF, when treating patients with single-segment LSS. Furthermore, Endo-P/TLIF-treated patients had earlier improvements in low back pain and could generally get out of bed 1–2 days postoperatively. This indicates that Endo-P/TLIF technology causes less tissue injury than MIS-TLIF technology, consequently allowing patients an earlier return to normal life.
The fusion rate of lumbar spine surgery is impacted by various factors, including endplate preparation, bone graft area, bone graft type, contact with endplate surface, and personal constitution. The surgical area was expanded by adjusting the lumbar bridge before surgery to increase the lamina space and by removing part of the facet joint. Nerve roots and the thecal sac were protected from using an endoscopic cannula, which also improved the safety of fusion device implantation. The use of an expandable cage provided adequate intervertebral support and indirect decompression of the spinal canal, with smaller resection pathways for bony structures. Furthermore, Zhang et al.  have confirmed that the surface of an expandable cage apparatus provides stable and good osseous bonding in endoscopic surgery. Nevertheless, MIS-TLIF is limited by a poor field visibility and it may be difficult to view the deeper surgical field . An endoscopic reamer and curette were used to treat cartilaginous endplates under direct vision, which was better than MIS-TLIF. Additionally, bone autografting and adequate bone graft sizing were used to increase the fusion rate. Zhao et al.  have suggested that pedicle screw fixation and installation and retention of a posterior spinal tension band can reduce complications, increase the rate and stability of intervertebral fusion, and reduce the occurrence of intervertebral fusion displacement. This is consistent with the results of our present study.
Recently, it has been reported that the volume of the multifidus dramatically decreases after open posterior lumbar fusion . Kawaguchi et al. have measured paravertebral tissue images of patients receiving posterior lumbar surgery and found that the degree of muscle damage in patients receiving MIS-TLIF significantly declined when compared to that in patients who underwent open surgery . It has been reported that the paraspinal muscles are the key to support the extension of the spine, maintain lumbar lordosis, and achieve dynamic spinal stability . Our study found that the early curative effect of single-segment LSS with Endo-P/TLIF is satisfactory. In this study, the single-segment Endo-P/TLIF surgical incisions included four incisions of approximately 1 cm. Decompression and percutaneous pedicle screw placement were achieved through progressive expansion of soft tissue to establish the working channel, without extensive injury to the muscle. At 1-year follow-up, the cross-sectional area of the postoperative paravertebral muscles in the Endo-P/TLIF group was larger than that in the MIS-TLIF group, confirming that Endo-P/TLIF can effectively avoid postoperative paravertebral muscle atrophy caused by intraoperative dissection.
At present, a major difficulty with Endo-P/TLIF technology is that it is highly technical. It requires a surgeon to have extensive experience in endoscopic spinal surgery and conventional open surgery. Additionally, Endo-P/TLIF surgery requires more time to complete for doctors who are applying the technique for the first time. Our experience with Endo-P/TLIF technology is summarized as follows. First, subperiosteal dissection helps to reduce intraoperative bleeding. Second, blurred field vision caused by intraoperative bleeding is a major concern in endoscopic lumbar fusion surgery. The concept of “pre-hemostasis” should be emphasized to reduce surgical bleeding. For peripheral soft tissue bleeding, it is recommended to use an external endoscopic ring saw to block bleeding. Radiofrequency can be used to gradually clean the surrounding soft tissue and expose the bone surface, with the tip of the articular process as the center. Additionally, bleeding occurs on the surface of the bone after the articular process and lamina were resected, especially in patients with osteoporosis in which bleeding is more severe. The use of radiofrequency cauterization is recommended to reduce this bleeding. Moreover, bleeding can occur in small venous plexuses from the nerve roots and intervertebral disc surfaces. Radiofrequency cauterization should be used for pre-hemostasis to reduce bleeding of this kind. Third, it is recommended to gradually expose the insertion of the ligamentum flavum in the proximal-lateral-distal direction. The ligamentum flavum should be removed after the insertion is fully exposed because it is easy to separate the ligamentum flavum from the thecal sac using water pressure. Fourth, the recommended endoscopic procedures are excision of the inferior articular process and part of the superior articular process, exposure of the upper and lower lamina, excision of the ligamentum flavum, and decompression of the lateral recess and nerve root, followed by intervertebral space-bone grafting and the implantation of a metal expandable interbody fusion device.