Early Clinical Results of Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion: A New Modified Technique for Treating Degenerative Lumbar Spondylolisthesis

Evolution of the Transforaminal Lumbar Interbody Fusion (TLIF): From Open to Percutaneous to Patient-Specific

The transforaminal lumbar interbody fusion (TLIF) has seen significant evolution since its early inception, reflecting advancements in surgical techniques, patient safety, and outcomes. Originally described as an improvement over the posterior lumbar interbody fusion (PLIF), the TLIF began as an open surgical procedure, that notably reduced the need for the extensive neural retractation that hindered the PLIF. In line with the broader practice of surgery, trending toward minimally invasive access, the TLIF was followed by the development of the minimally invasive TLIF (MIS-TLIF), a technique that further decreased tissue trauma and postoperative complications. Subsequent advancements, including Trans-Kambin's Triangle TLIF (percLIF) and transfacet LIF, have continued to refine surgical access, minimize surgical footprint, and reduce the risk of injury to the patient. The latest evolution, as we will describe it, the patient-specific TLIF, is a culmination of the aforementioned adaptations and incorporates advanced imaging and segmentation technologies into perioperative planning, allowing surgeons to tailor approaches based on individual patient anatomy and pathology. These developments signify a shift towards more precise methods in spine surgery. The ongoing evolution of the TLIF technique illustrates the dynamic nature of surgery and emphasizes the need for continued adaptation and refinement.

Comparison of Outcomes Between Endoscopic Transforaminal Lumbar Interbody Fusion and Minimally Invasive Transforaminal Lumbar Interbody Fusion in Patients With Single-Level Lumbar Degenerative Disease: A Retrospective Study

OBJECTIVE

The objective of this study was to compare the clinical and radiological outcomes of endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

METHODS

This retrospective study included 110 patients with single-level lumbar degenerative disease who underwent Endo-TLIF or MIS-TLIF between January 2019 and December 2021. Patients were divided into Endo-TLIF (n = 55) and MIS-TLIF groups (n = 55). Perioperative, clinical, and radiological outcomes were assessed.

RESULTS

The Endo-TLIF group had significantly lower blood loss and shorter hospital stay. However, the operation time was significantly longer and there was more x-ray exposure than in the MIS-TLIF group. There were no significant differences in complications between the groups. The Endo-TLIF group showed significantly lower creatine kinase levels than the MIS-TLIF group at 3 days postoperatively (P < 0.05), but not at 7 days postoperatively (P > 0.05). Oswestry Disability Index and visual analog scale scores were significantly reduced in both groups at different time points postoperation compared to preoperation. The visual analog scale score in the Endo-TLIF group was lower than that in the MIS-TLIF group at 3 days postoperatively. Moreover, no significant differences were found in fusion rates, lumbar lordosis, and lumbar segmental lordosis between the 2 groups (P > 0.05).

CONCLUSIONS

Endo-TLIF might be considered as an effective and reliable treatment option for single-level lumbar degeneration. It results in less trauma and faster postoperative recovery, but a longer operative time and more x-ray exposure than MIS-TLIF. Endo-TLIF has effects on clinical and radiological outcomes that are comparable to those of MIS-TLIF.

Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion (PETLIF): Current Techniques, Clinical Outcomes, and Narrative Review

Full endoscopic techniques are becoming more popular for degenerative lumbar pathologies. Percutaneous endoscopic lumbar interbody fusion (PETLIF) is a minimally invasive surgical technique for spondylolisthesis and lumbar spinal canal stenosis with instability. Nagahama first introduced PETLIF in 2019. This study investigated the clinical outcomes and complications of 24 patients who underwent PETLIF in our facility and compared them with previous studies. Literature searches were conducted on PubMed and Web of Science. The PETLIF surgical technique involves three steps to acquire disc height under general anesthesia. The procedure includes bone harvesting, spondylolisthesis reduction, endoscopic foraminoplasty, disc height expansion using an oval dilator, and intervertebral disc curettage. A cage filled with autologous bone is inserted into the disc space and secured with posterior fixation. Patients underwent PETLIF with an average operation time of 130.8 min and a blood loss of 24.0 mL. Postoperative hospital stays were 9.5 days. Improvement in VAS, disc height, spinal canal area, and % slip was observed, while lumbar lordosis remained unchanged. Complications included end plate injury, subsidence, and exiting nerve root injury. The differences between PETLIF and the extracted literature were found in patients' age, direct decompression, epidural or local anesthesia, approach, order of PPS, and cage insertion. In conclusion, PETLIF surgery is a practical, minimally invasive surgical technique for patients with lumbar degenerative diseases suffering from back and leg pain, demonstrating significant improvements in pain scores. However, it is essential to carefully consider the potential complications and continue to refine the surgical technique further to enhance the safety and efficacy of this procedure.

Minimally invasive endoscopy in spine surgery: where are we now?

INTRODUCTION

Endoscopic spine surgery (ESS) is a minimally invasive surgical technique that offers comparable efficacy and safety with less collateral damage compared to conventional surgery. To achieve clinical success, it is imperative to stay abreast of technological advancements, modern surgical instruments and technique, and updated evidence.

PURPOSES

To provide a comprehensive review and updates of ESS including the nomenclature, technical evolution, bibliometric analysis of evidence, recent changes in the spine communities, the prevailing of biportal endoscopy, and the future of endoscopic spine surgery.

METHODS

We conducted a comprehensive review of the literature on ESS for the mentioned topics from January 1989 to November 2022. Three major electronic databases were searched, including MEDLINE, Scopus, and Embase. Covidence Systematic Review was used to organize the eligible records. Two independent reviewers screened the articles for relevance.

RESULTS

In total, 312 articles were finally included for review. We found various use of nomenclatures in the field of ESS publication. To address this issue, we proposed the use of distinct terms to describe the biportal and uniportal techniques, as well as their specific approaches. In the realm of technical advancement, ESS has rapidly evolved from addressing disc herniation and spinal stenosis to encompassing endoscopic fusion, along with technological innovations such as navigation, robotics, and augmented reality. According to bibliometric analysis, China, South Korea, and the USA have accounted for almost three-quarters of total publications. The studies of the biportal endoscopy are becoming increasingly popular in South Korea where the top ten most-cited articles have been published. The biportal endoscopy technique is relatively simple to adopt, as it relies on a more familiar approach, requires less expensive instruments, has a shorter learning curve, and is also well-suited for interbody fusion. The uniportal approach provided the smallest area of soft tissue dissection. While robotics and augmented reality in ESS are not widely embraced, the use of navigation in ESS is expected to become more streamlined, particularly with the emergence of recent electromagnetic-based navigation technologies.

CONCLUSIONS

In this paper, we provide a comprehensive overview of the evolution of ESS, as well as an updated summary of current trends in the field, including the biportal and uniportal approaches. Additionally, we summarize the nomenclature used in ESS, present a bibliometric analysis of the field, and discuss future directions for the advancement of the field.

Kambin's triangle-related data based on magnetic resonance neurography and its role in percutaneous transforaminal endoscopic lumbar interbody fusion

BACKGROUND

The percutaneous transforaminal endoscopic lumbar interbody fusion (PETLIF) has many advantages as a new minimally invasive surgical technique, and its surgical approach passes through the Kambin's triangle. One of the greatest challenges in completing PETLIF is avoiding nerve root damage. In previous studies, the relevant anatomic data do not correspond well with current surgical techniques, and there is a paucity of studies based on magnetic resonance neurography (MRN), which is the clearest imaging method for nerve roots. The purpose of this study was to analyze the safety of the PETLIF at each lumbar segment based on measured results from the MRN imaging data and to propose a novel method of intraoperative positioning.

METHODS

The coronal images with the clearest course of nerve roots were chosen for retrospective observation. During the PETLIF, the secure region of the operation was considered to be a trapezium. The following parameters were measured, respectively: trapezoid area, height, and median line length, as well as the relevant parameters of the positional relation between the point "O," the most secure operating center point of the secure region, and each osseous anatomic landmark. And the data were compared with the size of the cage to obtain safety.

RESULTS

At L1-S1, with the downward motion of the target intervertebral space, the area increased from (67.94 ± 15.22) mm² to (140.99 ± 26.06) mm², and the height increased from (7.23 ± 1.17) mm to (12.59 ± 1.63) mm. At L1-L5, the length of the median line was increased from (9.42 ± 1.70) mm to (12.70 ± 1.88) mm. Even though it was reduced to (11.59 ± 1.99) mm at L5-S1, it was still longer than that at L3-L4. The safety obtained by the primary observational indicator was 34.52%, 33.33%, 53.57%, 96.43%, and 77.38%, respectively, at L1-S1. The safety obtained by the two secondary observational indicators was 77.38% and 95.24% at L3-L4 and 100% at L4-S1. There was no point "O" outside the anatomic mark line. The intraoperative positioning method of the point "O" was as follows: It was located medially and horizontally approximately 3/5 of the anatomic mark line at L1-L5; the horizontal distances were (0.48 ± 0.67) mm, (1.20 ± 0.89) mm, (2.72 ± 1.01) mm, and (3.69 ± 1.47) mm, respectively. In addition, it was necessary to locate (3.43 ± 1.41) mm inward at about 4/5 of the anatomic mark line at L5-S1.

CONCLUSIONS

The MRN allows clearer and more accurate visualization of the nerve roots, and the basic anatomic study of the Kambin's triangle based on this technology is of practical clinical significance. In the current study, it is believed that, during the PETLIF, cage implantation is the safest at L4-L5, followed by L5-S1; L1-L3 is more likely to cause nerve root injury, and L3-L4 is not less likely. To improve safety, a comprehensive individualized imaging assessment should be performed before surgery. This study also provides an easy method of intraoperative localization, which helps avoid nerve root injury.

Analysis of curative effect of percutaneous coaxial large channel endoscopic lumbar interbody fusion in the treatment of degenerative lumbar spinal stenosis

Objective

To investigate the clinical efficacy and technical points of Percutaneous Coaxial Large-channel Endoscopic Lumbar Interbody Fusion (PCLE-LIF) in the treatment of degenerative lumbar spinal stenosis.

Methods

The clinical data of patients with single-segment degenerative lumbar spinal stenosis who underwent PCLE-LIF surgery from January 2019 to June 2021 were retrospectively analyzed. Surgery-related data included symptom duration, operation time, hospital stay, and complication rate. Functional score data included low back pain and lower extremity pain VAS score, ODI score, and MacNab criteria were used to evaluate clinical effects. The Brantigan criteria were used to evaluate the interbody fusion.

Results

There were 62 patients in this group, including 35 males and 27 females. The surgical sites were all lower lumbar spine, including 35 cases of lumbar L4/5 and 27 cases of L5/S1. The length of hospital stay was 7.7 ± 1.4 days. All patients were followed up regularly for 1 year. The interbody fusion rate was 93.5% at 1 year after operation. There were 2 cases of numbness, 2 cases of nerve edema and pain, 1 case of cage displacement, and 1 case of pedicle screw loosening. The complication rate was 9.6%. The VAS scores of low back pain 1 day before surgery, 3 days, 3 months and 1 year after surgery were 4.48 ± 1.06, 0.84 ± 0.81, 0.40 ± 0.56, 0.39 ± 0.69, and the VAS of lower extremity pain at each time point of appeal were 5.58 ± 0.98, 0.91 ± 0.58, 0.31 ± 0.46, 0.19 ± 0.40. The ODI scores at 1 day before surgery, 3 months and 1 year after surgery were 60.01 ± 6.21, 15.58 ± 2.84, 8.82 ± 2.15. The ODI scores and VAS scores of low back pain and lower extremity pain at each follow-up time point after operation were significantly lower than those before operation (p < 0.05). The 1-year follow-up after operation was evaluated by the modified MacNab standard, and the results were excellent in 36 cases, good in 23 cases, fair in 3 cases, and poor in 0 cases, with an excellent and good rate of 95.2%.

Conclusion

Percutaneous coaxial large-channel endoscopic lumbar interbody fusion in the treatment of degenerative lumbar spinal stenosis has good short-term efficacy and high safety, and is worthy of popularization.

Safe Electromyography Stimulation Thresholds Within Kambin's Triangle During Endoscopic Transforaminal Lumbar Interbody Fusion

BACKGROUND

Transforaminal endoscopic approaches through Kambin's triangle traditionally require surgery to be performed without general anesthesia to allow live patient feedback. No reliable intraoperative neuromonitoring method specific to the dorsal root ganglion (DRG), the structure most at risk during this approach, currently exists.

OBJECTIVE

To correlate evoked electromyography (EMG) thresholds within Kambin's triangle with new postoperative pain or sensorimotor symptoms potentially resulting from DRG irritation.

METHODS

Data were prospectively collected for all patients undergoing endoscopic transforaminal lumbar interbody fusion (TLIF) under general anesthesia at a single institution. A stimulation probe was inserted into Kambin's triangle under fluoroscopic and robotic guidance, before passage of endoscopic instruments. EMG thresholds required to elicit corresponding myotomal responses were measured. Postoperatively, any potential manifestations of DRG irritation were recorded.

RESULTS

Twenty-four patients underwent a total of 34 transforaminal lumbar interbody fusion levels during the study period, with symptoms of potential DRG irritation occurring in 5. The incidence of new onset symptoms increased with lower stimulation thresholds. Sensitivities for EMG thresholds of ≤4, ≤8, and ≤11 mA were 0.6, 0.8, and 1, respectively. Corresponding specificities were 0.90, 0.69, and 0.55, respectively.

CONCLUSION

We demonstrated for the first time the feasibility of direct intraoperative neuromonitoring within Kambin's triangle in transforaminal endoscopic surgery. Eight milliampere seems to be a reasonable compromise between sensitivity and specificity for this monitoring technique. In the future, larger-scale studies are required to refine safe stimulation thresholds.

Full-Endoscopic versus Minimally Invasive Lumbar Interbody Fusion for Lumbar Degenerative Diseases : A Systematic Review and Meta-Analysis

Objective

Although full-endoscopic lumbar interbody fusion (Endo-LIF) has been tried as the latest alternative technique to minimally invasive transforaminal lumbar interobody fusion (MIS-TLIF) since mid-2010, the evidence is still lacking. We compared the clinical outcome and safety of Endo-LIF to MIS-TLIF for lumbar degenerative disease.

Methods

We systematically searched electronic databases, including PubMed, EMBASE, and Cochrane Library to find literature comparing Endo-LIF to MIS-TLIF. The results retrieved were last updated on December 11, 2020. The perioperative outcome included the operation time, blood loss, complication, and hospital stay. The clinical outcomes included Visual analog scale (VAS) of low back pain and leg pain and Oswestry disability index (ODI), and the radiological outcome included pseudoarthosis rate with 12-month minimum follow-up.

Results

Four retrospective observational studies and one prospective observational study comprising 423 patients (183 Endo-LIF and 241 MIS-TLIF) were included, and the pooled data analysis revealed low heterogeneity between studies in our review. Baseline characteristics including age and sex were not different between the two groups. Operation time was significantly longer in Endo-LIF (mean difference [MD], 23.220 minutes; 95% confidence interval [CI], 10.669–35.771; p=0.001). However, Endo-LIF resulted in less perioperative blood loss (MD, -144.710 mL; 95% CI, 247.941–41.478; p=0.023). Although VAS back pain at final (MD, -0.120; p=0.586), leg pain within 2 weeks (MD, 0.005; p=0.293), VAS leg pain at final (MD, 0.099; p=0.099), ODI at final (MD, 0.141; p=0.093) were not different, VAS back pain within 2 weeks was more favorable in the Endo-LIF (MD, -1.538; 95% CI, -2.044 to -1.032; p<0.001). On the other hand, no statistically significant group difference in complication rate (relative risk [RR], 0.709; p=0.774), hospital stay (MD, -2.399; p=0.151), and pseudoarthrosis rate (RR, 1.284; p=0.736) were found.

Conclusion

Relative to MIS-TLIF, immediate outcomes were favorable in Endo-LIF in terms of blood loss and immediate VAS back pain, although complication rate, mid-term clinical outcomes, and fusion rate were not different. However, the challenges for Endo-LIF include longer operation time which means a difficult learning curve and limited surgical indication which means patient selection bias. Larger-scale, well-designed study with long-term follow-up and randomized controlled trials are needed to confirm and update the results of this systematic review.

经皮内镜辅助腰椎椎间融合术的技术利弊分析及趋势展望

OBJECTIVE

To review and evaluate the technical advantages and disadvantages and research progress of percutaneous endoscopic lumbar interbody fusion.

METHODS

The domestic and foreign related research literature on percutaneous endoscopic lumbar interbody fusion was extensively consulted. The advantages, disadvantages, and effectiveness were summarized. And the development trend of this technology was prospected.

RESULTS

Compared with minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), percutaneous endoscopic lumbar interbody fusion has less intraoperative and postoperative bleeding, better improvement of low back pain in the early stage after operation, and similar long-term effectiveness, fusion rate, and incidence of complication, but a longer learning curve. The operation time of biportal and large-channel uniportal endoscopic lumbar fusion is close to that of MIS-TLIF, but the operation time of small-channel uniportal endoscopic fusion is longer than that of MIS-TLIF.

CONCLUSION

Percutaneous endoscopic lumbar interbody fusion has the advantages of less trauma and good effectiveness, but its learning curve is long, and indications should be strictly selected for this operation. In the future, with the continuous development and complementation of various endoscopic fusion technologies, this technology will gain better application prospects.

经皮同轴大通道内镜下与微创经椎间孔入路腰椎椎间融合术治疗退变性腰椎管狭窄症疗效比较

OBJECTIVE

To compare the effectiveness of percutaneous coaxial large-channel endoscopic lumbar interbody fusion (PE-LIF) and minimal invasive transforaminal lumbar interbody fusion (MIS-TLIF) in the treatment of degenerative lumbar spinal stenosis.

METHODS

The clinical data of 134 patients with single-segment degenerative lumbar spinal stenosis who met the selection criteria between January 2019 and January 2021 were retrospectively analyzed, including 52 cases in PE-LIF group and 82 cases in MIS-TLIF group. There was no significant difference in general data such as gender, age, disease duration, surgical segment, and preoperative visual analogue scale (VAS) scores of low back pain and lower extremity pain, and Oswestry disability index (ODI) between the two groups ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, hospitalization stay, and complications were recorded and compared between the two groups. The level of serum creatine kinase (CK) was recorded at 1 day before operation and at 1 and 3 days after operation to evaluate intraoperative muscle damage. The Brantigan criteria was used to evaluate the interbody fusion in the two groups. The VAS scores of low back pain and lower extremity pain at 1 day before operation and at 3 days, 3 months, and 1 year after operation, and the ODI scores at 1 day before operation and at 3 months and 1 year after operation were recorded and compared between the two groups.

RESULTS

There was no significant difference in operation time and hospitalization stay between the two groups ( P>0.05). The intraoperative blood loss and postoperative drainage in the PE-LIF group were significantly lower than those in the MIS-TLIF group ( P<0.05). There was no significant difference in serum CK between the two groups before operation ( P>0.05), and the serum CK in the PE-LIF group at 1 and 3 days after operation were significantly lower than those in the MIS-TLIF group ( P<0.05). All patients were followed up regularly for 1 year. The postoperative VAS scores of low back pain and lower extremity pain and ODI score in both groups were significantly lower than those before operation ( P<0.05); there was no significant difference between the two groups ( P>0.05). At 1 year after operation, 48 patients in PE-LIF group had successful interbody fusion, and 77 patients in MIS-TLIF group had successful interbody fusion. There was no significant difference in the interbody fusion distribution between the two groups at 3 months and 1 year after operation ( P>0.05). There were 2 and 3 cases of lower limb numbness, 1 and 3 cases of neuroedema pain, 1 and 1 case of Cage displacement, 1 and 1 case of pedicle screw loosening in the PE-LIF group and MIS-TLIF group, respectively. No infection or dural sac tearing occurred in the two groups. There was no significant difference in the incidence of complications between the two groups (9.6% vs. 9.8%) ( χ ²=0.001, P=0.979).

CONCLUSION

In the treatment of single-segment degenerative lumbar spinal stenosis, PE-LIF can achieve similar effectiveness as MIS-TLIF, and PE-LIF has less intraoperative blood loss and less muscle damage.

经皮内镜辅助腰椎椎间融合术现状与思考

OBJECTIVE

To summarize the progress of percutaneous endoscopic lumbar interbody fusion in the treatment of lumbar degenerative diseases.

METHODS

The relevant literature about percutaneous endoscopic lumbar interbody fusion at home and abroad in recent years was reviewed, the approaches, technical characteristics, short- and long-term effectiveness, and complications of different surgical procedures were summarized.

RESULTS

Percutaneous endoscopic lumbar interbody fusion is a safe and reliable treatment. At present, the main surgical methods in clinical application can be roughly summarized as percutaneous endoscopic posterior transforaminal lumbar interbody fusion (Endo-PTLIF), percutaneous endoscopic transforaminal lumbar interbody fusion (Endo-TLIF), percutaneous endoscopic oblique lumbar interbody fusion (Endo-OLIF), percutaneous endoscopic lumbar interbody fusion/Z's percutaneous endoscopic lumbar interbody fusion (Endo-LIF/ZELIF), and unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF). Each surgical method has its own technical characteristics and development.

CONCLUSION

Percutaneous endoscopic lumbar interbody fusion is a kind of combined technology based on the individualization of the patient's anatomical structure and the technical differentiation of the surgeon. Surgical experience, choosing adaptive indication and operative way reasonably are the key for the success.

Usefulness of 3D CT/MRI Fusion Imaging for the Evaluation of Lumbar Disc Herniation and Kambin's Triangle

Study design: Prospective study. Objective: The aim of this study is to visualize the morphology of a lumbar herniated disc and Kambin’s triangle in three dimensions (3D) based on preoperative CT/MRI fusion images. Methods: CT/MRI fusion images of 23 patients (10 males and 13 females; mean age 58.2 years) were used to evaluate Kambin’s triangle, which is created between the superior articular process (SAP), exiting nerve root (ENR), inferiorly by the superior endplate of the lower lumbar vertebra and dural canal medially at 60 degree and 45 degree endoscopic approach angles. The percentage of the safe usage of transforaminal endoscopic approach was evaluated to utilize a 5 mm dilater without partial facet resection in the fusion image. The 3D lumbar nerve root sleeve angulation (3DNRA), which is the angle between the axis of the thecal sac and the nerve root sleeve, was calculated. The herniated discs were also visualized in the CT/MRI fusion image. Results: The 3DNRA became smaller from L2 to S1. The L2 3DNRA was statistically larger than those of the other root, and the S1 3DNRA was significantly smaller than the others (p < 0.05). (L2, 41.0°; L3, 35.6°; L4, 36.4°; L5, 33.9°; and S1, 23.2°). The SAP-ENR distance at 60° was greatest at L4/5 (5.9 mm). Possible needle passages at 60° to each disc level were 89.1% at L2/3, 87.0% at L3/4 and 84.8% at L4/5. However, the safe 5 mm dilater passage at 60° without bony resection to each disc level were 8.7% at L2/3, 28.3% at L3/4 and 37.0% at L4/5. The 60° corridor at L2/3 was the narrowest (p < 0.01). All herniated discs were visualized in the fusion image and the root compression site was clearly demonstrated especially with foraminal/extraforaminal herniations. Conclusion: The 3D lumbar CT/MRI fusion image enabled a combined nerve-bony assessment of Kambin’s triangle and herniated disc. A fully endoscopic 5 mm dilater may retract the exiting nerve root in more than 60% of total cases. This new imaging technique could prove to be very useful for the safety of endoscopic lumbar disc surgery.

经皮内镜下与Wiltse入路经椎间孔腰椎间融合术治疗腰椎滑脱症的疗效比较

OBJECTIVE

To compare the effectiveness of percutaneous endoscopic transforaminal lumbar interbody fusion (PE-TLIF) and Wiltse-approach TLIF (W-TLIF) in the treatment of lumbar spondylolisthesis.

METHODS

The clinical data of 47 patients with lumbar spondylolisthesis who met the selection criteria between July 2018 and June 2019 were retrospectively analyzed, in which 21 patients were treated with PE-TLIF (PE-TLIF group) and 26 patients were treated with W-TLIF (W-TLIF group). There was no significant difference between the two groups in age, gender, disease duration, level of spondylolisthesis vertebrae, spondylolisthesis degree, spondylolisthesis type, and preoperative visual analogue scale (VAS) score of low back pain and leg pain, lumbar Japanese Orthopaedic Association (JOA) score, and the disc height (DH), segmental lordosis (SL), and Taillard index (TI) of the operated vertebrae ( P>0.05). The operation time, intraoperative blood loss, postoperative drainage, postoperative bedridden time, and complications were compared between the two groups. The VAS score and JOA score were used to evaluate the improvement of pain and function. At last follow-up, DH, SL, and TI of operated vertebrae were measured by X-ray films, and lumbar CT was performed to evaluate the interbody fusion.

RESULTS

Compared with W-TLIF group, the operation time in PE-TLIF group was significantly longer, but the intraoperative blood loss and postoperative drainage were significantly less, and the postoperative bedridden time was significantly shorter ( P<0.05). There were 2 cases of transient lower limb radiating pain in PE-TLIF group and 1 case of superficial incision infection in W-TLIF group. There was no significant difference in the incidence of complications (9.5% vs. 3.8%) between the two groups ( χ ²=0.037, P=0.848). The patients in both groups were followed up 12-24 months, with an average of 17.3 months in PE-TLIF group and 17.7 months in W-TLIF group. The VAS scores of low back pain and leg pain, and the JOA scores of the two groups significantly improved at each time point after operation when compared with those before operation ( P<0.05). Compared with W-TLIF group, the VAS scores of low back pain in PE-TLIF group significantly lower at 3 days and 3 months after operation ( P<0.05), and the JOA score of PE-TLIF group was significantly higher at 3 months after operation ( P<0.05), and there was no significant difference in each score at any other time point between the two groups ( P>0.05). At last follow-up, the DH, SL, and TI of operated vertebrae of the two groups significantly improved when compared with those before operation ( P<0.05), and there was no significant difference in the differences of each parameter between the two groups ( P>0.05). According to Suk's standard, the fusion rates of PE-TLIF group and W-TLIF group were 90.5% (19/21) and 92.3% (24/26), respectively, with no significant difference ( χ ²=0.000, P=1.000). At last follow-up, there was no case of Cage sunk into the adjacent vertebral body, or dislodgement of Cage anteriorly or posteriorly in both groups.

CONCLUSION

PE-TLIF and W-TLIF are both effective in the treatment of grade Ⅰ and Ⅱ lumbar spondylolisthesis. Although the operation time is prolonged, PE-TLIF has less intraoperative blood loss and postoperative drainage, shorter postoperative bedridden time, and can get more obvious short-term improvement of low back pain and function.

Unintentional Fusion in Preserved Facet Joints without Bone Grafting after Percutaneous Endoscopic Transforaminal Lumbar Interbody Fusion

Introduction

A percutaneous endoscopic transforaminal lumbar interbody fusion (PETLIF) procedure has been previously developed. During postoperative follow-up, in some patients, bone fusion occurred between opened facet joints, despite not having bone grafting in the facet joints. Here, we investigated facet fusion's frequency and tendencies following PETLIF.

Methods

A retrospective analysis was conducted on a prospectively collected, nonrandomized series of patients. Forty-two patients (6 males and 36 females, average age: 69.9 years) who underwent single-level PETLIF at our hospital from February 2016 to March 2019 were included in this study. Patients were assessed with lumbar X-ray images and computed tomography (CT) prior to, immediately after, and 1 year after surgery.

Results

Pseudarthrosis was not observed in any patients, and facet fusion was observed in 26 of 42 post-PETLIF patients (61.9%) by CT 1 year postoperatively. The average interfacet distance increased from 1.3 mm preoperatively to 4.5 mm postoperatively, and facet fusion was observed under the opened conditions of 3.8 mm at 1 year. Segmental lordotic angle of the fusion segment in the lumbar X-ray images was significantly larger in the facet fusion subgroup prior to surgery, immediately following surgery, and 1 year after surgery compared to the facet non-fusion group (p=0.02, p<0.01, p=0.01, respectively). There were no significant differences in patient background, correction loss of segmental lordosis, interfacet distance, or clinical score between the facet fusion and facet non-fusion subgroups.

Conclusions

Facet fusion was achieved over time within the facet joints that were opened through indirect decompression after PETLIF. We hypothesized that the preserved facet joints potentially became the base bed for spontaneous bone fusion due to the preserved facet joint capsule and surrounding soft tissue, which maintained cranio-caudal facet traffic and blood circulation in the facet joints. The complete preservation of the facet joints was a key advantage of minimally invasive lumbar interbody fusion procedures.

Level of evidence

Level III

A Narrative Review of Uniportal Endoscopic Lumbar Interbody Fusion: Comparison of Uniportal Facet-Preserving Trans-Kambin Endoscopic Fusion and Uniportal Facet-Sacrificing Posterolateral Transforaminal Lumbar Interbody Fusion

Uniportal endoscopic lumbar interbody fusion aims to achieve the bony union of 2 lumbar segments through cage insertion using full spinal endoscopy. Endoscopic fusion can adjust foraminal height and disc height, improve alignment, and minimize collateral soft tissue damage during the insertion of an interbody cage. The surgery is performed under constant irrigation with normal saline and an optical endoscopic lens close to the targeted disc segment. Two main subtypes of uniportal endoscopic fusion are currently described in the literature. We broadly classify them into facet-preserving and facet-sacrificing endoscopic lumbar interbody fusions. We have termed them uniportal facet-preserving trans-Kambin endoscopic fusion and uniportal facet-sacrificing posterolateral transforaminal lumbar interbody fusion. In this article, we review the current literature and discuss the history, indications, contraindications, technical differences, clinical outcomes, and complications of uniportal endoscopic interbody fusion surgery.

Full-Endoscopic Trans-Kambin Triangle Lumbar Interbody Fusion: Surgical Technique and Nomenclature

BACKGROUND

 Full-endoscopic lumbar surgery is used for decompression of lumbar spinal canal stenosis. Now, a cage can be inserted through Kambin's triangle for lumbar interbody fusion (LIF). We have been performing full-endoscopic trans-Kambin triangle LIF (KLIF) at our institution since 2018. In this article, we describe this technique and present our results.

METHODS

 We performed full-endoscopic one-level KLIF in 10 patients. The procedure is as follows. First, percutaneous pedicle screws are inserted. Listhesis is reduced if necessary. The endoscope is inserted in Kambin's triangle. Next, the superior articular process is partially removed, enlarging Kambin's triangle to allow safe insertion of the cage. A cannula is inserted into the disk to avoid damaging the exiting nerve. The disk material is shaved and curetted. Finally, the harvested bone is packed in a cage and inserted into the disk space. We analyze the complications, visual analog scores (VAS), and MacNab's criteria.

RESULTS

 One patient had an irritation in the exiting nerve at L4-L5. The VAS for back pain and leg pain decreased from 69 to 9 and from 60 to 9, respectively. The clinical outcome was considered excellent in eight and good in two patients.

CONCLUSIONS

 Kambin's triangle lies immediately behind the psoas major. Therefore, we consider KLIF as a lateral LIF procedure comparable with oblique or extreme LIF. However, unlike oblique or extreme LIF, there are no major vessels and organs in the surgical field; therefore, KLIF is the safest type of lateral LIF. Furthermore, using the endoscope, we can perform decompression directly using the facetectomy technique.

Morphological analysis of Kambin's triangle using 3D CT/MRI fusion imaging of lumbar nerve root created automatically with artificial intelligence

PURPOSE

We developed a software program that automatically extracts a three-dimensional (3D) lumbar nerve root image from magnetic resonance imaging (MRI) lumbar nerve volume data using artificial intelligence. The aim of this study is to evaluate the morphology of Kambin's triangle in three dimensions based on an actual endoscopic transforaminal surgical approach using three-dimensional (3D) computed tomography (CT)/ magnetic resonance imaging (MRI) fusion images of the lumbar spine and nerve tissue.

METHODS

Three-dimensional lumbar spine/nerve images of 100 patients (31 males and 69 females; mean age, 66.8 years) were used to evaluate the relationship between the superior articular process (SAP), exiting nerve root (ENR), and dural canal at the L2/3, L3/4, and L4/5 levels at 45° and 60° approach angles.

RESULTS

The SAP-ENR distance at 60° was the greatest at L4/5 and was significantly greater at L2/3 and L4/5 than at L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distance at 45° was the greatest at L2/3, and it was larger in L2/3 and L4/5 than in L3/4 (P < 0.01, P < 0.01, respectively). The SAP-ENR distances at L4/5 were significantly greater at 60° than at 45° (P < 0.01). The dural canal was located within Kambin's triangle on the plane of the upper endplate of the lower vertebra at L2/3 in 41.5% of the cases and at L3/4 in 14% of the cases at 60° but not at L4/5.

CONCLUSION

The 3D lumbar spine/nerve image enabled a combined assessment of the positional relationship between the SAP, ENR, and dural canal to quantify the safety zone of practical endoscopic spinal surgery using a transforaminal approach. Three-dimensional lumbar spine/nerve images could be useful for examining parameters, including bones and nerves, to ensure the safety of surgery.

"Pin Method" for Endoscopic Lumbar Interbody Fusion

BACKGROUND

 Endoscopic lumbar interbody fusion using a cage can have a similar fusion rate as minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) or open lumbar interbody fusion. Direct visual control during cage insertion is the key to prevent neural structure incarceration in endoscopic lumbar interbody fusion. Creating a track with any kind of retractor or cannula for cage insertion under fluoroscopic guidance is not safe enough, because the retractor and cannula can create many blind spots and can displace during cage insertion.

METHOD

 The pin method utilizes two flexible metallic guide pins inserted from the skin incision through the annulotomy site into the disk space until the anterior longitudinal ligament is reached under direct endoscopic monitoring. The two guide pins could be oriented parallel or perpendicular or even reduce to one or increase to many as needed to serve as a sliding track and a see-through barrier to prevent neural incarceration.

RESULTS AND CONCLUSION

 Two cases of L4/L5 grade 2 spondylolisthesis with neurogenic claudication were treated with endoscopic lumbar interbody fusion with 1-year follow-up, and the visual analog scale (VAS) score, Oswestry Disability Index (ODI) score, EuroQol five-dimensional questionnaire (EQ-5D, %) score, and modified Macnab score all improved greatly in both. The author developed an original, cheap, accessible, and safe method called the "pin method," which can be used in both full-endoscopic and biportal surgery and can apply to various approaches and has no limitation on the size and shape of the cage.

Initial Experience With a Full Endoscopic Facet Fusion in Combination With Endoscopic Interbody Fusion

Background

Facet fusion has been described in open and minimally invasive approaches to promote fusion. Our objective is to describe the technique of an endoscopic facet decortication and allograft placement as an adjunct to an interbody fusion.

Methodology

This was a descriptive analysis of patients who underwent endoscopic interbody fusion combined with facet fusion and percutaneous screw placement. General demographics, clinical presentation, length of stay, follow-up, and outcome were gathered. The technique involves endoscopic access to the Kambin’s triangle, discectomy/endplate preparation, expandable cage/allograft insertion, and percutaneous pedicle screw placement. A midline incision was performed, and the endoscope was advanced over the facet joints at the desired level. After removing the soft tissue with grasping forceps, cautery was used to disrupt the facet capsule. An articulating high-speed bur was used to drill inside and over the dorsal surface of the joint. Finally, allograft chips were placed through the endoscope cannula.

Results

From May 2019 to December 2019, four patients underwent endoscopic interbody fusion. All were female, with a mean age of 67.5 years (SD: 12.7). All had chronic low back pain and radiculopathy associated with Grade 1 spondylolisthesis. Two (50%) of the patients underwent two-level fusion. The median hospital stay was two days. Two (50%) reported improvement of both low back and radiculopathy symptoms. None of the patients had a significant complication or required reoperation in eight months’ mean follow-up.

Conclusions

Facet decortication and allograft placement are feasible using an endoscopic approach in conjunction with interbody fusion.

Early Clinical Evaluation of Percutaneous Full-endoscopic Transforaminal Lumbar Interbody Fusion with Pedicle Screw Insertion for Treating Degenerative Lumbar Spinal Stenosis

Objective

To compare the clinical efficacy of percutaneous full‐endoscopic transforaminal lumbar interbody fusion (Endo‐TLIF) with percutaneous pedicle screws (PPSs) performed by using a visualization system with that of minimally invasive transforaminal lumbar interbody fusion (MIS‐TLIF) for the treatment of degenerative lumbar spinal stenosis (LSS).

Methods

From June 2017 to May 2018, the data of a total of 78 patients who met the selection criteria were retrospectively reviewed and were divided into the Endo‐TLIF group (40 cases) and the MIS‐TLIF group (38 cases) according to the surgical method used. The visual analog scale (VAS) and the Japanese Orthopaedic Association (JOA) scale were administered preoperatively and at the 1‐week, 3‐month, and 1–2‐year follow‐ups. The fusion rate and major complications, including revision, were also recorded.

Results

All the patients were followed up for 24 to 34 months, with an average follow‐up of 30.7 months. The intraoperative blood loss and length of hospital stay for the Endo‐TLIF group (60.56 ± 0.36 mL, 8.12 ± 0.92 days, respectively) were statistically significantly lower than those for the MIS‐TLIF group (65.47 ± 0.91 mL, 9.66 ± 1.34 days, respectively) (P < 0.05). The VAS and JOA scores of the patients in the two groups at postoperative 1 week, 3 months, 1 year, 2 years (Endo‐TLIF VAS: 4.16 ± 0.92, 3.72 ± 1.54, 1.32 ± 0.45, 1.29 ± 0.34; JOA:16.71 ± 0.99, 19.86 ± 0.24, 24.91 ± 0.97, 25.88 ± 0.52; MIS‐TLIF VAS: 4.17 ± 1.41, 2.98 ± 0.91, 1.54 ± 0.32, 1.33 ± 0.18; JOA: 16.67 ± 0.67, 19.58 ± 0.65, 25.33 ± 0.73, 25.69 ± 0.33) were statistically significantly improved from the preoperative scores (Endo‐TLIF: 8.45 ± 1.44, 14.36 ± 0.56; MIS‐TLIF: 8.11 ± 0.93, 14.45 ± 0.34, respectively) (P < 0.01). The VAS and JOA scores of the Endo‐TLIF group were statistically significantly better than those of the MIS‐TLIF group at 3 months and 1 year after surgery (P < 0.05). There were no statistically significant differences in the scores between the two groups at any of the other time points (P > 0.05). There was no significant difference in the intervertebral altitude between the two groups at the 3‐month (11.36 ± 0.23, 11.21 ± 0.42, respectively) or final follow‐up (10.88 ± 0.64, 10.81 ± 0.39, respectively) (P > 0.05). Dural tears, cerebrospinal fluid leakage, infection, and neurologic injury did not occur. Both groups showed good intervertebral fusion at the last follow‐up. The intervertebral fusion rate was 97.5% (39/40) in the Endo‐TLIF group and 94.7% (36/38) in the MIS‐TLIF group, with no statistically significant difference between the two groups (χ² = 0.118, P = 0.731). At the final follow‐up, the modified MacNab's criteria were 92.5% and 89.5% between the two groups.

Conclusion

Endo‐TLIF with percutaneous pedicle screws (PPS) performed by using a visualization system for lumbar degenerative disease may be regarded as an efficient alternative surgery for degenerative lumbar spinal stenosis. It is a safe and minimally invasive way to perform this surgery and has shown satisfactory clinical outcomes.

Methods and Early Clinical Results of Percutaneous Lumbar Interbody Fusion

OBJECTIVE

Percutaneous lumbar interbody fusion (PELIF) is a procedure that includes the use of new devices, which allow minimally invasive diskectomy under the percutaneous full-endoscopic guidance and safe percutaneous insertion of a standard-sized cage. This procedure can be applied to severe disk degeneration, spondylolisthesis, and all lumbar intervertebral levels including the L5-S1 level. We report the methods and the clinical outcomes of this procedure.

METHODS

Percutaneous diskectomy was performed with an outer sheath cutter and other devices. A cage was inserted with an L-shaped retract-slider. Hybrid facet screw fixation was performed for severe disk degeneration without spondylolisthesis. Conventional percutaneous pedicle screw fixation was performed for spondylolisthesis. The subjects consisted of 21 patients, who underwent PELIF and were followed up for 1 year or longer.

RESULTS

No complications related to cage insertion were detected. The mean visual analogue scale scores were improved from 6.1 to 1.9 for lower back pain in severe disc degeneration cases without spondylolisthesis, and from 7.6 to 1.0 for lower extremity symptoms in spondylolisthesis cases.

CONCLUSION

The clinical outcomes were favorable. PELIF was found to be a minimally invasive method that did not compromise safety and efficiency. PELIF is a possible therapeutic option that should be considered for not only spondylolisthesis at various intervertebral levels but also for severe disk degeneration because of its minimal invasiveness.

Surgical Outcomes After Single-Level Endoscopic Transforaminal Lumbar Interbody Fusion: A Systematic Review and Meta-Analysis

Background and objective

Novel surgical advancements have introduced endoscopic operative techniques for low back surgery, including transforaminal lumbar interbody fusion (TLIF), which theoretically allows for improved decompression with minimal invasiveness. In addition, endoscopically performed TLIF has allowed for the use of local anesthesia as an alternative method to general anesthesia for patients. We aimed to evaluate the clinical outcomes in patients undergoing endoscopic TLIF and also compare the outcomes in patients undergoing general versus local anesthesia.

Methods

The databases of PubMed, Medline, Embase, and the Cochrane Library were queried for all studies involving patients undergoing endoscopic TLIF. After the extraction of the data and assessment of study quality via the Newcastle-Ottawa Scale, statistical analysis was performed with the R software (The R Foundation, Vienna, Austria) metafor package. The random-effects model was used as the data was largely heterogeneous (I² >50%).

Results

In total, 15 studies involving a total of 441 patients were selected for the final quantitative meta-analysis. The overall mean difference between the postoperative visual analog scale (VAS) leg scores and preoperative VAS scores was 3.45 (95% CI: 4.93-1.97, p: <0.01). Postoperative VAS low back scores revealed a mean difference of 3.36 (95% CI: 5.09-1.63, p: <0.01). The overall mean difference of ODI scores was 4.58 (95% CI: 6.76-2.40, p: <0.01). Mean blood loss was 136.32 mL and the mean operative time was 149.15 minutes. The mean length of stay postoperatively was lower in the local anesthesia group compared to the general anesthesia group (1.40 vs 5.99 days respectively). There were no outcome variables of patients undergoing general anesthesia versus local anesthesia that showed statistically significant differences in this analysis due to the small amount of data published on patients undergoing endoscopic TLIF with local anesthesia. In addition, the failure of studies in reporting standard deviations as data parameters further limited the quantitative analysis.

Conclusion

Endoscopic TLIF appears to be a viable option for patients undergoing lumbar interbody fusion. Initial data reveal that endoscopic TLIF with local anesthesia may offer patients outcomes similar to those in patients undergoing endoscopic TLIF with general anesthesia, with lower operative times and length of stay.

Full-Endoscopic Lumbar Interbody Fusion for Treating Lumbar Disc Degeneration Involving Disc Height Loss: Technical Report

Background and Objectives: Lumbar disc degeneration (LDD) is the main cause of lower back pain and leads to corresponding disc height loss. Although lumbar interbody fusion (LIF) is commonly used for treating LDD, several different treatment strategies are available. We performed a minimally invasive full-endoscopic LIF (FELIF) using a uniportal full-endoscopic system. Materials and Methods: FELIF was performed for 12 patients with LDD with disc-height loss using a 4.1 mm working channel endoscope and a newly developed slider for cage insertion. The mean age of the patients was 68.3 years; the patients presented with single vertebral level involvement. The Brandner’s disc index was used for evaluating the postoperative increase in the disc height. Preoperative and postoperative leg pain was evaluated using the numerical rating scale (NRS) score. Results: The mean operation time for FELIF was 109.4 min. The mean duration of hospital stay after FELIF was 7.7 days. There were no operative and postoperative complications, even without drainage during the mean follow-up period of 6.2 months (range, 2–10 months). The Brandner’s disc index improved statistically significant (p > 0.01). The mean preoperative and postoperative NRS scores were 6.5 and 1.2, respectively. Conclusions: FELIF using a 4.1 mm working channel endoscope can be used for treating LDD with disc height loss. Radiculopathy caused by foraminal stenosis was the most suitable operative indication for FELIF.