Surgical results and prognostic factors following percutaneous full endoscopic posterior decompression for thoracic myelopathy caused by ossification of the ligamentum flavum

Comparison of endoscopic decompression to open laminectomy in patients with thoracic ossified ligamentum flavum - a systematic review and meta-analysis

In recent years, there has been growing interest in an alternative approach for treating TOLF, such as endoscopic decompression, which minimizes the disruption of surrounding tissues. It is important to understand the advantages, disadvantages, and potential differences in outcomes associated with each approach. This comparative study aims to evaluate and contrast the effectiveness, safety, and outcomes of these two surgical techniques, open laminectomy and endoscopic decompression, in the management of thoracic OLF. The literature review was conducted on Embase, PubMed, Scopus and Google Scholar databases. After a thorough screening of all search results, 14 studies were shortlisted, from which data was extracted, and statistical analysis was done. Pooled analysis was done to ascertain the intra-operative and post-operative outcomes after surgery for TOLF. Overall, 351 patients were included in the study for evaluation. 174 patients were operated on by open laminectomy, and 177 patients were seen in the endoscopy group. Decreased operative time was seen in the endoscopic subgroup. The mean length of hospital stay of 6.6 days. Both groups showed improvement in mJOA and VAS score. The recovery rate for the reported study cohort was 66.8%, with the Endoscopic surgical approach showing a positive correlation with the mean recovery rate. The dural tear was the most common complication, with a rate of 6.6%. The mean estimated infection rate was 2.7% and postoperative CSF leak was 3.7%, with a trend of significantly higher rates in the open subgroup. Both of the groups showed improvement in functional scores, VAS scores, and cross-sectional area. However, the Endoscopic decompression group experienced reduced hospital stays, operating times, and intraoperative blood loss. The most frequent side effects were CSF leak and dural tear. A few cases showed revision and infection. None of the problems differed between the groups.

M1 macrophage-derived oncostatin M induces osteogenic differentiation of ligamentum flavum cells through the JAK2/STAT3 pathway

Background

M1 macrophages (Mφs) are involved in osteogenic differentiation of ligamentum flavum (LF) cells and play an important role in heterotopic ossification. However, the mechanism by which M1 Mφs influence osteogenic differentiation of LF cells has not been studied.

Methods

The effect of conditioned medium including secretions of M1 Mφs (CM-M1) on LF cells was analyzed by GeneChip profiling and ingenuity pathway analysis (IPA). THP-1 cells were polarized into M1 Mφs and CM-M1 was used to induce LF cells. In addition, LF cells were induced by CM-M1 in the presence of cyclooxygenase 2 (COX-2) inhibitors or oncostatin M (OSM)-neutralizing antibodies. Based on the presence of OSM, knockout of OSMR or GP130 receptors, or addition of the Janus kinase 2 (JAK2) inhibitor AZD1480 or signal transducer and activator of transcription 3 (STAT3) inhibitor Stattic were examined for effects on osteogenic differentiation of LF cells. OSM secretion was quantified by ELISA, while qPCR and western blot were used to evaluate expression of osteogenic genes and receptor and signaling pathway-related proteins, respectively.

Results

GeneChip and IPA results indicate that the OSM signaling pathway and its downstream signaling molecules JAK2 and STAT3 are significantly activated. ELISA results indicate that OSM is highly expressed in cells treated with CM-M1 and lowly expressed in cells treated with CM-M1 and a COX-2 inhibitor. Besides, CM-M1 induces osteogenic differentiation of LF cells, which is weakened when COX-2 inhibitors or OSM-neutralizing antibody are added to it. Recombinant OSM could induce osteogenic differentiation of LF cells and upregulate expression of OSMR, GP130, phosphorylated (P)-JAK2, and P-STAT3. Upon knockdown of OSMR or GP130, or the addition of AZD1480 or Stattic, P-JAK2 and P-STAT3 expression were decreased and osteogenic differentiation was reduced.

Conclusion

M1 Mφ-derived OSM induces osteogenic differentiation of LF cells and the JAK2/STAT3 signaling pathway plays an important role.

Safety and efficacy of one-hole split endoscope technique for surgical treatment of thoracic ossification of the ligamentum flavum

Surgical intervention is typically recommended for thoracic ossification of the ligamentum flavum (TOLF). This study aimed to evaluate the efficacy and safety of a novel non-coaxial one-hole split endoscope (OSE) technique for treating TOLF. We performed OSE procedure on 13 patients with TOLF from June 2022 to July 2023. The mean operative time was 117.5 ± 15.4 min. VAS scores for lower limbs decreased from 6.5 ± 0.8 preoperative to 1.6 ± 0.4 at the last follow-up (P < 0.001). ODI scores improved from 62.4 ± 5.7 preoperative to 18.6 ± 2.2 at the last follow-up (P < 0.001), and mJOA scores increased from 5.1 ± 1.6 preoperative to 8.4 ± 1.5 at the latest follow-up (P < 0.001). All patients achieved ASIA scale grade D or E at the final follow-up, except for two patients remained residual limb numbness. None of the thirteen patients suffered from severe perioperative complications. The OSE technique proves to be a safe and effective procedure for treating TOLF or even with dura mater ossification, characterized by minimal surgical trauma, relatively smooth learning curve and flexible operation.

Safety and Efficacy Outcomes Following Spinal Endoscopic Procedures for Thoracic Ligamentous Ossification: A Systematic Review and Meta-Analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

This study systematically reviewed and evaluated the safety and efficacy of spinal endoscopic techniques as a treatment for thoracic ligamentum flavum ossification (TOLF).

SUMMARY OF BACKGROUND DATA

The use of spinal endoscopic techniques for the treatment of TOLF has increased in recent years. The present study is the first comprehensive systematic review and meta-analysis focused on the use of spinal endoscopic techniques for TOLF.

MATERIALS AND METHODS

The Cochrane Central, PubMed, Web of Science, and Embase databases were systematically searched for studies focused on patients undergoing spinal endoscopic techniques to treat symptomatic TOLF.

RESULTS

This meta-analysis included 23 studies. We included 323 patients (177 males, 146 females) with a mean age of 58.40±10.06 years, with 304 total recorded lesion locations of which 245 were located in the lower thoracic spine. Complications affected 35/323 patients, and the mean operative duration for 305 patients was 108.15±47.34 minutes. For 187 patients, the mean operative bleeding was 25.13±12.54 mL, while for 87 patients the mean duration of hospitalization was 4.59±1.93 days. At last follow-up, functional assessment was performed for 260 patients, of whom 200 were in excellent condition, visual analog scale (VAS) scores were assessed for 160 patients, with a mean improvement of 4.40 (3.95, 4.86) Japanese Orthopedic Association (JOA) scores were recorded for 115 patients, with a mean improvement of 3.49 (2.79,4.18), and modified Japanese Orthopedic Association (mJOA) scores were recorded for 208 patients, with a mean improvement of 3.62 (2.89,4.35).

CONCLUSIONS

These results support several advantages of spinal endoscopic techniques for the treatment of symptomatic TOLF. These include low complication rates, rapid postoperative recovery, and good functional recovery when used for single-segment, non-nodular ossification and no combined dural ossification.

The Current Status of Awake Endoscopic Surgery: A Systematic Review and Meta-Analysis

OBJECTIVE

To examine the use of local anesthesia and/or conscious sedation in endoscopic spine procedures within the past decade.

METHODS

This systematic review abided by PRISMA guidelines. Embase, PubMed, Google Scholar, and Cochrane databases were searched for post-2011 articles with patients >18 years old, lumbar/cervical percutaneous endoscopic spine procedures using local/awake anesthesia, and patient/surgical outcomes. Reviews, book chapters, single case reports, or small case series (n ≤15 patients) were excluded. Scoring systems of the National Institutes of Health quality assessment tool, Newcastle-Ottawa Scale, and Cochrane Risk of Bias evaluated interventional case series, comparative studies, and randomized control trials, respectively.

RESULTS

Twenty-six articles were included, with 4 studies comparing general and local anesthesia. Of 2113 total patients, 1873 patients received local anesthesia. Significant improvements were seen in pain and disability scores. Studies that included MacNab scores showed that 96% of patients rated their postoperative satisfaction as excellent to good. Subanalysis of comparative studies showed a reduced risk of surgical/major medical complications and a slight increased risk for minor medical complications among awake spine patients. Length of stay was shorter for patients receiving local anesthesia.

CONCLUSIONS

The current systematic review and meta-analysis shows that use of local anesthesia is a safe and effective alternative to general anesthesia among different endoscopic spinal procedures. Although awake spine surgery is associated with a decreased risk of severe complications, lower revision rates, and higher postoperative satisfaction, more robust studies involving larger cohorts of patients are needed to evaluate the true impact of awake spine surgery on outcomes.

Complications of Endoscopic Thoracic Spine Surgery: Overview and Complication Avoidance

In endoscopic thoracic spine surgery, adaptations of thoracic surgical techniques such as full endoscopic uniportal and biportal surgical techniques have been developed. Full endoscopic uniportal surgery for thoracic disc herniation or thoracic ossified ligamentum flavum (OLF) has been performed via transforaminal and interlaminar approaches. In the case of thoracic OLF or thoracic spinal stenosis, the uniportal interlaminar approach is appropriate. The uniportal interlaminar approach has been used to treat thoracic OLF and has shown good surgical results. Thoracic OLF removal via a biportal endoscopic technique has been developed recently and is described in a few studies. Although endoscopic thoracic spine surgery has significant advantages, complications often occur with this approach. We reviewed the literature to date on the complications associated with endoscopic spine surgery in thoracic pathology. This review emphasizes how to avoid and manage complications. Based on the results of several previous studies, endoscopic thoracic spine surgery could be associated with fewer potential complications than conventional surgery. Endoscopic spine surgery has remarkable advantages; however, endoscopic thoracic surgery is technically challenging and is potentially associated with serious complications. To minimize the risk of avoidable complications, surgeons should be familiar with prevention methods and pitfalls.

Uniportal Thoracic Endoscopic Unilateral Laminotomy with Bilateral Decompression of Thoracic Ossification of Ligamentum Flavum: A Systematic Review of Current Literature

BACKGROUND

Thoracic ossification of ligamentum flavum (TOLF) is a rare disease that often results in worsening neurologic sequelae if left untreated. Although the gold standard treatment for TOLF is open posterior laminectomy, it is often accompanied by high rates of complications and perioperative morbidity. There have been studies looking into feasibility of endoscopic posterior decompression for TOLF, citing potential for lower perioperative morbidity and achieving similar functional outcomes to its open laminectomy counterparts. We provide an up-to-date systematic review of clinical outcomes after endoscopic posterior decompression for TOLF from the latest assemblage of evidence.

METHODS

A systematic review of the technique was conducted from May 2000 to May 2023. Articles were selected based on PRISMA guidelines. Eligibility of studies was independently by 2 reviewers, with disagreements resolved by a third author.

RESULTS

Nineteen primary references comprising 337 patients with TOLF who underwent endoscopic posterior decompression were included in the systematic review. Mean follow-up time across all studies ranged from 8.9 to 65.3 months. Mean age ranged from 51.2 to 63 years, with mean intraoperative blood loss ranging from 15 to 62 mL. There is significant improvement in visual analog scale (VAS) score, VAS back, VAS leg, modified Japanese Orthopaedic Association score, and Oswestry Disability Index compared with preoperative recorded values across all studies, with low rates of complications reported.

CONCLUSIONS

Endoscopic posterior spinal decompression is a safe and effective technique for treatment of TOLF, with a low rate of complications and improvement in pain and function.

A muscle-preserving, spinous process-splitting approach for ossification of the ligamentum flavum in the thoracic spine in professional athletes: a report of three cases

A muscle-preserving, spinous process-splitting approach may be a less invasive approach to conventional laminectomy in patients with thoracic ossification of the ligamentum flavum. Few reports have discussed the usefulness of this procedure for thoracic lesions in professional athletes who need highly active thoracic spinal function after surgery. The treatment of thoracic ossification of the ligamentum flavum using a spinous process-splitting approach in 3 professional athletes is presented. In all three cases the patients could return to play within 3 months after surgery without complications, and in two of the cases, there was no spinal deformity or local recurrence of ossification of the ligamentum flavum at the final follow-up at least 8 years after surgery. The spinous process-splitting approach could be a safe procedure for multi-level and all other forms of ossification of the ligamentum flavum and is less invasive to the paraspinal muscles, relieves back symptoms, and restores function for athletes.

Surgical outcomes of percutaneous endoscopic thoracic decompression in the treatment of multi-segment thoracic ossification of the ligamentum flavum

BACKGROUND

Previous studies have demonstrated satisfactory outcomes of percutaneous endoscopic thoracic decompression (PETD) for single-segment thoracic ossification of the ligamentum flavum (TOLF). However, the clinical outcomes of PETD in patients with multi-segment TOLF (mTOLF) remain unclear. The aim of the present study was to evaluate the efficacy and safety of PETD for patients with multi-segment mTOLF.

METHODS

Eighteen consecutive patients (41 segments) with mTOLF were treated with PETD between January 2020 and December 2021. The clinical outcomes were evaluated using the modified Japanese Orthopaedic Association (mJOA) score and Visual Analog Scale (VAS), whereas radiographic parameters were measured by cross-section area of the spinal canal and anteroposterior diameter of the spinal cord.

RESULTS

The follow-up period ranged from 14 to 34 months. The mean operation time and blood loss were 154.06 ± 32.14 min and 61.72 ± 12.72 ml, respectively. Hospital stay after first-stage operation was 10.89 ± 2.42 days. The mJOA score and VAS score significantly improved at the final follow-up, with a mean mJOA recovery rate of 63.3 ± 21.90%. The incidence of complications was 12.2% per level. The radiographic outcomes showed adequate decompression of the spinal cord.

CONCLUSIONS

The present study demonstrates that PETD is effective and safe as a minimally invasive procedure to treat patients with mTOLF. All patients showed relief of their symptoms and improvement in neurological function.

Identification of the Magna Radicular Artery Entry Foramen and Adamkiewicz System: Patient Selection for Open versus Full-Endoscopic Thoracic Spinal Decompression Surgery

BACKGROUND

Casually cauterizing the radicular magna during routine thoracic discectomy may have dire consequences.

METHODS

We performed a retrospective observational cohort study on patients scheduled for decompression of symptomatic thoracic herniated discs and spinal stenosis who underwent a preoperative computed tomography angiography (CTA) to assess the surgical risks by anatomically defining the foraminal entry level of the magna radicularis artery into the thoracic spinal cord and its relationship to the surgical level.

RESULTS

Fifteen patients aged 58.53 ± 19.57, ranging from 31 to 89 years, with an average follow-up of 30.13 ± 13.42 months, were enrolled in this observational cohort study. The mean preoperative VAS for axial back pain was VAS of 8.53 ± 2.06 and reduced to a postoperative VAS of 1.60 ± 0.92 (p < 0.0001) at the final follow-up. The Adamkiewicz was most frequently found at T10/11 (15.4%), T11/12 (23.1%), and T9/10 (30.8%). There were eight patients where the painful pathology was found far from the AKA foraminal entry-level (type 1), three patients with near location (type 2), and another four patients needing decompression at the foraminal (type 3) entry-level. In five of the fifteen patients, the magna radicularis entered the spinal canal on the ventral surface of the exiting nerve root through the neuroforamen at the surgical level requiring a change of surgical strategy to prevent injury to this important contributor to the spinal cord's blood supply.

CONCLUSIONS

The authors recommend stratifying patients according to the proximity of the magna radicularis artery to the compressive pathology with CTA to assess the surgical risk with targeted thoracic discectomy methods.

Successful treatment of thoracic myelopathy caused by spontaneous spinal epidural hematoma (SSEH) combined with calcification of the ligamentum flavum (CLF) by posterior percutaneous endoscopic surgery (PPES): A case report

Study Design

A retrospective case report.

Objective

To report a case who developed deteriorated paraplegia by spontaneous spinal epidural hematoma (SSEH) based on calcification of the ligamentum flavum (CLF) at the T10-11 level, achieved full neurological recovery following posterior percutaneous endoscopic surgery (PPES).

Summary of Background Data

CLF rarely occurs at the thoracic spine, and the symptom usually progress slowly. SSEH is another rare spinal lesion that might progress rapidly and cause emergent severe spinal cord compression syndrome. Coexistence of SSEH and CLF at the same thoracic level was rarely reported in English literature.

Methods

A 65-year-old man presented to our hospital with the complaint of sensorimotor loss on the lower limbs and dysfunction of bladder for 1 day after a progressive weakness and numbness of the lower limbs for 3 months. MR examination found a dorsal protruding mass at the T10-11 level, while computed tomography (CT) found the protruding mass contained scattered calcified deposits. The patient was diagnosed with thoracic CLF. Decompression via PPES was carried out to realize bilateral decompression through a unilateral approach.

Results

During the operation, the protruding mass was found to be composed of SSEH and CLF together. After the operation, the patient's neurological function recovered quickly. One week later, the patient could walk by himself. After 3 months, complete neurological function had recovered.

Conclusion

SSEH could develop based on CLF at thoracic level and cause serious neurological dysfunction. PPES might be an advisable method to remove CLF and evacuate SSEH with good clinical results.

Three-dimensional imaging analysis for the diagnosis of dural ossification in thoracic ossification of the ligamentum flavum: a multicenter study

Background

Unforeseen dural ossification (DO) increases the risk of complications in the surgical management of thoracic ossification of the ligamentum flavum (OLF). Several methods have been proposed to identify DO; however, these approaches either have low diagnostic accuracy or poor feasibility. Therefore, we aimed to determine the relationship between DO and the severity and range of thoracic OLF compression using a 3-dimensional (3D) imaging analysis and to evaluate its superiority in diagnosing DO over conventional measurement methods.

Methods

A total of 114 consecutive patients who underwent decompressive laminectomy for thoracic OLF in 4 institutions were retrospectively enrolled and divided into DO and non-DO groups. Univariate analysis was performed to determine the relationship between OLF compression and DO. We measured the 3D occupying ratio (OR; 3D OR = OLF volume/normal canal volume × 100%), calculated its cutoff values, and compared its diagnostic value in DO with that of conventional 1D and 2D radiological parameters in the whole thoracic spine.

Results

The 3D OR in the DO group (50.9%±7.9%) was significantly higher than that in the non-DO group (30.8%±7.5%; P<0.01). The overall reliability and reproducibility for measurements of the 3D OR (intra- and interobserver correlation coefficients 0.94 and 0.90, respectively) were excellent. Thus, the 3D OR could be used as an indicator to distinguish between DO and non-DO, with high diagnostic accuracy (91.2%). Moreover, a 3D OR of >43%, known as the "ossification zone", was indicative of DO in OLF, whereas a value of <37% was considered the "safe zone". Additionally, the 3D OR [area under the curve (AUC) =0.98, 95% confidence interval (CI): 0.93-0.99] showed a statistically higher diagnostic value for DO in the upper, middle, lower, and whole thoracic spine than did both 1D (AUC =0.81; 95% CI: 0.73-0.88) and 2D (AUC =0.87; 95% CI: 0.79-0.92) parameters (P<0.01).

Conclusions

DO was significantly associated with the severity and range of OLF compression. The 3D OR could be used as a critical diagnostic indicator for identifying DO in the whole thoracic spine, owing to its superiority over conventional radiological parameters. Classification of the 3D OR could maximize the clinical feasibility and thus help surgeons to decrease the incidence of DO-related surgical complications.

Analysis of the surgical strategy and postoperative clinical effect of thoracic ossification of ligament flavum with dural ossification

Purpose

Our research was designed to analyse the postoperative clinical results of patients suffering from single-segment thoracic ossification of the ligamentum flavum (TOLF) combined with dural ossification (DO) who underwent posterior laminar decompression and internal fixation.

Methods

This retrospective research included thirty-two patients who underwent surgery for ossifying the ligamentum flavum in the thoracic spine between January 2016 and January 2020. Patients were fallen into one group included patients with evidence of DO during surgery, and the other group included patients without evidence of DO. We assessed and compared general clinical characteristics and health-related outcomes before surgery and during follow-up.

Results

The DO group had a longer operation duration, more blood loss, and longer hospital stay (operation time: 94.75 ± 6.78 min vs. 80.00 ± 10.13 min, p < 0.001; blood loss: 331.67 ± 50.06 ml vs. 253.00 ± 48.24 ml, p < 0.001; length of hospital stay: 13.83 ± 2.76 days vs. 10.05 ± 2.33 days, p < 0.001).

Complications

There were 12 cases of cerebrospinal fluid leakage and 1 case of superficial wound infection in the DO group. However, the neurological recovery and health-associated quality of life (HRQOL) scores showed no statistically significant changes between the DO and non-DO groups (p > 0.05).

Conclusions

Posterior laminectomy and internal fixation combined with intraoperative resection of the ossified ligamentum flavum and dura is an efficient and relatively safe method for treating TOLF with DO, which can provide satisfactory results. Moreover, DO had no significant effect on postoperative neurological recovery and health-related quality of life scores.

Unilateral biportal endoscopic decompression for symptomatic thoracic ossification of the ligamentum flavum: a case control study

PURPOSE

Thoracic ossification of the ligamentum flavum (OLF) is an uncommon disease that mostly occurs in East Asians. Laminectomy is often considered when patients develop neuro-related symptoms but may associate with treatment-related complications. This study aimed to evaluate the efficacy and safety of unilateral biportal endoscopic (UBE) decompression treatment in patients with symptomatic OLF.

METHODS

From January 2020 to January 2021, patients with spinal cord compression symptoms and imaging-defined single-level thoracic OLF were enrolled in this study and received UBE decompression treatment. Their pre- and postoperative neurological statuses were evaluated by the modified Japanese Orthopaedic Association (mJOA) score, Visual Analog Scale (VAS) for leg pain, and Frankel grade.

RESULTS

Fourteen patients with an average age of 59.4 years were enrolled in the study. The mean operation time was 66.1 ± 15.4 minutes. Patients were followed up for at least one year after receiving the treatment. Our data suggested that their mJOA score (preop 6.2 ± 1.2, 1 year 8.5 ± 0.9; P < 0.001) and VAS score (preop 4.5 ± 2.0, 1 year 0.5 ± 0.9; P < 0.001) were significantly improved compared with that before operation. Cerebrospinal fluid leakage occurred in one patient, head and neck pain occurred in two patients, and hyperalgesia of lower limbs occurred in two patients. All these complications did not cause serious consequences.

CONCLUSION

This primary study indicated that the UBE decompression treatment can achieve satisfactory clinical results in patients with thoracic OLF at single level and provide an alternative treatment option.

Ossified Ligamentum Flavum: Epidemiology, Treatment, and Outcomes

Ossification of the ligamentum flavum (OLF) is an uncommon but potentially serious spinal condition which can cause progressive compression of the spinal canal with associated devastating neurologic compromise. Although debate exists regarding the exact etiology of OLF, overexpression of genes and transcription factors centered around the Notch and Wnt signaling pathways because of increased mechanical stress seems to be related. There are many clinical and radiographic presentations of OLF; however, progressive myelopathy is the most commonly encountered. Radiographic analysis may reveal isolated OLF or OLF combined with ossification of other areas of the spine, such as disk, posterior longitudinal ligament, and dura. When surgery is necessary for OLF, several surgical strategies exist including open laminectomy with excision, endoscopic decompression, Bridge Crane resection, en block resection, and combined anterior and posterior approaches. Resection may be complicated by dural adhesion or dural ossification, and postoperative neurologic deficits are not uncommon.

Clinical Efficacy of Endoscopic-Assisted Resection of Single-Segment Ossification of the Posterior Longitudinal Ligament in the Treatment of Thoracic Spinal Stenosis

Objective

To explore the clinical efficacy, characteristics and safety of endoscopic-assisted resection of single-segment posterior longitudinal ligament ossification in the treatment of thoracic spinal stenosis (TSS).

Method

Fifteen TSS patients, including 6 males and 9 females aged 43–70 years treated with endoscopic-assisted resection of single-segment posterior longitudinal ligament ossification through the transfacet joint approach by our team from November 2016 to June 2020 were retrospectively analyzed. The operation time, intraoperative blood loss, and postoperative complications were recorded. The VAS score, ODI and JOA score (full score, 11 points) were recorded before the operation, after the operation and at the last follow-up to evaluate the clinical efficacy and calculate the improvement rate.

Results

The ventral side of the spinal cord was decompressed in all patients, providing improvements in neurological symptoms and significant pain relief. The mean follow-up time was 20.27 ± 3.87 months. Mean operation time, intraoperative blood loss, and hospitalization time were found to be 84.80 ± 13.23 min, 36.33 ± 7.41 mL, 5.13 ± 1.02 days; respectively.The JOA score at the last follow-up was 8.6 ± 1.25, which was significantly better than the preoperative (5.53 ± 1.20) and postoperative (6.87 ± 1.31) scores (p < 0.05). The mean JOA score improvement rate was 56.5 ± 18.00%. The JOA score improvement rate classification at the last follow-up was excellent in 3 cases, good in 8 cases, effective in 3 cases, and no change in 1 case; for an effective rate of 93.33%. The VAS score significantly decreased from 6.67 ± 1.01 preoperatively to 3.47 ± 0.88 postoperatively and 1.73 ± 0.67 at the last follow-up (p < 0.05). The ODI significantly decreased from 72.07 ± 6.08 preoperatively to 45.93 ± 5.01 postoperatively and 12.53 ± 2.33 at the last follow-up (p < 0.05). Dural rupture occurred in 2 patients during the operation; 1 patient experienced neck discomfort during the operation, which was considered to be caused by high fluid pressure and was relieved by massage and by lowering the height of the irrigation fluid. No cases of cerebrospinal fluid leakage, wound infection or other complications occurred.

Conclusion

Endoscopic-assisted resection of posterior longitudinal ligament ossification through the facet joint approach is a safe and effective method for the treatment of TSS.

Full Endoscopic Thoracic Discectomy: Is the Interlaminar Approach an Alternative to the Transforaminal Approach? A Technical Note

BACKGROUND

Various approaches are used for decompressive surgeries in the thoracic spine depending on the location and consistency of the pathology, always avoiding manipulation of the thoracic spinal cord. Recently, there has been an effort to achieve adequate results and reduce morbidity with minimally invasive surgeries. Good outcomes and the advantages of full endoscopic spine surgery (FESS) have been proven for surgerical correction of herniated discs and stenoses in the lumbar and cervical spine. Similar evidence has recently been described for the thoracic spine, but it has not previously been reported in Brazil. Although the transforaminal approach is already established for the thoracic spine, the newly described interlaminar approach is equally efficient, and both techniques must be considered when treating thoracic spine diseases. The objective of the present article was to present the full endoscopic interlaminar and transforaminal techniques in patients with symptomatic disc herniation of the thoracic spine, discuss the rationality for implementing FESS in thoracic spine, and discuss the rationality in choosing between both approaches.

METHODS

Two patients were submitted to thoracic FESS. A transforaminal approach was chosen for a T10-T11 foraminal disc herniation; an interlaminar approach was selected for a paramedian T7-T8 disc extrusion. Data regarding operating time, intraoperative images, hospital stay, visual analog scales before and after FESS, course of recovery, and surgery satisfaction were evaluated.

RESULTS

The patients had eventless surgeries, improved from preoperative pain without morbidity. Both were satisfied and recovered well. Hospital stay was less than 6 hours after surgery.

CONCLUSIONS

Transforaminal and interlaminar FESS for thoracic disc herniation are safe, efficient, and minimally invasive alternatives.

CLINICAL RELEVANCE

Despite being an innovative technique with evident advantages, it should be carefully considered along with conventional technique for the treatment of thoracic spine diseases, since its clinical relevance is yet to be determined.

LEVEL OF EVIDENCE: 4

The clinical value of three-dimensional measurement in the diagnosis of thoracic myelopathy caused by ossification of the ligamentum flavum

Background

Thoracic ossification of the ligamentum flavum (OLF) is a major cause of thoracic myelopathy, which is often accompanied by multiple segmental stenosis or other degenerative spinal diseases. However, in the above situations, it is difficult to determine the exact segment responsible. The objective of this study was to analyze three-dimensional (3D) radiological parameters in order to establish a novel diagnostic method for discriminating the responsible segment in OLF-induced thoracic myelopathy, and to evaluate its superiority compared to the conventional diagnostic methods.

Methods

Eighty-one patients who underwent surgery for thoracic myelopathy caused by OLF from 2016 to 2020 were enrolled in this study as the myelopathy group, and 79 patients who had thoracic OLF but displayed no definite neurological signs from 2018 to 2020 were enrolled as the non-myelopathy group. We measured the one-dimensional (1D), two-dimensional (2D), and 3D radiological parameters, calculated their optimal cutoff values, and compared their diagnostic values.

Results

Significant differences were observed in the 1D, 2D, and 3D radiological parameters between the myelopathy and non-myelopathy groups (P<0.01). As a 3D radiological parameter, the OLF volume (OLFV) ratio (OLFV ratio = OLFV/normal canal volume × 100%) was the most accurate parameter for diagnosing OLF-induced thoracic myelopathy, with a diagnostic coincidence rate of 88.1%. We also found that an OLFV ratio of 26.3% could be used as the optimal cutoff value, with a sensitivity of 87.7% and a specificity of 88.6%. Moreover, the OLFV ratio [area under the curve (AUC): 0.92, 95% confidence interval (CI): 0.86-0.95] showed a statistically higher diagnostic value than the 1D and 2D parameters (AUC: 0.75, 95% CI: 0.67-0.81; AUC: 0.84, 95% CI: 0.77-0.89, respectively) (P<0.05). Pearson correlation analysis illustrated that the OLFV ratio was significantly negatively correlated with preoperative modified Japanese Orthopedic Association (mJOA) score (r=-0.73, 95% CI: -0.81 to -0.60, P<0.01).

Conclusions

Our results demonstrate the superiority of the OLFV ratio over the conventional 1D and 2D computed tomography (CT)-based radiological parameters for the diagnosis of OLF-induced thoracic myelopathy. The novel diagnostic method based on the OLFV ratio will help to determine the responsible segment in multi-segmental thoracic OLF or when thoracic OLF coexists with other degenerative spinal diseases. The OLFV ratio also accurately reflects the clinical state of symptomatic patients with thoracic OLF.

Full endoscopic surgery for thoracic pathology: an assessment of supportive evidence

In the last five years, surgeons have applied endoscopic transforaminal surgical techniques mastered in the lumbar spine to the treatment of thoracic pathology.

The aim of this systematic review was to collate the available literature to determine the place and efficacy of full endoscopic approaches used in the treatment of thoracic disc prolapse and stenosis.

An electronic literature search of PubMed, Embase, the Cochrane database and Google Scholar was performed as suggested by the Preferred Reporting Items for Systematic Review and Meta-analysis statements. Included were any full-text articles referring to full endoscopic thoracic surgical procedures in any language.

We identified 17 patient series, one cohort study and 13 case reports with single or of up to three patients.

Although the majority included disc pathology, 11 papers related cord compression in a proportion of cases to ossification of the ligamentum flavum or posterior longitudinal ligament. Two studies described the treatment of discitis and one reported the use of endoscopy for tumour resection.

Where reported, excellent or good outcomes were achieved for full endoscopic procedures in a mean of 81% of patients (range 46–100%) with a complication rate of 8% (range 0–15%), comparing favourably with rates reported after open discectomy (anterior, posterolateral and thoracoscopic) or by endoscopic tubular assisted approaches. Twenty-one of the 31 author groups reported use of local anaesthesia plus sedation rather than general anaesthesia, providing ‘self-neuromonitoring’ by allowing patients to respond to cord and/or nerve stimuli.

Cite this article: EFORT Open Rev 2021;6:50-60. DOI: 10.1302/2058-5241.6.200080

Microendoscopic Posterior Decompression for Treating Thoracic Myelopathy Caused by Ossification of the Ligamentum Flavum: Case Series

Background and Objectives: Ossification of the ligamentum flavum (OLF) is a relatively common cause of thoracic myelopathy. Surgical treatment is recommended for patients with myelopathy. Generally, open posterior decompression, with or without fusion, is selected to treat OLF. We performed minimally invasive posterior decompression using a microendoscope and investigated the efficacy of this approach in treating limited type of thoracic OLF. Materials and Methods: Microendoscopic posterior decompression was performed for 19 patients (15 men and four women) with thoracic OLF with myelopathy aged between 35 to 81 years (mean age, 61.9 years). Neurological examination and preoperative magnetic resonance imaging (MRI) and computed tomography (CT) were used to identify the location and morphology of OLF. The surgery was performed using a midline approach or a unilateral paramedian approach depending on whether the surgeon used a combination of a tubular retractor and endoscope. The numerical rating scale (NRS) and modified Japanese Orthopedic Association (mJOA) scores were compared pre- and postoperatively. Perioperative complications and the presence of other spine surgeries before and after thoracic OLF surgery were also investigated. Results: Four midline and 15 unilateral paramedian approaches were performed. The average operative time per level was 99 min, with minor blood loss. Nine patients had a history of cervical or lumbar spine surgery before or after thoracic spine surgery. The mean pre- and postoperative NRS scores were 6.6 and 5.3, respectively. The mean recovery rate as per the mJOA score was 33.1% (mean follow-up period, 17.8 months), the recovery rates were significantly different between patients who underwent thoracic spine surgery alone (50.5%) and patients who underwent additional spine surgeries (13.7%). Regarding adverse events, one patient experienced dural tear, another experienced postoperative hematoma, and one other underwent reoperation for adjacent thoracic stenosis. Conclusion: Microendoscopic posterior decompression was applicable in limited type of thoracic OLF surgery including beak-shaped type and multi vertebral levels. However, whole spine evaluation is important to avoid missing other combined stenoses that may affect outcomes.

Design of a robot-assisted system for transforaminal percutaneous endoscopic lumbar surgeries: study protocol

Background

Transforaminal percutaneous endoscopic lumbar surgeries (PELS) for lumbar disc herniation and spinal stenosis are growing in popularity. However, there are some problems in the establishment of the working channel and foraminoplasty such as nerve and blood vessel injuries, more radiation exposure, and steeper learning curve. Rapid technological advancements have allowed robotic technology to assist surgeons in improving the accuracy and safety of surgeries. Therefore, the purpose of this study is to develop a robot-assisted system for transforaminal PELS, which can provide navigation and foraminoplasty.

Methods

The robot-assisted system consists of three systems: preoperative planning system, navigation system, and foraminoplasty system. In the preoperative planning system, 3D visualization of the surgical segment and surrounding tissues are realized using the multimodal image fusion technique of computed tomography and magnetic resonance imaging, and the working channel planning is carried out to reduce the risk for injury to vital blood vessels and nerves. In the navigation system, the robot can obtain visual perception ability from a visual receptor and automatically adjust the robotic platform and robot arm to the appropriate positions according to the patient’s position and preoperative plan. In addition, the robot can automatically register the surgical levels through intraoperative fluoroscopy. After that, the robot will provide navigation using the 6 degree-of-freedom (DOF) robot arm according to the preoperative planning system and guide the surgeon to complete the establishment of the working channel. In the foraminoplasty system, according to the foraminoplasty planning in the preoperative planning system, the robot performs foraminoplasty automatically using the high speed burr at the end of the robot arm. The system can provide real-time feedback on the working status of the bur through multi-mode sensors such as multidimensional force, position, and acceleration. Finally, a prototype of the system is constructed and performance tests are conducted.

Discussion

Our study will develop a robot-assisted system to perform transforaminal PELS, and this robot-assisted system can also be used for other percutaneous endoscopic spinal surgeries such as interlaminar PELS and percutaneous endoscopic cervical and thoracic surgeries through further research. The development of this robot-assisted system can be of great significance. First, the robot can improve the accuracy and efficiency of endoscopic spinal surgeries. In addition, it can avoid multiple intraoperative fluoroscopies, minimize exposure to both patients and the surgical staff, shorten the operative time, and improve the learning curve of beginners, which is beneficial to the popularization of percutaneous endoscopic spinal surgeries.

Full-Endoscopic Spine Surgery for the Treatment of Lumbar Ossification of the Ligamentum Flavum: Technical Report

BACKGROUND

Ossification of the ligamentum flavum (OLF) is a relatively common disease in East Asia. Although surgical decompression using a posterior approach is commonly used to treat OLF, there are several different treatment strategies. The purpose of this study is to clarify the technically important points for the treatment of OLF using full-endoscopic spine surgery (FESS).

METHODS

FESS was performed on 7 patients with lumbar OLF. Patients had a mean age of 62.3 years and single-level involvement. Computed tomography and magnetic resonance imaging were used to classify the OLF. Two different types of spinal endoscope were used for posterior decompression. Interlaminal and translaminal approaches were performed in 6 and 1 patient, respectively. Preoperative and postoperative pain was evaluated using the numeric rating scale score.

RESULTS

The mean operation time was 84.1 minutes. Unilateral round-type OLF was treated using a 4.1-mm working channel endoscope. The bilateral type was treated using a 6.4-mm working channel endoscope. A dural tear occurred in 1 patient with beak-type OLF, but no symptoms resulting from the tear were observed. The mean preoperative and postoperative numeric rating scale scores were 7.7 and 1.6, respectively.

CONCLUSIONS

Posterior decompression using FESS can be used to treat patients with lumbar OLF. Unilateral round-type OLF with ipsilateral radiculopathy can be treated using a 4.1-mm working channel endoscope. Bilateral-type OLF with cauda equina symptoms should be treated using a 6.4-mm working channel endoscope.