Clinical relation among dural adhesion, dural ossification, and dural laceration in the removal of ossification of the ligamentum flavum

Hybrid decompression-based surgical strategy for treating multilevel thoracic ossification of the ligamentum flavum: a retrospective study

STUDY DESIGN

A retrospective study design was adopted.

PURPOSE

This study investigated the surgical modification of laminectomy, including piecemeal and en bloc resections, and compared this hybrid approach with conventional en bloc laminectomy for treating multilevel thoracic ossification of the ligamentum flavum (TOLF).

OVERVIEW OF LITERATURE

En bloc laminectomy is the most commonly used method for managing symptomatic TOLF. However, this approach can easily cause intraoperative spinal cord irritation, dural tear, and cerebrospinal fluid leakage (CFL).

METHODS

Motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SEPs) were recorded in 48 patients with TOLF (hybrid 20 vs. en bloc 28) during surgery. Patients were categorized based on MEP/SEP improvement, deterioration, or no change, and MEP/SEP improvement rates were measured in the improvement group. Furthermore, all patients were assessed using the Ashworth and modified Japanese Orthopedic Association scores.

RESULTS

The incidences of both MEP/SEP improvement (21.4% vs. 25.0%, p=0.772) and deterioration (21.4% vs. 20.0%, p=0.904) were similar between the en bloc and hybrid laminectomy groups, and no difference in preoperative and postoperative clinical assessments was observed between the two groups (p>0.05). In four patients (4/28, 14.3%) undergoing en bloc laminectomy, MEP amplitudes initially increased after OLF removal but gradually decreased. This delayed MEP reduction did not occur in the hybrid laminectomy group. Furthermore, more patients undergoing en bloc laminectomy had CFL than those undergoing hybrid laminectomy (46.4% vs. 15.0%, p=0.023). In the improvement group, the hybrid laminectomy group exhibited higher MEP improvement rates in the bilateral abductor hallucis than the en bloc laminectomy group (left side: 213.4%±35.9% vs. 152.5%±41.0%, p=0.028; right side: 201.2%±32.0% vs. 145.2%±46.3%, p=0.043).

CONCLUSIONS

Compared with en bloc laminectomy, hybrid laminectomy may be a safe and effective method for treating multilevel TOLF, potentially reducing intraoperative spinal cord irritation and CFL and causing relatively better functional recovery.

Thoracic Dorsal Spinal Cord Herniation: Brief Report and Review of Literature with an Attempt at Hypothesizing the Possible Pathogenesis

Spontaneous dorsal cord herniations are very rare, with only 3 reported cases published in the literature. We report a case of a 15-year-old girl, presenting with progressive symptoms of myelopathy, diagnosed with dorsal cord herniation. She was managed surgically. The herniated arachnoid forming the cyst wall was opened to find a dorsally herniated mass of the dorsal spinal cord. The dura was opened above and below the herniation and then around it to free the herniating nodule of the spinal cord. The nodule was not reducible and was partially amputated for biopsy, and to facilitate dural closure. The patient's post-operative course was uneventful with no fresh deficits. Lower limb weakness improved to 5/5 power with normal gait at 3 months follow-up. We speculate, after a literature review, that the dorsal cord herniation is a 'dorsal trans-dural appendage of the spinal cord' possibly resulting from (a) abnormal migration of neural crest cells during formation of dorsal meninges; or (b) abnormal differentiation of neural crest cells; or (c) abnormal signaling by the neural crest cells.

Quantitative evaluation of the lumbar ligamentum flavum using MRI T2-mapping: Efficacy of its clinical application in patients with lumbar spinal stenosis

OBEJECTIVE

To perform a magnetic resonance imaging T2-mapping of the ligamentum flavum in healthy individuals and patients with lumbar spinal stenosis scheduled for surgery and compare the T2 relaxation times.

SUBJECTS AND METHODS

The T2 relaxation time of the ligamentum flavum was compared among 3 groups, healthy young individuals (H group (age< 50)), healthy middle-aged and older individuals (H group (age≥50)), and patients with lumbar spinal stenosis (L group). Additionally, the thickness of the ligament was measured in the axial image plane, and the occupied area ratio of each fiber was measured by staining the surgically obtained ligament, and each was correlated with the T2 relaxation time. We also evaluated the adhesion of the ligamentum flavum with the dura mater during the surgery.

RESULTS

The T2 relaxation times were significantly prolonged in H group (age ≥50) and L group (P < 0.001) compared to H group (age<50). The relationship between collagen fiber and T2 relaxation times was significantly positive (r = 0.720, P < 0.001). Moreover, the relaxation times were significantly prolonged in those with adhesion of the ligamentum flavum with the dura mater (P < 0.05). The cut-off for the relaxation time was 50 ms (sensitivity: 62.50%, false positive rate: 10.8%).

CONCLUSION

Healthy middle-aged and older individuals and patients with lumbar spinal stenosis and adhesion of the ligamentum flavum with the dura mater have prolonged T2 relaxation times. Hence, the adhesion between the ligamentum flavum and dura mater should be considered in cases with a relaxation time ≥50 ms.

Learning Curve and Clinical Outcomes of Ultrasonic Osteotome-based En Bloc Laminectomy for Thoracic Ossification of the Ligamentum Flavum

OBJECTIVE

Despite rapid advances in minimally invasive surgery, en bloc laminectomy remains the most common surgical approach for treating thoracic ossification of the ligamentum flavum (TOLF). However, the learning curve of this risky operation is rarely reported. Therefore, we aimed to describe and analyze the learning curve of ultrasonic osteotome-based en bloc laminectomy for TOLF.

METHODS

Among 151 consecutive patients with TOLF who underwent en bloc laminectomy performed by one surgeon between January 2012 and December 2017, we retrospectively analyzed their demographic data, surgical parameters, and neurological function. Neurological outcome was evaluated with the modified Japanese Orthopaedic Association (mJOA) scale, and the Hirabayashi method was used to calculate the neurological recovery rate. The learning curve was assessed with logarithmic curve-fitting regression analysis. Univariate analysis methods were used for statistical analysis, including t-test, rank sum test, and chi-square test.

RESULTS

A total of 50% of learning milestones could be reached in approximately 14 cases, and the asymptote in 76 cases. Therefore, 76 of the 151 enrolled patients were defined as the "early group," and the remaining 75 were delimitated as the "late group" for comparison. There was a significant intergroup difference in the corrected operative time (94.80 ± 27.77 vs 65.93 ± 15.67 min, P < 0.001) and the estimated blood loss (median 240 vs 400 mL, P < 0.001). The overall follow-up was 83.1 ± 18.5 months. The mJOA significantly increased from a median of 5 (IQR: 4-5) before the surgery to 10 (IQR: 9-10) at the last follow-up (P < 0.001). The overall complication rate was 37.1%, and no significant intergroup difference was found, except for the incidence of dural tears (31.6% vs 17.3%, p = 0.042).

CONCLUSION

Initially, mastering the en bloc laminectomy technique using ultrasonic osteotome for TOLF treatment can be challenging, but the surgeon's experience improves as the operative time and blood loss decrease. Improved surgical experience reduced the risk of dural tears but was not associated with the overall complication rate or long-term neurological function. Despite the relatively long learning curve, en bloc laminectomy is a secure and valid technique for TOLF treatment.

Prevalence, diagnosis, and impact on clinical outcomes of dural ossification in the thoracic ossification of the ligamentum flavum: a systematic review

STUDY DESIGN

Systematic review.

BACKGROUND CONTEXT

Thoracic ossification of the ligamentum flavum (TOLF) has become the principal cause of thoracic spinal stenosis. Dural ossification (DO) was a common clinical feature accompanying with TOLF. However, on account of the rarity, we know little about the DO in TOLF so far.

PURPOSE

This study was conducted to elucidate the prevalence, diagnostic measures, and impact on the clinical outcomes of DO in TOLF by integrating the existing evidence.

METHODS

PubMed, Embase, and Cochrane Database were comprehensively searched for studies relevant to the prevalence, diagnostic measures, or impact on the clinical outcomes of DO in TOLF. All retrieved studies meeting the inclusion and criterion were included into this systematic review.

RESULTS

The prevalence of DO in TOLF treated surgically was 27% (281/1046), ranging from 11 to 67%. Eight diagnostic measures have been put forward to predict the DO in TOLF using the CT or MRI modalities, including "tram track sign", "comma sign", "bridge sign", "banner cloud sign", "T2 ring sign", TOLF-DO grading system, CSAOR grading system, and CCAR grading system. DO did not affect the neurological recovery of TOLF patients treated with the laminectomy. The rate of dural tear or CSF leakage in TOLF patients with DO was approximately 83% (149/180).

CONCLUSION

The prevalence of DO in TOLF treated surgically was 27%. Eight diagnostic measures have been put forward to predict the DO in TOLF. DO did not affect the neurological recovery of TOLF treated with laminectomy but was associated with high risk of complications.

Novel therapeutic strategy in the treatment of ossification of the ligamentum flavum associated with dural ossification

PURPOSE

To investigate the imaging characteristics of thoracic ossification of ligamentum flavum (OLF) combined with dural ossification (DO) and the clinical efficacy of zoning laminectomy.

METHOD

The clinical data of 48 patients with thoracic OLF combined with DO who underwent zoning laminectomy between June 2016 and May 2020 were retrospectively analyzed. The modified Japanese Orthopedic Association (mJOA) score was used to evaluate neurological function before and after surgery, and the clinical efficacy was evaluated according to the improvement rate.

RESULTS

The symptoms of all patients significantly improved after the operation, and the average follow-up time was 27.8 (10-47) months. In addition, the average mJOA score had increased from 5.0 (2-8) preoperatively to 8.7 (6-11) postoperatively (t = 18.880, P < 0.05). The average improvement rate was 62.6% (25-100%), with 16 patients graded as excellent, 21 as good, and 11 as fair. Cerebrospinal fluid leakage occurred in 12 cases (25.0%), and all of them healed well after treatment. No postoperative aggravation of neurological dysfunction, wound infection or hematoma occurred. At the last follow-up, there was no recurrence of symptoms and kyphosis.

CONCLUSION

The Zoning laminectomy described here is both safe and effective.

Zoning laminectomy for the treatment of ossification of the thoracic ligamentum flavum

OBJECTIVE

Spinal cord injury is a common occurrence during spinal surgery. In this study, we proposed a zoning laminectomy, which could reduce the incidence of nerve injury. We also discussed the safety and clinical efficacy of the zoning laminectomy for thoracic ossification of the ligamentum flavum (TOLF).

METHODS

Forty-five patients with TOLF who underwent zoning laminectomy from October 2016 to February 2020 were included in the retrospective analysis. The Japan Orthopedic Association (JOA) score was used to evaluate clinical outcomes. Meanwhile, the occurrence of complications was recorded.

RESULTS

All 45 patients underwent the operation successfully, and the mean follow-up period was 25.3 months, the mean operation time was 160.2 min, the average blood loss was 474.2 ml, and the average hospital time was 8.0 days. At the final evaluation, the JOA score was significantly higher than the preoperative JOA score (P < 0.001) and the overall recovery rate of the JOA score averaged 69.6%. Seventeen patients were graded as excellent, twenty-six as good, and two as fair. The complications included dural tears in nine patients (20.0%), cerebrospinal fluid leakage in seven patients (15.6%), deep infection in one patient (2.2%), and epidural hematoma in one patient (2.2%). All patients recovered well after treatment. Besides, there was no neurological deterioration and thoracic kyphosis occurred.

CONCLUSIONS

Zoning laminectomy adopts a phased resection from "safe zone" to "danger zone" and defines the safe removal range of the lamina, which reduces the risks of spinal cord injury caused by instrument manipulation. Therefore, it is a safe and effective surgical option.

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.

Diffuse Spinal Hyperostosis Causing Severe Spinal Stenosis and Thoracic Myelopathy

Introduction

Spinal stenosis has a wide range of causes including disc herniation, facet hypertrophy, degenerative spondylosis, facet cyst, ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL). We present three cases of diffuse spinal hyperostosis causing severe spinal stenosis and myelopathy, which demonstrate a unique association between obesity and a novel syndrome of hyperostosis.

Case Presentation

This report describes 3 morbidly obese patients with diffuse spinal hyperostosis causing critical thoracic stenosis. Their presenting complaints focus on lower extremity weakness and the CT/MRI imaging is striking for diffuse hyper-ossification at thoracic levels. Two patients were subsequently managed with spinal decompression, and one patient was managed non-operatively.

Discussion

Metabolic changes associated with obesity may result in diffuse hyperostosis with ligament ossification and spinal stenosis. Pre-operative imaging is essential to identify the degree of ossification and potential dural involvement as this may complicate management.

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.

Comparison of percutaneous endoscopic thoracic decompression and posterior thoracic laminectomy for treating thoracic ossification of the ligamentum flavum: a retrospective study

Background

Thoracic spinal stenosis (TSS) caused by ossification of the ligamentum flavum (OLF) is generally treated by surgical decompression. In this study, we compared the efficacy and safety of percutaneous endoscopic thoracic decompression (PETD) and posterior thoracic laminectomy (PTL) for treating thoracic ossification of the ligamentum flavum (TOLF).

Methods

Twenty consecutive patients with TSS caused by TOLF who were treated between April 2016 and May 2020 were included in this retrospective study. They were divided into the PETD (n = 11) and PTL (n = 9) groups. The mean follow-up period was 19.6 months. The visual analogue scale (VAS) score, the modified Japanese Orthopedic Association (mJOA) score and the recovery rate (RR) were used to evaluate the clinical outcomes.

Results

There were significant differences between PETD group and PTL group in operative time (min) (95.0 ± 18.8 vs 131.1 ± 19.0), postoperative drainage (mL) (20.2 ± 7.9 vs 586.1 ± 284.2), hospital stay (days) (4.4 ± 1.2 vs 10.4 ± 2.6) (P < 0.05 for all). However, both groups had similar and significant improvement in VAS and mJOA scores. The RR of two groups achieved the same improvement (81.8% VS 77.8%, P > 0.05).

Conclusions

The use of PETD and PTL for treating TOLF both achieved favorable outcomes. PETD is both minimally invasive and achieves similar postoperative symptom relief to PTL. Therefore, PETD could be considered as an effective alternative to traditional open surgery for TOLF in single-segment lower thoracic spine.

Thoracic ossification of the ligamentum flavum causing acute myelopathy in a patient with cervical ossification of the posterior longitudinal ligament: illustrative case

BACKGROUND

Ossification of the ligamentum flavum (OLF) has been well characterized as a distinct entity but also in tandem with ossification of the posterior longitudinal ligament (OPLL) in noncontiguous spinal regions. The majority of OLF cases are reported from East Asian countries where prevalent, but such cases are rarely reported in the North American population.

OBSERVATIONS

The authors present a case of a Thai-Cambodian American who presented with symptomatic thoracic OLF in tandem with asymptomatic cervical OPLL. A “floating” thoracic laminectomy, resection of OLF, and partial dural ossification (DO) resection with circumferential release of ossified dura were performed. Radiographic dural reexpansion and spinal cord decompression occurred despite the immediate intraoperative appearance of persistent thecal sac compression from retained DO.

LESSONS

Entire spinal axis imaging should be considered for patients with spinal ligamentous ossification disease, particularly in those of East Asian backgrounds. A floating laminectomy is one of several surgical approaches for OLF, but no consensus approach has been clearly established. High surgical complication rates are associated with thoracic OLF, most commonly dural tears/cerebrospinal fluid (CSF) leaks. DO commonly coexists with OLF, is recognizable on computed tomographic scans, and increases the risk of CSF leaks.

The role of cerebrospinal fluid cross-section area ratio in the prediction of dural ossification and clinical outcomes in patients with thoracic ossification of ligamentum flavum

Background

It is imperative to preoperatively distinguish dural ossification (DO) and thus anticipate the risks and outcome of the surgery for patients with ossification of ligamentum flavum (OLF). However, studies have disagreed as to the efficacy of the radiographic signs or factors to predict DO and surgical outcome. In additon, the association between the cerebrospinal fluid cross-section area ratio (CCAR) and DO or clinical outcome had not been reported. The purpose of this study was to analyse CCAR and its role in prediction of DO and neurological function recovery rate in patients with OLF.

Methods

Fifty-two consecutive patients with OLF, who underwent posterior thoracic decompression and fusion between September 2012 and March 2019 at a single institution, were retrospectively reviewed. Demographic data, radiographic signs of DO, CCAR, pre- and postoperative modified Japanese Orthopedic Association (mJOA) score were recorded.

Results

There were 27 patients in the DO group and 25 patients in the non-DO group, with a mean age at surgery of 57.4 years and 53.9 years, respectively. No significant differences were found in sex, age, segment of maximum compression and preoperative mJOA score between the two groups. The receiver operating characteristic curve showed that the value of CCAR had a relatively high value for diagnosis of DO and prediction of neurological function recovery rate (P = .000). According to the value of CCAR, three zones were defined as DO zone (≤14.3%), non-DO zone (≥44.5%), and gray zone (14.3 to 44.5%). When the value of CCAR≤14.3%, the recovery rate was poor or fair, while it had good or excellent recovery when CCAR≥45.2%.

Conclusion

The value of CCAR had a high diagnostic value for prediction of DO and neurological function recovery rate in patients with OLF.

Idiopathic dorsal spinal cord herniation perforating the lamina: a case report and review of the literature

Spinal cord herniation (SCH) is a rare condition associated with tethering of the spinal cord at the ventral dural defect. Idiopathic dorsal spinal cord herniation (IDSCH) is an extremely rare clinical entity. Here, we report the first case of IDSCH perforating the lamina in a patient with a history of ossification of the ligamentum flavum and diffuse idiopathic skeletal hyperostosis. Untethering of the spinal cord was performed by removing the surrounded ossified dura. Although urological symptoms and impaired proprioception remained, progressive neurological deterioration was prevented. Because this disease condition is extremely rare, it should be differentiated from ventral SCH.

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.

Precise Surgical Treatment of Thoracic Ossification of Ligamentum Flavum Assisted by O-Arm Computer Navigation: A Retrospective Study

OBJECTIVE

O-arm computer navigation-assisted technology (OACNAT) has been widely used in the treatment of thoracic ossification of ligamentum flavum (TOLF) in recent years, but there are few in-depth studies on the safety and effectiveness of this approach. The purpose of this study was to investigate the clinical effect of accurate surgical treatment for TOLF with OACNAT.

METHODS

From January 2010 to January 2018, the clinical data of 64 patients with TOLF who underwent laminectomy and internal fixation in the Third Hospital of Hebei Medical University were retrospectively reviewed. The patients were divided into group A (with OACNAT, n = 33) and group B (without OACNAT, n = 31) according to the application of OACNAT during the operation. The possible operation-related variables, imaging results, and clinical effects were compared between the 2 groups.

RESULTS

In terms of demographics, there were no significant differences between group A and group B in age, sex, body mass index, smoking, drinking, heart disease, hypertension and diabetes (P > 0.05). In terms of operation-related variables, imaging results, and clinical efficacy, there were significant differences in operation time, wound length, postoperative modified Japanese Orthopaedic Association (JOA) score, JOA score improvement rate, accuracy of screw placement, number of intraoperative fluoroscopy procedures, and cerebrospinal fluid leakage between group A and group B (P < 0.05). There were no significant differences in other variables between the 2 groups (P > 0.05). In contrast to group A, in group B, 2 patients had incorrect segmental localization, 3 patients had residual ossified ligamentum flavum after the operation, and 1 patient had postoperative neurologic impairment. On further analysis, compared with group B, group A had a shorter operation time, more accurate screw placement, fewer fluoroscopy procedures, higher JOA score improvement rate, and lower incidence of complications.

CONCLUSIONS

The use of OACNAT accurately located the position, size, shape, and boundary of ossification of the ligamentum flavum during the operation, which could guide accurate decompression and improve the accuracy of pedicle screw placement. This approach not only reduced the incidence of incorrect segmental localization and incomplete or excessive decompression but also reduced the risk of related complications and improved the accuracy, safety, and effectiveness of the operation.

Efficacy and Safety Analysis of Ultrasonic Bone Curette in the Treatment of Thoracic Spinal Stenosis

Objective

To investigate the efficacy and safety of ultrasonic bone curette in treating thoracic spinal stenosis.

Methods

A total of 30 patients of thoracic spinal stenosis who underwent posterior thoracic decompression in the hospital from December 2015 to 2017 were enrolled. Of these, 18 patients (group A) underwent posterior thoracic decompression using ultrasonic bone curette; and 12 patients underwent the treatment using a high‐speed drill (group B). The time of laminectomy, amount of intraoperative blood loss, presence or absence of cerebrospinal fluid leakage, and nerve root injury were recorded. All patients underwent X‐ray, computed tomography with three‐dimensional reconstruction, and magnetic resonance imaging before and after surgery. The Frankel classification and the Japanese Orthopaedic Association (JOA) scores were used to assess the neurological function and neurological recovery in patients. The measured data were statistically processed and analyzed using SPSS21.0 software, and the measurement data were expressed as mean ± SD.

Results

In groups A and B, the average time for single‐segment laminectomy was 3.3 ± 1.2 min and 6.0 ± 1.8 min and the mean bleeding volume was 105.5 ± 43.3 mL and 177.4 ± 54.7 mL, respectively, with a statistically significant difference between the groups. The difference in JOA scores before and after surgery in groups A and B was statistically significant. No significant difference was found between the groups, in group A, the improvement rate of nerve function at the last follow‐up was 71% and in group B, the improvement rate at the last follow‐up was 70%. In group A, at last follow‐up, two patients had Frankel grade B injury, one had grade C injury, seven had grade D injury, and eight had grade E injury. In group B, at last follow‐up, one patient had Frankel grade B injury, one had grade C injury, five had grade D injury, and five had grade E injury. The Frankel classification of both groups A and B significantly improved. Four patients experienced cerebrospinal fluid leakage in group A and five in group B, with no significant difference between the groups. There was no nerve root injury in both groups, and no complications, such as pulmonary infection and urinary tract infection, occurred after operation.

Conclusions

With the use of ultrasonic bone curette in posterior thoracic decompression, the decompression surgery could be completed relatively safely and quickly. It effectively reduced the amount of intraoperative blood loss.

Using Visual Trepan to Treat Single Segment Ossification of the Ligamentum Flavum Under Endoscopy

This article describes the trepan technique for treating single segment ossification of the ligamentum flavum (OLF) using an endoscope. OLF is the most common cause of thoracic spinal stenosis. The most common surgical procedures involve semi‐lamina or full‐lamina resection and decompression. However, considering the anatomical structure of the thoracic spinal canal and the combination of OLF, traditional surgery has higher risks, more complications, and greater technical requirements. In the past ten years, with the development of endoscopic technology, spinal endoscopy has been increasingly applied for the treatment of intervertebral disc herniation and spinal canal stenosis. The present study demonstrated the effectiveness of visual trepan decompression under spinal endoscopy used for patients with single segment OLF. This surgical procedure had many advantages, including a shorter operation time, minimal trauma, less expenditure, and better functional recovery over the conventional open surgery.

Benefits and Risks of Subsection Laminectomy with Pedicle Screw Fixation for Ossification of the Ligamentum Flavum of the Thoracic Spine: A Retrospective Study of 30 Patients

BACKGROUND This study aimed to evaluate the effectiveness of subsection laminectomy with pedicle screw fixation (SLPF) for the treatment of ossification of the ligamentum flavum of the thoracic spine. MATERIAL AND METHODS Thirty patients (age, 40-71 years) with ossification of the ligamentum flavum of the thoracic spine underwent SLPF (13 men, 17 women). Operative time, intraoperative blood loss, preoperative and postoperative change in thoracic kyphosis, and perioperative complications were recorded. The Japanese Orthopedic Association (JOA) score for severity of myelopathy and the American Spinal Injury Association (ASIA) motor and sensory impairment scale were used before and after surgery. RESULTS Mean operative time for SLPF was 208.4±38.3 min and mean intraoperative blood loss was 689.3±171.7 ml. The mean JOA score significantly increased from 5.7±1.9 before surgery to 8.8±2.2 at one month after surgery and 9.3±2.7 at the last follow-up (P<0.01). Postoperative improvement in neurological function increased by 68.3±14.4%. The postoperative ASIA grades significantly improved compared with the preoperative grades (P<0.01). The mean local Cobb angle significantly decreased from 17.8±4.3° before surgery to 15.4±3.6° at one month after surgery and 15.8±3.8° at the last follow-up (P<0.01). Three patients (10%) had operative cerebrospinal fluid (CSF) leak. Postoperatively, one patient had neurological deterioration, two patients had deep venous thrombosis (DVT), and one patient developed a wound infection. CONCLUSIONS SLPF was an effective procedure for the treatment of ossification of the ligamentum flavum of the thoracic spine.

The Effect of Using Visual Trepan to Treat Single-Segment Ossification of Ligamentum Flavum Under the Endoscope

OBJECTIVES

To evaluate the surgical outcome of using a trepan to treat single-segment ossification of ligamentum flavum under endoscopy and the clinical value of the new surgical treatment.

MATERIALS AND METHODS

Patients who underwent surgery for single-segment ossification of ligamentum flavum from January 2015 to June 2018 were included in a retrospective analysis. Endoscopic visual trepan decompression was performed in 26 patients and posterior spinal canal resection and decompression was performed in 11 patients. Japanese Orthopaedic Association scores, Japanese Orthopaedic Association improvement rate, and visual analog scale scores of both groups were recorded during follow-up. Computed tomography was used to evaluate patients' residual area ratio of the vertebral canal. Operative time, length of stay, amount of bleeding, and hospital cost in both groups were recorded.

RESULTS

Average follow-up time was 8.9 ± 2.7 months. Average operative time was 100.6 ± 35.0 minutes in the experimental group and 140.5 ± 28.3 minutes in the control group. At the final follow-up, the average improvement rate of Japanese Orthopaedic Association score was 78.3% in the experimental group and 84.2% in the control group. The average residual area ratio of the vertebral canal, which was <50% before the operation in both groups, recovered to 100% in both groups after the operation. Visual analog scale score of all patients was significantly (P < 0.05) reduced at the final follow-up.

CONCLUSIONS

The visual trepan technique using a spinal endoscope can be used to treat single-segment ossification of ligamentum flavum. Advantages include less trauma, faster recovery, and lower cost. However, more cases and long-term follow-up are required to further evaluate the clinical effectiveness and safety of this surgical method.

Percutaneous full endoscopic posterior decompression of thoracic myelopathy caused by ossification of the ligamentum flavum

PURPOSE

Ossification of ligamentum flavum (OLF) is the leading cause of progressive thoracic myelopathy (TM) in East Asian countries. Surgical decompression is the general treatment for TM. This study investigated the application of percutaneous full endoscopic posterior decompression (PEPD) for the treatment of thoracic OLF.

METHODS

Eighteen patients with TM were treated by PEPD under local anaesthesia. Patients had an average age of 59.1 years and single-level lesions mostly at the lower thoracic vertebrae. Computed tomography and magnetic resonance imaging were used to classify the OLF. The pre- and postoperative neurological statuses were evaluated using the American Spinal Injury Association (ASIA) sensory and motor score, modified Japanese Orthopaedic Association (mJOA) score and Frankel grade.

RESULTS

OLF for all patients was classed as lateral, extended, and enlarged types without comma and tram track signs. Decompression was completed, and a dome-shaped laminotomy was performed through limited laminectomy and flavectomy. Dural tears in 2 patients were the only observed complication. The average score of ASIA sensory and motor, mJOA, as well as the Frankel grade improved significantly after surgery at an average follow-up time of 17.4 months. The average recovery rate (RR) was 47.5% as calculated from the mJOA scores. According to RR, 10 cases were classified as good, 4 cases fair, and 4 cases unchanged.

CONCLUSIONS

For patients with thoracic OLF at a single level and lateral, extended, and enlarged types without comma and tram track signs, it is safe and reliable to perform PEPD, which has satisfactory clinical results. These slides can be retrieved under Electronic Supplementary Material.