Surgical technique modification of circumferential decompression for thoracic spinal stenosis and clinical outcome

Progressive thoracic myelopathy caused by ossification of posterior longitudinal ligament (OPLL) responds poorly to conservative therapy. The most direct decompression is extirpation of ossified posterior longitudinal ligament (PLL). Surgical outcomes of posterior approaches to remove ossified PLL are not always satisfactory because of the risk of neurological deterioration. In this study, we modified the conventional anterior decompression technique via a posterior approach for thoracic OPLL. From an anterior approach, the posterior cortex of vertebral body was exposed and the ossified PLL was removed. Then kyphosis correction was done via posterior instrumentation to reduce cord compression between dura under tension and the anterior canal wall. From the back, the distal end of the ossified PLL was displaced anteriorly to create a gap between ossified PLL and dura, remaining adhesions were divided and the ossified PLL was manipulated through this gap under direct vision. The surgical technique was applied in 20 patients with thoracic myelopathy caused by OPLL. One case of postoperative neurological deterioration was encountered but this recovered fully. Our outcomes were relatively favorable.

A comparison of the perioperative outcomes of anterior surgical techniques for the treatment of multilevel degenerative cervical myelopathy

OBJECTIVE

Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord dysfunction in adults. Multilevel ventral compressive pathology is routinely managed through anterior decompression and reconstruction, but there remains uncertainty regarding the relative safety and efficacy of multiple discectomies, multiple corpectomies, or hybrid corpectomy-discectomy. To that end, using a large national administrative healthcare data set, the authors sought to compare the perioperative outcomes of anterior cervical discectomy and fusion (ACDF), anterior cervical corpectomy and fusion (ACCF), and hybrid corpectomy-discectomy for multilevel DCM.

METHODS

Patients with a primary diagnosis of DCM who underwent an elective anterior cervical decompression and reconstruction operation over 3 cervical spinal segments were identified from the 2012-2017 National Surgical Quality Improvement Program database. Patients were separated into those undergoing 3-level discectomy, 2-level corpectomy, or a hybrid procedure (single-level corpectomy plus additional single-level discectomy). Outcomes included 30-day mortality, major complication, reoperation, and readmission, as well as operative duration, length of stay (LOS), and routine discharge home. Outcomes were compared between treatment groups by multivariable regression, adjusting for age and comorbidities (modified Frailty Index). Effect sizes were reported by adjusted odds ratio (aOR) or mean difference (aMD) and associated 95% confidence interval.

RESULTS

The study cohort consisted of 1298 patients; of these, 713 underwent 3-level ACDF, 314 2-level ACCF, and 271 hybrid corpectomy-discectomy. There was no difference in 30-day mortality, reoperation, or readmission among the 3 procedures. However, on both univariate and adjusted analyses, compared to 3-level ACDF, 2-level ACCF was associated with significantly greater risk of major complication (aOR 2.82, p = 0.005), longer hospital LOS (aMD 0.8 days, p = 0.002), and less frequent discharge home (aOR 0.59, p = 0.046). In contrast, hybrid corpectomy-discectomy had comparable outcomes to 3-level ACDF but was associated with significantly shorter operative duration (aMD -16.9 minutes, p = 0.002).

CONCLUSIONS

The authors found multiple discectomies and hybrid corpectomy-discectomy to have a comparable safety profile in treating multilevel DCM. In contrast, multiple corpectomies were associated with a higher complication rate, longer hospital LOS, and lower likelihood of being discharged directly home from the hospital, and may therefore be a higher-risk operation.

Integrated miRNA-mRNA network revealing the key molecular characteristics of ossification of the posterior longitudinal ligament

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) refers to an ectopic ossification disease originating from the posterior longitudinal ligament of the spine. Pressing on the spinal cord or nerve roots can cause limb sensory and motor disorders, significantly reducing the patient's quality of life. At present, the pathogenesis of OPLL is still unclear. The purpose of this study is to integrate microRNA (miRNA)-mRNA biological information data to further analyze the important molecules in the pathogenesis of OPLL, so as to provide targets for future OPLL molecular therapy.

METHODS

miRNA and mRNA expression profiles of GSE69787 were downloaded from Gene Expression Omnibus database and analyzed by edge R package. Funrich software was used to predict the target genes and transcription factors of de-miRNA. Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis of differentially expressed genes (DEGs) were carried out based on CLUEGO plug-in in Cytoscape. Using data collected from a search tool for the retrieval of interacting genes online database, a protein-protein interaction (PPI) network was constructed using Cytoscape. The hub gene selection and module analysis of PPI network were carried out by cytoHubba and molecular complex detection, plug-ins of Cytoscape software respectively.

RESULTS

A total of 346 genes, including 247 up-regulated genes and 99 down-regulated genes were selected as DEGs. SP1 was identified as an upstream transcription factor of de-miRNAs. Notably, gene ontology enrichment analysis shows that up- and down-regulated DEGs are mainly involved in BP, such as skeletal structure morphogenesis, skeletal system development, and animal organ morphogenesis. Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that only WNT signaling pathway was associated with osteogenic differentiation. Lymphoid enhancer binding factor 1 and wingless-type MMTV integration site family member 2 Wingless-Type MMTV Integration site family member 2 were identified as hub genes, miR-520d-3p, miR-4782-3p, miR-6766-3p, and miR-199b-5p were identified as key miRNAs. In addition, 2 important network modules were obtained from PPI network.

CONCLUSIONS

In this study, we established a potential miRNA-mRNA regulatory network associated with OPLL, revealing the key molecular mechanism of OPLL and providing targets for future treatment or prevent its occurrence.

Anterior controllable antidisplacement and fusion surgery for the treatment of extensive cervico-thoracic ossification of posterior longitudinal ligament with severe myelopathy: case report and literature review

OPLL generally occurs in the cervical spine and involves no more than three vertebral segments, while extensive OPLL that involves the cervico-thoracic spine and spans over multiple segments is rare. Surgically it is difficult to achieve a satisfactory clinical outcome without surgical complications via the traditional anterior or posterior approaches. We report the first application of Anterior controllable antidisplacement and fusion (ACAF) in treating extensive cervico-thoracic OPLL. A 45-year old patient experienced severe walking disturbance, bladder and bowel dysfunction for 5 months after a fall. His preoperative Japanese Orthopedic Association (JOA) score was 8 of 17. Preoperative CT and MRI demonstrated a K-line (-) and mixed-type extensive OPLL from C2 to T2, causing significant cord compression. After ACAF surgery, neurological symptoms improved immediately without postoperative complications. Postoperative CT and MRI scanning showed restoration of spinal canal cross section and cord decompression. At 6 months he was able to stand and walk again without assistance and urinary bladder and bowel function returned to normal completely. At 15 months his JOA score was 14 of 17. ACAF surgery provides a promising alternative for the treatment of extensive cervico-thoracic OPLL.

Risk factors for progression of ossification of the posterior longitudinal ligament in asymptomatic subjects

OBJECTIVE

The incidence and risk factors for the progression of ossification of the posterior longitudinal ligament (OPLL) have been previously reported in surgically and nonsurgically treated symptomatic patients. However, the correlates of OPLL progression in asymptomatic subjects with OPLL are not well characterized. This study aimed to clarify the incidence and risk factors for OPLL progression in asymptomatic subjects based on whole-body CT.

METHODS

The authors retrospectively reviewed 2585 healthy subjects who underwent whole-body CT at a single health center from September 2007 to December 2011. This study included asymptomatic subjects with OPLL who underwent CT scans twice with an interval of at least 5 years. Progression of OPLL was assessed based on initial and final CT scan. Subjects were divided into two groups: nonprogression (OPLL-NP) and progression (OPLL-P) groups. Clinical characteristics, bone mineral density status, OPLL types, and OPLL involvement of multiple vertebral levels between the two groups were compared. Risk factors for progression of OPLL were identified by logistic regression analysis after propensity score adjustment.

RESULTS

Of the 109 subjects with OPLL (91 men and 18 women), 20 (18.3%) exhibited OPLL progression (OPLL-P group). Subjects in the OPLL-P group were significantly younger (p = 0.031), had higher prevalence of multilevel OPLL involvement (p = 0.041) and continuous type of OPLL (p = 0.015), and had higher uric acid (UA) levels (p = 0.004) at the time of initial CT examination compared to the OPLL-NP group. Younger age (adjusted odds ratio [aOR] 0.95, 95% CI 0.90-0.99), OPLL involvement of multiple vertebral levels (aOR 2.88, 95% CI 1.06-7.83), continuous type of OPLL (aOR 4.21, 95% CI 1.35-13.10), and higher UA levels (aOR 2.09, 95% CI 1.24-3.53) were significant risk factors for OPLL progression.

CONCLUSIONS

Younger age, OPLL involvement of multiple vertebral levels, continuous type of OPLL, and higher UA levels are significant risk factors for OPLL progression in asymptomatic subjects.

Investigation of a three-dimensional printed dynamic cervical spine model for anatomy and physiology education

INTRODUCTION

Three-dimensional (3D) printing of anatomical structures is a growing method of education for students and medical trainees. These models are generally produced as static representations of gross surface anatomy. In order to create a model that provides educators with a tool for demonstration of kinematic and physiologic concepts in addition to surface anatomy, a high-resolution segmentation and 3D-printingtechnique was investigated for the creation of a dynamic educational model.

METHODS

An anonymized computed tomography scan of the cervical spine with a diagnosis of ossification of the posterior longitudinal ligament was acquired. Using a high-resolution thresholding technique, the individual facet and intervertebral spaces were separated, and models of the C3-7 vertebrae were 3D-printed. The models were placed on a myelography simulator and subjected to flexion and extension under fluoroscopy, and measurements of the spinal canal diameter were recorded and compared to in-vivo measurements. The flexible 3D-printed model was then compared to a static 3D-printed model to determine the educational benefit of demonstrating physiologic concepts.

RESULTS

The canal diameter changes on the flexible 3D-printed model accurately reflected in-vivo measurements during dynamic positioning. The flexible model also was also more successful in teaching the physiologic concepts of spinal canal changes during flexion and extension than the static 3D-printed model to a cohort of learners.

CONCLUSIONS

Dynamic 3D-printed models can provide educators with a cost-effective and novel educational tool for not just instruction of surface anatomy, but also physiologic concepts through 3D ex-vivo modeling of case-specific physiologic and pathologic conditions.

Biomarkers of Ossification of the Spinal Ligament

STUDY DESIGN

Literature review.

OBJECTIVES

To review biomarkers in patients with ossification of the spinal ligament (OSL), including ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum and to raise the present issues.

METHODS

A literature search was performed using PubMed and MEDLINE databases. The biomarkers were classified according to category. The number of the subjects and reproducibility were assessed.

RESULTS

Eleven articles were included in this review. There were 9 articles from Japan, 1 article from Taiwan, and 1 article from China. The biomarkers were classified into calcium-phosphate metabolism markers, bone turnover markers, sclerostin, dickkopf-1, secreted frizzled-related protein-1, fibroblast growth factor-23, fibronectin, menatetrenone, leptin, pentosidine, and hypersensitive C-reactive protein. However, there were several limitations in the research studies, such as small research field, small number of subjects, and a lack of reproducibility.

CONCLUSIONS

Although there have been several studies that have analyzed biomarkers for OSL, there are no definitive conclusions to date. Numerous issues will need to be resolved in the future. It is imperative to continue this research because the results might prove beneficial to elucidate the pathology of OSL and the measures to prevent the initiation and progression of the disease.

Effect of microscopically assisted decompression with micro-hook scalpel in the surgical treatment of ossification of the posterior longitudinal ligament

Objective

This study was performed to investigate the effect of microscopically assisted decompression using a micro-hook scalpel on ossification of the posterior longitudinal ligament (OPLL).

Methods

Sixty-one patients with OPLL were divided into Group A (posterior surgery with laminectomy of the responsible segment and lateral mass screw fixation) and Group B (anterior cervical corpectomy with intervertebral titanium cage fusion). Neurological function was assessed by the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) score, and recovery rate. The fixation status and the result of spinal canal decompression were radiographically assessed.

Results

In Groups A and B, the JOA score was significantly higher and the VAS score was significantly lower at 1 week postoperatively and at the final follow-up than during the preoperative period. The mean recovery rate in Group A and B was 59.92% ± 13.46% and 62.28% ± 14.00%, respectively. Postoperative radiographs showed good positioning and no damage to the internal fixation materials. The spinal canal was also fully decompressed.

Conclusions

Microscopically assisted decompression with a micro-hook scalpel in both anterior and posterior surgeries achieved good clinical effects in patients with OPLL.

Ossified Posterior Longitudinal Ligament Existing at an Intervertebral Level Limits Compensatory Mechanism of Cervical Lordosis after Muscle-Preserving Selective Laminectomy

Introduction

As C7 slope increases, lordotic change of C2-C7 angle compensates for adjustments in cervical sagittal balance. However, ossification of the posterior longitudinal ligament (OPLL) may affect the compensatory mechanism of the cervical spine. This study aims to evaluate the impact of OPLL on cervical lordotic compensation after muscle-preserving selective laminectomy (SL).

Methods

This study involved 235 patients with cervical spondylotic myelopathy (CSM) and OPLL who underwent ≥ 3 consecutive levels of SL. OPLL was classified into continuous, segmental, mixed, or localized type on the basis of the criteria previously reported. In this study, based on the motion preservation at the intervertebral level, patients were divided into CSM (n = 114), OPLL segmental type (OPLL-S; n = 44), and other types of OPLL (OPLL-O; i.e., continuous, mixed, and localized; n = 77). The cervical sagittal alignment, degree of spinal cord decompression, and surgical outcomes were compared among the three groups.

Results

The OPLL-O group had a larger postoperative C7 slope (p = 0.020), larger pre- (p = 0.021) and postoperative (p = 0.001) C2-C7 sagittal vertical axis, and greater pre- (p = 0.034) and postoperative (p = 0.002) C7 slope minus C2-C7 angle. Narrower postoperative spinal cord clearance (PSCC) from OPLL (p < 0.001) and more residual spinal cord compression (p < 0.001) were observed in the OPLL-O group. Correlation between postoperative C7 slope minus C2-C7 angle and PSCC was detected (r = −0.238, p < 0.001). The recovery rate of the Japanese Orthopedic Association score was slightly lower in the OPLL-O group (p < 0.001), and it was correlated with postoperative residual spinal cord compression (r = −0.305, p < 0.001).

Conclusions

OPLL-O limits cervical lordotic compensation, resulting in cervical sagittal balance mismatch. It affects the degree of spinal cord decompression, which might be related to surgical outcome.

Increase of the Serum FGF-23 in Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

Case-control study.

OBJECTIVES

To determine the possible pathogenesis of ossification of the posterior longitudinal ligament (OPLL) in regard to the serum concentration of fibroblast growth factor 23 (FGF-23).

METHODS

The study included 95 patients with OPLL and a control group of 73 age- and sex-matched volunteers. The serum concentrations of FGF-23, creatinine (Cre), alkaline phosphatase, calcium (Ca), inorganic phosphate (Pi), and hypersensitive C-reactive protein (hs-CRP) were analyzed from blood samples, and Cre, Ca, Pi, and tubular reabsorption of phosphate were measured using urine samples. We evaluated the severity of ossified spinal lesions in patients with OPLL according to the ossification index (the OP index and the OS index). Data was compared between the OPLL and control group and between the OPLL progression and no progression group.

RESULTS

Serum FGF-23 and hs-CRP were higher, and serum Pi was lower in patients with OPLL than in the controls. There was a positive correlation between FGF-23 and hs-CRP and a negative correlation between serum Pi and the OS index; however, the correlations were very weak. Overall, 31.7% of patients had progression of OPLL during follow-up. FGF-23 and hs-CRP were higher in the progression group than in the no progression group.

CONCLUSIONS

These results might indicate that FGF-23 and hs-CRP are positive markers for OPLL. Phosphate metabolism via FGF-23 might be a target for future study on the pathogenesis of OPLL.

The endoplasmic reticulum stress response participates in connexin 43-mediated ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) manifests as ectopic bone formation in spinal ligament tissue. As revealed by in vitro studies, fibroblasts from patients with OPLL or healthy ligament fibroblasts undergo mechanical stress (MS). We previously demonstrated that a cell-cell junction protein, connexin 43 (Cx43), is significantly up-regulated in OPLL cells and previous data indicated that some proteins related to the endoplasmic reticulum (ER) stress response are elevated during the development of OPLL. The present study utilized gain- and loss-of-function tools to delineate the contribution of the ER stress response within ligament fibroblasts under OPLL-inducing stimuli and the crosstalk between Cx43 signaling and the ER stress response. The ER stress process was augmented by the induction of Cx43 expression in OPLL cells or cells under MS. Cx43 over-expression also promoted ER stress and ossification in OPLL cells. Moreover, the activation of ER stress was accompanied with increased oxidative stress, which was inhibited by Cx43 gene silencing. Cx43 knockdown also improved ER stress-related ossification in OPLL cells. The blockage of ER stress using a chemical compound or small interfering RNA was sufficient to overcome MS-induced ossification in OPLL cells. These findings were further validated in patients with OPLL, as the mRNA levels of Cx43 and PKR-like endoplasmic reticulum kinase (a single-pass type I ER membrane protein kinase), a major transducer of ER stress, were significantly increased compared with non-OPLL subjects. In conclusion, this study demonstrates that ER stress participates in Cx43-related OPLL.

Differences in Postoperative Changes of Cervical Sagittal Alignment and Balance After Laminoplasty Between Cervical Spondylotic Myelopathy and Cervical Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To compare postoperative changes of cervical sagittal alignment (CSA) and cervical sagittal balance (CSB) after laminoplasty between cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) and to examine impacts of these radiologic changes on neurologic outcomes.

METHODS

A total of 168 consecutive patients with CSM (CSM group) and 51 consecutive patients with OPLL (OPLL group) were included. As indicators of CSA and CSB, the C2-7 angle and C1-C7 sagittal vertical axis (SVA) were, respectively, measured before surgery and at 2-year follow-up. Neurologic status was assessed using the Japanese Orthopaedic Association score before surgery and at 2-year follow-up.

RESULTS

Whereas both postoperative loss of C2-7 angle and increase of C1-C7 SVA were significantly greater in the elderly subgroup of the CSM group, patient age did not significantly affect these changes in the OPLL group. Preservation of C7 maintained C1-C7 SVA at postoperative 2 years only in the CSM group. Postoperative cervical kyphosis and sagittal imbalance significantly decreased neurologic improvement in the CSM group but not in the OPLL group.

CONCLUSIONS

Elderly patients with CSM have significantly greater postoperative loss of lordosis and increase in C1-C7 SVA than nonelderly patients, and both postoperative kyphotic deformity and sagittal imbalance significantly deteriorate neurologic recovery. On the other hand, although patients with OPLL, irrespective of patient age and preservation of C7, have significantly more loss of lordosis and increase in C1-C7 SVA than CSM patients, neither postoperative kyphotic deformity nor sagittal imbalance significantly deteriorates neurologic recovery in OPLL patients.

What Are the Important Predictors of Postoperative Functional Recovery in Patients With Cervical OPLL? Results of a Multivariate Analysis

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The objective of this study was to identify important predictors of poor functional recovery in patients undergoing surgery for cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

This was a retrospective cohort study of 142 OPLL patients with laminoplasty; 135 had complete radiographical data and were followed up for ≥2 years. The following OPLL characteristics were compared between patients with "good" and "poor" outcomes (Japanese Orthopedic Association [JOA] recovery rate ≥50% and <50%, respectively): number of ossified levels, OPLL classification, ossification shape, K-line, canal-occupying ratio, and increased magnetic resonance imaging (MRI) signal intensity. Predictors of functional recovery were identified.

RESULTS

Pre- and postoperative (2 years following surgery) JOA scores were 10.6 ± 2.9 and 14.1 ± 2.2, respectively, indicating significant improvement following laminoplasty (P < .001). The average JOA recovery rate was 53.4% ± 34.7%, with 81 (60.0%) and 54 (40.0%) patients in the better and poorer neurological outcome groups, respectively. The canal occupation ratio of OPLL ≤60%/>60% were 117 (86.7%) and 18 (13.3%) patients, respectively. In the stepwise logistic regression analysis, an occupation ratio greater than 60% was identified as a significant factor for poor postoperative neurological outcome (relative risk, 4.82; 95% confidential interval, 1.61-14.46, P = .005).

CONCLUSIONS

This multivariate analysis demonstrated a large size OPLL (occupying ratio >60%) was associated with a risk of poor neurological recovery roughly 5 times greater, and therefore other types of surgery are recommended in cases with such a ratio.

Effectiveness of titanium plate usage in laminoplasty

Background:

Laminoplasty is an established technique for the treatment of cervical stenosis. However, the usage of plates to maintain patency of the laminoplasty door has not been well reported. This study plans to compare the clinical outcomes of laminoplasty with the usage of Sofamor-Danek laminoplasty plates versus techniques without plate usage.

Materials and Methods:

This study conducted a 2-year medical record review of all patients with multilevel cervical myelopathy who were treated with laminoplasty at UCLA or Cedars-Sinai medical center. Of 46 patients 18 had sufficient documentation to assess clinical outcome, 11 of which had placement of laminoplasty plates. Clinical outcomes were assessed using Odom's scoring criteria.

Results:

Blood loss and hospital stay are decreased with plate usage during laminoplasty. Average Estimated Blood Loss (EBL) was 160 cc with plate and 380 cc without. Hospital stay was 4.8 days with plate and 5.6 days without. There were no complications during any of the laminoplasty procedures regardless of instrumentation. All patients demonstrated improvement in symptoms after laminoplasty, with 73% of patients in the plate cohort having Odom Scores of “Excellent” versus 44% in the nonplate group. All patients, regardless of technique, showed improvement in symptoms.

Conclusions:

Laminoplasty with plate utilization is an effective treatment for cervical myelopathy. The similarity in outcomes and complications between these two similar cohorts suggests plate usage in laminoplasty is an attractive alternative to other methods. We hope that future efforts will continue to demonstrate the effectiveness and perhaps superiority of plate utilization in laminoplasty.

A Systematic Review of Classification Systems for Cervical Ossification of the Posterior Longitudinal Ligament

DESIGN

Systematic review.

OBJECTIVE

To conduct a systematic review to (1) summarize various classification systems used to describe cervical ossification of the posterior longitudinal ligament (OPLL) and (2) evaluate the diagnostic accuracy of various imaging modalities and the reliability of these classification systems.

METHODS

A search was performed to identify studies that used a classification system to categorize patients with OPLL. Furthermore, studies were included if they reported the diagnostic accuracy of various imaging modalities or the reliability of a classification system.

RESULTS

A total of 167 studies were deemed relevant. Five classification systems were developed based on X-ray: the 9-classification system (0.60%); continuous, segmental, mixed, localized or focal, circumscribed and others (92.81%); hook, staple, bridge, and total types (2.40%); distribution of OPLL (2.40%); and K-line classification (4.19%). Six methods were based on computed tomography scans: free-type, contiguous-type, and broken sign (0.60%); hill-, plateau-, square-, mushroom-, irregular-, or round-shaped (5.99%); rectangular, oval, triangular, or pedunculate (1.20%); centralized or laterally deviated (1.80%); plank-, spindle-, or rod-shaped (0.60%); and rule of nine (0.60%). Classification systems based on 3-dimensional computed tomography were bridging and nonbridging (1.20%) and flat, irregular, and localized (0.60%). A single classification system was based on magnetic resonance imaging: triangular, teardrop, or boomerang. Finally, a variation of methods was used to classify OPLL associated with the dura mater (4.19%).

CONCLUSIONS

The most common method of classification was that proposed by the Japanese Ministry of Health, Labour and Welfare. Other important methods include K-line (+/-), signs of dural ossification, and patterns of distribution.

Restrictive ventilatory impairment improved by laminoplasty for ossification of the posterior longitudinal ligament

We report a woman with severe restrictive ventilatory impairment because of respiratory muscle paralysis caused by ossification of the posterior longitudinal ligament (OPLL). Laminoplasty improved her respiratory function and quality of life. Cervical myelopathy including OPLL should be considered as an important differential diagnosis in patients with respiratory dysfunction.

Anterior decompression and fusion versus laminoplasty for cervical myelopathy due to ossification of posterior longitudinal ligament: A meta-analysis

BACKGROUND

Both anterior decompression and fusion (ADF) and laminoplasty (LAMP) are frequently used for the treatment of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). However, some controversies still remained in surgical options. We investigated whether ADF had better neurological outcome than LAMP in the treatment of cervical myelopathy due to OPLL. Secondary outcomes included operation time, blood loss, rate of complication and reoperation.

METHODS

PubMed, EMBASE and the Cochrane Register of Controlled Trials database were searched to identify potential clinical studies compared ADF with LAMP for treatment of cervical myelopathy owing to OPLL. We also manually searched the reference lists of articles and reviews for possible relevant studies. Quality assessment was performed according to Cochrane Handbook and meta-analysis was conducted using Stata 12.0 software.

RESULTS

Nine studies involving 712 patients were finally included in this analysis. Compared with LAMP, ADF was associated with an increase of the Japanese Orthopaedic Association (JOA) score (WMD = 1.86, 95% CI 0.43 to 3.29, P = .011) and recovery JOA score at final follow-up (WMD = 30.94, 95% CI 20.56 to 41.33, P = .000). And, ADF was associated with a decrease of the late neurologic deterioration than LAMP group (RR = 0.34, 95% CI 0.12 to 0.92, P = .003). However, ADF was associated with an increase of the postoperative cervical lordosis (WMD = 4.47, 95% CI 1.58 to 7.36, P = .002) than LAMP. There was no significant difference between the complication, reoperation rate (P > .05). What's more, ADF was associated with an increase of the operation time than LAMP (P < .05).

CONCLUSIONS

ADF yields better neurological improvement, but higher cervical lordosis and longer operation time compared with LAMP for cervical myelopathy caused by OPLL. No significant difference was found in the complication and re-operation rate.

Histomorphometry of ectopic mineralization using undecalcified frozen bone sections

To investigate the correlation between mineral formation and enhanced expressions of some proteins using undecalcified frozen bone sections. Histological studies have revealed that some proteins, such as BMP2, BMPR1A, and Connexin 43, are expressed in and around sites of ectopic ossification. However, the relationship between the expressed proteins considered to be associated with the ossification and mineral formation in vivo is not clear. Ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1)-mutant spinal hyperostotic TWY mice and ICR mice as controls were euthanized after calcein labeling, and undecalcified frozen sections were obtained from the middle thoracic spine. Intervertebral disc areas were examined histologically and by measuring calcein-labeled areas and areas showing immunoreactivity for BMP2, BMPR1A, and Connexin 43. Calcein-labeled areas, indicating mineralization in the ectopic mineralization sites, were significantly larger in the mutant mice than in controls. The expression of Connexin 43 was elevated in the annulus fibrosus. Increases in the calcein-labeled areas was not correlated with increases in the areas showing immunoreactivity for Connexin 43 in the annulus fibrosus. There was no statistical correlation between enhanced immunohistochemical expression and elevated calcein-labeled areas. By applying the morphometrical analysis method using undecalcified frozen sections to ENPP1-mutant mice, quantitative evaluation of the mineralization and proteins expressed in the surrounding area in the same animal became possible.

Comparison of laminoplasty versus laminectomy and fusion in the treatment of multilevel cervical ossification of the posterior longitudinal ligament: A systematic review and meta-analysis

BACKGROUND

Laminoplasty (LP) and laminectomy with fusion (LF) were recognized as two reliable and effective way in treating multilevel cervical ossification of the posterior longitudinal ligament (OPLL). However, there was no clear conclusion on which method is better. A meta-analysis was conducted to evaluate the clinical results between LP and LF in the treatment of multilevel cervical OPLL.

METHODS

An extensive search of literature was performed in PubMed, Embase, the Cochrane library, CNKI (Chinese database), and WANFANG (Chinese database). The following outcomes were extracted: the Japanese Orthopedic Association (JOA) scores, visual analog scale (VAS), cervical lordosis, cervical range of motion (ROM), complications, blood loss, and operation time. Data analysis was conducted with RevMan 5.3.

RESULTS

A total of 11 studies were included in the final analysis. The results indicated that no significant differences between LP and LF group in terms of preoperative JOA scores (P = .58), postoperative JOA scores (P = .60), JOA scores improvement rate (P = 0.64), preoperative VAS (P = .34), postoperative VAS (P=.20), preoperative range of motion (ROM) (P = .10), postoperative ROM (P = .18), preoperative cervical lordosis (P = .56), C5 palsy (P = .16), and axial pain (P = .21). LF group showed larger postoperative cervical lordosis than LP group [standardized mean difference (SMD) = 1.13 (2.03, 0.24), P = .01]. However, LP group showed lower operation time [mean difference (MD) = 19.42 (26.87, 11.97), P < .001] and blood loss [MD = 94.78 (179.05, 10.51), P = .03] than LF group.

CONCLUSION

Both LP and LF can achieve clinical improvement in the treatment of multilevel cervical OPLL. LF was superior to LP in maintaining cervical lordosis. However, LP showed lower surgical trauma than LF. Kyphosis line (K-line) may be a good criterion in the selection of posterior surgery. LP was performed for the patients with K-line (+) and LF for K-line (-).

Relationship between Enlargement of the Cross-Sectional Area of the Dural Sac and Neurological Improvements after Cervical Laminoplasty: Differences between Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament

Introduction

The purpose of this study was to investigate the relationship between postoperative enlargement of the dural sac cross-sectional area at the symptomatic level and neurological improvements after laminoplasty.

Methods

The cross-sectional areas of the dural sac at the symptomatic level before and after laminoplasty and the expansion ratio (post-/preoperative cross-sectional area) were measured using magnetic resonance imaging in patients with ossification of the posterior longitudinal ligament (OPLL) (n = 25) and patients with cervical spondylotic myelopathy (CSM) (n = 49). The relationships between the expansion ratio and the Japanese Orthopedic Association (JOA) score, JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and postoperative laminae morphology were investigated.

Results

In the OPLL group, the expansion ratio was significantly positively correlated with the postoperative JOA score (P = 0.025), recovery rate of the JOA score (P = 0.026), and postoperative change in lower extremity sensory function according to the JOA score (P = 0.0375); furthermore, patients whose JOACMEQ responses indicated positive outcomes for lower extremity function had a significantly larger expansion ratio than patients with negative results (P = 0.027). In the CSM group, the expansion ratio showed no correlation with the JOA and JOACMEQ scores. The expansion ratio was significantly positively correlated with the width between bilateral gutters in both CSM (P = 0.025) and OPLL (P = 0.0451). In the OPLL group, the expansion ratio in those with a gutter position of less than 0.8 was significantly smaller than that those with a gutter position of more than 0.8 (P = 0.0156). However, there was no correlation between the gutter position and the recovery rate of the JOA score.

Conclusions

In OPLL, insufficient enlargement of the cross-sectional area of the dural sac at the symptomatic level leads to poor neurological improvements after laminoplasty.

Cervical Kyphotic Deformity after Laminoplasty in Patients with Cervical Ossification of Posterior Longitudinal Ligament with Normal Sagittal Spinal Alignment

Background

Preoperative cervico-thoracic kyphosis and cervical regional positive imbalance are the risk factors for postoperative cervical kyphosis after expansive laminoplasty (ELAP). However, the relationship between preoperative global sagittal spinal alignment and postoperative cervical kyphosis in patients with cervical ossification of the posterior longitudinal ligament (OPLL) is unclear. The purpose of this study was to investigate the relationship between the onset of postoperative cervical kyphosis after ELAP and the preoperative global spinal sagittal alignment in patients with OPLL with normal sagittal spinal alignment.

Methods

Sixty-nine consecutive patients without preoperative cervical kyphosis who underwent ELAP for OPLL and cervical spondylotic myelopathy (CSM) were enrolled. The global sagittal alignment radiography preoperatively and 1 year postoperatively were examined. The subjects were divided into a postoperative cervical lordosis group (LG) or a kyphosis group (KG) at 1 year postoperatively. The preoperative global sagittal spinal alignment between LG and KG in CSM and OPLL was compared.

Results

The occurrence of cervical kyphosis after ELAP was 7 of 27 cases (25.9%) in OPLL and 13 of 42 cases (31.0%) in CSM. In patients with CSM in the KG, C7 the sagittal vertical axis (SVA) was smaller than in the LG. In patients with cervical OPLL in the KG, C2-C7 angle, C2-C7 SVA, and thoracic kyphosis (TK) were smaller than those in the LG. In OPLL, the age of the KG was younger than that of LG; however, this was not a significant difference in CSM.

Conclusion

In patients with cervical OPLL without preoperative global spinal sagittal imbalance, preoperative small C2-C7 angle, C2-C7 SVA, TK, and younger age were typical characteristics of postoperative cervical kyphosis after ELAP.

High cord signals on magnetic resonance and other factors predict poor outcomes of cervical spine surgery: A review

Background:

High cord signals (HCS) on preoperative/postoperative T1, T1 gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA), and T2 magnetic resonance (MR) studies, postoperative failure of HCS to regress and/or cord re-expansion, and a triangular cord configuration are poor prognostic factors for surgical patients with cervical spondylotic myelopathy (CSM).

Methods:

Here, we reviewed the negative prognostic import of high Grades/Types and more extensive locations of preoperative/postoperative HCS on T1, T1 Gd-DTPA, and T2 MR studies in surgical patients with CSM. Additional predictors of poor operative outcomes included postoperative failure of HCS to regress, cord re-expansion at the site of a HCS, and the triangular vs. teardrop or boomerang cord configuration. The Types/Grades of HCS on MR follow:Type/Grade 0 – no/absent signal changes; Type/Grade 1 – mild/light/fuzzy/obscure/low cord signal (LCS) changes; Type/Grade 2 – sharp/intense/well-defined HCS; and Type/Grade 3 – mixed/HCS. The definitions of location/extent of LCS/HCS were: focal (1 level), multifocal (with skip areas), and multisegmental (continuous over >1 segment), while cord configuration was categorized as triangular, teardrop, or boomerang.

Results:

On MR studies, preoperative/postoperative Types/Grades 0–1 changes correlated with better prognoses (e.g., improved Japanese Orthopedic Association (JOA) scores or Nurick Grades), while Types/Grades 2–3 correlated with poorer outcomes. Multiple poor prognostic indicators also included; failure of postoperative HCS on MR to regress (particularly if multisegmental), postoperative cord re-expansion at the site of a prior HCS, and triangular cord configuration.

Conclusions:

Grade/Types 2–3 HCS on T1, T1 Gd-DTPA, and T2-weighted MR images on preoperative/postoperative MR studies, failure of HCS to regress (multisegmental), cord re-expansion at the site of a prior HCS, and a triangular cord configuration (atrophy) all contributed to poorer outcomes for CSM surgery.

High Osteogenic Potential of Adipose- and Muscle-derived Mesenchymal Stem Cells in Spinal-Ossification Model Mice

STUDY DESIGN

Basic experiments in a mouse model of ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVE

To assess the osteogenic potential of mesenchymal stem cells (MSCs) obtained from muscle and adipose tissue in Tiptoe-walking (ttw) mice, in which cervical OPLL compresses the spinal cord and causes motor and sensory dysfunction.

SUMMARY OF BACKGROUND DATA

In humans, MSCs have been implicated in the pathogenesis of cervical OPLL. Cervical OPLL in ttw mice causes chronic compression of the spinal cord. Few studies have compared the MSC osteogenic potential with behavioral changes in an OPLL animal model.

METHODS

We compared the osteogenic potential and behavioral characteristics of MSCs from ttw mice (4 to 20 weeks old) with those from control wild-type mice (without hyperostosis). Ligament ossification was monitored by micro-computed tomography and pathology; tissues were double stained with fluorescent antibodies against markers for MSCs (CD45 and CD105), at 8 weeks. The Basso Mouse Scale was used to assess motor function, and heat and mechanical tests to assess sensory function. The osteogenic potential of adipose and muscle MSCs was assessed by Alizarin Red S absorbance, staining for osteogenic mineralization, and real-time quantitative polymerase chain reaction for osteogenesis-related genes.

RESULTS

Spinal-ligament ossification began in ttw mice at 8 weeks of age, and the ossified area increased with age. Immunofluorescence staining identified MSCs in the ossification area. The ttw mice became hyposensitive at 8 weeks of age, and Basso Mouse Scale scores showed motor-function deficits starting at 12 weeks of age. Alizarin Red S staining for mineralization showed a higher osteogenic potential in the adipose- and muscle-derived MSCs from ttw mice than from wild-type mice at 4, 8, and 20 weeks of age. Real-time quantitative polymerase chain reaction showed that ttw MSCs strongly expressed osteogenesis-related genes.

CONCLUSION

MSCs derived from muscle and adipose tissue in ttw mice had a high osteogenic potential.

LEVEL OF EVIDENCE

N/A.

Life expectancy after cervical laminoplasty-Causes of the fatal prognosis at the early stage (within 5 years)

Introduction

In more than 20 years' follow-up after cervical laminoplasty, some patients died at an early stage, within 5 years postoperatively. The details remain unclear. This study was conducted to elucidate the clinical features in patients who died at an early stage after cervical laminoplasty to determine possible preventive measures against early death after surgery.

Methods

A total of 74 patients who died with the follow-up period were included. The patients were divided into two groups: patients with a short survival period (S group, died ≤5 years after surgery) and patients with a long survival period (L group, died >5 years after surgery). Diseases, gender, age, causes of the death, general complications before surgery, and the pre- and postoperative JOA scores were compared between the two groups.

Results

Eleven patients (15%) died within 5 years after laminoplasty. The average age at death in the S group was 68.7 years which was considerably younger than that in the L group (80.2 years). The ratio of pneumonia was higher in the S group, compared to that in the L group. Postoperative JOA score in the S group was lower than that in the L group.

Conclusions

11 patients out of 74 patients (15%) died within 5 years after laminoplasty. The average age at the death in the S group was much younger than that in the L group. The postoperative JOA score in the S group was lower than that in the L group. As pneumonia was more prevalent in the S group, it might be reasonable to give the information for the protection of pneumonia after cervical laminoplasty.