Posterolateral Floating Technique for the Thoracic Ossification of the Posterior Longitudinal Ligament with Navigation: A Technical Note.

We describe a floating technique via a posterolateral approach with intraoperative O-arm navigation to facilitate decompression of the spinal cord in thoracic myelopathy due to severe ossification of the posterior longitudinal ligament (OPLL). A 62-year-old man with myelopathy due to thoracic OPLL had left-leg muscle weakness, urinary disturbance, and spastic gait. Bilateral leg pain and gait disturbance had persisted for 2 years. He was successfully treated by the posterolateral OPLL floating procedure and posterior pedicle fixation under O-arm navigation. At a 2-year follow-up, manual muscle testing results and sensory function of the left leg had recovered fully. His cervical Japanese Orthopedic Association score had improved from 5/12 to 11/12. The novel intraoperative O-arm navigation-guided posterolateral floating procedure for thoracic OPLL is effective for achieving precise decompression and strong fixation with a posterior approach only and can provide an excellent result for severe thoracic OPLL without the risk of adverse events from intraoperative radiation.

Different standing postures are the influencing factors for the efficacy of laminoplasty in the treatment of K-Line (-) patients with ossification of the posterior longitudinal ligament.

OBJECTIVE: To investigate the relationship between different standing postures and surgical outcomes of K-Line (-) ossification of the posterior longitudinal ligament (OPLL) patients after laminoplasty with a titanium basket. There is a lack of data evaluating the relationship between the postoperative satisfaction of K-Line (-) patients and their standing postures. METHODS: OPLL patients enrolled in the study were divided into a K-Line (+) group (Group A) and a K-Line (- group (Group B) in natural and relaxed standing positions. We compared the postoperative outcomes after cervical laminoplasty with titanium basket surgery using the Japanese Orthopaedic Association score (JOA), recovery rate and the degree of improvement in the six JOA score items. The degree of satisfaction with the outcome was assessed at the 1-year follow-up using a 7-point numerical rating scale. RESULTS: A total of 34 K-Line (+) patients with OPLL (age 61.9 ± 2.9 years) in Group A and 40 K-Line (-)patients with OPLL (age 60.4 ± 3.5 years) in Group B in natural and relaxed standing positions were recruited. In Group A, the mean preoperative and postoperative JOA scores were 10.1 ± 1.4 and 13.1 ± 0.8 points, respectively, and in Group B, the mean preoperative and postoperative JOA scores were 9.7 ± 1.3 and 11.1 ± 0.9 points, respectively. A significant improvement in the JOA score was seen in both groups postoperatively, but the recovery rate of the patients' JOA scores was significantly lower in Group B. In Group A, significant improvements were seen in all JOA score items, but in Group B, improvements were seen only in upper- and lower-extremity sensory functions. CONCLUSION: Different standing postures are risk factors in the treatment of K-Line (-) patients, and therefore, natural and relaxed standing positions should be given more attention before devising the surgical plan.

Comparative Effectiveness and Functional Outcome of C2 Dome-like Expansive Versus C2 Expansive Open-door Laminoplasty for Upper Cervical Ossification of the Posterior Longitudinal Ligament: A Retrospective Cohort Study.

STUDY DESIGN: Retrospective Cohort Study. OBJECTIVES: This study compared the function and radiographical outcomes of the patients who underwent C2 dome-like expansive laminoplasty to those C2 expansive open-door laminoplasty for the treatment of OPLL with C2 involved. SUMMARY OF BACKGROUND DATA: There are few comparative studies of these two surgical methods. C2 dome-like and C2 expansive open-door laminoplasty are posterior approaches for posterior longitudinal ligament ossification with C2 level and above. METHODS: This study performed a retrospective cohort analysis of 59 patients with OPLL up to C2 which cause compression symptoms. 31 patients underwent C2 dome-like expansive laminoplasty with C3-7 expansive open-door laminoplasty (Group Dom) and 28 underwent C2-7 expansive open-door laminoplasty (Group Exp). The preoperative and postoperative space available for cord (SAC) of C2 segment, cervical curvature index of C2-7, C2-7 range of motion, Japanese orthopedic association (JOA) score, visual analog scale (VAS) score, and neck disability index (NDI) were used to assess clinical out-comes and statistically analyzed. RESULTS: The cervical curvature index, JOA score, and NDI significantly changed at the final follow-up in two groups with no significant intergroup differences. There were no significant differences in preoperative SAC and VAS between the two groups. At the final follow-up, the SAC of C2/3 in Group Exp was significantly larger than Group Dom, while the VAS and range of motion of Group Dom became significantly better than Group Exp. CONCLUSION: The C2 dome-like expansive laminoplasty can reduce postoperative neck pain more obviously and achieve better cervical curvature. C2 expansive open-door laminoplasty can get more adequate decompression in the spinal canal, which may be recommend to the patients with OPLL occupying more than 50% of the vertebral canal at C2/3, or with developmental spinal stenosis. LEVEL OF EVIDENCE: 3.

Transcranial Motor-evoked Potential Alert After Supine-to-Prone Position Change During Thoracic Ossification in Posterior Longitudinal Ligament Surgery: A Prospective Multicenter Study of the Monitoring Committee of the Japanese Society for Spine Surgery and Related Research.

STUDY DESIGN: A prospective, multicenter study. OBJECTIVE: To evaluate the usefulness of transcranial motor-evoked potentials (Tc-MEPs) during supine-to-prone position change for thoracic ossification of the posterior longitudinal ligament (T-OPLL). SUMMARY OF BACKGROUND DATA: Supine-to-prone position change might be a risk of spinal cord injury in posterior decompression and fusion surgeries for T-OPLL. METHODS: The subjects were 145 patients with T-OPLL surgically treated with posterior decompression and fusion using Tc-MEPs in 14 institutes. Tc-MEPs were monitored before surgery from supine-to-prone position and intraoperatively in seven institutes and only intraoperatively in the other seven institutes because of disapproval of the anesthesia department. In cases of Tc-MEP alert after position change, we adjusted the cervicothoracic posture. When the MEP did not recover, we reverted the position to supine and monitored the Tc-MEPs in supine position. RESULTS: There were 83 and 62 patients with/without Tc-MEP before position change to prone (group A and B). The true-positive rate was lower in group A than group B, but without statistical significance (8.4% vs. 16.1%, P = 0.12). In group A, five patients who had Tc-MEP alert during supine-to-prone position change were all female and had larger body mass index values and upper thoracic lesions. Among the patients, three underwent surgeries after cervicothoracic alignment adjustment, and two had postponed operations to 1 week later with halo-vest fixation because of repeated Tc-MEP alerts during position change to prone. The Tc-MEP alert at exposure was statistically more frequent in group B than in group A ( P = 0.033). CONCLUSION: Tc-MEP alert during position change is an important sign of spinal cord injury due to alignment change at the upper thoracic spine. Tc-MEP monitoring before supine-to-prone position change was necessary to prevent spinal cord injury in surgeries for T-OPLL.

Relationship between Scheuermann disease and symptomatic thoracic spinal stenosis: A retrospective study.

OBJECTIVE: This study aimed to investigate the possible relationship between Scheuermann disease (SD) and the pathophysiological factors of thoracic spinal stenosis (TSS), including ossification of the ligamentum flavum (OLF), ossification of the posterior longitudinal ligament (OPLL), and thoracic disc herniation (TDH) in patients with symptomatic TSS. METHODS: Demographic and radiological data from 66 consecutive patients diagnosed with symptomatic TSS from 2013 to 2018 were retrospectively collected and divided into 3 groups depending on the underlying pathomechanism of TSS: TDH group (18 patients; 6 women; mean age ± standard deviation [Sd] = 59.89 ± 11.34), OPLL group (12 patients; 8 women; mean age ± Sd = 56.08 ± 14.74), and OLF group (36 patients; 20 women; mean age ± Sd = 58.69 ± 9.77). A total of 41 age-matched healthy individuals (19 women; mean age ± Sd = 54.88 ± 13.63) were designated as the control group. In each group, both typical and atypical SD criteria were radiologically examined. The demographic data and presence of SD between the control group and 3 subgroups of TSS pathomechanisms were evaluated. RESULTS: SD characteristics were identified in 83.33% (15/18) of patients in the TDH group, 44.44% (16/36) in the OLF group, 25% (3/12) in the OPLL group, and 17.07% (7/41) of the control individuals. When analyzed by the chi-squared test and logistic regression analysis, the presence of SD was significantly associated with TDH (P < 0.01) and OLF (P < 0.05) but not OPLL (P > 0.05). Patients with TDH and OLF showed peak involvement of T10/11, and patients with OPLL did not. Furthermore, we determined that age, sex, body-mass index, and smoking status were not the risk factors for TDH, OPLL, and OLF (P > 0.05). SD was found to be a risk factor for TDH (P < 0.01) and OLF (P < 0.05) but not for OPLL (P > 0.05). CONCLUSION: Evidence from this study indicated that SD might be a risk factor for OLF and TDH but not for OPLL.

Autophagy in spinal ligament fibroblasts: evidence and possible implications for ossification of the posterior longitudinal ligament.

BACKGROUND: The molecular mechanisms of ossification of the posterior longitudinal ligament (OPLL) remain to be elucidated. The aim of the present study was to investigate the autophagy of spinal ligament fibroblasts derived from patients with OPLL and to examine whether autophagy-associated gene expression was correlated with the expression of osteogenic differentiation genes. METHODS: Expression of autophagy-associated genes was detected in 37 samples from 21 OPLL patients and 16 non-OPLL patients. The correlation of autophagy-associated gene expression and the expression of osteogenic differentiation genes was analyzed by Pearson's correlation. The expression of autophagy-associated genes of ligament fibroblasts was assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting, and immunofluorescence. The incidence of autophagy was assessed by flow cytometry. After knockdown using small interfering RNA targeting Beclin1, the expression of osteogenic differentiation genes were compared in spinal ligament fibroblasts. RESULTS: In clinical specimens, mRNA expression levels of microtubule-associated protein 1 light chain 3 and Beclin1 were higher in the OPLL group compared with the non-OPLL group. Pearson correlation analysis demonstrated that Beclin1 expression was positively correlated with expression of osteocalcin (OCN) (r = 0.8233, P < 0.001), alkaline phosphatase, biomineralization associated (ALP) (r = 0.7821, P < 0.001), and collagen type 1 (COL 1) (r = 0.6078, P = 0.001). Consistently, the upregulation of autophagy-associated genes in ligament fibroblasts from patients with OPLL were further confirmed by western blotting and immunofluorescence. The incidence of autophagy was also increased in ligament fibroblasts from patients with OPLL. Furthermore, knockdown of Beclin1 led to a decrease in the expression of OCN, ALP, and COL 1 by 63.2% (P < 0.01), 52% (P < 0.01), and 53.2% (P < 0.01) in ligament fibroblasts from patients with OPLL, respectively. CONCLUSIONS: Beclin1-mediated autophagy was involved in the osteogenic differentiation of ligament fibroblasts and promoted the development of OPLL.

Dkk1 acts as a negative regulator in the osteogenic differentiation of the posterior longitudinal ligament cells.

Ossification of the posterior longitudinal ligament (OPLL) is a spinal disorder characterized by progressive ectopic bone formation in the PLL of the spine. Dickkopf-1 (Dkk1) is a secreted inhibitor of the Wnt pathway that negatively regulates bone formation during skeletal development. However, whether Dkk1 impacts the pathogenesis of OPLL has not been reported. This study is to investigate the role of Dkk1 in the development of OPLL. Our results show that the serum levels of Dkk1 are decreased in OPLL patients compared with non-OPLL controls. The expression of Dkk1 is also reduced in OPLL ligament cells. Downregulation of Dkk1 in ligament cells is associated with activation of the Wnt/ß-catenin signaling, as indicated by stabilized ß-catenin and increased T-cell factor-dependent transcriptional activity. Functionally, Dkk1 exerts a growth-inhibitory effect by repressing proliferation but promoting apoptosis of ligament cells. Dkk1 also suppresses bone morphogenetic protein 2-induced entire osteogenic differentiation of ligament cells, and this suppression is mediated via its inhibition of the Wnt pathway. Our results demonstrate for the first time that Dkk1 acts as an important negative regulator in the ossification of the PLL. Targeting the Wnt pathway using Dkk1 may represent a potential therapeutic strategy for the treatment of OPLL.

Concomitant Fahr's syndrome and thoracic ossification of the posterior longitudinal ligament caused by idiopathic hypoparathyroidism - case report.

BACKGROUND: Fahr's syndrome presenting multiple and symmetric calcification of basal ganglia and cerebral cortex is rare, and idiopathic hypoparatyroidism is known as one of the causes. The relationship between ossification of posterior longitudinal ligament (OPLL) and idiopathic hypoparatyroidism is also reported in a few cases. Here, we report a patient presenting concomitant Fahr's syndrome and thoracic OPLL developed by idiopathic hypoparatyroidism. CASE PRESENTATION: 53-year-old female patient presented myelopathic sign including gait disturbance and both leg weakness (Grade 3) for 4 months after slip down, and has the history of anti-epileptic medication for several years. Magnetic resonance imaging revealed cord compression by the mixed-type OPLL from T5 to T9, and decompressive surgery was planned. Sudden onset generalized tonic-clonic seizure attack developed before the surgery. Hypocalcemia (3.7 mg/dL) with QT prolongation on electrocardiogram, hypomagnesemia (1.4 mg/dL), hyperphosphatemia (7.7 mg/dL), hypoparathyroidism, and normal range of vitamin D was noted. Brain study showed Fahr's syndrome with multiple and symmetric calcification of basal ganglia, cerebral cortex, and cerebellum. Decompressive laminectomy was performed after transient correction of hypocalcemia. The myelopathic symptoms improved to normal walking by the 14-month follow-up. The cause of hypoparathyroidism was concluded to be idiopathic. CONCLUSION: Concomitant expression of Fahr's syndrome and OPLL related with idiopathic hypoparatyroidism is very rare. However, we recommend considering the possibility of hypoparathyroidism and Fahr's syndrome when we evaluate the patients with OPLL to avoid the risks of sudden onset seizure and cardiac arrhythmia due to cerebral lesions and hypocalcemia.

Postoperative Progression of Cervical Ossification of Posterior Longitudinal Ligament: A Systematic Review.

OBJECTIVE: The purpose of this study was to provide a systematic and comprehensive review of the existing literature regrading postoperative ossification of posterior longitudinal ligament (OPLL) progression. METHODS: Using the PRISMA guidelines, we conducted an exhaustive review of electronic databases. Potential articles were screened and related information was extracted and analyzed. Twenty-four articles with low-quality evidence were included in the review. The findings of the literature review were divided into several groups: the relationship of surgery to OPLL progression; incidence and risk factors; timing and process of OPLL progression; the effect of additional instrumentation on progression; and neurologic deterioration related with progression. RESULTS: There was no definitive conclusion for whether surgery could accelerate OPLL progression compared with the natural course. The incidence of postoperative OPLL progression was reported from 3.3% to 74.5%. Younger age, involvement of multiple levels and mixed or continuous types are recognized as risk factors. OPLL could progress transversely and longitudinally and progression in length appeared more significant than progression in thickness. Although radiologic OPLL progression was observed significantly more frequently after laminoplasty than after fusion surgery, whether additional instrumented fusion could suppress progression needs further research. Radiographic progression of OPLL did not positively correspond with neurologic deterioration. CONCLUSIONS: The lack of high-level evidence makes it difficult to draw definite conclusions and further research and long-term follow-up clinical studies are needed to better understand postoperative OPLL progression.

Anterior Controllable Antedisplacement Fusion as a Choice for Ossification of Posterior Longitudinal Ligament and Degenerative Kyphosis and Stenosis: Postoperative Morphology of Dura Mater and Probability Analysis of Epidural Hematoma Based on 63 Patients.

OBJECTIVE: We studied the postoperative morphology of the dura mater and analyzed the probability of epidural hematoma (EH) after anterior controllable antedisplacement and fusion (ACAF). METHODS: A total of 63 patients with a diagnosis of ossification of the posterior longitudinal ligament (OPLL) and degenerative kyphosis and stenosis (DKS) had undergone ACAF from 2016 to 2017. All these patients had undergone cervical plain films, computed tomography, and magnetic resonance imaging (MRI). The operation duration, blood loss, and hospital stay were estimated. Radiological assessments included the occupying rate, OPLL type and extent, kyphotic angle, decompression width, and postoperative area of the spinal canal. On sagittal MRI, the postoperative morphology of dura mater was observed. The Japanese Orthopaedic Association scoring system was used to evaluate neurological status. EH and other surgery-related complications were recorded. RESULTS: Of the 63 patients, 39 had OPLL and 24 had DKS. All the patients were followed up for 3-18 months (average, 12.5). The mean decompression width and postoperative spinal canal area were 18.7 ± 1.1 mm and 167.7 ± 34.6 mm2 in the OPLL group and 17.9 ± 0.9 mm and 263.1 ± 46.9 mm2 in the DKS group, respectively. On sagittal MRI, the dura mater was classified into 4 types according to its morphology (dune, ladder, wave, and mixed type), protecting the spinal cord as would a suspensory tent. No patient presented with EH. The mean postoperative Japanese Orthopaedic Association score at the last follow-up examination was significantly better than preoperatively. CONCLUSIONS: The dura mater can protect the spinal cord like a suspensory tent after ACAF. The occurrence of EH is rare when ACAF is used to treat OPLL and DKS.

Risk Factors of Cage Subsidence in Patients with Ossification of Posterior Longitudinal Ligament (OPLL) After Anterior Cervical Discectomy and Fusion.

BACKGROUND There are numerous reports on cage subsidence after ACDF; however, few studies have identified its risk factors. The current study aimed to identify risk factors for cage subsidence after ACDF using the PEEK cage packed with local autobone implant with plate and provides evidence for surgical decision-making. MATERIAL AND METHODS We retrospectively reviewed 77 patients with OPLL who underwent 1/2-level ACDF using the PEEK cage packed with local autobone implant with plate from March 2013 to December 2015. Implant subsidence was defined as the decrease in interbody height at the final follow-up compared to that measured on the first postoperative day ≥2 mm. Intervertebral fusion was evaluated on the basis of no motion across the fusion site and the presence of trabeculae between bone and implant in the X-rays. Multivariate logistic regression analysis was used to identify the risk factors for cage subsidence. RESULTS In comparing the end-plate removal group with the end-plate preservation group, we found that the fusion rate (removal group, 35.90%; preservation group, 10.50%) and the change of IH (P=0.011) were significantly different during the first 6 weeks after surgery. Advanced age (OR=1.34, 95% CI=1.04-1.24, P=0.004), end-plate removal (OR=11.84, 95% CI=2.91-48.28, P=0.001), and nonunion within 6 weeks after surgery (OR=22.67, 95% CI=2.36-217.67, P=0.007) played an important role in predicting cage subsidence. CONCLUSIONS These findings suggest that advanced age, end-plate removal, and nonunion within 6 weeks after surgery are risk factors for the cage subsidence after ACDF using the PEEK cage packed with local autobone implant with plate in patients with OPLL.

Combined use of leptin and mechanical stress has osteogenic effects on ossification of the posterior longitudinal ligament.

PURPOSE: To evaluate the effects of leptin/leptin receptor (LepR) combined with mechanical stress on the development of ossification of the posterior longitudinal ligament (OPLL), which is a disease characterized by ectopic bone formation of the posterior longitudinal ligament (PLL) and can lead to radiculopathy and myelopathy. METHODS: Six human samples of the PLL were analyzed for the expression of leptin and LepR by RT-PCR and western blotting. PLL cells were stimulated with leptin and mechanical stress delivered via a Flexcell tension system, and osteogenic differentiation was evaluated by RT-PCR and western blotting analysis of osteogenic marker expression as well as by alkaline phosphatase (ALP) staining and alizarin red S staining. Activation of mitogen-activated protein kinase (MAPK), Janus kinase (JAK) 2-signal transducer, activator of transcription (STAT) 3 and phosphatidylinositol 3-kinase (PI3K)-Akt was evaluated by western blotting. RESULTS: Samples from the OPLL group had higher LepR mRNA and protein levels and lower leptin levels than those from healthy controls. Exposure to leptin and Flexcell increased the number of ALP-positive cells and calcium nodules in a dose-dependent manner; this effect was accompanied by upregulation of the osteogenic markers osteocalcin, runt-related transcription factor 2 (RUNX2) and osteopontin. Extracellular signal-regulated kinase, P38 MAPK, JAK2, STAT3, PI3K and Akt signaling, was also activated by the combined effects of leptin and mechanical stress. CONCLUSIONS: Leptin and LepR are differentially expressed in OPLL tissues, and the combined use of leptin/LepR and mechanical stress promotes osteogenic differentiation of PLL cells via MAPK, JAK2-STAT3 and PI3K/Akt signaling. These slides can be retrieved under Electronic Supplementary Material.

Effect of posterior instrumented fusion on three-dimensional volumetric growth of cervical ossification of the posterior longitudinal ligament: a multiple regression analysis.

BACKGROUND CONTEXT: Despite the fact that ossification of posterior longitudinal ligament (OPLL) is a three-dimensional disease, conventional studies have focused mainly on a two-dimensional measurement, and it is difficult to accurately determine the volume of OPLL growth and analyze the factors affecting OPLL growth after posterior decompression (laminoplasty or laminectomy and fusion). PURPOSE: The present study aimed to investigate the factors affecting OPLL volume growth using a three-dimensional measurement. STUDY DESIGN/SETTING: This was a retrospective case study. PATIENT SAMPLE: Eighty-three patients with cervical OPLL who were diagnosed as having multilevel cervical OPLL of more than three levels on cervical computed tomography (CT) scans were retrospectively reviewed from June 1, 1998, to December 31, 2015. OUTCOME MEASURES: The OPLL volume from the C1 vertebrae to the C7 vertebrae was measured on preoperative and the most recent follow-up CT scans. METHODS: Eighty-three patients were retrospectively examined for age, gender, body mass index, hypertension, diabetes, type of OPLL, surgical method, preoperative cervical curvature, and preoperative and postoperative cervical range of motion. Preoperative cervical CT and the most recent follow-up cervical CT scans were converted to Digital Imaging and Communications in Medicine data, and the OPLL volume was three-dimensionally measured using the Mimics program (Materialise, Leuven, Belgium). The OPLL volume growth was analyzed using univariate and multivariate analyses. RESULTS: The average follow-up period was 32.36 (±23.39) months. Patients' mean age was 54.92 (±8.21) years. In univariate analysis, younger age (p=.037) and laminoplasty (p=.012) were significantly associated with a higher mean annual growth rate of OPLL (%/y). In multivariate analysis, only laminoplasty (p=.027) was significantly associated with a higher mean annual growth rate of OPLL (%/y). The mean annual growth rate of OPLL was about seven times faster with laminoplasty (8.00±13.06%/y) than with laminectomy and fusion (1.16±9.23%/y). CONCLUSIONS: Posterior instrumented fusion has the effect of reducing OPLL growth rate compared with motion-preserving laminoplasty. Patients' age and the surgical method need to be considered in surgically managing the multilevel OPLL.

Multiplex analysis of serum hormone and cytokine in patients with cervical cOPLL: towards understanding the potential pathogenic mechanisms.

Cervical ossification of the posterior longitudinal ligament (cOPLL) is one of the major causes of myelopathy. However, the mechanism underlying remains elusive. In the present study, using MILLIPLEX magnetic bead panel, we investigated four serum hormones and six serum cytokines in cOPLL patients and healthy subjects. The results showed that tumor necrosis factore-α (TNF-α) were significantly increased, and DDK-1 was significantly decreased in the serum from male and female cOPLL patients compared with those from healthy controls, respectively. Osteopontin (OPN) and fibroblast growth factor-23 (FGF-23) were significantly increased in male cOPLL patients compared with that in healthy male controls. Further analysis showed that FGF-23 and OPN significantly increased, dickkopf-1 (DKK-1) decreased in the extensive cOPLL group. In addition, a significant positive correlation between the OPN and FGF-23 was observed in male cOPLL patients. The results are useful for understanding the mechanism underlying cOPLL.

Role of Cx43-Mediated NFкB Signaling Pathway in Ossification of Posterior Longitudinal Ligament: An In Vivo and In Vitro Study.

STUDY DESIGN: In vivo and in vitro experiments. OBJECTIVE: To illustrate the further molecular mechanism of Cx43-mediated osteoblastic differentiation of ligament cells. SUMMARY OF BACKGROUND DATA: Ossification of the posterior longitudinal ligament (OPLL) is one of the main causes of myelopathy in Asians, but its etiology has not been clarified. We have previously found the mechanical stress can upregulate Cx43 expression in ligament cells, which transduces mechanical signal to promote osteoblastic differentiation. METHODS: The posterior longitudinal ligaments were collected intraoperatively. Ligament fibroblasts were isolated and cultured, and an in vitro mechanical loading model was established. In vivo and in vitro expression levels of Cx43 protein were compared between OPLL and non-OPLL patients. The activation of nuclear factor (NF)-κB (p65) signal and related inflammatory responses were detected in ligament cells under mechanical loading. The mechanical stress-induced inflammatory response and osteoblastic differentiation of OPLL cells were investigated after the treatment with Cx43 siRNA or NFкB (p65) inhibitor. RESULTS: We first confirmed higher Cx43 levels in both in vivo ligament tissue from OPLL patients and in vitro cultured OPLL cells. We also found NFκB (p65) signal and related inflammatory response were activated by mechanical stimulation. The activation of NFκB (p65) signal was dependent upon Cx43, as its knockdown reduced signal. Moreover, treatment with Cx43 siRNA or NFкB (p65) inhibitor significantly decreased the mechanical-induced inflammation response, but partly attenuated mechanical-stimulated osteoblastic differentiation of OPLL cells. CONCLUSION: Cx43-mediated NFкB (p65) signal played an important role in mechanical stress-induced OPLL by transduction of mechanical signal, while giving rise to the activation of inflammatory response in ligament fibroblastsLevel of Evidence: N/A.

Are There Differences in the Progression of Ossification of the Posterior Longitudinal Ligament Following Laminoplasty Versus Fusion?: A Meta-Analysis.

STUDY DESIGN: Systematic review and meta-analysis of studies for the treatment of cervical myelopathy with ossification of the posterior longitudinal ligament (OPLL) treated with laminoplasty or fusion. OBJECTIVE: To delineate whether OPLL continues to progress after laminoplasty compared with fusion and to clarify the relationship between radiological progression of OPLL and neurological decline. SUMMARY OF BACKGROUND DATA: Laminoplasty is usually performed in patients with multilevel OPLL due to the surgical morbidity of anterior surgery. However, the disadvantage of laminoplasty is that the remaining OPLL can progress after the surgery. METHODS: A literature search of PubMed, Embase, Web of Science, and the Cochrane library was performed to identify investigations concerning the progression of OPLL after laminoplasty or fusion. The pooled results were analyzed by calculating the effect size based on the event rate and the logit event rate. RESULTS: We included data from 11 studies involving 530 patients, of whom 429 underwent laminoplasty and 101 underwent fusion surgery. The prevalence of radiological OPLL progression was 62.5% (95% confidence interval [CI] 55.3%-69.3%) for the laminoplasty group and 7.6% (95% CI 3.4%-15.9%) for the fusion group. The laminoplasty displayed substantially high prevalence of the progression of OPLL compared with the fusion group. In the laminoplasty group, the prevalence of OPLL progression increased with time and reached 60% at about 10-year follow-up. The prevalence for neurological decline was similar for about 2 years, 8.3% (95% CI 3.7%-17.9%) for the laminoplasty group and 3.8% (95% CI 1.3%-10.2%) for the fusion group. CONCLUSION: Laminoplasty frequently induces progression of OPLL compared with fusion surgery, but does not make significant clinical deterioration. However, laminoplasty may not be recommended for OPLL patient because it can be getting worse with time. LEVEL OF EVIDENCE: 1.

Predictors of Surgical Outcome in Acute Spinal Cord Injury Patients with Cervical Ossification of the Posterior Longitudinal Ligament.

OBJECTIVE: A retrospective study was conducted to clarify the predictors of the operation results for ossification of the posterior longitudinal ligament (OPLL) patients with acute spinal cord injury (SCI). Detailed analyses of surgical outcomes of OPLL patients with SCI have been rare because most surveys have aimed to investigate OPLL or SCI, but not both. PATIENTS AND METHODS: A total of 36 patients who underwent operation for OPLL between January 2011 and December 2011 were included in this analysis. We investigated the patients' characteristics and surgical approaches and compared the radiographic characteristics of OPLL patients with SCI. RESULTS: The mean modified Japanese Orthopaedic Association (mJOA) score improved dramatically after operation (P = 0.006). The mean preoperative mJOA score was greater in patients with Nurick 3 than in patients with Nurick 4 and 5 (P = 0.041). The preoperative mJOA score was dramatically lower in patients caused by traffic accident and in patients with segmental OPLL lesion (P < 0.05). The postoperative mJOA score was dramatically lower in patients with continuous OPLL lesion than in the segmental OPLL lesion (P = 0.028). Changing in mJOA score was significantly different between the patients with high-intensity zone (HIZ) and without HIZ on magnetic resonance imaging. CONCLUSIONS: HIZ on magnetic resonance imaging was significantly related to the surgical outcomes, which should be highlighted in the preoperative communication with patients. Patients with lower Nirick grade and segmental OPLL would show better symptom before the operation. In addition, SCI caused by slipping or falling showed better symptoms before the operation. Patients with segmental OPLL should show better resolution of symptoms after the operation.