Does Ossification of the Posterior Longitudinal Ligament Progress After Fusion?

Prospective Investigation of the Posterior Longitudinal Ligament and Disc Complex after Posterior Stabilization and Decompression Surgery in Patients With Non-OPLL (Ossification of the Posterior Longitudinal Ligament) Cervical Spondylotic Myelopathy

BACKGROUND

Cervical spondylotic myelopathy (CSM) is a prevalent cause of spinal cord dysfunction in adults, primarily from degenerative changes. The efficacy of treatment strategies, especially surgical approaches, remains debated.

OBJECTIVE

This study aimed to assess the long-term impact of posterior fusion laminectomy on the posterior longitudinal ligament (PLL) thickness, disc complex, and myelomalacia signal changes in CSM patients.

METHODS

A single-centre, prospective study from January 2020 to December 2021 included CSM patients without ossified posterior longitudinal ligament (OPLL). Magnetic resonance imaging (MRI) data from baseline, 6, and 12 months postoperatively were collected. Measurements on the MRI were performed using the Osirix MD software, focusing on the PLL width, myelopathic foci dimensions, and canal diameter.

RESULTS

Out of the 82 initially enrolled patients, 64 were considered for analysis. Postoperatively, a significant reduction in PLL width and myelopathic foci dimensions was observed, alongside a considerable increase in the canal diameter. Clinical outcomes based on the Modified Japanese Orthopaedic Association (mJOA) scale also showcased marked improvements post-surgery.

CONCLUSIONS

Posterior fusion laminectomy effectively reduces anterior pressure in CSM patients. This treatment may represent an optimal surgical approach for selected CSM cases. Furthermore, more extensive studies with extended follow-up are advocated.

Giant calcified thoracic disk herniations: ossification of PLL or autonomous entity?

BACKGROUND

Giant calcified thoracic disk herniation (GCTD) is an uncommon event, which requires surgical treatment in less than 1% of patients. GCDTs are a specific subgroup of herniated thoracic disks occupying more than 40% of the spinal canal showing calcifications associated with a certain degree of ossification. In this paper, we are reporting our whole experience in the surgical management of GCTDs through anterior approaches. We believe that they present characteristics that associate them to the circumscribed type of ossified posterior longitudinal ligament (OPLL) with a possible common pathophysiology consisting in the dural violation.

METHODS

Twenty-three consecutive patients with GCDTs were managed through anterior approaches during the period 1996-2019 at the Niguarda Hospital, Milan, Italy. Clinical data, radiological features, surgical reports, histological findings, and outcomes were reviewed.

RESULTS

There was no mortality, whereas permanent morbidity consisted of 1 case of worsened paraparesis due to accidental spinal cord contusion. One patient required reoperation to repair a postoperative cerebrospinal fluid (CSF) leakage. All patients underwent postoperative MRI which showed excellent decompression of cord and dural sac in all cases. Histological study of en-bloc removed GCTD showed typical calcification patterns of the PLL.

CONCLUSIONS

GCDTs may be assimilated to the so-called "circumscribed type" of OPLL. The GCDTs may show the same radiological CT and MRI pattern of OPLL. The anterior accesses now represent the standard of care for GCTDs. The use of operative microscope and intraoperative monitoring is mandatory. The risk of CSF leakage can be markedly reduced by meticulous reconstruction of the dura and the placement of spinal drainage. Adequate exposition may sometimes require one or two levels of corpectomy with consequent vertebral body reconstruction and fixation of anterior column of the spine.

ENPP1 in Blood and Bone: Skeletal and Soft Tissue Diseases Induced by ENPP1 Deficiency

The enzyme ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) codes for a type 2 transmembrane glycoprotein that hydrolyzes extracellular ATP to generate pyrophosphate (PPi) and adenosine monophosphate, thereby contributing to downstream purinergic signaling pathways. The clinical phenotypes induced by ENPP1 deficiency are seemingly contradictory and include early-onset osteoporosis in middle-aged adults and life-threatening vascular calcifications in the large arteries of infants with generalized arterial calcification of infancy. The progressive overmineralization of soft tissue and concurrent undermineralization of skeleton also occur in the general medical population, where it is referred to as paradoxical mineralization to highlight the confusing pathophysiology. This review summarizes the clinical presentation and pathophysiology of paradoxical mineralization unveiled by ENPP1 deficiency and the bench-to-bedside development of a novel ENPP1 biologics designed to treat mineralization disorders in the rare disease and general medical population.

[Repeated cervical laminoplasty for progressive ossification of posterior longitudinal ligament: a case report]

Posterior longitudinal ligament ossification is a progressive disease resulting in severe multilevel spinal stenosis with myelopathy. Decompression via anterior or posterior approach is the main treatment option. Decompressive laminoplasty is currently considered the most effective and safest method. This procedure provides favorable outcomes with low trauma and short surgery time. Redo surgeries are rare and most often performed within 2 years after primary laminoplasty. The most common causes are progressive spinal stenosis following posterior longitudinal ligament ossification, insufficient primary decompression and progressive cervical spine kyphosis. Considering few data on redo laminoplasty, we present a patient with progressive ossification of posterior longitudinal ligament who underwent redo surgery at the same level in 10 years after primary laminoplasty.

Are clinical outcomes affected by laminoplasty method and K-line in patients with cervical ossification of posterior longitudinal ligament? A multicenter study

BACKGROUND

Open-door laminoplasty (ODL) and French-door laminoplasty (FDL) are the main laminoplasty techniques used to treat cervical ossification of the posterior longitudinal ligament (C-OPLL). However, few studies have compared the outcomes of ODL and modified FDL (mFDL) for C-OPLL. We explored the differences in outcomes between ODL and mFDL for C-OPLL and analyzed the technical efficacy of each procedure in patients with K-line (+) or (-) C-OPLL.

METHODS

From January 2010 to December 2015, 202 patients with K-line (+) or (-) C-OPLL were retrospectively recruited from 4 institutions. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score, JOA score recovery rate, operative time, blood loss, and complications. Univariate analysis and binary logistic regression models were adjusted for confounding factors.

RESULTS

Two hundred patients (mFDL, n = 69; ODL, n = 131) with a median follow-up of 42 months (range 36-54 months) were included. The postoperative JOA score significantly improved in both groups (P < 0.05). After adjusting for confounding factors, there was a statistically significant difference in blood loss (≥ 300 mL) between the two groups (P = 0.005), but there was no significant difference in the postoperative JOA score (≥ 14) (P = 0.062), JOA score recovery rate (≥ 0.82) (P = 0.187), or operative time (≥ 90 min) (P = 0.925). C5 palsy tended to occur more often in the mFDL group, although the difference was not significant (P > 0.05). The stratified analysis of the K-line status showed more blood loss in K-line (+) patients who underwent mFDL, but there was no significant difference in the postoperative JOA score, JOA score recovery rate, or operative time between the ODL and mFDL groups. Additionally, there was no significant difference in blood loss, postoperative JOA score, JOA score recovery rate, or operative time among all patients with K-line (+) or (-) C-OPLL in both groups.

CONCLUSIONS

Both ODL and mFDL are effective for patients with C-OPLL. However, more blood loss tends to occur during mFDL. This study showed no significant difference in the operative time or incidence of complications between the two techniques. The efficacy of ODL and mFDL was not affected by the K-line status (+ or -) in patients with C-OPLL.

Laminoplasty and simultaneous C2 semi-laminectomy with internal fixation in treating ossification of the posterior longitudinal ligament in cervical discs at C2 segment

OBJECTIVE

To explore the effect of open-door laminoplasty and simultaneous C2 semi-laminectomy with lateral mass screw fixation (LSLF) in treating ossification of the posterior longitudinal ligament (OPLL) in cervical discs at C2 segment.

METHODS

In this retrospective study, 76 patients diagnosed with OPLL in cervical discs at C2 segment from November 2016 to May 2019 were included. These patients were assigned into a LSLF group (n=41, LSLF surgery) and LF group (n=35, laminectomy and lateral mass screw fixation) according to the treatment they received. The surgery time and intraoperative blood loss were recorded. Improvements in neurological function (JOA score), cervical curvature index (CCI), spinal cord drift distance, cross-sectional area (CSA) of the posterior muscles from cervical spine, occurrence of C5 palsy, and severity of axial symptoms were evaluated between LSLF group and LF group.

RESULTS

Compared with LF group, the operative time was longer and blood loss volume was higher in LSLF group (P<0.05). No statistical difference was found in decompression width between LSLF group and LF group, while the drift distance of spinal cord in LSLF group was larger than that in LF group (P<0.05). No obvious differences were observed in anteroposterior dural sac diameter after the surgery between LSLF group and LF group. CSA in LF group decreased more than that in LSLF group (P<0.05). No remarkable difference was obtained in CCI at the final follow-up between LSLF group and LF group. The NDI score after surgery in the LSLF group was significantly decreased compared to LF group (P<0.05), while no differences were observed in JOA scores or the neurological recovery rate between LSLF group and LF group. The occurrence of C5 palsy in the LSLF group was 4.9%, which was less than that of LF group (20.0%). In contrast to LF group, postoperative axial symptoms in LSLF group were decreased (P<0.05).

CONCLUSION

Compared to LF, LSLF could better improve neck functions, and reduce the severity of axial symptoms and the occurrence of C5 palsy for patients with OPLL at C2 segment.

Progression of Ossification of Posterior Longitudinal Ligament After Anterior Cervical Discectomy and Fusion in Military Patients Exposed to Minor Trauma

Objective

Ossification of the posterior longitudinal ligament (OPLL) can progress even after cervical spine surgery and may cause neurological injury as a result of minor trauma. The purpose of this study was to investigate the preventive factors associated with OPLL progression after anterior cervical discectomy and fusion (ACDF), a procedure commonly performed in clinical practice.

Methods

We retrospectively investigated 295 male soldiers who underwent ACDF surgery between 2012 and 2017. Patients who were followed up for >12 months using dynamic radiography and computed tomography (CT) were included in the study. Radiological parameters investigated included OPLL progression, C2-C7 angles on dynamic radiography, segmental angles, C2-C7 cervical sagittal vertical axis (C2-C7 SVA), and the T1 slope. These parameters were measured preoperatively and 1 year postoperatively.

Results

A total of 49 patients were enrolled, and 10 patients were confirmed to have OPLL progression. Comparison between the OPLL progression and non-progression groups showed no statistically significant differences in pre- and postoperative cervical range of motion. However, statistically significant differences were observed in the postoperative neutral C2-C7 angle (progression -3.9°±6.4° vs. non-progression -13.4°±7.9°, p=0.001) and the SVA change (progression 5.8±7.9 mm vs. non-progression -3.7±6.3 mm, p=0.00). The cutoff values were -8.01° for the postoperative neutral C2-C7 angle and 1.4 mm for SVA changes.

Conclusion

Increased SVA (>1.4 mm) and a small postoperative neutral C2-C7 angle (>-8.01°) 1 year after ACDF were associated with OPLL progression. It is important to be mindful of these factors during follow-up after ACDF, because additional surgical treatment may be necessary for OPLL progression due to neurological injury caused by minor trauma.

Laminectomy with instrumented fusion vs. laminoplasty in the surgical treatment of cervical ossification of the posterior longitudinal ligament: A multicenter retrospective study

Laminectomy with instrumented fusion (LF) has demonstrated better prevention of ossification of posterior longitudinal ligament (OPLL) growth compared to laminoplasty (LP). There remains uncertainty, however, as to which surgical approach is more beneficial with respect to clinical outcomes and complications. We retrospectively reviewed 273 cervical OPLL patients of more than 3 levels, from the two institutions' databases, who underwent LF or LP between January 1998 and January 2016. Each 273 patient (85 with LF, 188 with LP) was assessed for postoperative neurologic and radiologic outcomes, complications and reoperations. The mean length of follow-up was 40.11 months. There were baseline differences between cohorts. Overall, postoperative JOA recovery rate at last follow up was significantly better in the LP group with similar improvement in visual analog neck score. Postoperative C2-7 Cobb angle was decreased compared to baseline for both LF and LP cohorts, but there was no significant difference between groups. Complications occurred in 19 (22.35%) LF patients, and 11 (5.85%) LP patients, with higher incidence of C5 palsy and instrumentation failure in the LF group. Four LF patients (4.71%) and five LP patients (2.66%) underwent reoperation during the follow up period.

Unveiling the genetic variation of severe continuous/mixed-type ossification of the posterior longitudinal ligament by whole-exome sequencing and bioinformatic analysis

BACKGROUND CONTEXT

Ossification of the posterior longitudinal ligament (OPLL) in the cervical spine is known as a rare, complex genetic disease, its complexity being partly because OPLL is diagnosed by radiological findings regardless of clinical or genetic evaluations. Although many genes associated with susceptibility have been reported, the exact causative genes are still unknown.

PURPOSE

We performed an analysis using next-generation sequencing and including only patients with a clear involved phenotype.

STUDY DESIGN/SETTING

This was a case control study.

PATIENT SAMPLE

A total of 74 patients with severe OPLL and 26 healthy controls were included.

OUTCOME MEASURES

Causal single-nucleotide variant (SNV), gene-wise variant burden (GVB), and related pathway METHOD: We consecutively included the severe OPLL patients with continuous-/mixed-type and an occupying ratio of ≥ 40%, and performed whole-exome sequencing (WES) and bioinformatic analysis. Then, a validation test was performed for candidate variations. Participants were divided into 4 groups (rapidly-growing OPLL, growing rate ≥ 2.5%/y; slow-growing, < 2.5%/y; uncertain; and control).

RESULTS

WES was performed on samples from 74 patients with OPLL (rapidly-growing, 33 patients; slow-growing, 37; and uncertain, 4) with 26 healthy controls. Analysis of 100 participants identified a newly implicated SNV and 4candidate genes based on GVB. The GVB of CYP4B1 showed a more deleterious score in the OPLL than the control group. Comparison between the rapidly growing OPLL and control groups revealed seven newly identified SNVs. We found significant association for 2 rare missense variants; rs121502220 (odds ratio [OR] = infinite; minor allele frequency [MAF] = 0.034) in NLRP1 and rs13980628 (OR= infinite; MAF = 0.032) in SSH2. The 3 genes are associated with inflammation control and arthritis, and SSH2 and NLRP1 are also related to vitamin D modulation.

CONCLUSIONS

Identification of unique variants in novel genes such as CYP4B1 gene may induce the development of OPLL. In subgroup analysis, NLRP1 and SSH2 genes coding inflammation molecules may related with rapidly-growing OPLL.

Preoperative Radiological Parameters to Predict Clinical and Radiological Outcomes after Laminoplasty

Many studies have focused on pre-operative sagittal alignment parameters which could predict poor clinical or radiological outcomes after laminoplasty. However, the influx of too many new factors causes confusion. This study reviewed sagittal alignment parameters, predictive of clinical or radiological outcomes, in the literature. Preoperative kyphotic alignment was initially proposed as a predictor of clinical outcomes. The clinical significance of the K-line and K-line variants also has been studied. Sagittal vertical axis, T1 slope (T1s), T1s-cervical lordosis (CL), anterolisthesis, local kyphosis, the longitudinal distance index, and range of motion were proposed to have relationships with clinical outcomes. The relationship between loss of cervical lordosis (LCL) and T1s has been widely studied, but controversy remains. Extension function, the ratio of CL to T1s (CL/T1s), and Sharma classification were recently proposed as LCL predictors. In predicting postoperative kyphosis, T1s cannot predict postoperative kyphosis, but a low CL/T1s ratio was associated with postoperative kyphosis.

Predictors of neurologic outcome after surgery for cervical ossification of the posterior longitudinal ligament differ based on myelopathy severity: a multicenter study

OBJECTIVE

The purpose of this retrospective multicenter study was to compare prognostic factors for neurological recovery in patients undergoing surgery for cervical ossification of the posterior longitudinal ligament (OPLL) based on their presenting mild, moderate, or severe myelopathy.

METHODS

The study included 372 consecutive patients with OPLL who underwent surgery for cervical myelopathy between 2006 and 2016 in East Asian countries with a high OPLL prevalence. Baseline and postoperative clinical outcomes were assessed using the Japanese Orthopaedic Association (JOA) myelopathy score and recovery ratio. Radiographic assessment included occupying ratio, cervical range of motion, and sagittal alignment parameters. Patient myelopathy was classified as mild, moderate, or severe based on the preoperative JOA score. Linear and multivariate regression analyses were performed to identify patient and surgical factors associated with neurological recovery stratified by baseline myelopathy severity.

RESULTS

The mean follow-up period was 45.4 months (range 25-140 months). The mean preoperative and postoperative JOA scores and recovery ratios for the total cohort were 11.7 ± 3.0, 14.5 ± 2.7, and 55.2% ± 39.3%, respectively. In patients with mild myelopathy, only age and diabetes correlated with recovery. In patients with moderate to severe myelopathy, older age and preoperative increased signal intensity on T2-weighted imaging were significantly correlated with a lower likelihood of recovery, while female sex and anterior decompression with fusion (ADF) were associated with better recovery.

CONCLUSIONS

Various patient and surgical factors are correlated with likelihood of neurological recovery after surgical treatment for cervical OPLL, depending on the severity of presenting myelopathy. Older age, male sex, intramedullary high signal intensity, and posterior decompression are associated with less myelopathy improvement in patients with worse baseline function. Therefore, myelopathy-specific preoperative counseling regarding prognosis for postoperative long-term neurological improvement should include consideration of these individual and surgical factors.

Relationship Between Endplate Defects, Modic Change, Facet Joint Degeneration, and Disc Degeneration of Cervical Spine

Objective

The “disc degeneration precedes facet joint osteoarthritis” hypothesis and multidimensional analysis were actively discussed in lumbar spine. However, in cervical spine degeneration, the multifactorial analyzes of disc degeneration (DD), Modic changes (Mcs), facet degeneration, and endplate degeneration (ED) is still limited. In this cross-sectional study, we aimed to analyze the prevalence and interrelationship of cervical DD parameters.

Methods

We retrospectively recruited 62 patients aged between 60 and 70 years. The disc height, segmental angle, ossified posterior longitudinal ligament (OPLL), ED, facet joint degeneration (FD), uncovertebral joint degeneration (UD), DD, spinal stenosis (SS), Mc, and cord signal change (CS) were evaluated using a previously well-known grading system.

Results

The prevalence of cervical degenerative parameters were DD (grade 1, 1.2%; grade 2, 13.3%; grade 3, 54.8%; grade 4, 19.0%; grade 5, 11.7%), OPLL (26.2%), SS (grade 0, 7.7%; grade 1, 42.3%; grade 2, 26.2%; grade 3, 23.8%), UD (39.1%), ED (normal, 69.0%; focal defect, 9.7%; corner defect, 11.7%; erosion, 6.9%; sclerosis, 2.8%), and FD (normal, 48.8%; narrowing, 27.0%; hypertrophied, 24.2%). The interrelationship of degenerative parameters showed close relation between UD, SS, DD, OPLL, Mc. ED, and CS has partial relation with degenerative finding. FD only has relation with UD, and Mc.

Conclusion

Our results may indicate that FD is a degeneration that occurs independently, rather than as a result of other degenerative factors.