Consensus statement on diagnosis and treatment of cervical ossification of posterior longitudinal ligament from Asia Pacific Spine Society (APSS) 2020

Foramen Facet Spinal Classification for Ossification of the Posterior Longitudinal Ligament on Computed Tomography: Closely Related to Clinical Efficacy

STUDY DESIGN

Retrospective study.

OBJECTIVE

To develop and validate computed tomography (CT)-based classification schemes to eliminate ambiguity as much as possible and evaluate the adequacy and clinical value of its classification.

BACKGROUND

There is no objective criteria for laminoplasty of more than one million Chinese patients with ossification of the posterior longitudinal ligament (OPLL) every year. CT imaging can accurately show the location, size, and shape of ossification, it is very important to propose a recognized simple classification of ossifications.

PATIENTS AND METHODS

From 2016 to 2018, 100 patients with "moderate to severe" OPLL on CT were performed according to the following criteria. This study simply classifies the grade of the ossification as 1-2-3, the zone is A-B by the foramen facet spinal canal classification, and the interexaminer reliability is 96%. A prospective series of 60 patients for laminoplasty was performed between 2018 and 2019, and this classification scheme was verified according to the new standard. All patients with size 1 were selectively excluded from consideration for surgery. The Japanese Orthopedic Association scores from both series are superior to most published results for patients with OPLL.

RESULTS

The first and second series reported good to excellent results of 89% and 93.3%, respectively, and 80% and 85% for 24 months. The difference in the incidence of C5 paralysis and axial pain was statistically significant among the different zones, and most of them recovered within 6 months. The most common size and location types are 2-AB, 3-AB, and 2A. The most severe type is 3-AB.

CONCLUSIONS

The foramen facet spinal classification of OPLL is a simple and reliable method for objectively evaluating the ossification of patients with OPLL based on CT research.

LEVEL OF EVIDENCE

Level III.

Sorafenib inhibits ossification of the posterior longitudinal ligament by blocking LOXL2-mediated vascularization

Ossification of the Posterior Longitudinal Ligament (OPLL) is a degenerative hyperostosis disease characterized by the transformation of the soft and elastic vertebral ligament into bone, resulting in limited spinal mobility and nerve compression. Employing both bulk and single-cell RNA sequencing, we elucidate the molecular characteristics, cellular components, and their evolution during the OPLL process at a single-cell resolution, and validate these findings in clinical samples. This study also uncovers the capability of ligament stem cells to exhibit endothelial cell-like phenotypes in vitro and in vivo. Notably, our study identifies LOXL2 as a key regulator in this process. Through gain-and loss-of-function studies, we elucidate the role of LOXL2 in the endothelial-like differentiation of ligament cells. It acts via the HIF1A pathway, promoting the secretion of downstream VEGFA and PDGF-BB. This function is not related to the enzymatic activity of LOXL2. Furthermore, we identify sorafenib, a broad-spectrum tyrosine kinase inhibitor, as an effective suppressor of LOXL2-mediated vascular morphogenesis. By disrupting the coupling between vascularization and osteogenesis, sorafenib demonstrates significant inhibition of OPLL progression in both BMP-induced and enpp1 deficiency-induced animal models while having no discernible effect on normal bone mass. These findings underscore the potential of sorafenib as a therapeutic intervention for OPLL.

A Clinical Classification of Cervical Ossification of the Posterior Longitudinal Ligament to Guide Surgical Strategy

STUDY DESIGN

A clinical classification of cervical ossification of the posterior longitudinal ligament (COPLL) was developed based on imaging findings.

OBJECTIVE

This study aimed to establish a clinical classification for COPLL and provide corresponding surgery strategies for each subtype.

SUMMARY OF BACKGROUND DATA

A practical and reliable classification is needed to guide the treatment of COPLL.

MATERIALS AND METHODS

This study retrospectively reviewed plain radiographs, computed tomography scans, and magnetic resonance images of patients diagnosed with COPLL between 2018 and 2022 at Shanghai Changzheng Hospital. The types of COPLL were classified according to the location, morphology, and canal-occupying ratio (OR) of the ossification mass. Interobserver and intraobserver reliability were evaluated using Cohen's kappa.

RESULTS

A total of 1000 cases were included, which were classified into five types: focal type (F type), short-sequential type (S type), long-sequential type (L type), high type (H type), and mixed type (M type). In addition, each type could be classified into subtype 1 or subtype 2 according to the canal-OR. Then each type could be further classified into other subtypes according to location and morphology. The interobserver reliabilities in the first and second rounds were 0.853 and 0.887, respectively. The intraobserver reliability was 0.888.

CONCLUSION

The authors classified COPLL into a system comprised of five types and several subtypes according to canal-OR, location, and morphology. Surgical strategies for each subtype are also suggested. This provides a theoretical guide for the description and surgical management of COPLL.

Static mechanical analysis of the vertebral body after modified anterior cervical discectomy and fusion (partial vertebral osteotomy): a finite element model

BACKGROUND

Modified anterior cervical discectomy and fusion (Mod ACDF) can effectively address ossification of the posterior longitudinal ligament (OPLL), which is difficult to remove directly from the posterior edge of the vertebral body, with considerably lesser damage as compared to anterior cervical corpectomy and fusion (ACCF). We compared the static mechanics of different anterior approaches by using an ideal finite element model.

METHODS

A complete finite element model was established and classified into the following three surgical models according to different model cutting operations: ACDF, ACCF, and Mod ACDF. Three different bone volume situations (normal bone mineral density, osteopenia, and osteoporosis) were simulated. After fixing the lower surface of C5 or C6, a load was applied to the upper surface of C4, and the stress distribution and displacement of the upper surface of C5 or C6 were observed and the related values were recorded.

RESULTS

The average Von Mises Stress and displacement levels of Mod ACDF were between those of ACDF and ACCF; with the peak Von Mises Stress occurring on the posterior side of the vertebral body (Points 1-4). The change in Von Mises Stress of the vertebral body is not significant during bone loss. However, the degree of displacement of the vertebral body surface and risk of vertebral collapse are increased (100 N: 13.91 vs. 19.47 vs. 21.62 μm; 150 N: 19.60 vs. 29.30 vs. 31.64 μm; 200 N: 28.53 vs. 38.65 vs. 44.83 μm).

CONCLUSIONS

The static biomechanical effects caused by Mod ACDF are intermediate between ACDF and ACCF, and the risk of vertebral body collapse is lower than that by ACCF. Therefore, Mod ACDF may be an effective solution when targeting OPLL with poorly positioned posterior vertebral body edges.

Delayed Hemorrhage Followed by Vertebral Artery Injury during Cervical Anterior Controllable Antedisplacement and Fusion Surgery: Case Report and Literature Review

Background

Vertebral artery injury (VAI) during cervical spine surgery is rare. Anterior controllable ante‐displacement and fusion (ACAF) surgery is a novel technique for treating degenerative cervical spine disorders, especially ossification of the posterior longitudinal ligament. To date, there have been no reports of VAI during cervical ACAF surgery. Here, we report a rare case of perioperative complication of VAI during ACAF surgery. The available English literature that provides treatment instructions were reviewed.

Case Presentation

A patient diagnosed with mixed ossification of the posterior longitudinal ligament (OPLL) underwent ACAF surgery from C2–C6. Two level transverse foramina were ruptured, and severe bleeding was encountered during ACAF osteotomy. Hemostatic tamponade was performed using bone waxes. The patient had delayed hemorrhage on postoperative day 6. Emergence angiography revealed two vertebral artery pseudoaneurysms in the ruptured transverse foramina. A balloon‐expandable covered stent was deployed to treat the pseudoaneurysm. The patient recovered without complications.

Conclusion

ACAF surgery is a good choice for multiple‐level OPLL disease, but special attention should be paid to VAI in the perioperative period. Intraoperative tamponade with bone wax and postoperative digital subtraction angiography (DSA) are effective in preventing disaster‐related hemorrhage.