A Novel Anterior Revision Surgery for the Treatment of Cervical Ossification of Posterior Longitudinal Ligament: Case Report and Review of the Literature

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

PURPOSE

The study aimed to develop an evidence-based expert consensus statement on diagnosis and treatment of cervical ossification posterior longitudinal ligament (OPLL).

METHOD

Delphi method was used to perform such survey, and the panel members from Asia Pacific Spine Society (APSS) 2020 were invited to answer the open-ended questions in rounds 1 and 2. Then the results were summarized and developed into a Likert-style questionnaire for voting in round 3, and the level of agreement was defined as 80%. In the whole process, we conducted a systematic literature search on evidence for each statement.

RESULTS

Cervical OPLL can cause various degrees of neurological symptoms, an it's thought to be more common in Asia population. CT reconstruction is an important imaging examination to assist diagnosis and guide surgical choice. Segmental, continuous, mixed, and focal type is the most widely used classification system. The non-surgical treatment is recommended for patients with no or mild clinical symptoms, or irreversible neurological damage, or failed surgical decompression, or condition cannot tolerant surgery, or refusing surgery. As OPLL may continue to develop gradually, surgical treatment would be considered in their course inevitably. The surgical choice should depend on various conditions, such as involved levels, thickness, and type of OPLL, skill-experiences of surgeons, which are listed and discussed in the article.

CONCLUSION

In this statement, we describe the clinical features, classifications, and diagnostic criteria of cervical OPLL, and review various surgical methods (such as their indications, complications), and provide a guideline on their choice strategy.

circSKIL promotes the ossification of cervical posterior longitudinal ligament by activating the JNK/STAT3 pathway

Ossification of the posterior longitudinal ligament (OPLL) is a hyperostotic spinal condition that involves genetic factors as well as non-genetic factors, and its underlying molecular mechanism is largely unknown. Recently, circular RNAs (circRNAs) have been attracting the attention of researchers since they have important regulatory roles in many diseases, including bone metabolism disorders. The present study aimed to investigate the role of circRNA SKI-like proto-oncogene (circSKIL) in OPLL disease progression. First, primary posterior longitudinal ligament cells from patients with cervical spondylotic myelopathy (CSM) without OPLL (control group) and CSM patients with OPLL (OPLL group) were isolated, and the expression levels of circSKIL in ligament cells was found to be significantly increased in the OPLL group compared with control. This result was also confirmed in OPLL tissues. Next, circSKIL was overexpressed in control ligament cells, and the proliferation, mineralization, and osteogenic differentiation of ligament cells were found to be significantly enhanced; the phosphorylation levels of both JNK and STAT3 were upregulated. By contrast, the knockdown of circSKIL in OPLL ligament cells inhibited proliferation, mineralization, and osteogenic differentiation and inactivated the JNK/STAT3 pathway. Therefore, circSKIL may have a significant role in osteogenic differentiation and could serve as a potential target to prevent OPLL progression.

Analysis of the Incompletely Hoisted Vertebrae in the Anterior Controllable Antedisplacement and Fusion Surgery: Causes and Prevention

PURPOSE

Anterior controllable antedisplacement and fusion (ACAF) has been reported to be a safe and effective technique. However, incompletely hoisted vertebrae (IV) were found in the postoperative images. This study aims to analyze the causes and prevention of IV.

METHODS

The ACAF-treated case series subjects were retrospectively reviewed. The vertebrae were separated into the IV group and completely hoisted vertebrae (CV) group according to the gap between the vertebrae and plate. The radiographic data, degree of cervical lordosis, bone mineral density, number of hoisted vertebrae, operative time, blood loss, and Japanese Orthopaedic Association score were compared between the patients with IV and the patients without IV.

RESULTS

A total of 248 vertebrae were hoisted in the enrolled patients. Intervertebral disc height in the IV group was 3.7±0.4 mm, which is significantly lower than that in the CV group. The anterior or posterior overhanging lip, osteoporosis, and oblique osteotomy troughs and hinges existing after osteotomy were found to be impingements preventing the hoisting of the vertebrae. There were no differences in the age, sex, degree of cervical lordosis, number of hoisted vertebrae, and neurological improvement rate between the groups of patients with and without IV.

CONCLUSIONS

Lower intervertebral space height and impingements preventing hoisting were found to be possible causes of IV in ACAF. Measures to prevent the problem should be carried out.

Promoting effect of long non-coding RNA SNHG1 on osteogenic differentiation of fibroblastic cells from the posterior longitudinal ligament by the microRNA-320b/IFNGR1 network

Long non-coding RNAs (lncRNAs) have been noted to influence the progression of ossification of posterior longitudinal ligament (OPLL). The work aims to probe the effect of lncRNA SNHG1 on osteogenic differentiation of ligament fibroblastic cells (LFCs). Aberrantly expressed lncRNAs in ossified PLL tissues were screened out by microarray analysis. Gain- and loss-of function experiments of SNHG1 were performed to identify its role in osteogenic differentiation of LFCs. The downstream molecules of SNHG1 were explored. Altered expression of miR-320b was introduced in LFCs as well. The interactions among SNHG1, miR-320b and IFNGR1 were identified. Consequently, SNHG1 was found highly expressed in OPLL patients. Silencing of SNHG1 inhibited BMP-2, RUNX2 and OCN expression and the ALP activity and reduced osteogenic differentiation of LFCs. Importantly, SNHG1 could and upregulate IFNGR1 through serving as a sponge for miR-320b. Over-expression of miR-320b inhibited osteogenic differentiation of LFCs and inactivated the JAK/STAT signaling pathway. Further administration of Fedratinib, a JAK2-specific agonist, increased osteogenic differentiation of LFCs. To conclude, the study suggested that SNHG1 could upregulate IFNGR1 by sequestering miR-320b and activate the JAK/STAT signaling. Silencing of SNHG1 could reduce the osteogenic differentiation and mineralization of LFCs. The study may offer new insights into OPLL treatment.

Effect of K-line on posterior cervical surgery in patients with posterior longitudinal ligament ossification

PURPOSE

To evaluate the effect of K-line on posterior single-door decompression with fusion fixation (PFF) and posterior single-door decompression with non-fusion fixation (PNF) for patients with ossification of posterior longitudinal ligament (OPLL).

METHODS

A total of 65 patients with OPLL were analyzed retrospectively. They consisted of 44 patients with positive K-line, designated as the K ( +) group, and 21 patients with negative K-line, designated as K (-). The patients were also divided into a PFF group (38 patients) and a PNF group (27 patients). The Japanese Orthopaedic Association (JOA) score, C2-C7 Cobb angle, improvement rate of JOA score, and complications were calculated and statistically analyzed between the groups.

RESULTS

In the K ( +) group, there were no significant differences in the incidence of C5 nerve root palsy and C2-C7 Cobb angle between the two groups of surgical patients, but there were significant differences in the improvement rate of JOA score and the incidence of axial pain. In the K (-) group, there were no significant differences in the incidence of axial pain, the incidence of C5 nerve root palsy, and preoperative C2-C7 Cobb angle between the two groups, but significant differences were observed in the improvement rate of JOA score and C2-C7 Cobb angle at the last follow-up.

CONCLUSION

In the K ( +) group, the improvement rate of JOA score was higher and the incidence of axial pain was lesser in the PNF group than in the PFF group. In the K (-) group, the improvement rate of JOA score was higher in the PFF group than in the PNF group, and there was significant loss of C2-C7 Cobb angle in the PNF group.

How to Avoid Postoperative Remaining Ossification Mass in Anterior Controllable Antedisplacement and Fusion Surgery

Objectives

To retrospectively review the cases with ossification of the posterior longitudinal ligament (OPLL) treated with anterior controllable antedisplacement and fusion (ACAF). Patients with postoperative remaining ossification mass (PROM) are analyzed to figure out the causes and preventions of this problem.

Methods

A total of 115 patients were included. PROM was identified as remaining OPLL existed in the spinal canal other than included in the vertebral-OPLL complex on postoperative computed tomography. The Japanese Orthopaedic Association scoring system was used to evaluate the neurologic status. Surgery-related complications such as cerebrospinal fluid (CSF) leakage and spinal cord or nerve injury were all recorded. The patients with the PROM group and those without the PROM group were compared.

Results

There were 14 patients with wide-base OPLL (12.2%) and 10 patients (8.7%) with PROM among the 115 patients with OPLL. The 10 patients with PROM were all with wide-base OPLL. The average improvement rate of Japanese Orthopaedic Association score in patients without PROM was significantly larger than that in patients with PROM (69.5 ± 22.6% vs. 36.7 ± 22.0, P < 0.01). Incidence rate of postoperative CSF leakage and neural deterioration were significantly higher in patients with PROM than that in patients without PROM (CSF leakage, 40.0% vs. 5.9%; neural deterioration, 50.0% vs. 3.0%). No other complications were observed.

Conclusions

The occurrence of PROM might cause complications and poor neural function recovery in patients treated with ACAF. Surgical techniques should be noted to avoid PROM in ACAF surgery.

Radiological Characteristics and Surgical Outcome of Patients with Long Ossification of the Posterior Longitudinal Ligament Resulting in Ossified Lesions in the Upper Cervical Spine

OBJECTIVE

Designing surgical strategies for ossified lesions in the upper cervical spine is challenging owing to the complex anatomic structures. The present study aimed to clarify the prevalence of ossified lesions in the upper cervical spine in patients with ossification in the posterior longitudinal ligament and illustrate the clinical features, radiological findings, and surgical outcomes of this abnormality.

METHODS

Demographic and clinical data were collected for all patients preoperatively and included age, gender, body mass index, alcohol and tobacco use, history of diabetes, visual analog score, and Japanese Orthopaedic Association score. The cervical angle, morphology of ossification in the posterior longitudinal ligament, K-line, occupation ratio, space available for the spinal cord, high-intensity zone, and compression ratio of the spinal cord were calculated. The operative approach, technique used, and complications were recorded.

RESULTS

A total of 38 patients were enrolled. The upper cervical segment in 23 patients was not surgically addressed. In the group with the upper cervical segment addressed surgically, 10 patients were treated with C3-C6 open-door laminoplasty and C2 partial laminectomy, 1 with C1-C7 laminoplasty, 1 with C2-C7 laminoplasty, 2 with C3-C6 total and C2 partial laminectomy, and 1 with C1-C5 laminectomy and occipitocervical fusion.

CONCLUSIONS

The development of ossified lesions in the upper cervical spine has a high incidence. Decompressive surgery for upper cervical spine segments should be recommended for patients with severe narrowing of the spinal canal and a high signal intensity that extends to the upper cervical segment of the spinal cord. We hope that the findings from the present study will aid in clinical decision-making and provide useful information that can be incorporated into future guidelines.

Computer-assisted virtual operation planning in anterior controllable anterior-displacement and fusion surgery for ossification of the posterior longitudinal ligament based on actual computed tomography data

OBJECTIVES

To investigate the effect of computer-assisted virtual operation planning (CAVOP) on anterior controllable anterior-displacement and fusion (ACAF) surgery for ossification of the posterior longitudinal ligament (OPLL).

PATIENTS AND METHODS

A total of 25 patients with OPLL were enrolled in the study from September 2017 to December 2017. Preoperative Computed tomography (CT) scanning data were input into Mimics software to reconstruct three-dimensional (3D) models of actual cervical OPLL.Preoperative simulation of each surgical procedure and measurement of main parameters for intraoperative decision were conducted. Postoperative CT were used to test the clinical value of the preoperative planning. Width of vertebrae-OPLL complex (VOC), thickness of resected vertebral body (VB), height of intervertebral spacer, and length of screws and anterior plate were analyzed.

RESULTS

There were no significant differences between the length of screws, width of VOC, and thickness of anterior resection of vertebrae in preoperative CT and postoperative CT. Statistical differences were found between preoperative and postoperative height of intervertebral space and length of anterior plate.

CONCLUSION

A virtual ACAF surgical procedure for OPLL is feasible and useful clinically in surgical planning. It may provide a valuable tool for surgeons in formulating an appropriate surgical plan.

Anterior Controllable Antedisplacement and Fusion as Revision Surgery After Posterior Decompression Surgery in Patients with Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

The aim of the present study was to evaluate the surgical outcomes of anterior controllable antedisplacement and fusion (ACAF) as a revision surgery after posterior decompression surgery (PDS) in patients with ossification of the posterior longitudinal ligament (OPLL).

METHODS

From June 2016 to May 2017, 15 patients (7 men; 8 women) had undergone ACAF as revision after PDS. The Japanese Orthopaedic Association (JOA) score was used to evaluate the pre- and postoperative neurological function. The kappa line and complications were also evaluated.

RESULTS

The 15 patients were followed up for 15.1 ± 1.8 months (range, 12-18). The mean interval between the initial PDS and revision ACAF was 40.3 ± 11.3 months (range, 24-62). The JOA score improved from 8.9 ± 1.6 (range, 5-11) before revision ACAF to 13.9 ± 1.6 (range, 11-16) at the final follow-up evaluation (P < 0.05). The JOA recovery rate was 61.9% ± 15.8% (range, 37.5%-90.9%). The kappa line of 7 patients improved from negative values to positive values after ACAF. Five complications (33.3%) developed in 5 patients. No instrument failure or neurological deterioration was observed during the follow-up period.

CONCLUSION

In the present study, the outcomes of ACAF for revision surgery for OPLL were satisfactory. ACAF could improve neurological function significantly and is an alternative surgical procedure for revision of PDS for OPLL.