A new method to determine whether ossified posterior longitudinal ligament can be resected completely and safely: spinal canal "Rule of Nine" on axial computed tomography

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.

Anterior Controllable Antedisplacement and Fusion (ACAF) Technique for the Treatment of Multilevel Cervical Spondylotic Myelopathy With Spinal Stenosis (MCSMSS): A Retrospective Study of 54 Cases

STUDY DESIGN

Retrospective study.

OBJECTIVE

To investigate the clinical effect of anterior controllable antedisplacement and fusion (ACAF) technique for the treatment of multilevel cervical spondylotic myelopathy with spinal stenosis (MCSMSS), compared with hybrid decompression fixation (HDF).

SUMMARY OF BACKGROUND DATA

A retrospective analysis of 94 cases with MCSMSS was carried out. Fifty-four patients were treated with ACAF, whereas 40 patients were treated with HDF.

METHODS

The operation time, intraoperative blood loss, postoperative complications, Japanese Orthopedic Association score, Neck Disability Index score, parameters at axial computed tomography, cervical curvature and the Kang grade were compared between 2 groups.

RESULTS

The patients were followed up for 12-17 (15.6±1.6) months. Compared with HDF, ACAF group achieved better decompression according to computed tomography measurement and Kang grade (P<0.05), and recovered to a greater cervical Cobb angle (P<0.05). However, Japanese Orthopedic Association score and Neck Disability Index showed no significant difference 1 year after surgery (P>0.05). In addition, ACAF presented longer operation time (P<0.05) and similar intraoperative blood loss (P>0.05), compared with HDF. In terms of complications, ACAF produced less incidences of cerebrospinal fluid leakage, implant complication, epidural hematoma, and C5 palsy compared with HDF.

CONCLUSIONS

ACAF is an effective method for the treatment of MCSMSS. In comparison to HDF, ACAF has the advantages of more sufficient decompression, more satisfactory cervical curvature, and lower incidence rates of complications.

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.

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.

Novel Technique as a Revision Surgery for Failed Anterior Cervical Corpectomy and Fusion in the Treatment of Cervical Myelopathy Due to Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

This article aimed to introduce a novel technique, the "seesaw technique," for failed anterior cervical corpectomy and fusion (ACCF) in the treatment of cervical ossification of the posterior longitudinal ligament.

METHODS

A patient who underwent ACCF 12 years ago and suffered gradually deteriorating neurologic function was referred to our institution. Preoperative imaging showed residual ossified mass at C5/6 level, causing compression to his spinal cord. He patient was treated by the seesaw technique. The main surgical procedures include removal of the plate and screws, removal of the osteophytes and diskectomy of C4/5, resection of the anterior part of C5 vertebral body, establishment of a transverse hinge at C7 vertebral body, installation of cervical plate and hoisting tool, and antedisplacement of C5 vertebral body and titanium mesh. Images were investigated before and after the procedure. The Japanese Orthopaedic Association score was used to evaluate his neurologic function, and surgery-related complications were also analyzed.

RESULTS

The patient acquired significant improvement of his neurologic function 2 days after the surgery, and he could walk by himself without assistance. Postoperative images showed his spinal canal was enlarged sufficiently and the compression at C5/6 level was also released. At 13 months follow-up, his Japanese Orthopaedic Association score increased from 9 before surgery to 14, with an improvement rate of 62.5%. No surgery-related complications were observed during the whole follow-up.

CONCLUSION

The seesaw technique provides satisfactory outcomes with wide enough decompression window and serves as a safe, effective surgical alternative for patients with failed ACCF.

Ossification of the ligamentum flavum in the upper cervical spine: A report of two cases and literature review

Ossification of the ligamentum flavum (OLF) is rarely observed in the cervical spine, particularly not in the upper cervical spine. The present report describes two cases of OLF combined with cervical myelopathy and provides a literature review with a comparative analysis of previous studies and the present cases. Pre-operative CT, MRI and histological examination were performed to confirm the diagnosis of these patients (A 37-year-old female and 63-year-old male). In both cases, histological examination of surgical specimens revealed OLF. The symptoms of the two patients significantly improved after surgery and no recurrence was observed at 13 months after surgery. Furthermore, the clinical outcomes were satisfactory and the internal fixation was solid in the two cases. Review of the literature suggested that further research is required to reveal the optimal treatment methods for upper cervical OLF.

Review of Radiological Parameters, Imaging Characteristics, and Their Effect on Optimal Treatment Approaches and Surgical Outcomes for Cervical Ossification of the Posterior Longitudinal Ligament

Determining the optimal surgical method for cervical ossification of the posterior longitudinal ligament (OPLL) is challenging. The surgical indication should be made based on not only radiological findings, but also the patient’s age, preoperative neurological findings, social background, activities of daily life, and the presence or absence of comorbid diseases. Anterior resection for OPLL with or without wide corpectomy and fusion, posterior decompression with or without relatively long fusion, or anterior and posterior combined surgery may be considered. When evaluating the clinical condition of patients with cervical OPLL before surgery, various radiological parameters should be carefully considered, including the number of spinal segments involved, the cervical alignment or tilt angle, the relationship between OPLL and the C2–7 line (termed the “K-line”), the occupying ratio of OPLL, and the involvement of dural ossification. The objective of this article is to review the radiological parameters in current use for deciding upon the optimal surgical strategy and for predicting surgical outcomes, focusing on cervical OPLL.

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.

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.

Factors associated with surgical outcomes of cervical ossification of the posterior longitudinal ligament

To investigate factors associated with surgical outcomes of cervical ossification of the posterior longitudinal ligament (OPLL). This retrospective study included patients (662 males and 251 females; mean age 55.8 years) with symptomatic OPLL. All patients had been diagnosed with OPLL based on cervical magnetic resonance imaging and computed tomography scans. Demographic, surgical outcome was measured using visual analog scale (VAS) and Japanese Orthopedic Association (JOA) scale scores. The results of our study indicated radicular pain was more common in segmental and circumscribe OPLL subtypes (P < 0.05). An anterior approach was favored in patients with less than 3 involved vertebral levels (P < 0.05). All surgical methods showed good outcomes (P < 0.05). Continuous and mixed OPLL subtypes showed worse surgical outcome with higher VAS and JOA scores (P < 0.05). Laminoplasty and anterior cervical discectomy and fusion were significantly associated with a higher recovery rate (P < 0.05). Among these patients, there were more complications with the anterior approach (P < 0.05). Male gender, open door laminoplasty ipsilateral, and ipsilateral-to-symptom-side opening were associated with postoperative C5 palsy (P < 0.05). Cervical OPLL may cause myelopathy, surgery is a safe and effective treatment for OPLL. There were no differences in clinical outcome according to surgical type, but complication rates varied depending on sex and surgical approach to symptom.

A Modified Laminoplasty Technique to Treat Cervical Myelopathy Secondary to Ossification of the Posterior Longitudinal Ligament (OPLL)

BACKGROUND This study aimed to evaluate the validity of modified laminoplasty in treating close-base OPLL with an occupying ratio of more than 60%. MATERIAL AND METHODS Forty-seven close-base OPLL patients with an occupying ratio of more than 60% were treated through modified laminoplasty (N=22) and combined anterior-posterior approach (N=25) in the study, including 17 females and 30 males, with a mean age of 60.59±6.76 years (ranging from 46 to 75 years). The patients' characteristics, the recovery rate of neurological function, length of the operation, intraoperative blood loss, hospital costs, and complications were recorded and compared between the 2 groups. RESULTS The recovery rate of neurological function did not demonstrate a significant difference between the 2 groups (P=0.886). However, length of the operation and intraoperative blood loss in the modified laminoplasty group were shorter than those in the combined anterior-posterior approach group (P=0.001 and P=0.023). Moreover, the mean hospital costs in the modified laminoplasty group (5166.61±123.27 USD) decreased by 33.6% compared with the combined anterior-posterior approach group (7780.12±256.73 USD). Additionally, the complications of the modified laminoplasty group were lower than in the combined anterior-posterior approach group. CONCLUSIONS Modified laminoplasty may be considered a safe and effective strategy for patients that have demonstrated close-base OPLL with an occupying ratio of more than 60% and who cannot endure the trauma caused by the combined anterior-posterior approach due to medical disease.

Anterior discectomy could still be an alternative to corpectomy in highly migrated cervical disc herniation

OBJECTIVE

For cases of cervical disc herniation, highly migrated cervical disc (HMCD) is clinically rare and usually treated with anterior cervical corpectomy and fusion (ACCF). This study aims to analyze the feasibility of anterior cervical discectomy and fusion (ACDF) for the patients with HMCD.

METHOD

Clinical data of 32 patients with HMCD treated with ACDF or ACCF were retrospectively reviewed. Migration distances of the disc prolapses were measured. The mJOA score was used to evaluate surgical effect.

RESULTS

ACDF was successful in 27 patients while ACCF was used for the remaining 5 because of epidural disc prolapse adhesion or unreachable migrated fragments. Complete spinal cord decompression without residual disc fragments was observed in postoperative MRI of all cases. The mean migration distance of the disc prolapses in ACDF group was 7.3 mm, comparing to 11.4 mm in ACCF group. No disc prolapse in ACDF group exceeded the axial length of the vertebral bodies while three of five in ACCF group did. Preoperative mean mJOA scores in ACDF group and ACCF group were 8.20 ± 2.75 and 6.10 ± 2.15, respectively. Postoperative mean mJOA scores in those two groups were significantly improved to 14.70 ± 1.55 (p < .001) and 12.80 ± 1.72 (p < .001), with an improvement rate of 72.80 ± 4.76% and 62.90 ± 9.46%, respectively.

CONCLUSION

ACDF is feasible for patients with HMCD except for cases of epidural disc prolapse adhesion or huge disc prolapse which migrates over the axial length of the vertebral body. Clinical symptoms can be significantly improved with few serious complications in those patients including ones underwent alternative ACCF due to a failed ACDF.

The preparation of rat's acellular spinal cord scaffold and co-culture with rat's spinal cord neuron in vitro

STUDY DESIGN

The rat's acellular spinal cord scaffold (ASCS) and spinal cord neurons were prepared in vitro to explore their biocompatibility.

OBJECTIVES

The preparation of ASCS and co-culture with neuron may lay a foundation for clinical treatment of spinal cord injury (SCI).

SETTING

Tianjin Medical University General Hospital, ChinaMethods:ASCS was prepared by chemical extraction method. Hematoxylin and eosin (H&E), myelin staining and scanning electron microscope were used to observe the surface structure of ASCS. Spinal cord neurons of rat were separated in vitro, and then co-cultured with prepared ASCS in virto.

RESULTS

The prepared ASCS showed mesh structure with small holes of different sizes. H&E staining showed that cell components were all removed. The ASCS possessed fine three-dimensional network porous structure. DNA components were not found in the ASCS by DNA agarose gel electrophoresis. The cultured cells express neuron-specific enolase (NSE) antigen with long axons. H&E staining showed that the neurons adhered to the pore structures of ASCS, and the cell growth was fine. The survival rate of co-cultured cells was (97.53±1.52%) by MTT detection. Immunohistochemical staining showed that neurons on the scaffold expressed NSE and NeuN antigen. Cells were arranged closely, and the channel structures of ASCS were fully filled with neurons. The cells accumulated in the channel and grew well in good state.

CONCLUSION

The structure of ASCS remained intact, and the neurons were closely arranged in the scaffolds. These results may lay a solid foundation for clinical treatment of SCI when considering glial scar replacement by biomaterials.

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

Purpose

A meta-analysis was conducted to evaluate the clinical outcomes, complications, reoperation rates, and late neurological deterioration between anterior decompression and fusion (ADF) and laminoplasty (LAMP) in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

All related studies published up to August 2015 were acquired by searching PubMed and EMBASE. Exclusion criteria were case reports, revision surgeries, combined anterior and posterior surgeries, the other posterior approaches including laminectomy or laminectomy and instrumented fusion, non-English studies, and studies with quality assessment scores of <7. The main end points including Japanese Orthopedic Association (JOA) score, recovery rate of JOA, cervical lordosis, complication rate, reoperation rate, and late neurological deterioration were analyzed. All available data was analyzed using RevMan 5.2.0 and Stata 12.0.

Results

A total of seven studies were included in the meta-analysis. The mean surgical level of ADF was 3.1, and the mean preoperative occupation ratios of ADF and LAMP group were 55.9% and 51.9%, respectively. No statistical difference was observed with regard to preoperative occupation ratio and preoperative JOA score. Although LAMP group had a higher preoperative cervical lordosis than ADF group (P<0.05, weighted mean difference [WMD] =−5.73, 95% confidence interval [CI] =−9.67–−1.80), significantly decreased cervical lordosis was observed in LAMP group after operation. ADF group had higher postoperative JOA score (P<0.05, WMD =2.18, 95% CI =0.98–3.38) and neurological recovery rate (P<0.05, WMD =27.22, 95% CI =15.20–39.23). Furthermore, ADF group had a lower late neurological deterioration rate than the LAMP group (P<0.05, risk difference =0.16, 95% CI =0.04–0.73). The complication rates of both groups had no statistical difference. However, LAMP group had a significantly lower reoperation rate than ADF group. The reoperation rate of ADF group (20.5%) was almost six times that of LAMP group (3.5%).

Conclusion

Our meta-analysis suggested that ADF was associated with better postoperative neurological function, neurological recovery rate, and less late neurological deterioration than LAMP in the treatment of multilevel cervical OPLL with a high mean occupation ratio. LAMP was associated with a decreased postoperative cervical lordosis, which might be a cause of late neurological deterioration. The complication rates of both groups showed no statistical difference. However, the reoperation rate was significantly higher in ADF group compared with LAMP group. Benefits and risks should be balanced when ADF or LAMP is selected.