Progression of Cervical Ossification of Posterior Longitudinal Ligament After Laminoplasty or Laminectomy With Posterior Fixation

Radiographic characterization of OPLL progression in patients receiving laminoplasty with a minimum of two-years follow-up

Ossification of the posterior longitudinal ligament (OPLL) is a common cause of degenerative cervical myelopathy (DCM) in Asian populations. Characterization of OPLL progression following laminoplasty remains limited in the literature. 29 patients with OPLL received cervical laminoplasty and a minimum of 2-years follow-up. Clinical and radiological surveillance occurred at 3-months, 6-months, 12-months post-op and then at yearly intervals. Transverse (anteroposterior) diameter and sagittal length of OPLL in relation to their cervical vertebral level of localisation was assessed upon immediate post-op radiographs compared to those obtained at subsequent follow-up. OPLL progression was defined as an increase in transverse dimensions and/or length by ≥ 2 mm. The average period of clinical follow-up was 6.7 ± 3.3 years. Upon latest follow-up, 79% of patients demonstrated at least 2 mm of transverse or longitudinal progression of OPLL. This corresponded to 2-years and 5-year progression rates of 54% and 71% respectively. OPLL located over C5 demonstrated the greatest transverse progression rate at (0.24 ± 0.34 mm / year). The mean overall longitudinal progression rate was 1.61 ± 2.06 mm / year. No patients experienced neurological decline resulting from OPLL progression requiring revision decompression during the period of post-operative observation. Characterizing transverse and longitudinal progression by cervical level via radiographs has implications in surgical planning for OPLL and should be consolidated upon post-operative CT/MRI scans as well as larger sample sizes.

Factors Associated With Repeat Surgery in Cervical Ossification of the Posterior Longitudinal Ligaments: Minimum 8-year Follow-up Study

STUDY DESIGN

Single-center retrospective study.

OBJECTIVE

The objective of this study is to identify the factors leading to repeat surgery in patients with cervical ossification of the longitudinal ligament (OPLL) during a minimal 8-year follow-up after the initial surgery.

SUMMARY OF BACKGROUND DATA

The long-term effects of cervical OPLL are well known, but it's not always clear how many patients need to have surgery again because their neurological symptoms get worse.

METHODS

This study is included 117 patients who underwent surgery for cervical OPLL and had a follow-up of at least 8 years. OPLL type, surgical extent, surgical method, and sagittal radiological parameters were measured, and OPLL characteristics were analyzed.

RESULTS

The average age of patients at the time of surgery was 53.2 years, with a male-to-female ratio of 78:39. The median follow-up duration was 122 months (96-170 mo). Out of the total, 20 cases (17.1%) necessitated repeat surgery, among which 8 cases required surgery at the same site as the initial operation. The highest rate of repeat surgery was observed in patients who underwent total laminectomy without fusion (TL), where 6 out of 21 patients (29%) needed a second surgery, and 5 of these (23%) involved the same surgical site. Patients who underwent repeat surgery at the same site exhibited a greater range of motion (ROM) one year postsurgery (16.4 ± 8.5° vs. 23.1 ± 12.7°, P =0.041). In addition, the ROM at 1 year was higher in patients who underwent TL compared with those who had laminoplasty. Furthermore, the recurrence rate for hill-shape OPLL was higher at 30.8% compared to 10% for plateau-shape OPLL ( P = 0.05).

CONCLUSION

Larger cervical ROM 1 year after surgery is related to repeat surgery at the same level as previous surgery, especially in laminectomy without fusion surgery.

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.

Effect of mechanical stimulation on tissue heterotopic ossification: an in vivo experimental study

Background: Heterotopic ossification of tendons and ligaments (HOTL) is a common clinical condition characterized by the absence of discernible features and a lack of effective treatment. In vitro experiments have demonstrated that mechanical stimulation can induce cell differentiation toward osteogenesis, thereby promoting heterotopic ossification. Currently, there are few experimental designs aimed at inducing ligament stretching in mice, and the mechanism of heterotopic ossification may not entirely mirror that observed in clinical cases. Therefore, there is an urgent imperative to develop a novel and feasible animal model. Methods: In this study, all the Enpp1 gene deficiency mice (a mouse model with heterotopic ossification of multiple ligaments) were divided into three groups: the control group, the spinal brake group, and the hyperactive group (treadmill training group). An external spinal fixation device was designed to restrict mice's spinal flexion and extension at 6 weeks of age. The brace was adjusted weekly according to the changes in the size of the mice. Additionally, treadmill training was used to increase activity in the spinal ligaments and Achilles tendons of the mice. Micro-CT scanning and HE staining were performed at 12, 20, and 28 W to evaluate the degree of ossification in the spinal ligament and Achilles tendon. What's more, As one of the mechanical stimulation transduction signals, YAP plays a crucial role in promoting osteogenic differentiation of cells. Immunofluorescence was utilized to assess YAP expression levels for the purpose of determining the extent of mechanical stimulation in tissues. Results: Our findings showed that a few ossification lesions were detected behind the vertebral space of mice at 8 weeks of age. Spinal immobilization effectively restricts the flexion and extension of cervical and thoracic vertebrae in mice, delaying spinal ligament ossification and reducing chronic secondary spinal cord injury. Running exercises not only enhance the ossification area of the posterior longitudinal ligament (PLL) and Achilles tendons but also exacerbate secondary spinal cord injury. Further immunofluorescence results revealed a notable increase in YAP expression levels in tissues with severe ossification, suggesting that these tissues may be subjected to higher mechanical stimulation. Conclusion: Mechanical stimulation plays a pivotal role in the process of heterotopic ossification in tissues. Our study provided valid animal models to further explore the pathological mechanism of mechanical stimulation in HOTL development.

Comparison of the outcome after anterior cervical ossified posterior longitudinal ligament en bloc resection versus posterior total laminectomy and fusion in patients with ossification of the cervical posterior longitudinal ligament: a prospective randomized controlled trial

The optimal procedure for the treatment of ossification of the posterior longitudinal ligament (OPLL) remains controversial. The aim of this study was to compare the outcome of anterior cervical ossified posterior longitudinal ligament en bloc resection (ACOE) with posterior laminectomy and fusion with bone graft and internal fixation (PTLF) for the surgical management of patients with this condition. Between July 2017 and July 2019, 40 patients with cervical OPLL were equally randomized to undergo surgery with an ACOE or a PTLF. The clinical and radiological results were compared between the two groups. The Japanese Orthopaedic Association (JOA) score and recovery rate in the ACOE group were significantly higher than those in the PTLF group during two years postoperatively, provided that the canal occupying ratio (COR) was > 50%, or the K-line was negative. There was no significant difference in JOA scores and rate of recovery between the two groups in those in whom the COR was < 50%, or the K-line was positive. There was no significant difference in the Cobb angle between C2 and C7, sagittal vertical axis, cervical range of motion (ROM), and complications between the two groups. Compared with PTLF, ACOE is a preferred surgical approach for the surgical management of patients with cervical OPLL in that it offers a better therapeutic outcome when the COR is > 50%, or the K-line is negative, and it also preserves better cervical curvature and sagittal balance. The prognosis of ACOE is similar to that of PTLE when the COR is < 50%, or the K-line is positive.

Cervical Myelopathy: An Update on Posterior Decompression

STUDY DESIGN

This was a narrative review.

OBJECTIVE

The aim was to discuss current methods and review updated outcome studies regarding posterior decompression in the management of cervical myelopathy.

SUMMARY OF BACKGROUND DATA

Progressive myelopathy in the cervical segments is an indication for urgent surgical management. Although nonoperative treatment is an option in mild to moderate cases, the majority of patients will experience deterioration in neurological function requiring surgical decompression.

METHODS

A review of the literature was performed using PubMed to provide updated information regarding posterior cervical decompression in the management of myelopathy.

RESULTS

There are numerous studies comparing outcome data between cervical laminectomy and fusion with laminoplasty. While each technique has advantages and disadvantages, both provide adequate decompression and good long-term outcomes in patients meeting appropriate criteria.

CONCLUSIONS

Posterior decompression is an important approach for spine surgeons to have in their toolkits when treating cervical myelopathy.

Comparison of Interventions for Cervical Ossification of Posterior Longitudinal Ligament: A Systematic Review and Network Meta-Analysis

OBJECTIVE

To summarize the literature and systematically evaluate outcomes for ossification of posterior longitudinal ligament interventions including anterior cervical corpectomy and fusion (ACCF), anterior controllable antedisplacement and fusion (ACAF), laminoplasty (LP), and laminectomy with fusion (LF).

METHODS

We searched PubMed, Embase, Web of Science, and the Cochrane Library from January 1990 to March 2021. Patient demographic data, Japanese Orthopaedic Association score, cervical lordosis and overall complications were analyzed.

RESULTS

We evaluated 30 studies involving 2038 patients. Patients undergoing ACCF had improved Japanese Orthopaedic Association scores compared with patients undergoing LP (weighted mean difference [WMD] 1.17, 95% confidence interval [CI] 0.49-1.85) and LF (WMD 1.21, 95% CI 0.17-2.24). Patients with ACAF had better cervical lordosis compared with patients with ACCF (WMD 7.00, 95% CI 0.72-13.27), LP (WMD 10.27, 95% CI 4.64-15.90), and LF (WMD 8.98, 95% CI 2.48-15.47). Additionally, ACAF (odds ratio 0.24, 95% CI 0.07-0.84) and LP (odds ratio 0.50, 95% CI 0.28-0.90) had a lower incidence of complications compared with ACCF.

CONCLUSIONS

Japanese Orthopaedic Association score outcomes indicated that ACCF was superior to LP and LF. ACAF had the largest cervical lordosis among all procedures. ACCF showed a higher incidence of overall complications compared with ACAF and LP.

Modified K-line for Making Decisions Regarding the Surgical Approach in Patients with K-line (-) OPLL

Objective

To investigate whether the modified K‐line can be used to predict the clinical outcome and to determine the surgical approach for K‐line (−) patients with cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

A new modified K‐line was defined as the line connecting the midpoints of the spinal cord at C₄ and C₆ on the lateral cervical radiographs. A total of four consecutive patients (three men and one woman) with cervical myelopathy due to OPLL were included in this research. The patients were diagnosed with OPLL with K‐line (−) while they were also classified as modified K‐line (+). Preoperative modified K‐line was used to predict the surgical outcome in K‐line (−) patients with OPLL according to the original K‐line. And a modified laminoplasty with C₃ laminectomy and C_4‐6 bilateral open‐door laminoplasty was adopted to perform on all the patients. The Japanese Orthopaedic Association scores before surgery and at 1‐year follow‐up after surgery were evaluated and the recovery rate was calculated. The visual analogue scale (VAS) scores were also evaluated before surgery and after surgery. Furthermore, cervical plain radiographs in neutral position before surgery and after surgery were obtained to measure C₂–C₇ angles for assessing the cervical sagittal alignment.

Results

The results showed that good neurological improvement could be achieved in all K‐line (−) patients who underwent C₃ laminectomy with C₄–C₆ bilateral open‐door laminoplasty. The Postoperative JOA scores improved from 13.5 to 16.5, from 11 to 16.5, from 13 to 16, and from 12.5 to 13, respectively. The mean recovery rate was 65.4% in the K‐line (−) patients. And the VAS scores dropped from 3 to 1, 5 to 2, 5 to 3, and 4 to 2, respectively. The JOA and VAS scores showed satisfaction in all patients at the 1‐year follow‐up. Relatively satisfactory and stable cervical sagittal alignment was observed on postoperative lateral radiography in all patients at the 3‐month follow‐up period. There were no postoperative complications associated with this technique found in all the patients.

Conclusions

Modified K‐line may predict the clinical outcome of this modified laminoplasty and offer guidance regarding the choice of surgical method for K‐line (−) patients with OPLL. Additionally, C₃ laminectomy with C₄–C₆ bilateral open‐door laminoplasty should be recommended for the use in patients with K‐line (−) OPLL, who were also classified as modified K‐line (+). However, further studies with more cases will be required to reveal its generalizability and availability.

Review of laminoplasty versus laminectomy in the surgical management of cervical spondylotic myelopathy

Background:

We reviewed the literature comparing the indications/efficacy of laminectomy (LA) with or without fusion versus laminoplasty (LP) in the treatment of cervical spondylotic myelopathy (CSM).

Methods:

We identified 14 studies in PubMed/Medline to include in our analysis. Outcomes were assessed utilizing the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS), Neck Disability Index, and Nurick scale. Variables studied included ossification of the posterior longitudinal ligament (OPLL), cervical range of motion (ROM), the C2-C7 sagittal Cobb angle, the Ishihara index, and the Hirabayashi scale. Patients with cervical trauma/fracture, infection, or tumor were excluded from the study.

Results:

In these 14 studies, there were no significant differences between LA and LP groups in terms of preoperative versus postoperative: JOA scores (e.g., including the improvement rate), VAS scores, and ROM. However, the LA patients demonstrated greater postoperative cervical lordosis versus those in the LP group.

Conclusion:

At present, there are no guidelines for choosing LA versus LP for treating CSM. Factors that should be considered when choosing one procedure over the other should include the patients’ preoperative clinical status, the type of CSM, the pathological extent of OPLL, and whether there is a sufficient cervical lordotic curvature.

Influence of K-line on intraoperative and hidden blood loss in patients with ossification of the posterior longitudinal ligament when undergoing unilateral open-door laminoplasty

Background

The K-line is a virtual straight line that connects the midpoints of the anteroposterior spinal canal diameter from C2 to C7 on a cervical lateral X-ray film. Patients with cervical ossification of the posterior longitudinal ligament (OPLL), in which the peak of the OPLL exceeds the K-line (K-line [-]), are less likely to experience sufficient decompression after laminoplasty compared with patients for whom the OPLL does not exceed the K-line (K-line [+]). This retrospective study investigated the influence of K-line position relative to the OPLL on intraoperative and hidden blood loss during unilateral open-door laminoplasty for OPLL.

Methods

Data were retrospectively analyzed of 108 patients with OPLL who underwent unilateral open-door laminoplasty between April 2015 and March 2018. Patient cases were categorized as K-line (+) or (-). The evaluated perioperative parameters were haematocrit, haemoglobin, intraoperative and hidden blood loss, surgical time, postoperative drainage, and complications. Radiological parameters included ossification occupancy ratio and C2-7 lordosis.

Results

The K-line (+) and K-line (-) groups were statistically comparable with regard to age, gender, body mass index, OPLL classification, medication history, C2-7 lordosis, postoperative haemoglobin and haematocrit, postoperative drainage, hidden blood loss, and complications. The occupying ratio of the K-line (-) group was significantly greater than that of the K-line (+) group (49.5 ± 15.3% cf. 42.3 ± 10.1%; P = 0.006), and the intraoperative blood loss was also significantly higher (286 ± 110.5 mL cf. 205.5 ± 98.3 L, P = 0.003). The hidden blood loss of the K-line (-) group was higher than that of the K-line (+), but not significantly (295.5 ± 112.6 mL cf. 265.6 ± 103.8 mL; P = 0.072).

Conclusion

Intraoperative and hidden blood loss associated with unilateral open-door laminoplasty can be predicted by the spatial relationship of the K-line and osteophyte. This relationship is a simple and practical index that may help surgeons determine the appropriate surgical strategy for patients with OPLL.