Comparative Analysis of Postoperative Sagittal Balance in Expansive Open-Door Laminoplasty versus Laminectomy with Fusion for Multilevel Ossification of Posterior Longitudinal Ligament: A Retrospective Study

BACKGROUND This single-center study included 80 patients with multilevel cervical ossification of the posterior longitudinal ligament (OPLL) and aimed to compare postoperative sagittal balance following treatment with expansive open-door laminoplasty (LP) vs total laminectomy with fusion (LF). MATERIAL AND METHODS Data of 80 patients with multilevel OPLL treated with LP vs LF between January 2017 and January 2022 were retrospectively analyzed. The basic data, cervical sagittal parameters, and clinical outcomes of the patients were counted in the preoperative and postoperative periods, and complications were recorded. Forty patients underwent LP and 40 underwent LF. Cervical sagittal parameters were compared between and within the 2 groups. Clinical outcomes and complications were compared between the 2 groups. RESULTS At last follow-up, the postoperative C2-C7 Cobb angel, T1 slope (T1S), and C7 slope (C7S) were significantly higher in the LF group than in the LP group (P<0.001). C2-C7 SVA (cSVA) was slightly higher in the LF group (P>0.05) and significantly higher in the LP group (P<0.05). The incidence of postoperative complications in the LP group was significantly lower than in the LF group (P=0.02). The postoperative scores on the Visual Analog Scale (VAS), Neck Disability Index (NDI), and Japanese Orthopedic Association (JOA) were significantly improved in both groups (P<0.001). CONCLUSIONS Both procedures had good outcomes in neurological improvement. After posterior surgery, the cervical vertebrae all showed a tilting forward. Compared to LP, LF may change cervical balance in Cobb angel, T1S. LF has better efficacy in improving cervical lordosis compared with LP. Patients with high T1 slope after surgery may has more axial pain.

[Treatment of cervical ossification of posterior longitudinal ligament with titanium alloy trabecular bone three-dimensional printed artificial vertebral body]

Objective

To evaluate the effectiveness of using titanium alloy trabecular bone three-dimensional (3D) printed artificial vertebral body in treating cervical ossification of the posterior longitudinal ligament (OPLL).

Methods

A retrospective analysis was conducted on clinical data from 45 patients with cervical OPLL admitted between September 2019 and August 2021 and meeting the selection criteria. All patients underwent anterior cervical corpectomy and decompression, interbody bone graft fusion, and titanium plate internal fixation. During operation, 21 patients in the study group received titanium alloy trabecular bone 3D printed artificial vertebral bodies, while 24 patients in the control group received titanium cages. There was no significant difference in baseline data such as gender, age, disease duration, affected segments, or preoperative pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), vertebral height, and C 2-7Cobb angle ( P>0.05). Operation time, intraoperative blood loss, and occurrence of complications were recorded for both groups. Preoperatively and at 3 and 12 months postoperatively, the functionality and symptom relief were assessed using JOA scores, VAS scores, and NDI evaluations. The vertebral height and C 2-7 Cobb angle were detected by imaging examinations and the implant subsidence and intervertebral fusion were observed.

Results

The operation time and incidence of complications were significantly lower in the study group than in the control group ( P<0.05), while the difference in intraoperative blood loss between the two groups was not significant ( P>0.05). All patients were followed up 12-18 months, with the follow-up time of (14.28±4.34) months in the study group and (15.23±3.54) months in the control group, showing no significant difference ( t=0.809, P=0.423). The JOA score, VAS score, and NDI of the two groups improved after operation, and further improved at 12 months compared to 3 months, with significant differences ( P<0.05). At each time point, the study group exhibited significantly higher JOA scores and improvement rate compared to the control group ( P<0.05); but there was no significantly difference in VAS score and NDI between the two groups ( P>0.05). Imaging re-examination showed that the vertebral height and C 2-7Cobb angle of the two groups significantly increased at 3 and 12 months after operation ( P<0.05), and there was no significant difference between 3 and 12 months after operation ( P>0.05). At each time point, the vertebral height and C 2-7Cobb angle of the study group were significantly higher than those of the control group ( P<0.05), and the implant subsidence rate was significantly lower than that of the control group ( P<0.05). However, there was no significant difference in intervertebral fusion rate between the two groups ( P>0.05).

Conclusion

Compared to traditional titanium cages, the use of titanium alloy trabecular bone 3D-printed artificial vertebral bodies for treating cervical OPLL results in shorter operative time, fewer postoperative complications, and lower implant subsidence rates, making it superior in vertebral reconstruction.

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.

Comparison of Postoperative Complications and Outcomes in Anterior Cervical Spine Surgery: Ossification of the Posterior Longitudinal Ligament Versus Cervical Spondylotic Myelopathy

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To compare the frequency of complications and outcomes between patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine and those with cervical spondylotic myelopathy (CSM) who underwent anterior surgery.

SUMMARY OF BACKGROUND DATA

Anterior cervical spine surgery for OPLL is an effective surgical procedure; however, it is complex and technically demanding compared with the procedure for CSM. Few reports have compared postoperative complications and clinical outcomes after anterior surgeries between the 2 pathologies.

METHODS

Among 1434 patients who underwent anterior cervical spine surgery at 3 spine centers within the same spine research group from January 2011 to March 2021, 333 patients with OPLL and 488 patients with CSM were retrospectively evaluated. Demographics, postoperative complications, and outcomes were reviewed by analyzing medical records. In-hospital and postdischarge postoperative complications were investigated. Postoperative outcomes were evaluated 1 year after the surgery using the Japanese Orthopaedic Association score.

RESULTS

Patients with OPLL had more comorbid diabetes mellitus preoperatively than patients with CSM ( P <0.001). Anterior cervical corpectomies were more often performed in patients with OPLL than in those with CSM (73.3% and 14.5%). In-hospital complications, such as reoperation, cerebrospinal fluid leak, C5 palsy, graft complications, hoarseness, and upper airway complications, occurred significantly more often in patients with OPLL. Complications after discharge, such as complications of the graft bone/cage and hoarseness, were significantly more common in patients with OPLL. The recovery rate of the Japanese Orthopaedic Association score 1 year postoperatively was similar between patients with OPLL and those with CSM.

CONCLUSION

The present study demonstrated that complications, both in-hospital and after discharge following anterior spine surgery, occurred more frequently in patients with OPLL than in those with CSM.

Comparison of Anterior Controllable Antedisplacement and Fusion Versus Laminoplasty in the Treatment of Multisegment Ossification of Cervical Posterior Longitudinal Ligament: A Meta-Analysis of Clinical

OBJECTIVE

This study aims to provide a comprehensive summary of the existing literature and conduct a systematic evaluation of the clinical outcomes associated with anterior controllable antedisplacement and fusion (ACAF) and posterior laminoplasty (LP) for the treatment of multisegment ossification of the cervical posterior longitudinal ligament (OPLL).

METHODS

We conducted an electronic search of databases, including PubMed, Embase, Cochrane Library, and CNKI, from the inception of the initial database to March 2023. We analyzed various parameters, including demographic data, operation time, intraoperative blood loss, cervical curvature, Japanese Orthopaedic Association (JOA) scores, Visual Analog Scale (VAS) scores, and postoperative complications. Two independent reviewers screened the literature, extracted data, and assessed the risk of bias in the included studies. Meta-analysis was performed using RevMan 5.4 software.

RESULTS

Our evaluation encompassed 7 studies involving a total of 467 patients. The patient cohort was divided into 2 groups: Group A (ACAF) comprised 226 patients, while Group B (LP) comprised 241 patients. Overall, our statistical analysis revealed significant differences between the 2 groups (P < 0.05) in terms of intraoperative blood loss, operative time, JOA score, JOA score improvement rate, postoperative VAS score, postoperative cervical curvature, and the incidence of certain postoperative complications (C5 nerve root paralysis, dysphagia, and axial symptoms). However, there was no statistically significant difference in the incidence of postoperative cerebrospinal fluid leakage and postoperative total complications between the 2 groups (P > 0.05).

CONCLUSIONS

The findings of this study suggest that, in the treatment of multilevel cervical OPLL, ACAF yields superior outcomes compared to LP. Specifically, ACAF improves postoperative neurologic function, reduces postoperative pain, lowers intraoperative blood loss, improves postoperative cervical curvature, and decreases the incidence of C5 nerve root paralysis and postoperative axial symptoms. Nonetheless, ACAF is associated with longer operative times and a higher incidence of postoperative dysphagia, though the overall incidence of postoperative complications is similar. It is important to note that these conclusions should be interpreted cautiously due to the limited sample size and the variable quality of the included studies. Further research involving larger, high-quality studies is warranted to validate these findings.

Comparison of radiological and clinical outcomes of cervical laminoplasty versus lateral mass screw fixation in patients with ossification of the posterior longitudinal ligament

PURPOSE

This study aimed to compare cervical sagittal parameters and clinical outcomes between patients undergoing cervical laminoplasty(CL) and those undergoing lateral mass screw fixation(LMS).

METHODS

We retrospectively studied 67 patients with multilevel ossification of the posterior longitudinal ligament (OPLL) of the cervical spine who underwent lateral mass screw fixation (LMS = 36) and cervical laminoplasty (CL = 31). We analyzed cervical sagittal parameters (C2-7 sagittal vertical axis (C2-7 SVA), C0-2 Cobb angle, C2-7 Cobb angle, C7 slope (C7s), T1 slope (T1s), and spino-cranial angle (SCA)) and clinical outcomes (visual analog scale [VAS], neck disability index [NDI], Japanese Orthopaedic Association [JOA] scores, recovery rate (RR), and minimum clinically significant difference [MCID]). The cervical sagittal parameters at the last follow-up were analyzed by binary logistic regression. Finally, we analyzed the correlation between the cervical sagittal parameters and each clinical outcome at the last follow-up after surgery in both groups.

RESULTS

At the follow-up after posterior decompression in both groups, the mean values of C2-C7 SVA, C7s, and T1s in the LMS group were more significant than those in the CL group (P ≤ 0.05). Compared with the preoperative period, C2-C7 SVA, T1s, and SCA gradually increased, and the C2-C7 Cobb angle gradually decreased after surgery (P < 0.05). The improvement in the JOA score and the recovery rate was similar between the two groups, while the improvement in the VAS-N score and NDI score was more significant in the CL group (P = 0.001; P = 0.043). More patients reached MCID in the CL group than in the LMS group (P = 0.036). Binary logistic regression analysis showed that SCA was independently associated with whether patients reached MCID at NDI postoperatively. SCA was positively correlated with cervical NDI and negatively correlated with cervical JOA score at postoperative follow-up in both groups (P < 0.05); C2-7 Cobb angle was negatively correlated with cervical JOA score at postoperative follow-up (P < 0.05).

CONCLUSION

CL may be superior to LMS in treating cervical spondylotic myelopathy caused by OPLL. In addition, smaller cervical SCA after posterior decompression may suggest better postoperative outcomes.

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.

Different cutoff value of motor evoked potentials for the postoperative outcome in the ossification of the posterior longitudinal ligament surgery in the cervical and thoracic spine

BACKGROUND CONTEXT

Transcranial muscle motor evoked potentials (Tc-mMEPs), a key component of intraoperative neurophysiologic monitoring (IONM), effectively reflect the changes in corticospinal tract integrity and are closely related to the occurrence of the postoperative motor deficit (PMD). Most institutions have applied a specified (fixed) alarm criterion for the heterogeneous groups in terms of etiologies or lesion location. However, given the high risk of PMD in ossification of the posterior longitudinal ligament (OPLL) surgery, it is essential to determine a tailored cutoff value for IONM.

PURPOSE

We aimed to establish the intraoperative cutoff value of Tc-mMEPs reduction for predicting PMD in OPLL according to lesion levels.

DESIGN

Retrospective analysis using a review of electrical medical records.

PATIENT SAMPLE

In this study, we included 126 patients diagnosed with OPLL, who underwent surgery and IONM.

OUTCOME MEASURES

The occurrence of PMD immediately and 1 year after operation, as well as the decrement of intraoperative Tc-mMEPs amplitude.

METHODS

We analyzed OPLL surgery outcomes using Tc-mMEPs monitoring. Limbs with acceptable baseline Tc-mMEPs in the tibialis anterior or abductor hallucis were included in the final set. PMD was defined as a ≥1 decrease in Medical Research Council score in the legs, and it was evaluated immediately and 1year after operation. The reduction ratios of Tc-mMEPs amplitude compared with baseline value were calculated at the two time points: the maximal decrement during surgery and at the end of surgery. Receiver operating characteristic curve analysis was used to determine the cutoff value of Tc-mMEPs amplitude decrement for predicting PMDs.

RESULTS

In total, 203 limbs from 102 patients with cervical OPLL and 42 limbs from 24 patients with thoracic OPLL were included. PMD developed more frequently in thoracic lesions than in cervical lesions (immediate, 9.52% vs 2.46%; 1 year, 4.76% vs 0.99%). The Tc-mMEPs amplitude cutoff point at the end of surgery for PMD (both immediate and 1-year) was a decrease of 93% in cervical and 50% in thoracic OPLL surgeries. Similarly, the Tc-mMEPs amplitude cutoff point at the maximal decrement during surgery for PMD (both immediate and 1 year) was a reduction of 97% in cervical and 85% in thoracic OPLL surgeries.

CONCLUSIONS

The thoracic lesion exhibited a lower cutoff value than the cervical lesion for both immediate and long-term persistent PMD in OPLL surgery (Tc-mMEPs at the end of surgery measuring 93% vs 50%; and Tc-mMEPs at the maximal decrement measuring 97% vs 85% for cervical and thoracic lesions, respectively). To enhance the reliability of monitoring, considering the application of tailored alarm criteria for Tc-mMEPs changes based on lesion location in OPLL could be beneficial.

A Convolutional Neural Network for Automated Detection of Cervical Ossification of the Posterior Longitudinal Ligament using Magnetic Resonance Imaging

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

We aimed to develop and validate a convolutional neural network (CNN) model to distinguish between cervical ossification of posterior longitudinal ligament (OPLL) and multilevel degenerative spinal stenosis using Magnetic Resonance Imaging (MRI) and to compare the diagnostic ability with spine surgeons.

SUMMARY OF BACKGROUND DATA

Some artificial intelligence models have been applied in spinal image analysis and many of promising results were obtained; however, there was still no study attempted to develop a deep learning model in detecting cervical OPLL using MRI images.

MATERIALS AND METHODS

In this retrospective study, 272 cervical OPLL and 412 degenerative patients underwent surgical treatment were enrolled and divided into the training (513 cases) and test dataset (171 cases). CNN models applying ResNet architecture with 34, 50, and 101 layers of residual blocks were constructed and trained with the sagittal MRI images from the training dataset. To evaluate the performance of CNN, the receiver operating characteristic curves of 3 ResNet models were plotted and the area under the curve were calculated on the test dataset. The accuracy, sensitivity, and specificity of the diagnosis by the CNN were calculated and compared with 3 senior spine surgeons.

RESULTS

The diagnostic accuracies of our ResNet34, ResNet50, and ResNet101 models were 92.98%, 95.32%, and 97.66%, respectively; the area under the curve of receiver operating characteristic curves of these models were 0.914, 0.942, and 0.971, respectively. The accuracies and specificities of ResNet50 and ResNet101 models were significantly higher than all spine surgeons; for the sensitivity, ResNet101 model achieved better values than that of the 2 surgeons.

CONCLUSION

The performance of our ResNet model in differentiating cervical OPLL from degenerative spinal stenosis using MRI is promising, better results were achieved with more layers of residual blocks applied.

[Clinical observation on the treatment of ossification of the posterior longitudinal ligament of the cervical spine using 3D printed self-stable zero-profile artificial vertebral body]

Objective: To observe the clinical efficacy of a 3D printed self-stable zero-profile artificial vertebral body for anterior cervical corpectomy decompression and fusion in the treatment of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. Methods: In this prospective randomized controlled trial, patients diagnosed with OPLL in Luohe Central Hospital from January to July 2022 were divided into a zero-profile group (3D printed self-stable zero-profile artificial vertebral body was used for internal fixation and fusion after anterior cervical subtotal decompression,) and titanium-mesh group (titanium-mesh and titanium plate were used for internal fixation and fusion after anterior cervical subtotal decompression) according to envelope random method. Operation time, intraoperative blood loss, Japanese Orthopaedic Association (JOA) score and improvement rate, incidence of postoperative prosthesis subsidence, and bone graft fusion were recorded and compared between the two groups. Results: Finally, 21 patients in the zero notch group and 20 patients in the titanium mesh group were included in the study and were followed-up. In the zero-profile group, there were 16 males and 5 females, aged (48.0±12.7) years. In the titanium-mesh group, there were 14 males and 6 females, aged (49.8±10.2) years. All the 41 patients successfully completed the operation. In the zero-profile group, the surgical time was (50.04±8.45) minutes, the blood loss was (95.38±26.07) ml and the hospitalization cost was (42.32±6.12) thousand yuan. In the titanium-mesh group, the surgical time was (59.20±11.95) minutes, the blood loss was (93.10±27.86) ml and the hospitalization cost was (42.10±6.71) thousand yuan. The surgical time in the zero-profile group was shorter than that in the titanium-mesh group (P=0.007), and there was no statistically significant difference in blood loss and hospitalization costs between the two groups (both P>0.05). The 41 patients were followed-up for (14.29±1.45) months. Four cases (20.0%) in the titanium mesh group experienced swallowing difficulties and 0 cases in the zero incision group, the difference between the two groups was statistically significant (P=0.048). No intraoperative hematoma, spinal cord nerve recompression, airway crisis, incision infection complications, and no steel plate or screw breakage or displacement occurred after surgery. At the last follow-up, all cases had bone fusion. At the follow-up of 12 months after surgery, the JOA score of the zero incision group increased from preoperative (10.33±1.71) points to (15.47±0.81) points, with an improvement rate of 76.1%±15.7%; the JOA score of the titanium mesh group increased from (10.30±1.75) points to (15.30±0.92) points, with an improvement rate of 73.2%±16.7%; there was no statistically significant difference in improvement rate between the two groups (P=0.580). At the follow-up of 12 months after surgery, 1 case (4.8%) in the zero incision group and 8 cases (40.0%) in the titanium mesh group experienced implant sinking, and the difference between the two groups was statistically significant (P=0.009). Conclusion: Compared with titanium-mesh, 3D printed self-stable zero-profile artificial vertebral body for the treatment of OPLL of the cervical spine can achieve good surgical efficacy, shorter surgical time, lower incidence of postoperative chronic swallowing discomfort, and can provide a better bone material bonding interface and be less prone to prosthesis settlement.

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.

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.

Percutaneous Fully-endoscopic Anterior Transcorporeal Procedure for the Treatment of Isolated Ossification of the Posterior Longitudinal Ligament in the Cervical Spine: A Case Report

BACKGROUND

With the development of spinal endoscopic techniques, on the basis of our previous experience in treating various types of cervical disc herniation with this endoscopic technique, we took the lead in applying the percutaneous fully endoscopic anterior transcorporeal procedure to be utilized in the treatment of the isolated cervical ossification of the posterior longitudinal ligament (OPLL).

CASE PRESENTATION

A 66-year-old male patient who weighed 57 kg, with a height of 169 cm was admitted to the hospital on September 16, 2021 because of recurrent pain and numbness in the neck, shoulder, and right arm for 2 years, which as aggravated for the last 2 weeks. Two years ago, the patient developed neck and shoulder pain accompanied by right arm pain without obvious predisposing factors, and numbness in the first web space of the right hand. In the last 2 weeks, he had difficulty moving the right arm, but no pain or numbness in the contralateral arm. MRI and CT scans demonstrated that the ossified posterior longitudinal ligament of the cervical 5/6 vertebrae with spinal canal stenosis and seriously compressed the spinal cord patient was treated with a percutaneous fully endoscopic anterior transcorporeal procedure.

CONCLUSION

Our percutaneous fully endoscopic anterior transcorporeal procedure is a feasible, minimally invasive surgery for treating isolated ossification of the posterior longitudinal ligament in the cervical spine.

Effects of Cervical Paravertebral Extensors in Patients with Cervical Ossification of the Posterior Longitudinal Ligament Grouped According to mK-Line

OBJECTIVES

The objective of this study was to quantify the morphology, composition, and asymmetry of the paravertebral extensor muscles (PSEMs) in patients with cervical ossification of the posterior longitudinal ligament (OPLL) who had different modified K-line (mK-line) and the minimum interval between the mK-line and OPLL (INTmin ) values and to investigate the relationship between PSEMs and symptoms and outcomes following laminoplasty. These original findings elucidated that the atrophy of PSEMs could predict decompression outcomes and provided a theoretical basis for paraspinal muscle rehabilitation.

METHODS

A total of 94 consecutive patients who underwent laminoplasty for OPLL between January 2020 and January 2022 were enrolled in this retrospective study. The relative cross-sectional areas (rCSA), functional cross-sectional areas (rFCSA), and FCSA/CSA ratio of the multifidus (MF), semispinalis cervicalis (SSCe), semispinalis capitis (SSCa), and splenius capitis (SpCa) were measured at the C3-C7 segments on cervical magnetic resonance imaging (MRI). This study compared the differences between the mK-line (+) group and the mK-line (-) group, as well as between the INTmin  <4 mm group and the INTmin  ≥4 mm group, using the independent t-test or Mann-Whitney test for continuous variables and the χ2 -test for categorical variables. The correlations between the PSEMs and symptoms were analyzed using either the Pearson or Spearman correlation coefficient.

RESULTS

The relative total CSA (rTCSA) of the PSEMs, especially the MF, was significantly smaller in the mK-line (-) group. However, the FCSA/CSA of the right deep extensor muscle (DEM) was larger. The asymmetry of the MF TFCSA/TCSA showed a significant difference between the mK-line groups. In the INTmin  <4 mm group, the PSEMs rCSA and rFCSA were significantly smaller, while the bilateral MF TFCSA/TCSA and right SSCe TFCSA/TCSA were larger. The asymmetry of the superficial extensor muscle rCSA was significantly lower in the group with INTmin  <4 mm. The postoperative modified Japanese Orthopedic Association score (mJOA) and mJOA recovery rate were positively correlated with the INTmin and DEM rCSA and negatively correlated with the asymmetry of MF FCSA/CSA.

CONCLUSIONS

In patients with mK-line (-) or INTmin  <4 mm, the PSEMs were smaller, and the DEM atrophy and composition changes were predominant. The MF asymmetry was higher in patients with mK-lines (-), whereas the SEM atrophy and asymmetry were more prevalent in patients with INTmin  <4 mm. The DEM was related to the preoperative and postoperative mJOA scores. DEM-preserving surgery or DEM-specific rehabilitation exercises can improve the recovery of patients with OPLL during the perioperative period. In addition, attention should be paid to the evaluation of the SEM, especially the SpCa at the C3 and C5 levels.

Assessing Range of Motion Gap in Circumferential Surgery for Cervical Myelopathy due to Ossification of the Posterior Longitudinal Ligament

OBJECTIVE

Only a few studies have investigated the gap range of motion (gROM) in cervical myelopathy or deformity caused by ossification of the posterior longitudinal ligament (OPLL). The aim of this study is to investigate the correlation between the individual gROM and the postoperative clinical outcomes of patients with OPLL.

METHODS

Consecutive patients of cervical myelopathy caused by OPLL were analyzed retrospectively. The clinical outcomes were evaluated using Visual Analogue Scale scores of the neck and arm pain and the Japanese Orthopaedic Association scores. Radiologic measurements included flexion ROM (fROM), which was defined as the difference of cervical lordosis in flexion and neutral positions, extension ROM (eROM), defined as the difference between neutral and extension positions, and gROM, defined as the difference between fROM and eROM. Patients were grouped by the values of gROM, and comparisons of all outcomes were made between the groups.

RESULTS

A total of 42 patients underwent surgery. The patients with greater gROM did not differ from those with smaller gROM by demographic characteristics. During follow-up (mean 45.8 months), both groups had similar improvements, but the C5 palsy rates were higher in the greater gROM group than in the smaller gROM group (71% and 22%, P < 0.05).

CONCLUSIONS

Simultaneous circumferential decompression and fixation is an effective surgical option for patients with cervical myelopathy caused by OPLL. A higher rate of postoperative C5 palsy was observed in the patients with greater gROMs after surgery, although all patients presented with similar clinical improvements.

Clinical outcome of surgical management of mild cervical compressive myelopathy based on minimum clinically important difference

BACKGROUND CONTEXT

Cervical compressive myelopathy (CCM), caused by cervical spondylosis (cervical spondylotic myelopathy [CSM]) or ossification of the posterior longitudinal ligament (OPLL), is a common neurological disorder in the elderly. For moderate/severe CCM, surgical management has been the first-line therapeutic option. Recently, surgical management is also recommended for mild CCM, and a few studies have reported the surgical outcome for this clinical population. Nonetheless, the present knowledge is insufficient to determine the specific surgical outcome of mild CCM.

PURPOSE

To examine the surgical outcomes of mild CCM while considering the minimum clinically important difference (MCID).

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patients who underwent subaxial cervical surgery for CCM caused by CSM and OPLL between 2013 and 2022 were enrolled.

OUTCOME MEASURES

The Japanese Orthopedic Association score (JOA score) was employed as the clinical outcomes. Based on previous reports, the JOA score threshold to determine mild myelopathic symptoms was set at ≥14.5 points, and the MCID of the JOA score for mild CCM was set at 1 point.

METHODS

The patients with a JOA score of ≥14.5 points at baseline were stratified into the mild CCM and were examined while considering the MCID. The mild CCM cohort was dichotomized into the improvement group, including the patients with an achieved MCID (JOA score ≥1 point) or with a JOA score of 17 points (full mark) at 1 year postoperatively, and the nonimprovement group, including the others. Demographics, symptomatology, radiographic findings, and surgical procedure were compared between the two groups and studied using the receiver operating characteristic (ROC) curve.

RESULTS

Of 335 patients with CCM, 43 were stratified into the mild CCM cohort (mean age, 58.5 years; 62.8% male). Among them, 25 (58.1 %) patients were assigned to the improvement group and 18 (41.9 %) were assigned to the nonimprovement group. The improvement group was significantly younger than the nonimprovement group; however, other variables did not significantly differ. ROC curve analysis showed that the optimal cutoff point of the patient's age to discriminate between the improvement and nonimprovement groups was 58 years with an area under the curve of 0.702 (p=.015).

CONCLUSIONS

In the present study, the majority of patients with mild CCM experienced improvement reaching the MCID of JOA score at 1 year postoperatively. The present study suggests that for younger patients with mild CCM, especially those aged below 58 years, subjective neurological recovery is more likely to be obtained. Meanwhile, the surgery takes on a more prophylactic significance to halt disease progression for older patients. The results of this study can help in the decision-making process for this clinical population.

Validating the preoperative Japanese Core Outcome Measures Index for the Neck and comparing quality of life in patients with cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament by the patient-reported outcome measures

PURPOSE

This cross-sectional study serves two main purposes. Firstly, it aims to validate the preoperative Japanese Core Outcome Measures Index for the Neck (COMI-Neck) in patients with cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL). Secondly, it seeks to elucidate differences in preoperative quality of life (QOL) between these two cervical pathologies using patient-reported outcome measures (PROMs).

METHODS

A total of 103 preoperative patients (86 with CSM and 17 with OPLL) scheduled for cervical spine surgery were included in the study. Validated PROMs, including the Japanese COMI-Neck, Neck Disability Index (NDI), EuroQol-5 Dimension-3 level (EQ-5D-3L), and SF-12v2, were used to assess QOL. Baseline demographic and clinical data were collected, and statistical analyses were performed to compare the PROMs between CSM and OPLL groups.

RESULTS

The Japanese COMI-Neck demonstrated good construct validity, with positive correlations with NDI and negative correlations with EQ-5D-3L and SF-12v2. Comparison of preoperative PROMs between CSM and OPLL groups revealed differences in age, body mass index, and EQ-5D-3L scores. The CSM group had higher NDI scores for concentration and lower EQ-5D-3L scores for self-care compared to the OPLL group.

CONCLUSIONS

This study validated the preoperative Japanese COMI-Neck in CSM and OPLL patients and identified specific QOL issues associated with each condition. The findings highlight the importance of considering disease-specific QOL and tailoring treatment plans accordingly. Further research should include postoperative assessments and a more diverse population to enhance generalizability.

The clinical efficacy of laminectomy fusion fixation and posterior single open-door laminoplasty in the treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL): a retrospective study

BACKGROUND

To compared the clinical efficacy of two surgical methods, posterior laminectomy fusion fixation, and posterior single open-door laminoplasty, in treating multilevel cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

The study retrospectively included 102 patients treated between December 2016 and December 2020. The patients were included into an observation group (56 cases) treated with total laminectomy and lateral screw fixation, and a control group (46 cases) treated with single open-door laminoplasty.

RESULTS

After 24 months, both groups showed significant improvement in Japanese Orthopaedic Association (JOA) scores and Visual Analogue Scale (VAS) scores, indicating better clinical symptoms and functional recovery. There was no significant difference in preoperative JOA and VAS scores between the two groups (P > 0.05). At 24 months after surgery, there was no significant difference in JOA and VAS scores between the two groups (P > 0.05). However, the observation group had a significantly higher cervical curvature index (CCI) and lower range of motion (ROM) of the cervical spine compared to the control group (P < 0.05). The CCI in control group was lower than before surgery, while the CCI in observation group was higher than before surgery, and CCI in the control group was considerably lower than that in the observation group (P < 0.05). The complication rate was lower in the control group, with fewer cases of axial symptoms, fifth cervical nerve root palsy, and overall complications. The overall complication rate was 25.0% (14/56) in the observation group and 10.8% (5/46) in the control group (P < 0.05).

CONCLUSIONS

Both posterior laminectomy fusion fixation and posterior single open-door laminoplasty yield positive outcomes in improving clinical neurological function, cervical curvature, range of motion of the cervical spine, and cervical sagittal balance. Although open-door laminoplasty is less effective than total laminectomy in maintaining CCI and sagittal balance, it excels in preserving cervical range of motion, less surgical trauma and complications. Thus, open-door laminoplasty may be a suitable first-choice treatment for multi-segmental cervical OPLL, especially for patients with lordotic cervical spine physiological curvature.

Automated Detection of the Thoracic Ossification of the Posterior Longitudinal Ligament Using Deep Learning and Plain Radiographs

Ossification of the ligaments progresses slowly in the initial stages, and most patients are unaware of the disease until obvious myelopathy symptoms appear. Consequently, treatment and clinical outcomes are not satisfactory. This study is aimed at developing an automated system for the detection of the thoracic ossification of the posterior longitudinal ligament (OPLL) using deep learning and plain radiography. We retrospectively reviewed the data of 146 patients with thoracic OPLL and 150 control cases without thoracic OPLL. Plain lateral thoracic radiographs were used for object detection, training, and validation. Thereafter, an object detection system was developed, and its accuracy was calculated. The performance of the proposed system was compared with that of two spine surgeons. The accuracy of the proposed object detection model based on plain lateral thoracic radiographs was 83.4%, whereas the accuracies of spine surgeons 1 and 2 were 80.4% and 77.4%, respectively. Our findings indicate that our automated system, which uses a deep learning-based method based on plain radiographs, can accurately detect thoracic OPLL. This system has the potential to improve the diagnostic accuracy of thoracic OPLL.

Anterior direct decompression significantly relieves spinal cord high signal in patients with ossification of the posterior longitudinal ligament: a case-control study

BACKGROUND

In patients with cervical spondylotic myelopathy caused by ossification of the posterior longitudinal ligament, high cord signal (HCS) is frequently observed. However, limited research has investigated the variations in HCS improvement resulting from different surgical approaches. This study aims to explore the potential relationship between the choice of surgical approach and the postoperative improvement of intramedullary high signal in ossification of the posterior longitudinal ligament (OPLL) patients.

METHODS

We extensively reviewed the patients' medical records, based on which demographic information such as gender, age, and body mass index (BMI) were recorded, and assessed the severity of the patients' neurological status preoperatively and postoperatively by using the Japanese Orthopedic Association score (JOAs), focusing on consecutive preoperative and postoperative Magnetic resonance imaging (MRI) T2WI measurements, to study the statistical correlation between the improvement of HCS and the choice of surgical approach.

RESULTS

There were no significant differences in demographic, imaging parameters, and clinical symptoms between patients undergoing anterior and posterior surgery (p > 0.05, Table 1). However, both improvement in JOAs (Recovery2) and improvement in HCS (CR2) were significantly better in the anterior surgery group two years after surgery (p < 0.05, Table 1). Multifactorial logistic regression analysis revealed that posterior surgery and higher preoperative signal change ratio (SCR) were identified as risk factors for poor HCS improvement at the two-year postoperative period (p < 0.05, Table 2). Table 1 Differences in demographic, imaging parameters, and clinical symptoms in patients with anterior and posterior approach Anterior approach Posterior approach P-Values Demographic data  Sex (male/female) 10/12 6/17 0.175  Age 58.59 ± 5.68 61.43 ± 9.04 0.215  Hypertension 14/8 14/9 0.848  Diabetes 16/6 19/4 0.425  BMI 25.58 ± 4.72 26.95 ± 4.58 0.331  Smoking history 19/3 16/7 0.175 Preoperative measured imaging parameters  Preoperative SCR 1.615 ± 0.369 1.668 ± 0.356 0.623  CR1 0.106 ± 0.125 0.011 ± 0.246 0.08  CNR 0.33 ± 0.073 0.368 ± 0.096 0.15  C2-7 Cobb angle 8.977 ± 10.818 13.862 ± 13.191 0.182  SVA 15.212 ± 8.024 17.46 ± 8.91 0.38  mK-line INT 3.694 ± 3.291 4.527 ± 2.227 0.323 Imaging follow-up  6 months postoperative SCR 1.45 ± 0.44 1.63 ± 0.397 0.149  2 years postoperative SCR 1.26 ± 0.19 1.65 ± 0.35 0.000**  CR2 0.219 ± 0.14 - 0.012 ± 0.237 0.000** Clinical symptoms  Preoperative JOAs 10.64 ± 1.59 10.83 ± 1.47 0.679  6 months postoperative JOAs 11.82 ± 1.37 11.65 ± 1.4 0.69  2 years postoperative JOAs 14.18 ± 1.01 12.52 ± 2.06 0.001**  Recovery1 0.181 ± 0.109 0.128 ± 0.154 0.189  Recovery2 0.536 ± 0.178 0.278 ± 0.307 0.001** *, statistical significance (p < 0.05). **, statistical significance (p < 0.01) BMI = body mass index. SCR = the signal change ratio between the localized high signal and normal spinal cord signal at the C7-T1 levels. CR1 = the regression of high cord signals at 6 months postoperatively (i.e., CR1 = (Preoperative SCR-SCR at 6 months postoperatively)/ Preoperative SCR). CR2 = the regression of high cord signal at 2 years postoperatively (i.e., CR2 = (Preoperative SCR-SCR at 2 years postoperatively)/ Preoperative SCR). CNR = canal narrowing ratio. SVA = sagittal vertical axis. mK-line INT = modified K-line interval. JOAs = Japanese Orthopedic Association score. Recovery1 = degree of JOAs recovery at 6 months postoperatively (i.e., Recover1 = (JOAs at 6 months postoperatively-Preoperative JOAs)/ (17- Preoperative JOAs)). Recovery2 = degree of JOAs recovery at 2 years postoperatively (i.e., Recover2 = (JOAs at 2 years postoperatively-Preoperative JOAs)/ (17-Preoperative JOAs)) Table 2 Linear regression analyses for lower CR2 values 95% CI P value Uni-variable analyses Demographic data  Sex (male/female) - 0.01 0.221 0.924  Age - 0.015 0.003 0.195  Hypertension - 0.071 0.204 0.334  Diabetes - 0.195 0.135 0.716  BMI - 0.375 0.422 0.905  Smoking history - 0.249 0.077 0.295  Surgical approach - 0.349 - 0.113 0.000# Preoperative measured imaging parameters  C2-7 Cobb angle - 0.009 0.002 0.185  SVA - 0.008 0.008 0.995  mK-line INT - 0.043 0.005 0.122  Preoperative SCR 0.092 0.445 0.004#  CR1 0.156 0.784 0.004#  CNR - 0.76 0.844 0.918 Multi-variable analyses  Surgical approach - 0.321 - 0.118 0.000**  Preoperative SCR 0.127 0.41 0.000**  CR1 - 0.018 0.501 0.067 #, variables that achieved a significance level of p < 0.1 in the univariate analysis *statistical significance (p < 0.05). **statistical significance (p < 0.01) BMI = body mass index. SCR = the signal change ratio between the localized high signal and normal spinal cord signal at the C7-T1 levels. CR1 = the regression of high cord signals at 6 months postoperatively (i.e., CR1 = (Preoperative SCR-SCR at 6 months postoperatively)/ Preoperative SCR). CR2 = the regression of high cord signal at 2 years postoperatively (i.e., CR2 = (Preoperative SCR-SCR at 2 years postoperatively)/ Preoperative SCR). CNR = canal narrowing ratio. SVA = sagittal vertical axis. mK-line INT = modified K-line interval CONCLUSIONS: For patients with OPLL-induced cervical spondylotic myelopathy and intramedullary high signal, anterior removal of the ossified posterior longitudinal ligament and direct decompression offer a greater potential for regression of intramedullary high signal. At the same time, this anterior surgical strategy improves clinical neurologic function better than indirect decompression in the posterior approach.

Reoperation rate and risk factors of reoperation for ossification of the posterior longitudinal ligament (OPLL): a systematic review and meta-analysis

Revision surgery for OPLL is undesirable for both patients and physicians. However, the risk factors for reoperation are not clear. Thus, we sought to review the existing literature and determine the factors associated with higher reoperation rates in patients with OPLL. A search was performed using Pubmed, Embase, Web of Sciences, and Ovid to include studies regarding the risk factors of reoperation for OPLL. RoBANS (Risk of Bias Assessment tool for Nonrandomized Studies) was used for risk of bias analysis. Heterogeneity of studies and publication bias was assessed, and sensitivity analysis was performed. Statistical analysis was performed with a p-value < 0.05 using SPSS software (version 23). Twenty studies with 129 reoperated and 2,793 non-reoperated patients were included. The pooled reoperation rate was 5% (95% CI: 4% to 7). The most common cause of reoperation was residual OPLL or OPLL progression (n = 51, 39.53%). An increased risk of additional surgery was found with pre-operative cervical or thoracic angle (Standardized mean difference = -0.44; 95% CI: -0.69 to -0.19; p = 0.0061), post-operative CSF leak (Odds ratio, OR = 4.97; 95% CI: 2.48 to 9.96; p = 0.0005), and graft and/or hardware failure (OR = 192.09; 95% CI: 6.68 to 5521.69; p = 0.0101). Apart from the factors identified in our study, the association of other variables with the risk of second surgery could not be ruled out, owing to the complexity of the relationship and significant bias in the current literature.

Deep learning-based prediction model for postoperative complications of cervical posterior longitudinal ligament ossification

PURPOSE

Postoperative complication prediction helps surgeons to inform and manage patient expectations. Deep learning, a model that finds patterns in large samples of data, outperform traditional statistical methods in making predictions. This study aimed to create a deep learning-based model (DLM) to predict postoperative complications in patients with cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

This prospective multicenter study was conducted by the 28 institutions, and 478 patients were included in the analysis. Deep learning was used to create two predictive models of the overall postoperative complications and neurological complications, one of the major complications. These models were constructed by learning the patient's preoperative background, clinical symptoms, surgical procedures, and imaging findings. These logistic regression models were also created, and these accuracies were compared with those of the DLM.

RESULTS

Overall complications were observed in 127 cases (26.6%). The accuracy of the DLM was 74.6 ± 3.7% for predicting the overall occurrence of complications, which was comparable to that of the logistic regression (74.1%). Neurological complications were observed in 48 cases (10.0%), and the accuracy of the DLM was 91.7 ± 3.5%, which was higher than that of the logistic regression (90.1%).

CONCLUSION

A new algorithm using deep learning was able to predict complications after cervical OPLL surgery. This model was well calibrated, with prediction accuracy comparable to that of regression models. The accuracy remained high even for predicting only neurological complications, for which the case number is limited compared to conventional statistical methods.

Risk Factors for Significant Intraoperative Blood Loss during Anterior Cervical Decompression and Fusion for Degenerative Cervical Diseases

OBJECTIVES

Anterior cervical decompression and fusion (ACF) has become a widely accepted surgical treatment for degenerative cervical diseases, but occasionally, significant intraoperative blood loss (SIBL), which is defined as IBL of 500 mL or more, will occur. We aimed to investigate the independent risk factors for SIBL during ACF for degenerative cervical diseases.

METHODS

We enrolled 1150 patients who underwent ACF for degenerative cervical diseases at our hospital between 2013 and 2019. The patients were divided into two groups: the SIBL group (n = 38) and the non-SIBL group (n = 1112). Demographic, surgical and radiographic data were recorded prospectively to investigate the independent risk factors for SIBL. For counting data, the chi-square test or Fisher's exact probability test was used. Student's t-test or the Mann-Whitney rank sum test was used for comparisons between groups of measurement data. Univariate analysis and multivariate logistic regression analysis were further used to analyze the significance of potential risk factors.

RESULTS

The incidence of SIBL during ACF was 3.3% (38/1150). A multivariate analysis revealed that female sex (odds ratio [OR], 6.285; 95% confidence interval [CI], 2.707-14.595; p < 0.001), corpectomy (OR, 3.872; 95% CI, 1.616-9.275; p = 0.002), duration of operation ≥150 min (OR, 8.899; 95% CI, 4.042-19.590; p < 0.001), C3 involvement (OR, 4.116; 95% CI, 1.808-9.369; p = 0.001) and ossification of posterior longitudinal ligament (OPLL) at the surgical level (OR, 6.007; 95% CI, 2.218-16.270; p < 0.001) were independent risk factors for SIBL. Patients with SIBL had more days of first-degree/intensive nursing (p = 0.003), longer length of stay (p = 0.003) and higher hospitalization costs (p = 0.023).

CONCLUSION

Female sex, corpectomy, duration of operation, C3 involvement and OPLL at the surgical level were independent risk factors for SIBL during ACF. SIBL in ACF was associated with more days of first-degree/intensive nursing, longer length of stay and higher hospitalization costs.

Transdural circumferential decompression for thoracic spinal stenosis caused by beak-type ossification of the posterior longitudinal ligament: a technical note

PURPOSE

Thoracic myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine is usually progressive and responds poorly to conservative therapy, making surgery the only effective treatment option. A variety of surgical procedures have been developed to treat thoracic OPLL. However, the optimal surgical approach for removal of thoracic OPLL remains unclear. In the present study, we described a newly modified posterior approach for the removal of OPLL: circular decompression via dural approach, and complete removal of OPLL can be achieved under direct vision and without neurological deficit.

MATERIALS AND METHODS

Three patients with beak-type thoracic OPLL presented with progressive thoracic myelopathy and leg weakness. Magnetic resonance imaging showed the spinal cord severely compressed. The surgical management of the three patients involved the 'cave-in' circular decompression and transdural resection of OPLL.

RESULTS

Transdural circumferential decompression was successfully performed in all three patients. Clinical outcome measures, including pre- and postoperative radiographic parameters, were assessed. All of the patients were followed up for an average of 12 months (ranging from 10 to 15 months), and no surgery-related complications occurred. Weakness relief and neural function recovery were satisfactorily achieved in all patients by the final follow-up.

CONCLUSIONS

Transdural circumferential decompression was an effective method for thoracic spinal stenosis caused by concurrent beak-type OPLL, by which OPLL could be safely removed. It is especially useful when there is a severe adhesion between the dura OPLL.

High whole-body bone mineral density in ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

Recent studies suggest that ossification of the posterior longitudinal ligament (OPLL) is exacerbated by systemic metabolic disturbances, including obesity. However, although an increase in bone mineral density (BMD) measured at the lumbar spine has been reported in patients with OPLL, no studies have investigated the systemic BMD of patients with OPLL in detail.

PURPOSE

We investigated whether patients with OPLL develop increased whole-body BMD.

STUDY DESIGN

Single institution cross-sectional study.

PATIENT SAMPLE

Data were collected from Japanese patients with symptomatic OPLL (OPLL [+]; n=99). Control data (OPLL [-]; n=226) without spinal ligament ossification were collected from patients who underwent spinal decompression, spinal fusion, or hip replacement surgery.

OUTCOME MEASURES

Demographic data, including age, body mass index (BMI), comorbidities, history of treatment for osteoporosis, and history of vertebral and nonvertebral fractures, was obtained from all participants. In addition, whole-body BMD, including the lumbar spine, thoracic spine, femoral neck, skull, ribs, entire upper extremity, entire lower extremity, and pelvis, were measured in all participants using whole-body dual-energy X-ray absorptiometry.

METHODS

Patient data were collected from 2018 to 2022. All participants were categorized based on sex, age (middle-aged [<70 years] and older adults [≥70 years]), and OPLL type (localized OPLL [OPLL only in the cervical spine], diffuse OPLL [OPLL in regions including the thoracic spine]), and OPLL [-]) and each parameter was compared. The factors associated with whole-body BMD were evaluated via multivariable linear regression analysis.

RESULTS

Compared with the OPLL (-) group, the OPLL (+) group of older women had significantly higher BMD in all body parts (p<.01), and the OPLL (+) group of older men had significantly higher BMD in all body parts except the ribs, forearm, and skull (p<.01). The factors associated with increased BMD of both the femoral neck (load-bearing bone) and skull (nonload-bearing bone) were age, BMI, and coexisting diffuse OPLL in women and BMI and coexisting localized OPLL in men.

CONCLUSIONS

Patients with OPLL have increased whole-body BMD regardless of sex, indicating that it is not simply due to load-bearing from obesity. These findings suggested that OPLL is associated with a systemic pathology.

Preoperative Symptom Duration Influences Neurological Recovery and Patient-Reported Outcome Measures After Surgical Treatment of Cervical Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

A prospective multicenter study.

OBJECTIVE

To investigate the effect of preoperative symptom duration on neurological recovery for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

The optimal timing to perform surgery in the setting of cervical OPLL remains unknown. It is important to know the influence of symptom duration on postoperative outcomes to facilitate discussions regarding the timing of surgery.

PATIENTS AND METHODS

The study included 395 patients (291 men and 104 women; mean age, 63.7 ± 11.4 yr): 204 were treated with laminoplasty, 90 with posterior decompression and fusion, 85 with anterior decompression and fusion, and 16 with other procedures. The Japanese Orthopedic Association (JOA) score and patient-reported outcomes of the JOA Cervical Myelopathy Evaluation Questionnaire were used to assess clinical outcomes preoperatively and 2 years after surgery. Logistic regression analysis was used to identify factors associated with the achievement of minimum clinically important difference (MCID) after surgery.

RESULTS

The recovery rate was significantly lower in the group with symptom duration of ≥5 years compared with the groups with durations of <0.5 years, 0.5 to 1 year, and 1 to 2 years. Improvement of JOA Cervical Myelopathy Evaluation Questionnaire in the upper extremity function score ( P < 0.001), lower extremity function ( P = 0.039), quality of life ( P = 0.053), and bladder function ( P = 0.034) were all decreased when the symptom duration exceeded 2 years. Duration of symptoms ( P = 0.001), age ( P < 0.001), and body mass index ( P < 0.001) were significantly associated with the achievement of MCID. The cutoff value we established for symptom duration was 23 months (area under the curve, 0.616; sensitivity, 67.4%; specificity, 53.5%).

CONCLUSIONS

Symptom duration had a significant impact on neurological recovery and patient-reported outcome measures in this series of patients undergoing surgery for cervical OPLL. Patients with symptom duration exceeding 23 months may be at greater risk of failing to achieve MCID after surgery.

LEVEL OF EVIDENCE

3.

Characteristics of Postoperative C5 Palsy Following Anterior Decompression and Fusion Surgery for Cervical Degenerative Disorders: Trends Associated with Advancements in Surgical Technique

OBJECTIVE

To investigate trends in the characteristics of postoperative C5 palsy following anterior decompression and fusion associated with advancements in this surgical procedure to treat cervical degenerative disorders.

METHODS

We included 801 consecutive patients who underwent anterior decompression and fusion for cervical degenerative disorders from 2006 to 2019 and investigated the incidence, onset, and prognosis of C5 palsy. In addition, we compared the incidence of C5 palsy with that found in our previous investigation.

RESULTS

The cases of 42 (5.2%) patients were complicated by C5 palsy. For patients with ossification of the longitudinal ligament (OPLL), 22 (12.4%) of 177 were complicated with C5 palsy, and the incidence was significantly higher than that in patients without OPLL (20 [3.2%] of 624, P < 0.01). The incidence of C5 palsy in patients without OPLL was significantly lower than that found in our previous investigation (P < 0.01). The incidence of C5 palsy in patients that required contiguous multilevel corpectomy was significantly higher in patients that required within a single corpectomy (P < 0.01). At 1-year follow-up, muscle strength in 3 (6.1%) of 49 limbs had not improved sufficiently.

CONCLUSIONS

With advancements in surgical techniques which allowed necessary and sufficient spinal cord decompression and avoided unnecessary corpectomy, the incidence of C5 palsy in patients without OPLL was decreased significantly. By contrast, for patients with OPLL, the incidence of C5 palsy was similar to the incidence found previously, perhaps because a broad and contiguous multilevel corpectomy was usually needed to decompress the spinal cord sufficiently.

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.

Predictors of the Need for Surgery in Cervical Ossification of the Posterior Longitudinal Ligament: A Retrospective Cohort Longitudinal Study Using a Claims-based Database

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to determine predictors associated with the needfor cervical ossification of the posterior longitudinal ligament (cOPLL) surgery amongindividuals with cOPLL.

SUMMARY OF BACKGROUND DATA

cOPLL is a spinal disorder caused by ectopic ossification of the posterior longitudinal ligament. However, factors associated with a higher rate of surgery to treat the neurological symptoms of cOPLL are poorly understood.

MATERIALS AND METHODS

This retrospective population-based cohort study using a commercial administrative claims database from JMDC Inc. (Tokyo, Japan) enrolled patients newly diagnosed with cOPLL from April 2005 to October 2020 and followed to April 2021. A total of 1506 cOPLL patients aged 18 years or older with no history of cervical spine surgery and with a record of metabolic profiles obtained at general health checkups were included. Cox proportional hazards regression models identified patient characteristics and comorbidities associated with cOPLL surgery.

RESULTS

Of 1506 patients with cOPLL with a median of 1.8 years of follow-up after initial cOPLL diagnosis, 439 (29.2%) received cOPLL surgery. The 1-year cumulative incidence (95% CI) was 26.0% (23.7-28.2). In multivariable Cox proportional regression analysis, male (hazard ratio: 1.68; 95% CI: 1.26-2.24; P < 0.001) and obesity (body mass index: ≥25) (hazard ratio: 1.45; 95% CI: 1.10-1.89; P = 0.007) were associated with an increased risk of cOPLL surgery.

CONCLUSIONS

In this large claims-based study of adults newly diagnosed with cOPLL, males and obesity were associated with a higher risk of cOPLL surgery. These findings may help clinicians to predict the future course of cOPLL in patients, although further research is needed to elucidate the biological role of these progression-associated factors.

Residual Neuropathic Pain in Postoperative Patients With Cervical Ossification of Posterior Longitudinal Ligament

STUDY DESIGN

A prospective multi-institutional observational study.

OBJECTIVE

To investigate and identify risk factors for residual neuropathic pain after surgery in patients with cervical ossification of posterior longitudinal ligament (c-OPLL).

SUMMARY OF BACKGROUND DATA

Patients with c-OPLL often require surgery for numbness and paralysis of the extremities; however, postoperative neuropathic pain can considerably deteriorate their quality of life.

METHODS

Out of 479 patients identified from multicenter c-OPLL registries between 2014 and 2017, 292 patients who could be followed up for 2 years postoperatively were reviewed, after excluding patients with nervous system comorbidities. Demographic details; medical history; radiographic factors including the K-line, spinal canal occupancy rate of OPLL, cervical kyphosis angle, and presence of spinal cord myelomalacia; preoperative Japanese Orthopaedic Association (JOA) score; surgical procedure (fusion or decompression surgery); postoperative neurological deterioration; and the visual analogue scale for pain and numbness in the upper extremities (U/E) or trunk/lower extremities (L/E) at baseline and at 2 years postoperatively were assessed. Patients were grouped into residual and non-residual groups based on a postoperative visual analogue scale ≥40 mm. Risk factors for residual neuropathic pain were evaluated by multiple logistic regression analysis.

RESULTS

The prevalence of U/E and L/E residual pain in postoperative c-OPLL patients was 51.7% and 40.4%, respectively. The U/E residual group had a poor preoperative JOA score and longer illness duration, and fusion surgery was more common in the residual group than in non-residual group. The L/E residual group was older with a poorer preoperative JOA score. On multivariate analysis, risk factors for U/E residual pain were long illness duration and poor preoperative JOA score, whereas those for L/E residual pain were age and poor preoperative JOA score.

CONCLUSIONS

The risk factors for residual spinal neuropathic pain after c-OPLL surgery were age, long duration of illness, and poor preoperative JOA score.

LEVEL OF EVIDENCE

IV.

Effect of K‑line on posterior cervical surgery versus anterior cervical surgery in patients with multi-level ossification of posterior longitudinal ligament

PURPOSE

To evaluate the influence of K-line on the outcome of open-door laminoplasty versus anterior cervical corpectomy decompression and fusion (ACCF) for patients with more than two levels of ossification of the posterior longitudinal ligament (OPLL).

METHODS

60 patients undergoing open-door laminoplasty and 62 patients undergoing ACCF from January 2013 to January 2020 with more than 2 years of follow-up were included. Eighty-four cases with the ossification mass not beyond the K-line were grouped as K-line (+), while thirty-eight cases were grouped as K-line (-). The operation time, intraoperative blood loss, hospital stay, preoperative, postoperative, and last follow-up JOA scores, and postoperative complications were investigated.

RESULTS

The improvement rate of JOA scores after posterior approaches in cases of group K-line (+) and K-line (-) was 72.4% and 53.1%, respectively, which showed a significant difference (P < 0.01). In group K-line (+), the improvement of JOA scores for open-door laminoplasty was 73.4% and 71.8% for ACCF, which showed no significant difference (P > 0.05). In group K-line (-), the improvement of JOA scores for ACCF was 52.1% and 42.9% for open-door laminoplasty, which showed a significant difference (P < 0.05). The incidence of C5 palsy was significantly lower in cases with ACCF than in cases with open-door laminoplasty (P < 0.05).

CONCLUSION

For patients with more than two levels of OPLL, preoperative K-line (+) predicates a better outcome than K-line (-). For cases with K-line (-), ACCF provides better neurologic function recovery. For patients with K-line (+), open-door laminoplasty provides the same neurologic function recovery of ACCF.

To infer the probability of cervical ossification of the posterior longitudinal ligament and explore its impact on cervical surgery

The ossification of the posterior longitudinal ligament (OPLL) in the cervical spine is commonly observed in degenerative changes of the cervical spine. Early detection of cervical OPLL and prevention of postoperative complications are of utmost importance. We gathered data from 775 patients who underwent cervical spine surgery at the First Affiliated Hospital of Guangxi Medical University, collecting a total of 84 variables. Among these patients, 144 had cervical OPLL, while 631 did not. They were randomly divided into a training cohort and a validation cohort. Multiple machine learning (ML) methods were employed to screen the variables and ultimately develop a diagnostic model. Subsequently, we compared the postoperative outcomes of patients with positive and negative cervical OPLL. Initially, we compared the advantages and disadvantages of various ML methods. Seven variables, namely Age, Gender, OPLL, AST, UA, BMI, and CHD, exhibited significant differences and were used to construct a diagnostic nomogram model. The area under the curve (AUC) values of this model in the training and validation groups were 0.76 and 0.728, respectively. Our findings revealed that 69.2% of patients who underwent cervical OPLL surgery eventually required elective anterior surgery, in contrast to 86.8% of patients who did not have cervical OPLL. Patients with cervical OPLL had significantly longer operation times and higher postoperative drainage volumes compared to those without cervical OPLL. Interestingly, preoperative cervical OPLL patients demonstrated significant increases in mean UA, age, and BMI. Furthermore, 27.1% of patients with cervical anterior longitudinal ligament ossification (OALL) also exhibited cervical OPLL, whereas this occurrence was only observed in 6.9% of patients without cervical OALL. We developed a diagnostic model for cervical OPLL using the ML method. Our findings indicate that patients with cervical OPLL are more likely to undergo posterior cervical surgery, and they exhibit elevated UA levels, higher BMI, and increased age. The prevalence of cervical anterior longitudinal ligament ossification was also significantly higher among patients with cervical OPLL.

MRI-based detection of cervical ossification of the posterior longitudinal ligament using a novel automated machine learning diagnostic tool

OBJECTIVE

Currently, CT is considered the gold standard for the diagnosis of ossification of the posterior longitudinal ligament (OPLL). The objective of this study was to develop artificial intelligence (AI) software and a validated model for the identification and representation of cervical OPLL (C-OPLL) on MRI, obviating the need for spine CT.

METHODS

A retrospective evaluation was performed of consecutive imaging studies of all adult patients who underwent both cervical CT and MRI for any clinical indication within a span of 36 months (between January 2017 and July 2020) in a single tertiary-care referral hospital. C-OPLL was identified by a panel of neurosurgeons and a neuroradiologist. MATLAB software was then used to create an AI tool for the diagnosis of C-OPLL by using a convolutional neural network method to identify features on MR images. A reader study was performed to compare the performance of the AI model to that of the diagnostic panel using standard test performance metrics. Interobserver variability was assessed using Cohen's kappa score.

RESULTS

Nine hundred consecutive patients were found to be eligible for radiological evaluation, yielding 65 identified C-OPLL carriers. The AI model, utilizing MR images, was able to accurately segment the vertebral bodies, PLL, and discoligamentous complex, and detect C-OPLL carriers. The AI model identified 5 additional C-OPLL patients who were not initially detected. The performance of the MRI-based AI model resulted in a sensitivity of 85%, specificity of 98%, negative predictive value of 98%, and positive predictive value of 85%. The overall accuracy of the model was 98%, with a kappa score of 0.917.

CONCLUSIONS

The novel AI software developed in this study was highly specific for identifying C-OPLL on MRI, without the use of CT. This model may obviate the need for CT scans while maintaining adequate diagnostic accuracy. With further development, this MRI-based AI model has the potential to aid in the diagnosis of various spinal disorders and its automated layers may lay the foundation for MRI-specific diagnostic criteria for C-OPLL.

Degenerative cervical myelopathy: Where have we been? Where are we now? Where are we going?

Degenerative cervical myelopathy (DCM), a recently coined term, encompasses a group of age-related and genetically associated pathologies that affect the cervical spine, including cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament (OPLL). Given the significant contribution of DCM to global disease and disability, there are worldwide efforts to promote research and innovation in this area. An AO Spine effort termed 'RECODE-DCM' was initiated to create an international multistakeholder consensus group, involving patients, caregivers, physicians and researchers, to focus on launching actionable discourse on DCM. In order to improve the management, treatment and results for DCM, the RECODE-DCM consensus group recently identified ten priority areas for translational research. The current article summarizes recent advancements in the field of DCM. We first discuss the comprehensive definition recently refined by the RECODE-DCM group, including steps taken to arrive at this definition and the supporting rationale. We then provide an overview of the recent advancements in our understanding of the pathophysiology of DCM and modalities to clinically assess and diagnose DCM. A focus will be set on advanced imaging techniques that may offer the opportunity to improve characterization and diagnosis of DCM. A summary of treatment modalities, including surgical and nonoperative options, is then provided along with future neuroprotective and neuroregenerative strategies. This review concludes with final remarks pertaining to the genetics involved in DCM and the opportunity to leverage this knowledge toward a personalized medicine approach.

Increased Cellular Expression of Interleukin-6 in Patients With Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

We performed histologic, immunohistochemical, immunoblot examination and suspension array analyses of cytokine expression in cultured cells derived from human cervical ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVE

To determine the roles of interleukin-6 (IL-6) during the maturation of osteoblasts and chondrocytes associated with the development of OPLL.

SUMMARY OF BACKGROUND DATA

Ectopic OPLL affects ~3% of the general population, with a higher incidence in Asian ethnic groups. Alterations in cytokine profiles may influence osteoblast differentiation, but the mechanisms and signaling pathways associated with the ossification process remain unclear.

METHODS

Samples were collected from 14 patients with OPLL who had undergone spinal surgery and seven with cervical spondylotic myelopathy without OPLL. Tissue sections were used for histologic and immunohistochemical studies, and primary cells from ligamentum samples were used for cytokine array and immunoblotting. A suspension array was used to measure the concentrations of 27 inflammatory cytokines or growth factors.

RESULTS

Suspension array and immunoblot analyses revealed significantly elevated levels of IL-6 in OPLL patients. Alterations in IL-6 concentrations were found to alter the expression of the genes Sox9 , Runx2 , and SIRT1 . In addition, immunohistochemical analysis revealed that these factors are present in mesenchymal cells within the degenerative portion of the ligament matrix that is adjacent to the ossification front.

CONCLUSIONS

IL-6 plays a profound role in the osteoblast differentiation process along with the induction of chondrocyte hypertrophy and cell apoptosis in the early stages of ossification in OPLL. These changes in cytokine profiles are essential factors for regulation of the ectopic ossified plaque in OPLL.

Neurological Survivorship Following Surgery for Degenerative Cervical Myelopathy: A Longitudinal Study on 195 Patients

BACKGROUND

Long-term data on postoperative neurological survivorship for patients with degenerative cervical myelopathy (DCM) undergoing decompressive surgery are limited. The purposes of this study were to assess neurological survivorship after primary decompressive surgery for DCM and to identify predictors for postoperative deterioration.

METHODS

A longitudinal clinical data set containing surgical details, medical comorbidities, and radiographic features was assembled for 195 patients who underwent a surgical procedure for DCM between 1999 and 2020, with a mean period of observation of 75.9 months. Kaplan-Meier curves were plotted, and a log-rank test was performed for the univariate analysis of factors related to neurological failure. Lasso regression facilitated the variable selection in the Cox proportional hazards model for multivariate analysis.

RESULTS

The overall neurological survivorship was 89.3% at 5 years and 77.3% at 10 years. Cox multivariate analysis following lasso regression identified elevated hazard ratios (HRs) for suture laminoplasty (HR, 4.76; p < 0.001), renal failure (HR, 4.43; p = 0.013), T2 hyperintensity (HR, 3.34; p = 0.05), and ossification of the posterior longitudinal ligament (OPLL) (HR, 2.32; p = 0.032). Subgroup analysis among subjects with OPLL demonstrated that the neurological failure rate was significantly higher in the absence of fusion (77.8% compared with 26.3%; p = 0.019).

CONCLUSIONS

Overall, patients who underwent a surgical procedure for DCM exhibited an extended period with neurological improvement. Cervical fusion was indicated in OPLL to reduce neurological failure. Our findings on predictors for early deterioration facilitate case selection, prognostication, and counseling as the volume of primary cervical spine surgeries and reoperations increases globally.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

[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.

Predictors for cervical kyphotic deformity following laminoplasty: a systematic review and meta-analysis

OBJECTIVE

Laminoplasty is a common treatment for cervical spondylotic myelopathy (CSM) and for ossification of the posterior longitudinal ligament (OPLL). However, approximately 21% of patients undergoing laminoplasty develop cervical kyphotic deformity (KD). Because of the high prevalence rate of KD, several studies have sought to identify predictors for this complication, but the findings remain highly inconsistent. Therefore, the authors performed a systematic review and meta-analysis to establish reliable preoperative predictors of KD.

METHODS

PubMed, Scopus, and Web of Science databases were used to systematically extract potential references. The first phase of screening required the studies to be written in the English language, involve patients treated for CSM and/or OPLL via laminoplasty, and report postoperative cervical KD. The second phase required the studies to provide more than 10 patients and include a control group. The mean difference (MD) and odds ratio (OR) were calculated for continuous and dichotomous parameters. Study quality was evaluated using the Newcastle-Ottawa Scale. CSM and OPLL patients were further assessed by performing subgroup analyses.

RESULTS

Thirteen studies comprising patients who developed cervical KD (n = 296) and no KD (n = 1254) after receiving cervical laminoplasty for CSM or OPLL were included in the meta-analysis. All studies were retrospective cohorts and were rated as high quality. In the combined univariate analysis of CSM and OPLL patients undergoing laminoplasty, statistically significant predictors for postoperative KD included age (MD 2.22, 95% CI 0.16-4.27, p = 0.03), preoperative BMI (MD 0.85, 95% CI 0.06-1.63, p = 0.04), preoperative C2-7 range of flexion (MD 10.42, 95% Cl 4.24-16.59, p = 0.0009), preoperative C2-7 range of extension (MD -4.59, 95% CI -6.34 to -2.83, p < 0.00001), and preoperative center of gravity of the head to the C7 sagittal vertical axis (MD 26.83, 95% CI 9.13-44.52, p = 0.003). Additionally, among CSM patients, males were identified as having a greater risk for postoperative KD (OR 1.73, 95% CI 1.02-2.93, p = 0.04).

CONCLUSIONS

The findings from this study currently provide the largest and most reliable review on preoperative predictors for cervical KD after laminoplasty. Given that several of the included studies identified optimal cutoff points for the variables that are significantly associated with KD, further investigation into the development of a preoperative risk scoring system that can accurately predict KD in the clinical setting is encouraged. PROSPERO registration no.: CRD42022299795 (https://www.crd.york.ac.uk/PROSPERO/).

Dural ossification associated with ossification of posterior longitudinal ligament in the cervical spine: a retrospective analysis

OBJECTIVE

Dural ossification (DO) is common in patients with ossification of the posterior longitudinal ligament (OPLL). The existence of DO makes surgery challenging and increases the risk of complications. The aim of this study was to investigate the incidence, distribution and radiological characteristics of DO associated with OPLL.

METHODS

From January 2017 to January 2019, 55 patients with cervical OPLL were treated in our single center using an anterior cervical approach microsurgery. Preoperative CT images of decompressed segments were evaluated to identify imaging signs of DO. The 'double-layer sign' (DLS), 'parenthese sign' (PS) and 'hook sign' (HS) were considered to be characteristic imaging findings of DO in OPLL. Two kinds of confusing signs (false double-layer) were identified.

RESULTS

Nineteen segments from 15 patients with OPLL had DO related to OPLL. The incidence of DO in OPLL segments was 30.16% (19/63), and the incidence of DO in patients with OPLL was 27.27% (15/55). DO occurred at the intervertebral space level in 14 cases and at the posterior level of the vertebral body in 5 cases. The sensitivity and specificity of imaging diagnosis were 89.47% (17/19) and 81.82% (36/44), respectively. The positive predictive value was relatively low, 68.00% (17/25), due to the false-positive double-layer sign. The negative predictive value was 94.74% (36/38).

CONCLUSION

DO was relatively common in cervical OPLL. DLS might be misdiagnosed. PS and HS can vividly and intuitively describe the imaging features of DO and have high diagnostic accuracy.

Relationship between K-line distance and surgical outcome in cases of laminoplasty for cervical ossification of the posterior longitudinal ligament

Although previous studies indicate that changes in cervical alignment after laminoplasty and dynamic factors influence surgical outcomes of cervical ossification of the posterior longitudinal ligament (OPLL), the relationship between the surgical outcomes, the distance between the kyphosis-line (K-line) and OPLL, and dynamic factors have not yet been quantitatively evaluated. The purpose of the present study was to analyze the relationship between ΔK-line distance and surgical outcomes in cases of laminoplasty for OPLL of the cervical spine. We retrospectively reviewed 46 consecutive patients (33 men and 13 women) with cervical OPLL who underwent laminoplasty. "K-line distance" was measured as the minimum interval between the K-line and OPLL on lateral radiographs. The following factors were analyzed: K-line distance in neutral, flexion, and extension neck positions, ΔK-line distance, preoperative C2-7 range of motion (ROM), preoperative segmental ROM, preoperative C2-7 lordotic angle, occupying ratio of the OPLL, disease duration, preoperative and postoperative Japanese Orthopaedic Association (JOA) score, and recovery rate. Patients were divided into flexion K-line (+) and flexion K-line (-) groups. We then analyzed the influence of the K-line distance on surgical outcomes and conducted multivariate analysis to analyze the factors affecting surgical outcomes. The JOA score recovery rate in the flexion K-line (-) group was significantly lower than that in the flexion K-line (+) group (P = .024). The ΔK-line distance was significantly negatively correlated with the JOA score recovery rate (r = -0.531, P < .001). Additionally, multivariate analysis showed that ΔK-line distance (OR = -2.143, P = .015) was negatively correlated with the JOA score recovery rate. The ΔK-line distance is considered useful for the quantitative evaluation of dynamic factors and static compression factors due to OPLL through the measurement of dynamic radiographic images.

[Intraoperative ultrasound assisted circumferential decompression for multilevel ossification of the posterior longitudinal ligament in thoracic vertebrae]

OBJECTIVE

To analyze the effect of short-segment circumferential decompression and the nerve function improvement in 30 cases of multilevel thoracic OPLL assisted by intraoperative ultrasound.

METHODS

A total of 30 patients with multilevel thoracic OPLL from January 2016 to January 2021 were enrolled, all of whom were located by intraoperative ultrasound and underwent circumferential decompression. There were 14 males and 16 females, with an average age of (49.3±11.4) years. The initial symptoms were mainly numbness and weakness of lower limbs (83.3%), and the mean duration of symptoms was (33.9±42.9) months (1-168 months). Neurological function was assessed by the Modified Japanese Orthopedic Association (mJOA) score (0-11) preoperative and at the last follow-up, in which the rate of neurological improvement was calculated by the Harabayashi method. The patients were divided into excellent improved group and poor improved group according to the improvement of neurological function. The age, body mass index (BMI), duration of symptoms, operation time, blood loss, mJOA score, surgical level, and cerebrospinal fluid leakage of the two groups were collected and analyzed for statistical differences. The factors influencing the improvement of neurological function were analyzed by univariate and multivariate Logisitic regression analysis.

RESULTS

The mean operation time was 137.4±33.8 (56-190) min, and the mean blood loss was (653.7±534.2) mL (200－3 000 mL). The preoperative mJOA score was 6.0±2.1 (2－9), and the last follow-up mJOA score was 7.6±1.9 (4－11), which was significantly improved in all the patients (P < 0.001). The average improvement rate of neurological function was 38.1%±24.4% (14.3%－100%), including 75%－100% in 4 cases, 50%－74% in 3 cases, 25%－49% improved in 14 cases, and 0%－24% in 9 cases. There was significant difference in intraoperative blood loss between the excellent improved group and the poor improved group (P=0.047). Intraoperative blood loss was also an independent risk factor in regression analysis of neurological improvement.

CONCLUSION

Thoracic circumferential decompression assisted with intraoperative ultrasound can significantly improve the neurological function of patients with multilevel OPLL and achieve good efficacy. The improvement rate of nerve function can be improved effectively by controlling intraoperative blood loss.

Different standing postures are the influencing factors for the efficacy of laminoplasty in the treatment of K-Line (-) patients with ossification of the posterior longitudinal ligament

OBJECTIVE

To investigate the relationship between different standing postures and surgical outcomes of K-Line (-) ossification of the posterior longitudinal ligament (OPLL) patients after laminoplasty with a titanium basket. There is a lack of data evaluating the relationship between the postoperative satisfaction of K-Line (-) patients and their standing postures.

METHODS

OPLL patients enrolled in the study were divided into a K-Line (+) group (Group A) and a K-Line (- group (Group B) in natural and relaxed standing positions. We compared the postoperative outcomes after cervical laminoplasty with titanium basket surgery using the Japanese Orthopaedic Association score (JOA), recovery rate and the degree of improvement in the six JOA score items. The degree of satisfaction with the outcome was assessed at the 1-year follow-up using a 7-point numerical rating scale.

RESULTS

A total of 34 K-Line (+) patients with OPLL (age 61.9 ± 2.9 years) in Group A and 40 K-Line (-)patients with OPLL (age 60.4 ± 3.5 years) in Group B in natural and relaxed standing positions were recruited. In Group A, the mean preoperative and postoperative JOA scores were 10.1 ± 1.4 and 13.1 ± 0.8 points, respectively, and in Group B, the mean preoperative and postoperative JOA scores were 9.7 ± 1.3 and 11.1 ± 0.9 points, respectively. A significant improvement in the JOA score was seen in both groups postoperatively, but the recovery rate of the patients' JOA scores was significantly lower in Group B. In Group A, significant improvements were seen in all JOA score items, but in Group B, improvements were seen only in upper- and lower-extremity sensory functions.

CONCLUSION

Different standing postures are risk factors in the treatment of K-Line (-) patients, and therefore, natural and relaxed standing positions should be given more attention before devising the surgical plan.

K-line in patients with cervical ossification of the posterior longitudinal ligament: relationship with change in sagittal cervical curvature and laminoplasty outcomes

INTRODUCTION

To analyze how K-line is related to change in sagittal cervical curvature and laminoplasty outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL).

MATERIALS AND METHODS

The study retrospectively analyzed 81 patients with OPLL who had undergone posterior cervical single-door laminoplasty and arch plate fixation between June 2011 and June 2017. Fifty-five were K-line positive (K[+]) and 26 were K-line negative (K[-]). Clinical and radiological results were compared between the groups. Patients were followed up for at least 2 years.

RESULTS

Before the operation, Japanese Orthopedic Association (JOA) score, visual analogue scale (VAS) score, neck disability index (NDI), and short-form-36 (SF-36) quality of life score did not differ significantly between the groups. Neurological function was improved in both groups after the procedure. At last follow-up, JOA score, VAS score, NDI, SF-36 score, and JOA score improvement rate differed significantly between the groups. Before the operation, at the 3-month and final follow-ups, C2-7 Cobb angle, T1 slope, and C2-7 SVA differed significantly between the groups. The changes were more marked in the K(-) group than in the K(+) group. The incidence of cervical kyphosis differed significantly between the groups (P < 0.05), as well as between patients with lordosis < 7° and those with lordosis ≥ 7°.

CONCLUSIONS

K-line negativity and lordosis < 7° may predict kyphosis after laminoplasty in patients with OPLL. The cervical curvature in patients with OPLL tends towards kyphosis and anteversion after laminoplasty, which contributes to the reduced clinical effect of the procedure.

[Imaging features of developmental stenosis of atlas with degenerative cervical myelopathy]

Objective: To investigate the imaging features of patients with developmental stenosis of atlas (small atlas) complicated with degenerative cervical myelopathy and to explore the diagnostic criteria of small atlas. Methods: The clinical data of patients with degenerative cervical myelopathy treated by posterior cervical laminoplasty and resection of posterior arch of atlas from 2006 to 2020 in the Department of Orthopedics, Peking University Third Hospital were retrospectively analyzed. Sixteen cases had spinal cord compression at C₁ level after the exclusion of ossification of cervical posterior longitudinal ligament (OPLL) and other pathology. These cases were suspected small atlas (small atlas group). Forty-six cases without posterior arch resection in the same period were selected as control group. The middle sagittal diameter of atlas and the vertical distance from posterior tubercle of atlas to occipitoaxial line under CT in both groups were compared. The sagittal diameter of the spinal canal at the atlas level under MRI, the Japanese Orthopaedic Association (JOA) score for functional state of cervical spine before operation and at last follow-up were also measured. Results: There were 9 males and 7 females in the small atlas group, aged (63±12) years. There were 21 males and 25 females in the control group, aged (57±10) years. The patients in both group were followed-up for at least one year. The sagittal diameter of atlas in the small atlas group was (26.4±3.1) mm, which was significantly smaller than that in the control group [(29.6±2.2) mm, P=0.010]. The vertical distance from the posterior tubercle of atlas to the occipitoaxial line in the small atlas group was larger than that in the control group[(6.79±1.17) mm vs (5.57±1.29) mm, P=0.001]. The diameter of atlas canal in the small atlas group was (8.25±1.44) mm which was significantly smaller than that in the control group [(13.00±1.66) mm, P<0.001]. The JOA score of the small atlas group before operation and at the last follow-up were both slightly lower than that in the control group (both P<0.05), but there was no significant difference in the recovery rate of JOA score between the two groups (61.9% vs 66.0%, P=0.066). Among the 16 cases in the small atlas group, 5 cases of occipital-axial connection were located at the posterior 1/3 of the posterior arch of atlas, and 11 cases of occipital-axial connection were completely located at the posterior arch of atlas. Conclusions: The effective sagittal diameter of atlas is smaller in small atlas group which can lead to more severe cervical myelopathy. The presence of a small atlas should be highly suspected when the sagittal diameter of atlas canal is less than 26 mm under CT. The existence of the small atlas should be alert when the occipitalaxial line is located at the dorsal 1/3 or behind of the posterior arch of atlas.

Anterior controllable antedisplacement and fusion: quantitative analysis of a single surgeon's learning experience

BACKGROUND CONTEXT

Anterior controllable antedisplacement and fusion (ACAF) is a novel surgical technique for the treatment of ossification of the posterior longitudinal ligament (OPLL) but the surgical learning curve for this technique has not been previously characterized.

PURPOSE

The aim of this study was to quantify a surgeon's learning curve for ACAF and the effect of surgeon experience on postoperative outcomes.

STUDY DESIGN

Prospective study of a single institution and single surgeon experience with ACAF surgery.

PATIENT SAMPLE

A total of 70 consecutive patients with OPLL undergoing ACAF surgery by a single, non-ACAF trained surgeon between 2017 and 2020 were analyzed.

OUTCOME MEASURES

Intraoperative and postoperative outcomes (blood loss, operative time, errors of surgical procedure, length of hospital stay, Japanese Orthopedic Association (JOA) scoring system, and surgical complications) were assessed.

METHODS

We prospectively reviewed the first 70 ACAF procedures between 2017 and 2020 performed by a single, non-ACAF trained surgeon. The function relationship between the operative time and case number was fitted using a locally weighted scatterplot smoothing (LOESS) plot. Spearman's correlation analysis was performed to determine factors affecting the operative time. The operative time-related learning curve for ACAF was established and difficulty of each procedure was assessed using a cumulative sum (CUSUM) model. The association between the specific errors of surgical procedures and surgeon experience was further analyzed. A modified CUSUM model was also used to establish the surgical procedure-related learning curve, and thus whether these two learning curves matched with each other was observed. Postoperative outcomes in relation to surgeon experience was compared using a Wilcoxon rank sum test and Chi-squared test.

RESULTS

Operative time presented a specific pattern of fewer patient-dependent changes as the case number increased. Spearman's correlation analysis showed the operative time was more affected by the case number (r=-0.73) than the complexity of condition and number of levels hoisted. The operative time-related CUSUM model identified the early (first 29 cases) and late phase (late 41 cases) of the learning process, which was also confirmed by a modified CUSUM model based on surgical procedure. The critical point of the CUSUM model for bilateral osteotomies was at case number 29, and time reduction after the early phase was approximately 34 minutes. Length of hospital stay and blood loss were less during the late phase than during the early phase (p<.05). Although no significant difference was observed in postoperative JOA scores between two phases, patients in the late phase obtained higher recovery rates of neurologic function than those in the early phase (p<.01). There was significant difference in the number of specific errors between the two phases (p=.02). There were no significant differences in overall complication rates between two phases, but a higher incidence of certain complications caused by specific errors was observed in the early phase (p=.02), including CSF leakage, C5 palsy and incomplete decompression.

CONCLUSIONS

We described, for the first time, a detailed learning curve for ACAF surgery. About 29 cases were needed to achieve mastery of ACAF. Once mastered, the surgeon could deal with various OPLL presentations in a universal way regardless of condition complexity and number of surgical levels. Bilateral osteotomies were the most difficult part of ACAF and produced the greatest reduction in time after mastery. We found a close association between specific errors of surgical procedure for ACAF and surgeon experience. Furthermore, certain complications caused by these errors should be on the alert during the early phase of learning ACAF, including CSF leakage, C5 palsy and incomplete decompression.

Could Machine Learning Better Predict Postoperative C5 Palsy of Cervical Ossification of the Posterior Longitudinal Ligament?

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

The objective of this study was to investigate whether machine learning (ML) can perform better than a conventional logistic regression in predicting postoperative C5 palsy of cervical ossification of the posterior longitudinal ligament (OPLL) patients.

SUMMARY OF BACKGROUND DATA

C5 palsy is one of the most common postoperative complications after surgical treatment of OPLL, with an incidence rate of 1.4%-18.4%. ML has recently been used to predict the outcomes of neurosurgery. To our knowledge there has not been a study to predict postoperative C5 palsy of cervical OPLL patient with ML.

METHODS

Four sampling methods were used for data balancing. Six ML algorithms and conventional logistic regression were used for model development. A total of 35 ML prediction model and 5 conventional logistic prediction models were generated. The performances of each model were compared with the area under the curve (AUC). Patients who underwent surgery for cervical OPLL at our institute from January 1998 to January 2012 were reviewed. Twenty-five variables of each patient were used to make a prediction model.

RESULTS

In total, 901 patients were included [651 male and 250 female, median age: 55 (49-63), mean±SD: 55.9±9.802]. Twenty-six (2.8%) patients developed postoperative C5 palsy. Age (P=0.043), surgical method (P=0.0112), involvement of OPLL at C1-3 (P=0.0359), and postoperative shoulder pain (P≤0.001) were significantly associated with C5 palsy. Among all ML models, a model using an adaptive reinforcement learning algorithm and downsampling showed the largest AUC (0.88; 95% confidence interval: 0.79-0.96), better than that of logistic regression (0.69; 95% confidence interval: 0.43-0.94).

CONCLUSIONS

The ML algorithm seems to be superior to logistic regression for predicting postoperative C5 palsy of OPLL patient after surgery with respect to AUC. Age, surgical method, and involvement of OPLL at C1-C3 were significantly associated with C5 palsy. This study demonstrates that shoulder pain immediately after surgery is closely associated with postoperative C5 palsy of OPLL patient.

Vertebral Body Rotational Osteotomy for Decompressing an Eccentrically Protruded Ossification of the Posterior Longitudinal Ligament: A Technical Note

Vertebral body sliding osteotomy has been reported as a technique to manage cervical myelopathy caused by ossification of the posterior longitudinal ligament. It involves mobilization and anteriorly translating the vertebral body and ossified mass as a whole. The main advantage of the procedure is decreased rate of complication such as dural tear, implant dislodgement, and pseudarthrosis, which demonstrates high rate in anterior cervical corpectomy and fusion. Vertebral body rotational osteotomy is a modification of vertebral body sliding osteotomy. It is indicated for laterally deviated ossified mass to achieve further decompression. This is a technical note describing the procedures of vertebral body rotational osteotomy.

Anterior Canal Reconstruction and Fusion for Myelopathy Caused by Degenerative Cervical Kyphosis and Stenosis With or Without Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

This was a retrospective study.

OBJECTIVE

To introduce an anterior surgical technique for myelopathy caused by degenerative cervical kyphosis and stenosis (DCKS) with or without ossification of the posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

The optimal approach in the treatment of DCKS remains a controversy because each anterior or posterior route surgery has advantages and disadvantages.

MATERIALS AND METHODS

In the period from June 2017 through June 2019, a consecutive cohort of adults diagnosed with DCKS underwent anterior canal reconstruction and fusion (ACRF). All patients underwent x-ray, computed tomography, and magnetic resonance imaging of the cervical spine. Radiologic assessment included kyphosis, canal area, canal reconstruction, OPLL, and spinal cord curvature and morphology. The Japanese Orthopaedic Association (JOA) scoring system was used to evaluate the neurological status. Surgery-related and implant-related complications were all recorded. Follow-up was carried out at 3, 6, 12, 24, and 36 months postoperation.

RESULTS

Fourty-one patients were included in the study, of which 19 presented with OPLL. Postoperatively, the canal area were significantly greater at last follow-up compared with preoperation (208.4 vs. 123.2 mm2; P=0.001). There was significant kyphosis correction (-17.6 vs. 8.5 degrees, P=0.001) at last follow-up. Ninety-six segmental canal reconstruction were performed, 89 (92.7%) reached bone fusion at both grooves with a mean time of 7.9 months. On sagittal magnetic resonance imaging, 33 (80.5%) patients presented with lordosis in the spinal cord curvature, 8 (19.5%) with straight. The mean JOA score at last follow-up was significantly better than preoperation (15.0 vs. 9.3 points; P<0.01). One patient presented with cerebrospinal fluid leakage, 1 with screw displacement and 2 with dysphagia.

CONCLUSION

ACRF, receiving good correction of kyphosis, amplified canal area, solid instrumented fusion and circumferential decompression, is an effective and safe surgical technique for cervical myelopathy caused by DCKS with or without OPLL.

LEVEL OF EVIDENCE

Level III-a retrospective analysis.

The Kappa Line as a Regional Modification of the K-line: A Predictor of Neurological Outcome and Indicator of the Adequate Level of Decompression in Selective Laminoplasty

STUDY DESIGN

This is a retrospective cohort study.

OBJECTIVE

The aim was to introduce Kappa line (modification of K-line) for the prediction of postoperative neurological recovery after selective cervical laminoplasty (LMP) and use in determining the decompression level.

SUMMARY OF BACKGROUND DATA

The K-line is a radiographic marker that can predict prognosis and aid in surgical planning for patients undergoing LMP through C3 to C7. However, its efficacy in LMP involving limited segments is unclear. Furthermore, no specific radiographic marker to predict the prognosis of selective LMP has been reported.

MATERIALS AND METHODS

Fifty-one consecutive patients with a minimum 2-year follow-up after selective LMP for cervical myelopathy caused by ossification of posterior longitudinal ligament were retrospectively reviewed. The Kappa line was defined as a straight line connecting the midpoints of the spinal canal made by remaining bony structure after decompression procedures on a plain lateral radiograph in the neutral position. Patients were classified as K-line (+) or (-) and Kappa line (+) or (-) based on whether the ossified mass crossed the indicator line.

RESULTS

The Kappa line (+) group demonstrated significantly higher Japanese Orthopaedic Association (JOA) recovery rate (P=0.01), final JOA score (P<0.01), and dural sac diameter (P<0.01) postoperatively than the Kappa line (-) group. Cord compression grade was significantly lesser in the Kappa line (+) group. However, the K-line-based classification did not demonstrate significant difference in JOA recovery rate, final JOA score, and cord compression grade between the (+) and (-) groups; the dural sac diameter was significantly higher in the K-line (+) group (P<0.01).

CONCLUSIONS

The Kappa line showed better correlation with ossification of posterior longitudinal ligament size and cervical alignment, providing better prediction of neurological recovery and remaining cord compression following selective LMP. Therefore, the Kappa line can aid in determining the level of decompression in selective LMP.