Risk of spinal cord injury in patients with cervical spondylotic myelopathy and ossification of posterior longitudinal ligament: a national cohort study

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.

Comparative Study of the Cytokine Profiles of Serum and Tissues from Patients with the Ossification of the Posterior Longitudinal Ligament

BACKGROUND

The ossification of the posterior longitudinal ligament (OPLL) is one of the contributing factors leading to severe cervical spondylotic myelopathy (CSM). The mechanism causing ossification is still unclear. The current study was designed to analyze the specimens of patients with or without OPLL.

METHODS

The study collected 51 patients with cervical spondylosis. There were six serum samples in both the non-OPLL (NOPLL) and OPLL groups. For tissue analysis, there were seven samples in the NOPLL group and five samples in the OPLL group. The specimens of serum and tissue were analyzed by using Human Cytokine Antibody Arrays to differentiate biomarkers between the OPLL and NOPLL groups, as well as between serum and OPLL tissue. Immunohistochemical staining of the ligament tissue was undertaken for both groups.

RESULTS

For OPLL vs. NOPLL, the serum leptin levels are higher in the OPLL group, corroborating others' observations that it may serve as a disease marker. In the tissue, angiogenin (ANG), osteopontin (OPN), and osteopro-tegerin (OPG) are higher than they are in the OPLL group (p < 0.05). For serum vs. OPLL tissue, many chemotactic cytokines demonstrated elevated levels of MIP1 delta, MCP-1, and RANTES in the serum, while many cytokines promoting or regulating bone genesis were up-regulated in tissue (oncostatin M, FGF-9, LIF, osteopontin, osteoprotegerin, TGF-beta2), as well as the factor that inhibits osteoclastogenesis (IL-10), with very few cytokines responsible for osteoclastogenesis. Molecules promoting angiogenesis, including angiotensin, vEGF, and osteoprotegerin, are abundant in the OPLL tissue, which paves the way for robust bone growth.

Characteristics of the cervical spine and cervical cord injuries in older adults with cervical ossification of the posterior longitudinal ligament

Although the incidence of cervical spinal cord injury (CSCI) with ossification of the posterior longitudinal ligament (OPLL) has increased in older adults, its etiology and neurological outcomes remain unknown. We identified OPLL characteristics and determined whether they influence neurological severity and improvement of CSCI in older patients. This multicenter retrospective cohort study identified 1512 patients aged ≥ 65 years diagnosed with CSCI on admission during 2010-2020. We analyzed CSCI etiology in OPLL patients. We performed propensity score-adjusted analyses to compare neurological outcomes between patients with and without OPLL. Cases were matched based on variables influencing neurological prognosis. The primary neurological outcome was rated according to the American Spine Injury Association (ASIA) impairment scale (AIS) and ASIA motor score (AMS). In 332 OPLL patients, the male-to-female ratio was approximately 4:1. Half of all patients displayed low-energy trauma-induced injury and one-third had CSCI without a bony injury. Propensity score matching created 279 pairs. There was no significant difference in the AIS grade and AMS between patients with and without OPLL during hospitalization, 6 months, and 12 months following injury. OPLL patients tended to exhibit worse neurological findings during injury; nevertheless, OPLL was not associated with poor neurological improvement in older CSCI patients.

Prevalence of pre-existing factors causing spinal cord compression: Is there a difference between patients suffering from cervical spinal cord injury with and without bone injury?

BACKGROUND

Recently, the prevalence of elderly patients suffering from cervical spinal cord injury (CSCI) without bone injury has been increasing in various countries. Pre-existing factors causing spinal cord compression, such as ossification of the posterior longitudinal ligament (OPLL), can increase the risk of CSCI without bone injury. However, no study has compared the prevalence of pre-existing factors between CSCI with and without bone injury. This study aimed to compare the prevalence of pre-existing factors between CSCI with and without bone injury.

METHODS

In 168 consecutive patients with CSCI, pre-existing factors including OPLL, posterior spur of the vertebral body, developmental stenosis, disc bulge and calcification of yellow ligament (CYL) were evaluated on imaging studies. The prevalence of each type of pre-existing factors was compared between patients with and without bone injury.

RESULTS

The prevalence of pre-existing factors in patients without bone injury (86%) was significantly higher than in those with bone injury (20%) (P < 0.001; odds ratio, 23.9). The most common pre-existing factor was OPLL followed by developmental stenosis, posterior spur, disc bulge and CYL in both groups. OPLL, development stenosis and posterior spur were significantly more common in patients without bone injury compared to those with bone injury (P < 0.01).

CONCLUSIONS

Prevalence of pre-existing factors, such as OPLL, development stenosis and posterior spur was significantly higher in patients without bone injury than in those with bone injury. Thus, these pre-existing factors might be a potential risk of CSCI without bone injury.

Nature or nurture: a latent ossification of the posterior longitudinal ligament after atlantoaxial fusion. Illustrative case

BACKGROUND

The natural history of ossification of the posterior longitudinal ligament (OPLL) remains poorly understood and multiple etiologies have been reported. However, most have focused on the characteristics of the patient rather than alternation of mechanical stress after spinal fusion.

OBSERVATIONS

This report describes, for the first time, a de novo OPLL found at the subaxial cervical spine 7 years after an atlantoaxial fusion surgery. A 57-year-old female initially required atlantoaxial arthrodesis for os odontoideum and stenosis that caused myelopathy. The posterior fusion surgery went smoothly without complications and the patient had good recovery of neurological functions. There was no associated instability, trauma, or reoperations during the follow-up. Seven years later, the patient presented with slight neck pain and a newly developed OPLL at C3-4 caudal to the C1-2 fusion construct.

LESSONS

Conflicting with the conventional concept that OPLL is common in elderly men with genetic or hormonal factors, or associated spondyloarthropathies, OPLL could develop in women even after solid C1-2 fusion. The adjacent subaxial cervical spine is not free of risks for subsequent development of OPLL and cervical spondylotic myelopathy. This case illustration extends the scope of etiologies of OPLL within the present literature.

Detecting ossification of the posterior longitudinal ligament on plain radiographs using a deep convolutional neural network: a pilot study

BACKGROUND CONTEXT

Its rare prevalence and subtle radiological changes often lead to difficulties in diagnosing cervical ossification of the posterior longitudinal ligament (OPLL) on plain radiographs. However, OPLL progression may lead to trauma-induced spinal cord injury, resulting in severe paralysis. To address the difficulties in diagnosis, a deep learning approach using a convolutional neural network (CNN) was applied.

PURPOSE

The aim of our research was to evaluate the performance of a CNN model for diagnosing cervical OPLL.

STUDY DESIGN AND SETTING

Diagnostic image study.

PATIENT SAMPLE

This study included 50 patients with cervical OPLL, and 50 control patients with plain radiographs.

OUTCOME MEASURES

For the CNN model performance evaluation, we calculated the area under the receiver operating characteristic curve (AUC). We also compared the sensitivity, specificity, and accuracy of the diagnosis by the CNN with those of general orthopedic surgeons and spine specialists.

METHODS

Computed tomography was used as the gold standard for diagnosis. Radiographs of the cervical spine in neutral, flexion, and extension positions were used for training and validation of the CNN model. We used the deep learning PyTorch framework to construct the CNN architecture.

RESULTS

The accuracy of the CNN model was 90% (18/20), with a sensitivity and specificity of 80% and 100%, respectively. In contrast, the mean accuracy of orthopedic surgeons was 70%, with a sensitivity and specificity of 73% (SD: 0.12) and 67% (SD: 0.17), respectively. The mean accuracy of the spine surgeons was 75%, with a sensitivity and specificity of 80% (SD: 0.08) and 70% (SD: 0.08), respectively. The AUC of the CNN model based on the radiographs was 0.924.

CONCLUSIONS

The CNN model had successful diagnostic accuracy and sufficient specificity in the diagnosis of OPLL.

Prognostic Factors for Cervical Spinal Cord Injury without Major Bone Injury in Elderly Patients

In the current aging society, there has been a marked increase in the incidence of cervical spinal cord injury (CSCI) without major bone injury. This multi-center study aimed to identify predictors of neurological improvement in elderly patients with CSCI without major bone injury. The participants were 591 patients aged ≥65 years with CSCI without major bone injury and a minimum follow-up period of three months. Neurologic status was defined using the American Spinal Injury Association (ASIA) impairment scale (AIS). Univariate and multi-variate analyses were performed to identify prognostic factors for walking recovery in AIS A-C cases and full upper extremity motor recovery in AIS D cases. In AIS A-C cases, body mass index (odds ratio (OR): 1.112), magnetic resonance imaging signal change (OR: 0.240), AIS on admission (OR: 3.497), comorbidity of dementia/delirium (OR: 0.365), and post-injury pneumonia (OR: 0.194) were identified as independent prognostic factors for walking recovery. The prevalence of ossification of the posterior longitudinal ligament (OR: 0.494) was also found to be an independent prognostic factor in AIS B and C cases only. In AIS D cases, age (OR: 0.937), upper extremity ASIA motor score on admission (OR: 1.230 [per 5 scores]), and operation (OR: 0.519) were independent prognostic factors for full motor recovery. The severity of AIS at admission was the strongest predictor of functional outcomes. Promoting rehabilitation, however, through measures to reduce cognitive changes, post-injury pneumonia, and unhealthy body weight changes can contribute to greater neurological improvement in AIS A-C cases.

Improving Awareness Could Transform Outcomes in Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 1]

STUDY DESIGN

Literature Review (Narrative).

OBJECTIVE

To introduce the number one research priority for Degenerative Cervical Myelopathy (DCM): Raising Awareness.

METHODS

Raising awareness has been recognized by AO Spine RECODE-DCM as the number one research priority. This article reviews the evidence that awareness is low, the potential drivers, and why this must be addressed. Case studies of success from other diseases are also reviewed, drawing potential parallels and opportunities for DCM.

RESULTS

DCM may affect as many as 1 in 50 adults, yet few will receive a diagnosis and those that do will wait many years for it. This leads to poorer outcomes from surgery and greater disability. DCM is rarely featured in healthcare professional training programs and has received relatively little research funding (<2% of Amyotrophic Lateral Sclerosis or Multiple Sclerosis over the last 25 years). The transformation of stroke and acute coronary syndrome services, from a position of best supportive care with occasional surgery over 50 years ago, to avoidable disability today, represents transferable examples of success and potential opportunities for DCM. Central to this is raising awareness.

CONCLUSION

Despite the devastating burden on the patient, recognition across research, clinical practice, and healthcare policy are limited. DCM represents a significant unmet need that must become an international public health priority.

Combined Anterior and Posterior Decompression With Fusion for Cervical Ossification of the Posterior Longitudinal Ligament

Objective:

Cervical myelopathy caused by ossification of the posterior longitudinal ligament (OPLL) is not uncommon among Asian ethnic groups. Despite reports comparing the pros and cons of anterior- and posterior-only approaches, the optimal management remains debatable. This study aimed to evaluate the outcomes of patients who underwent a combined anterior and posterior approach, simultaneous circumferential decompression and fixation, for cervical OPLL.

Method:

The study retrospectively reviewed patients with OPLL and who underwent circumferential decompression and fixation, combined anterior corpectomy and posterior laminectomy. The clinical outcomes were evaluated by the Visual Analog Scale of neck and arm pain, the Japanese Orthopedic Association scores, Neck Disability Index, and Nurick scores at each time-point of evaluation. Radiological evaluations included plain and dynamic radiographs and computed tomography for every patient within 2 years post-operation. Subgroup analyses were further performed between the groups, with and without intra-operative cerebrospinal fluid (CSF) leakage.

Results:

A total of 41 patients completed the follow-up for more than 2 years (mean = 39.8 months) and were analyzed. Continuous-type OPLL was the most common (44%), followed by segmental (27%), mixed (22%), and localized types (7%) in the cohort. Myelopathy and all other functional outcomes improved significantly at 2 years post-operation (all p < 0.05). There were 13 (32%) patients who had intra-operative CSF leakage. At 2 years post-operation, there were no differences in the demographics, functional outcomes, and complication rates between the CSF-leakage and no-leakage groups. The CSF-leakage group had more patients with continuous-type OPLL than the no-leakage group (77 vs. 29%, p = 0.004 < 0.05). During the follow-up, there was no secondary or revision surgery for pseudomeningocele, pseudarthrosis, or other surgery-related complications.

Conclusions:

Simultaneous circumferential decompression and fixation combine the surgical benefits of sufficient decompression by the posterior approach and direct decompression of OPLL by the anterior approach. It is an effective surgical option for patients with cervical myelopathy caused by OPLL, given that myelopathy unanimously improved without neurological complications in this study. The fusion rates were high, and reoperation rates were low. Despite higher rates of CSF leakage, there were no related long-term sequelae, and minimal wound complications.

High incidence of venous thromboembolism after acute cervical spinal cord injury in patients with ossification of the posterior longitudinal ligament

Objective: To determine the incidence of venous thromboembolism (VTE) in patients with acute cervical spinal cord injury (SCI) and ossification of the posterior longitudinal ligament (OPLL).Design: Prospective cohort study.Setting: A department of a university hospital in Japan.Participants: This study included 57 patients (OPLL, n = 10; non-OPLL, n = 47) treated for acute cervical SCI between January 2011 and April 2017. Patients were classified according to motor complete paralysis (MC), motor incomplete paralysis (MIC), or normal motor function, based on American Spinal Injury Association (ASIA) Impairment Scale results.Interventions: N/A.Outcome Measures: All patients were screened for VTE by D-dimer monitoring, and some underwent ultrasonography. If ultrasonography indicated deep venous thrombosis (DVT) or if the D-dimers increased to ≥10 µg/mL, patients underwent contrast venography to detect VTE, including DVT or pulmonary embolism. We compared blood coagulability and VTE incidence in the OPLL and non-OPLL groups.Results: VTE occurred in 11 (19.3%) of 57 patients. The incidence of VTE was higher in the OPLL group than in the non-OPLL group (50% vs. 12.8%; P = 0.017) and higher in the MC group (57.1%) than in the MIC (8.3%; P = 0.002) or normal group (5.3%; P = 0.002). In the MC group, VTE occurred in 50% of OPLL patients and in 62.5% of non-OPLL patients (P = 0.529). In the MIC group, VTE occurred in 50% of OPLL patients and in none of the non-OPLL patients (P = 0.022).Conclusions: Patients with OPLL tended to develop VTE after SCI with motor complete and incomplete paralysis.

Does surgical treatment increase the progression of spinal cord injury in patients with ossification of posterior longitudinal ligament of cervical spine? A systematic review and meta-analysis

PURPOSE

The purpose of this study is to explore if the surgical treatment will accelerate the progression of spinal cord injury (SCI) in patients with cervical Ossification of the posterior longitudinal ligament (OPLL) and if surgery will have better curative effect than conservative treatment.

METHODS

An extensive search of literature was implemented in PubMed, EMBASE, and other online databases. The quality of the included articles was evaluated according to the Newcastle-Ottawa Quality Assessment Scale, as recommended by the Cochrane manual, and meta-analysis was performed using the review manage5.3 software.

RESULTS

No obvious statistical difference was observed in the rate of SCI progression (P > 0.05, OR 1.15 [0.66, 2.00]), cervical range of motion, (P > 0.05, weighted mean difference (WMD) 4.52 [-5.75, 14.79]), and Japanese Orthopedic Association scores before surgery (P > 0.05, WMD -2.78 [-7.87, 2.32]) between the surgical group and conservative treatment group. However the surgical group illustrated obviously higher neurofunctional recovery rate (P < 0.05, OR 6.07 [1.55, 23.78]) and postoperative JOA score of the surgery group (P < 0.05, WMD -0.77 [-1.21, -0.33]) than conservative group.

CONCLUSIONS

Based on this meta-analysis, there is not enough evidence to indicate that surgery will accelerate the progress of SCI with OPLL. However, the superiority of surgical efficacy can be observed over conservative treatment in terms of relieving neurological symptoms.

Use of residual neural network for the detection of ossification of the posterior longitudinal ligament on plain cervical radiography

Ossification of the posterior longitudinal ligament (OPLL) causes serious problems, such as myelopathy and acute spinal cord injury. The early and accurate diagnosis of OPLL would hence prevent the miserable prognoses. Plain lateral radiography is an essential method for the evaluation of OPLL. Therefore, minimizing the diagnostic errors of OPLL on radiography is crucial. Image identification based on a residual neural network (RNN) has been recognized to be potentially effective as a diagnostic strategy for orthopedic diseases; however, the accuracy of detecting OPLL using RNN has remained unclear. An RNN was trained with plain lateral cervical radiography images of 2,318 images from 672 patients (535 images from 304 patients with OPLL and 1,773 images from 368 patients of Negative). The accuracy, sensitivity, specificity, false positive rate, and false negative rate of diagnosis of the RNN were calculated. The mean accuracy, sensitivity, specificity, false positive rate, and false negative rate of the model were 98.9%, 97.0%, 99.4%, 2.2%, and 1.0%, respectively. The model achieved an overall area under the curve of 0.99 (95% confidence interval, 0.97-1.00) in which AUC in each fold estimated was 0.99, 0.99, 0.98, 0.98, and 0.99, respectively. An algorithm trained by an RNN could make binary classification of OPLL on cervical lateral X-ray images. RNN may hence be useful as a screening tool to assist physicians in identifying patients with OPLL in future setting. To achieve accurate identification of OPLL patients clinically, RNN has to be trained with other cause of myelopathy.

Degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) frequently leads to severe neurologic disability but is still frequently underdiagnosed. One explanation may be the variability of the symptoms presented by the patients, from paresthesia to quadriplegia, making it another great masquerader. What do we know? How can we manage better these patients? We will review the keys points concerning its challenging diagnosis (clinical and radiologic), some of the recent discoveries about DCM, notably the underlying genetic mutations identified, linked to its pathophysiology, before addressing the consensual points concerning its management and the major evolutive risk: acute decompensation.

Prevalence of Ossification of Posterior Longitudinal Ligament in Patients With Degenerative Cervical Myelopathy: Cervical Spine 3D CT Observations in 7210 Cases

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

The aim of this study was to investigate the prevalence of ossification of posterior longitudinal ligament (OPLL) in patients with degenerative cervical myelopathy (DCM).

SUMMARY OF BACKGROUND DATA

OPLL of the cervical spine is one of the main entities of DCM in Asian populations. However, few studies have reported the prevalence of cervical OPLL in DCM patients.

METHODS

A total of 7210 DCM patients (4546 males and 2664 females; mean age: 54 years) who underwent cervical spine three-dimensional computed tomography (3D-CT) at the Shanghai Changzheng Hospital between January 2012 and December 2016 were included in this study. Demographic data including age, sex, height, body weight, body mass index (BMI), concomitant diabetes mellitus (DM), and hypertension were recorded. The imaging diagnosis criterion for OPLL was thickness >2 mm on axial imaging.

RESULTS

The overall prevalence of OPLL in the 7210 DCM patients was 18.22%, including 19.73% in males and 15.65% in females, with a significant difference between the two groups (P < 0.001). The prevalence of OPLL in DM and hypertensive patients was significantly higher than that in non-DM and normotensive patients (24.16% vs. 18.76% and 22.26% vs. 17.91%, both P < 0.001). Comparison by age and BMI showed that the prevalence of OPLL was the highest in the 70- to 79-year age group (21.91%) and obesity group (26.51%), respectively.

CONCLUSION

This CT-based study revealed that the overall prevalence of OPLL in DCM patients was 18.22%. Furthermore, old age, male sex, comorbid hypertension or DM, and high BMI were risk factors for cervical OPLL. Given its high prevalence, CT examination is suggested to identify possible OPLL in DCM patients.

LEVEL OF EVIDENCE

2.

Investigation of a three-dimensional printed dynamic cervical spine model for anatomy and physiology education

INTRODUCTION

Three-dimensional (3D) printing of anatomical structures is a growing method of education for students and medical trainees. These models are generally produced as static representations of gross surface anatomy. In order to create a model that provides educators with a tool for demonstration of kinematic and physiologic concepts in addition to surface anatomy, a high-resolution segmentation and 3D-printingtechnique was investigated for the creation of a dynamic educational model.

METHODS

An anonymized computed tomography scan of the cervical spine with a diagnosis of ossification of the posterior longitudinal ligament was acquired. Using a high-resolution thresholding technique, the individual facet and intervertebral spaces were separated, and models of the C3-7 vertebrae were 3D-printed. The models were placed on a myelography simulator and subjected to flexion and extension under fluoroscopy, and measurements of the spinal canal diameter were recorded and compared to in-vivo measurements. The flexible 3D-printed model was then compared to a static 3D-printed model to determine the educational benefit of demonstrating physiologic concepts.

RESULTS

The canal diameter changes on the flexible 3D-printed model accurately reflected in-vivo measurements during dynamic positioning. The flexible model also was also more successful in teaching the physiologic concepts of spinal canal changes during flexion and extension than the static 3D-printed model to a cohort of learners.

CONCLUSIONS

Dynamic 3D-printed models can provide educators with a cost-effective and novel educational tool for not just instruction of surface anatomy, but also physiologic concepts through 3D ex-vivo modeling of case-specific physiologic and pathologic conditions.

Muscular Activity Modulation During Post-operative Walking With Hybrid Assistive Limb (HAL) in a Patient With Thoracic Myelopathy Due to Ossification of Posterior Longitudinal Ligament: A Case Report

Disorders of the central nervous system sometimes cause severe sensory motor paralysis accompanied by gait impairment. Recently, there are several reports on the effectiveness of robot-assisted gait training for patients experiencing these issues. The purpose of this case report was to assess the neuromechanical effect of a wearable robot suit HAL (Hybrid Assistive Limb) during post-operative gait training in a patient with gait impairment due to compressive myelopathy caused by ossification of the posterior longitudinal ligament (OPLL). For this purpose, we compared lower limb muscular activities while the patient was walking with and without the robot through a course of treatment sessions by (i) gait phase-dependent muscle usage analysis, (ii) muscle synergy analysis, and (iii) muscle network analysis. The results show (i) enhanced activity of the extensor muscles for weight-bearing in the initial sessions by using HAL and reduced knee extensor and increased hip extensor activations for achieving larger steps and faster gait in the later sessions; (ii) involvement of a greater number of synergies during walking with HAL than without HAL; and (iii) modulated muscle network property during walking with HAL remaining until the next HAL session. The patient's gait was improved after completing HAL sessions, acquiring close to normal joint profile with greater range of joint movement, faster walking speed, and larger step length. We discuss that the muscular activity modulation during walking with HAL suggests altered control of the muscles by the central nervous system during post-operative walking. Activity-dependent sensorimotor augmentation by HAL is discussed in the context of recovery of gait control by the central nervous system. The relationship between the altered control and the achieved gait recovery requires further investigation.

Degenerative cervical myelopathy - update and future directions

Degenerative cervical myelopathy (DCM) is the leading cause of spinal cord dysfunction in adults worldwide. DCM encompasses various acquired (age-related) and congenital pathologies related to degeneration of the cervical spinal column, including hypertrophy and/or calcification of the ligaments, intervertebral discs and osseous tissues. These pathologies narrow the spinal canal, leading to chronic spinal cord compression and disability. Owing to the ageing population, rates of DCM are increasing. Expeditious diagnosis and treatment of DCM are needed to avoid permanent disability. Over the past 10 years, advances in basic science and in translational and clinical research have improved our understanding of the pathophysiology of DCM and helped delineate evidence-based practices for diagnosis and treatment. Surgical decompression is recommended for moderate and severe DCM; the best strategy for mild myelopathy remains unclear. Next-generation quantitative microstructural MRI and neurophysiological recordings promise to enable quantification of spinal cord tissue damage and help predict clinical outcomes. Here, we provide a comprehensive, evidence-based review of DCM, including its definition, epidemiology, pathophysiology, clinical presentation, diagnosis and differential diagnosis, and non-operative and operative management. With this Review, we aim to equip physicians across broad disciplines with the knowledge necessary to make a timely diagnosis of DCM, recognize the clinical features that influence management and identify when urgent surgical intervention is warranted.

Natural History of Acromegaly: Incidences, Re-operations, Cancers, and Mortality Rates in a National Cohort

BACKGROUND

Acromegaly is so rare that its natural history, including incidence, risk of cancers, and mortality rates, remains elusive. This natural study utilized a nationwide database to provide a better understanding of acromegaly's disease course.

METHODS

A cohort of 1,195 acromegaly patients were identified and followed-up from 1997 to 2013. Incidence, operation, and re-operation rates were calculated. Excessive mortality and cancer risk related to acromegaly were estimated by standardized mortality ratio (SMR) and standardized incidence ratio (SIR).

RESULTS

The incidence was 2.78 per million-person-years, with little gender predominance (female vs. male, 49.5 vs. 50.5%, respectively). There was female predominance only among 50 and 60 year-olds (incidence rate ratio: 1.37 and 1.43, p < 0.001 and p = 0.002). Among them, 673 (56.3%) had hypophysectomy surgery, and the young-onset (<40 years) patients had more re-operations (15.5%, p = 0.01). The overall mortality rate was 22.3 per 1,000 person-years, with a median survival of 4.67 years (with no gender differences, p = 0.38). The overall SMR of acromegaly patients was 1.41, and the onset-age-specific SMRs of the early- and middle-onset patients were higher than for those with late-onset. There were 87 newly diagnosed cancers in the cohort, with an incidence rate of 10.6 per 1,000 person-years (median 5.4 years). The overall SIR of cancers was 1.91, and there were no differences among gender, onset-age, and disease duration (all SIR >1, approximately 2).

CONCLUSION

Acromegaly is associated with an excessive risk of mortality and two-fold higher risk of cancers. Patients with acromegaly should be managed appropriately after the diagnosis.

Recent advances in the management of cervical spondylotic myelopathy: bibliometric analysis and surgical perspectives

OBJECTIVE

Cervical spondylotic myelopathy (CSM) has become a prevalent cause of spinal cord dysfunction among the aging population worldwide. Although great strides have been made in spine surgery in past decades, the optimal timing and surgical strategy to treat CSM have remained controversial. In this article the authors aimed to analyze the current trends in studies of CSM and to summarize the recent advances of surgical techniques in its treatment.

METHODS

The PubMed database was searched using the keywords pertaining to CSM in human studies that were published between 1975 and 2018. Analyses of both the bibliometrics and contents, including the types of papers, authors, affiliations and countries, number of patients, and the surgical approaches were conducted. A systematic review of the literature was also performed with emphasis on the diagnosis and treatment of mild CSM.

RESULTS

A total of 1008 papers published during the span of 44 years were analyzed. These CSM studies mainly focused on the natural history, diagnosis, and treatment, and only a few prospective randomized trials were reported. For the authors and affiliations, there was a shift of clustering of papers toward Asian countries in the past decades. Regarding the treatment for CSM, there was an exponential growth of surgical series published, and there was a trend toward slightly more anterior than posterior approaches through the past decade. Patients with CSM had increased risks of neurological deterioration or spinal cord injury with nonoperative management. Because surgery might reduce the risks, and early surgery was likely to be correlated with better outcomes, there was a trend toward attention to mildly symptomatic CSM.

CONCLUSIONS

There is emerging enthusiasm for research on CSM worldwide, with more publications originating in Asian countries over the past few decades. The surgical management of CSM is evolving continuously toward early and anterior approaches. More prospective investigations on the optimal timing and choices of surgery are therefore needed.

Persistent knee pain after uncomplicated total knee arthroplasty secondary to undiagnosed spondylotic myelopathy: a case report

Introduction

Knee osteoarthritis and cervical spondylotic myelopathy are both frequent disorders in the aging patient. Total knee arthroplasty is an increasingly common surgical procedure, with approximately 20% of patients describing persistent knee pain after the procedure, for which it is often difficult to find a cause. We review known reasons for pain after total knee arthroplasty and present a new clinically challenging case of persistent knee pain due to previously undiagnosed cervical spondylotic myelopathy.

Case presentation

Our patient presented with painful knee spasms after an uncomplicated total knee arthroplasty. Her workup revealed cervical spondylotic myelopathy with isolated changes in tone in the affected extremity as well as weakness and atrophy in non-painful limbs. Her clinical status improved after cervical decompression and fusion. We perform a literature review for prior reports of isolated knee pain due to cervical spondylotic myelopathy and find no previous reported association with total knee arthroplasty.

Discussion

Cervical spondylotic myelopathy is the most common spinal cord disorder in older adults. Incidence increases with age and the clinical manifestations may present with a variety of neurological findings. Careful musculoskeletal and neurologic examination is critical to an accurate and timely diagnosis.

RE-CODE DCM (REsearch Objectives and Common Data Elements for Degenerative Cervical Myelopathy): A Consensus Process to Improve Research Efficiency in DCM, Through Establishment of a Standardized Dataset for Clinical Research and the Definition of the Research Priorities

STUDY DESIGN

Mixed-method consensus process.

OBJECTIVES

Degenerative cervical myelopathy (DCM) is a common and disabling condition that arises when mechanical stress damages the spinal cord as a result of degenerative changes in the surrounding spinal structures. RECODE-DCM (REsearch Objectives and Common Data Elements for Degenerative Cervical Myelopathy) aims to improve efficient use of health care resources within the field of DCM by using a multi-stakeholder partnership to define the DCM research priorities, to develop a minimum dataset for DCM clinical studies, and confirm a definition of DCM.

METHODS

This requires a multi-stakeholder partnership and multiple parallel consensus development processes. It will be conducted via 4 phases, adhering to the guidance set out by the COMET (Core Outcomes in Effectiveness Trials) and JLA (James Lind Alliance) initiatives. Phase 1 will consist of preliminary work to inform online Delphi processes (Phase 2) and a consensus meeting (Phase 3). Following the findings of the consensus meeting, a synthesis of relevant measurement instruments will be compiled and assessed as per the COSMIN (Consensus-based Standards for the Selection of Health Measurement Instruments) criteria, to allow recommendations to be made on how to measure agreed data points. Phase 4 will monitor and promote the use of eventual recommendations.

CONCLUSIONS

RECODE-DCM sets out to establish for the first time an index term, minimum dataset, and research priorities together. Our aim is to reduce waste of health care resources in the future by using patient priorities to inform the scope of future DCM research activities. The consistent use of a standard dataset in DCM clinical studies, audit, and clinical surveillance will facilitate pooled analysis of future data and, ultimately, a deeper understanding of DCM.

Long Term Outcomes and Effects of Surgery on Degenerative Spinal Deformity: A 14-Year National Cohort Study

Degenerative spinal deformity (DSD) has become a prevalent cause of disability and pain among the aging population worldwide. Though surgery has emerged as a promising option for DSD, the natural course, outcomes, and effects of surgery on DSD have remained elusive. This cohort study used a national database to comprehensively follow up patients of DSD for all-cause mortality, respiratory problems, and hip fracture-related hospitalizations. All patients were grouped into an operation or a non-operation group for comparison. An adjustment of demographics, comorbidities, and propensity-score matching was conducted to ameliorate confounders. A Cox regression hazard ratio (HR) model and Kaplan-Meier analysis were also applied. The study comprised 21,810 DSD patients, including 12,544 of the operation group and 9266 of the non-operation group. During the 14 years (total 109,591.2 person-years) of follow-up, the operation group had lower mortality (crude hazard ratio = 0.40), lower respiratory problems (cHR = 0.45), and lower hip fractures (cHR = 0.63) than the non-operation group (all p < 0.001). After adjustment, the risks for mortality and respiratory problems remained lower (adjusted HR = 0.60 and 0.65, both p < 0.001) in the operation than the non-operation group, while hip fractures were indifferent (aHR = 1.08, p > 0.05). Therefore, surgery for DSD is invaluable since it could reduce the risks of mortality and of hospitalization for respiratory problems.

Association of Depression and Cervical Spondylosis: A Nationwide Retrospective Propensity Score-Matched Cohort Study

Objective: Depression is a psychiatric disorder associated with poorer health outcomes. Inappropriate mechanical stress and aging are factors associated with developing cervical spondylosis. The connection between cervical spondylosis and depression is not developed. Methods: From the health insurance claims data of Taiwan, we identified 34,166 persons newly diagnosed with depression in 2000⁻2010 and 34,166 persons without the disorder frequency matched by sex, age and diagnosis year. Both cohorts were followed up to the end of 2013 to estimate incident cervical spondylosis. We further examined the risk of cervical spondylosis in depressed people taking antidepressants. Results: The incidence of cervical spondylosis was 1.8-fold greater in the depression cohort than in comparison cohort (9.46 vs. 5.36 per 1000 person-years), with an adjusted hazard ratio (aHR) of 1.79 (95% confidence interval (CI) = 1.66⁻1.92). The incidence of cervical spondylosis increased in patients who had taken medications of serotonin-specific reuptake inhibitors (SSRIs) or of non-SSRIs than in those without these medicines (9.13 or 11.5 vs. 6.54 per 1000 person-years, respectively). Conclusions: Patients with depression are at an increased risk of developing cervical spondylosis. Additional efforts in reducing the risk of cervical spondylosis might be required in depressed individuals undergoing anti-depressive therapy.

Risk of posterior circulation stroke in patients with cervical spondylosis: A nationwide, population-based study

BACKGROUND AND AIMS

Cervical spondylosis (CS) is reported to be associated with vertebrobasilar insufficiency. However, few cohort studies have investigated the association between CS and posterior circulation ischemic stroke.

METHODS

The study cohort comprised 27,990 patients aged ≥18 years with a first diagnosis of CS. The controls consisted of patients with propensity score matched for age, sex, and comorbidities at a ratio of 1:1. We investigated the relationships of CS with ischemic stroke and all-cause mortality. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). The average follow-up duration was 6.13 (SD = 3.18) and 6.07 (SD = 3.19) years in the CS and non-CS cohorts, respectively.

RESULTS

The mean age of CS patients and non-CS patients was 54.9 ± 13.4 and 55.1 ± 14.9 years. Fifty-eight point five percent of CS patients and 59.2% of non-CS patients were women. CS patients were 1.46 folds more likely to develop a posterior circulation ischemic stroke (95% CI, 1.23-1.72) than non-CS patients. CS patients with myelopathy exhibited a 1.50-fold risk (95% CI, 1.21-1.86) of posterior circulation ischemic stroke compared with non-CS patients; CS patients without myelopathy were at a 1.43-fold risk (95% CI, 1.18-1.73) of posterior ischemic stroke compared with non-CS patients. The risk of posterior ischemic stroke was non-significant between non-CS patients and CS patients who had received spinal anterior decompression (adjusted HR, 1.66; 95% CI, 0.78-3.52), while receiving posterior decompression was associated with a 4.23-fold risk of posterior ischemic stroke (95% CI, 1.05-17.0).

CONCLUSIONS

This population-based study showed that CS is associated with an increased risk of posterior circulation ischemic stroke. Surgical posterior decompression was associated with the highest risk of posterior ischemic stroke.

Ossification of the posterior longitudinal ligament in the cervical spine: a review

Ossification of the posterior longitudinal ligament (OPLL) is a rare pathologic process of lamellar bone deposition that can result in spinal cord compression. While multiple genetic and environmental factors have been related to the development of OPLL, the pathophysiology remains poorly understood. Asymptomatic patients may be managed conservatively and patients with radiculopathy or myelopathy should be considered for surgical decompression. Multiple studies have demonstrated the morphology and size of the OPLL as well as the cervical alignment have significant implications for the appropriate surgical approach and technique. In this review, we aim to address all the available literature on the etiology, history, presentation, and management of OPLL in an effort to better understand OPLL and give our recommendations for the treatment of patients presenting with OPLL.

Ossification of the Posterior Longitudinal Ligament in Cervical Spine: Prevalence, Management, and Prognosis

Ossification of the posterior longitudinal ligament (OPLL) in the cervical spine and related neurological complications are not uncommon in East Asian countries. The estimated prevalence of cervical OPLL-related hospitalization is 7.7 per 100,000 person-years in Taiwan, and higher incidence rates have been observed in elderly and male patients. Although cervical OPLL is frequently insidious, it can eventually cause myelopathy and predispose patients to spinal cord injury (SCI). There are multiple options for managing cervical OPLL, ranging from observation to many kinds of surgical procedures, including posterior laminoplasty, laminectomy with or without fusion, anterior corpectomy with or without instrumentation, and circumferential decompression and fusion. None of these surgical approaches is free of complications. However, to date, there is still a lack of consensus regarding the choice of the surgical approach and the timing of surgical intervention. Cervical SCI and related neurological disabilities are more likely to occur in OPLL patients, who should therefore be cautioned regarding the possibility of a subsequent SCI if treated without surgery. This article aimed to review the prevalence, management strategies, and prognosis of cervical OPLL.

Microscope Enhanced the Efficacy and Safety of Anterior Cervical Surgery for Managing Cervical Ossification of the Posterior Longitudinal Ligament

Background

We aimed to compare microscope-assisted anterior cervical surgery with traditional open-base surgery for treating cervical ossification of the posterior longitudinal ligament (OPLL).

Material/Methods

Patients were grouped into microscope-assisted anterior cervical surgery group (case group, n=30) and conventional anterior cervical surgery group (control group, n=30). Baseline characteristics, intraoperative and post-operative indexes including operation time, blood loss amount, duration of hospitalization, visual analogue scale (VAS), and complication rate were recorded. The neurological functions of patients were assessed using the Japanese Orthopaedic Association (JOA) score. Furthermore, the corresponding rate of improved JOA score (RIS) in each group was also calculated to evaluate surgery outcomes.

Results

The average blood loss amount and hospital stay duration in the case group were lower than in the control group (p<0.05). The post-operative VAS scores of both groups were decreased significantly. Particularly the post-operative VAS score in the case group was significantly lower than that in the control group (p<0.05). While the improvement rate of JOA scores in the case group was significantly higher than that in control group after cervical spine surgery. A significantly higher RIS rate was observed in the case group (p<0.05). Furthermore, post-operative complications of patients in the case group were lower than those in the control group (p<0.05).

Conclusions

Compared to conventional anterior cervical surgery, surgeries operated with microscope exhibit higher efficacy and safety including less bleeding amount, shorter operation time, released pain degree, improved neurological functions, and fewer incidences of complications.