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Study Design: A retrospective analysis., Objective: This research sought to develop a predictive model for surgical outcomes in patients with cervical ossification of the posterior longitudinal ligament (OPLL) using deep learning and machine learning (ML) techniques., Summary of Background Data: Determining surgical outcomes assists surgeons in communicating prognosis to patients and setting their expectations. Deep learning and ML are computational models that identify patterns from large data sets and make predictions., Methods: Of the 482 patients, 288 patients were included in the analysis. A minimal clinically important difference (MCID) was defined as gain in Japanese Orthopaedic Association (JOA) score of 2.5 points or more. The predictive model for MCID achievement at 1 year postsurgery was constructed using patient background, clinical symptoms, and preoperative imaging features (x-ray, CT, MRI) analyzed through LightGBM and deep learning with RadImagenet., Results: The median preoperative JOA score was 11.0 (IQR: 9.0-12.0), which significantly improved to 14.0 (IQR: 12.0-15.0) at 1 year after surgery ( P < 0.001, Wilcoxon signed-rank test). The average improvement rate of the JOA score was 44.7%, and 60.1% of patients achieved the MCID. Our model exhibited an area under the receiver operating characteristic curve of 0.81 and the accuracy of 71.9% in predicting MCID at 1 year. Preoperative JOA score and certain preoperative imaging features were identified as the most significant factors in the predictive models., Conclusion: A predictive ML and deep learning model for surgical outcomes in OPLL patients is feasible, suggesting promising applications in spinal surgery., Level of Evidence: 4., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: This study aimed to investigate the effect of surgery within 8 hours on perioperative complications and neurological prognosis in older patients with cervical spinal cord injury by using a propensity score-matched analysis., Methods: The authors included 87 consecutive patients older than 70 years who had cervical spinal cord injury and who had undergone posterior decompression and fusion surgery within 24 hours of injury. The patients were divided into two groups based on the time from injury to surgery: surgery within 8 hours (group 8 hours) and between 8 and 24 hours (group 8-24 hours). Following the preliminary study, the authors established a 1:1 matched model using propensity scores to adjust for baseline characteristics and neurological status on admission. Perioperative complication rates and neurological outcomes at discharge were compared between the two groups., Results: Preliminary analysis of 87 prematched patients (39 in group 8 hours and 48 in group 8-24 hours) revealed that the motor index score (MIS) on admission was lower for lower extremities (12.3 ± 15.5 vs 20.0 ± 18.6, respectively; p = 0.048), and total extremities (26.7 ± 27.1 vs 40.2 ± 30.6, respectively; p = 0.035) in group 8 hours. In terms of perioperative complications, group 8 hours had significantly higher rates of cardiopulmonary dysfunction (46.2% vs 25.0%, respectively; p = 0.039). MIS improvement (the difference in scores between admission and discharge) was greater in group 8 hours for lower extremities (15.8 ± 12.6 vs 9.0 ± 10.5, respectively; p = 0.009) and total extremities (29.4 ± 21.7 vs 18.7 ± 17.7, respectively; p = 0.016). Using a 1:1 propensity score-matched analysis, 29 patient pairs from group 8 hours and group 8-24 hours were selected. There were no significant differences in baseline characteristics, neurological status on admission, and perioperative complications between the two groups, including cardiopulmonary dysfunction. Even after matching, MIS improvement was significantly greater in group 8 hours for upper extremities (13.0 ± 10.9 vs 7.8 ± 8.3, respectively; p = 0.045), lower extremities (14.8 ± 12.7 vs 8.3 ± 11.0, respectively; p = 0.044) and total extremities (27.8 ± 21.0 vs 16.0 ± 17.5, respectively; p = 0.026)., Conclusions: Results of the comparison after matching demonstrated that urgent surgery within 8 hours did not increase the perioperative complication rate and significantly improved the MIS, suggesting that surgery within 8 hours may be efficient, even in older patients.

This prospective multicenter study, established by the Japanese Ministry of Health, Labour and Welfare and involving 27 institutions, aimed to compare postoperative outcomes between laminoplasty (LM) and posterior fusion (PF) for cervical ossification of the posterior longitudinal ligament (OPLL), in order to address the controversy surrounding the role of instrumented fusion in cases of posterior surgical decompression for OPLL. 478 patients were considered for participation in the study; from among them, 189 (137 and 52 patients with LM and PF, respectively) were included and evaluated using the Japanese Orthopaedic Association (JOA) scores, the JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and radiographical measurements. Basic demographic and radiographical data were reviewed, and the propensity to choose a surgical procedure was calculated. Preoperatively, there were no significant differences among the participants in terms of patient backgrounds, radiographical measurements (K-line or cervical alignment on X-ray, OPLL occupation ratio on computed tomography, increased signal intensity change on magnetic resonance imaging), or clinical status (JOA score and JOACMEQ) after adjustments. The overall risk of perioperative complications was found to be lower with LM (odds ratio [OR] 0.40, p = 0.006), and the rate of C5 palsy occurrence was significantly lower with LM (OR 0.11, p = 0.0002) than with PF. The range of motion (20.91° ± 1.05° and 9.38° ± 1.24°, p < 0.0001) in patients who had PF was significantly smaller than in those who had LM. However, multivariable logistic regression analysis showed no significant difference among the participants in JOA score, JOA recovery rate, or JOACMEQ improvement at two years. In contrast, OPLL progression was greater in the LM group than in the PF group (OR 2.73, p = 0.0002). Both LM and PF for cervical myelopathy due to OPLL had resulted in comparable postoperative outcomes at 2 years after surgery., (© 2022. The Author(s).)

Importance: The optimal management for acute traumatic cervical spinal cord injury (SCI) is unknown., Objective: To determine whether early surgical decompression results in better motor recovery than delayed surgical treatment in patients with acute traumatic incomplete cervical SCI associated with preexisting canal stenosis but without bone injury., Design, Setting, and Participants: This multicenter randomized clinical trial was conducted in 43 tertiary referral centers in Japan from December 2011 through November 2019. Patients aged 20 to 79 years with motor-incomplete cervical SCI with preexisting canal stenosis (American Spinal Injury Association [ASIA] Impairment Scale C; without fracture or dislocation) were included. Data were analyzed from September to November 2020., Interventions: Patients were randomized to undergo surgical treatment within 24 hours after admission or delayed surgical treatment after at least 2 weeks of conservative treatment., Main Outcomes and Measures: The primary end points were improvement in the mean ASIA motor score, total score of the spinal cord independence measure, and the proportion of patients able to walk independently at 1 year after injury., Results: Among 72 randomized patients, 70 patients (mean [SD] age, 65.1 [9.4] years; age range, 41-79 years; 5 [7%] women and 65 [93%] men) were included in the full analysis population (37 patients assigned to early surgical treatment and 33 patients assigned to delayed surgical treatment). Of these, 56 patients (80%) had data available for at least 1 primary outcome at 1 year. There was no significant difference among primary end points for the early surgical treatment group compared with the delayed surgical treatment group (mean [SD] change in ASIA motor score, 53.7 [14.7] vs 48.5 [19.1]; difference, 5.2; 95% CI, -4.2 to 14.5; P = .27; mean [SD] SCIM total score, 77.9 [22.7] vs 71.3 [27.3]; P = .34; able to walk independently, 21 of 30 patients [70.0%] vs 16 of 26 patients [61.5%]; P = .51). A mixed-design analysis of variance revealed a significant difference in the mean change in ASIA motor scores between the groups (F1,49 = 4.80; P = .03). The early surgical treatment group, compared with the delayed surgical treatment group, had greater motor scores than the delayed surgical treatment group at 2 weeks (mean [SD] score, 34.2 [18.8] vs 18.9 [20.9]), 3 months (mean [SD] score, 49.1 [15.1] vs 37.2 [20.9]), and 6 months (mean [SD] score, 51.5 [13.9] vs 41.3 [23.4]) after injury. Adverse events were common in both groups (eg, worsening of paralysis, 6 patients vs 6 patients; death, 3 patients vs 3 patients)., Conclusions and Relevance: These findings suggest that among patients with cervical SCI, early surgical treatment produced similar motor regain at 1 year after injury as delayed surgical treatment but showed accelerated recovery within the first 6 months. These exploratory results suggest that early surgical treatment leads to faster neurological recovery, which requires further validation., Trial Registration: ClinicalTrials.gov Identifier: NCT01485458; umin.ac.jp/ctr Identifier: UMIN000006780.

Ossification of the posterior longitudinal ligament (OPLL) is a progressive disease. The bridging of ossified lesions to the vertebral body gradually increases, thereby decreasing the mobility of the cervical spine; thus, cervical spine function may decrease over time. However, cervical spine function in patients with cervical OPLL has not been evaluated in large prospective studies. Therefore, we conducted a prospective multicenter study to clarify whether ossification spread can influence cervical spine function and quality of life (QOL) in patients with cervical OPLL. In total, 238 patients (162 men, 76 women; mean age, 63.9 years) were enrolled from 16 institutions. Each patient underwent whole spine computed tomography and was evaluated for cervical spine function and QOL using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). In the multivariate regression analysis, a higher neck VAS score and a larger number of bridge formations of OPLL in the whole spine were significant predictors of adverse outcomes related to cervical spine function. This is the first prospective multicenter study to reveal the impact of ossification spread on cervical spine function. These findings are important to understand the natural course of OPLL and can serve as controls when evaluating postoperative cervical spine function., (© 2021. The Author(s).)

Cervical ossification of the posterior longitudinal ligament (OPLL) is a contributing factor to spinal cord injury or trauma-induced myelopathy in the elderly. To reduce the incidence of these traumas, it is essential to diagnose OPLL at an early stage and to educate patients how to prevent falls. We thus evaluated the ability of our convolutional neural network (CNN) to differentially diagnose cervical spondylosis and cervical OPLL. We enrolled 250 patients with cervical spondylosis, 250 patients with cervical OPLL, and 180 radiographically normal controls. We evaluated the ability of our CNN model to distinguish cervical spondylosis, cervical OPLL, and controls, and the diagnostic accuracy was compared to that of 5 board-certified spine surgeons. The accuracy, average recall, precision, and F1 score of the CNN for classification of lateral cervical spine radiographs were 0.86, 0.86, 0.87, and 0.87, respectively. The accuracy was higher for CNN compared to any expert spine surgeon, and was statistically equal to 4 of the 5 experts and significantly higher than that of 1 expert. We demonstrated that the performance of the CNN was equal or superior to that of spine surgeons.

Although favourable surgical outcomes for myelopathy caused by cervical ossification of the posterior longitudinal ligament (OPLL) have been reported, factors significantly associated with post-operative neck pain attenuation still remain unclear. The primary aim of the present study was to determine factors significantly associated with post-operative neck pain attenuation in patients with cervical OPLL using a prospective multi-centre registry of surgically treated cervical OPLL. Significant postoperative neck pain reduction (50% reduction of neck pain) was achieved in 31.3% of patients. There was no significant difference in neck pain attenuation between surgical procedures. Statistical analyses with univariate analyses followed by stepwise logistic regression revealed neurological recovery as a factor having a significant positive association with post-operative neck pain attenuation (p = 0.04, odds ratio 5.68 (95% confidence interval: 1.27-22.2)). In conclusion, neurological recovery was an independent factor having a significant positive association with post-operative neck pain attenuation in patients with cervical myelopathy caused by OPLL who underwent cervical spine surgery.

Purpose: To elucidate the independent preoperative factors that have a significant impact on poor surgical outcome after laminoplasty for K-line (+) ossification of the posterior longitudinal ligament (OPLL). Analyses in K-line (+) patient population can exclude the influence by mal-alignment and thick OPLL, both of which are well known two major factors that have significant impact on clinical outcome., Methods: The present study included 72 patients (50 male and 22 female) who underwent laminoplasty for K-line (+) cervical OPLL and were followed-up for at least 1 year. Recovery of Japanese Orthopedic Association score (JOA score) for cervical myelopathy was used as the measure of clinical outcome. For radiographic assessment, the type of OPLL, the maximum OPLL occupation ratio, the C2-C7 angle, and the segmental range of motion at the peak of OPLL (segmental ROM) were assessed. To elucidate the factors that are significantly associated with a poor clinical outcome after laminoplasty for K-line (+) OPLL, statistical analyses were conducted., Results: The mean preoperative JOA score was 8.9 points and improved to 12.8 points after surgery. The recovery of JOA score was 47 ± 35%. Stepwise logistic regression following univariate analyses revealed that preoperative segmental ROM at the peak of OPLL is an independent factor associated with a poor outcome (p = 0.04, odds ratio = 1.15)., Conclusions: Large preoperative segmental ROM at the peak of the OPLL is an independent factor that has significant impact on poor surgical outcome after laminoplasty for K-line (+) OPLL.

Background: Ossification of the posterior longitudinal ligament of the spine (OPLL) is characterized by heterotopic bone formation in the posterior longitudinal ligament of the spine. We know that the size and distribution of the ossified lesions in patients with OPLL are different in each case. However, the characteristics of the patients with radiologically severe cervical OPLL remain unknown., Methods: The participants of our study were symptomatic patients with cervical OPLL who were diagnosed by standard radiographs of the cervical spine. Whole-spine CT data and demographic data such as age and sex were obtained from 20 institutions belonging to the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. According to the number of the levels involved by OPLL, we stratified the patients into two subgroups: severe group (S-group) and non-severe group (NS-group) to delineate the characteristics of radiologically severe patients with cervical OPLL. We also evaluated the most compressed level and the degree of occupying ratio of cervical spinal canal by OPLL at the most compressed level., Results: A total of 234 patients with a mean age of 65 years were recruited. The S-group consisted of 48 patients (21%, 12 females and 36 males) and the NS-group consisted of 92 patients (79%, 22 females and 70 males). The mean age of males in the S-group (68 years old) was significantly higher than that of males in the NS-group (64 years old); however there was no significant difference in the mean age in females between the S-group (69 years old) and the NS-group (66 years old). No significant difference of body mass index, ossification of the nuchal ligament-positivity and presence of diabetes mellitus were found between the S- and the NS-group., Conclusions: It is likely that the manner of extension of cervical OPLL is different between male and female patients., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background and Objectives: Dropped head syndrome (DHS) is characterized by apparent neck extensor muscle weakness and difficulty in extending the neck to raise the head against gravity. DHS affects forward vision and eating behavior, and hence impairs quality of life. However, standardized treatment of DHS has not yet been established. The purpose of this preliminary study is to seek for a possibility of effective non-surgical, conservative treatment for DHS, by applying a robotic treatment. Materials and Methods : A wearable exoskeleton type robot suit hybrid assistive limb (HAL) was applied to three patients with DHS. A course of HAL treatment included 10 sessions of gait training using HAL. One session lasted about an hour. Case 1 completed the course twice, the first time in two weeks (one session per day) and second time in 10 months (one session per month). Case 2 and Case 3 completed the course once in 10 weeks (one session per week) and in 6 months (one session per 2.5 weeks), respectively. Immediate and lasting effects of HAL on the reduction of cervical sagittal vertical alignment (SVA) during gait was evaluated using a motion capture system. Results : Case 1 showed improvement of cervical alignment during gait after the HAL courses of both different frequencies. Case 2 did not show improvement of cervical alignment during gait. Case 3 showed improvement of cervical kyphosis but not of cervical sagittal alignment during gait. Conclusions : The results of the preliminary study suggest that gait training using HAL may be an effective option of conservative treatment for a part of DHS patients. They also suggest that a lack of immediate effects on the cervical alignment and a lack of ability to perform compensatory trunk motion may indicate a non-responding patient. Generalization of the results requires further research with more cases., Competing Interests: Y.S. (Yoshiyuki Sankai) is the C.E.O., shareholder, and director of CYBERDYNE Inc. which produces the robot suit HAL. CYBERDYNE had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. The other authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Background: The optimal surgical procedure for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) remains controversial because there are few comprehensive studies investigating the surgical methods. Therefore, we conducted a systematic review and meta-analysis to evaluate evidence in the literature and compare the surgical outcomes of anterior decompression with fusion (ADF) and laminoplasty (LAMP), which are representative procedures for cervical OPLL., Methods: An extensive literature search was performed using PubMed, Embase, and the Cochrane Library to identify comparative studies of ADF and LAMP for cervical OPLL. The language was restricted to English, and the year of publication was from January 1980 to December 2018. We extracted outcomes from the studies, such as preoperative and postoperative Japanese Orthopaedic Association (JOA) score, cervical alignment, surgical complications and reoperation rate. Then, meta-analysis was performed for these surgical outcomes., Results: Twelve studies were obtained, including 1 prospective cohort study and 11 retrospective cohort studies. In the meta-analysis, neurological recovery rate in JOA score was greater in ADF than in LAMP, especially in patients with a large canal occupying ratio (≥60%) and preoperative kyphotic alignment. ADF also exhibited more favorable results in postoperative cervical alignment. In contrast, operating time and intraoperative blood loss were greater in ADF. Surgical complications were more frequently seen in ADF, leading to higher rates of reoperation., Conclusions: This systematic review and meta-analysis showed both the merits and shortcomings of ADF and LAMP. ADF resulted in more favorable neurological recovery compared to LAMP, especially for patients with massive OPLL and kyphotic alignment. Postoperative cervical lordosis was also better preserved in ADF. However, ADF was associated with greater surgical invasion and higher incidences of surgical complications., (Copyright © 2019 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Recent reports indicate that oxidative stress induced by reactive oxygen species is associated with the pathobiology of neurodegenerative disorders that involve neuronal cell apoptosis. Here we conducted a cross-sectional study to evaluate serum levels of oxidative stress in cervical compression myelopathy., Methods: Thirty-six serum samples were collected preoperatively from patients treated for acutely worsening compression myelopathy (AM) and chronic compression myelopathy (CM). Serum levels of oxidative stress markers were evaluated by measuring derivatives of reactive oxygen metabolites (ROM), which reflect concentrations of hydroperoxides. ROM in healthy individuals range from 250 to 300 (U. CARR), whereas ROM >340-400 and > 400 define moderate and severe levels of oxidative stress, respectively. Difference of ROM by the cause of disorders whether cervical spondylotic myelopathy (CSM) or cervical ossification of longitudinal ligament (OPLL), correlations between ROM and patient age, body mass index (BMI), history of smoking, existence of diabetes were examined. Neurological evaluations according to Japanese Orthopaedic Association (JOA) scores were performed and correlated with ROM., Results: ROM increased to 349.5 ± 54.8, representing a moderate oxidative stress, in CM samples. ROM increased to 409.2 ± 77.9 in AM samples, reflecting severe oxidative stress which were significantly higher than for CM samples (p < 0.05). There was no significant difference by the cause of disorders (CSM or OPLL). ROM were significantly increased in AM serum samples from female patients versus AM male and CM patients (p < 0.05). There were no correlations between ROM and age, BMI, history of smoking, and existence of diabetes. A negative correlation between ROM and recovery rate of JOA score (R 2  = 0.454, p = 0.047) was observed in the AM group., Conclusions: Although moderate oxidative stress was present in patients with CM, levels of oxidative stress increased in severity in patients with AM. These results suggest that postsurgical neurological recovery is influenced by severe oxidative stress in AM.

The aim of this study was to investigate the incidence and characteristics of implant failure in posterior cervical long-segment fusion surgery. We retrospectively reviewed 51 cases of posterior cervical long-segment fusion surgery that used pedicle screws, lateral mass screws, or laminar screws. The cranial end of the fusion was C2 or C3, and the caudal end of the fusion was C7 or T1. All patients were observed with CT scans at 6 months postoperatively. We evaluated the loosening and breakage of the implanted screws or rods. In the 51 patients, 257 pedicle screws, 9 laminar screws and 233 lateral mass screws were placed. Implant failure occurred in 25 patients (49.0%). Screw loosening was found in 42 screws (8.4%). Screw breakage occurred in 6 (1.2%) screws. The implant failures were particularly observed in both ends of the fusion level. When C7 was the end of the lower instrumented level, the incidence was 40% without C6 pedicle screws, 33% with unilateral C6 pedicle screws, and 0% with bilateral C6 pedicle screws. The present study revealed that the incidence of implant failures of the screws in long-segment posterior cervical fusion surgery was higher, especially in the caudal end of the fusion levels. In cases where C7 was the lowest instrumented vertebra, buttress screw insertion to C6 is recommended to avoid implant failure of C7 pedicle screws., (Copyright © 2019. Published by Elsevier Ltd.)

Background: Previous studies have shown that patients with cervical ossification of the posterior longitudinal ligament (OPLL) often have co-existing ossification of the nuchal ligament (ONL). However, no studies have focused on ONL and its relevance to the severity of OPLL or ossification of other spinal ligaments, such as anterior longitudinal ligament (OALL), ligamentum flavum (OLF), and supraspinous/interspinous ligament (OSIL)., Methods: In this multicenter study, we investigated ossification of the spinal ligaments in the whole spine computed tomography (CT) images of 233 cervical OPLL patients. The severity of ossification was evaluated using ossification index for each spinal ligament, calculated as the sum of the level of ossification. We compared the severity of ossification in each spinal ligament between patients with ONL and those without ONL. Furthermore, we investigated how the number of segments, where ONL exists, affects the severity of ossification in each spinal ligament., Results: One hundred thirty patients (55.8%) had co-existing ONL in the cervical OPLL patients included in this study. The ONL (+) group included more male and aged patients. The cervical ossification indexes of OPLL and OALL were higher in ONL (+) patients than in ONL (-) patients. The thoracolumbar ossification indexes of OALL and OSIL were also higher in ONL (+) patients. Logistic regression analysis revealed that age, gender and cervical OA-index were independent factors correlating to the existence of ONL. In the cervical spine, both the ossification indexes of OALL and OPLL increased as the levels of ONL increased. Similarly, in the thoracolumbar spine, both the ossification indexes of OALL and OSIL were increased as the levels of cervical ONL increased. In the multiple regression analysis, cervical OA-index and thoracolumbar OSI-index showed significant correlation with the number of ONL levels., Conclusions: Co-existence of ONL in cervical OPLL patients was associated with the severity of spinal hyperostosis especially in cervical OPLL, OALL, thoracolumbar OALL and OSIL., (Copyright © 2018 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Purpose: Addition of posterior instrumented fusion to laminoplasty (posterior decompression with instrumented fusion: PDF) can improve the surgical outcome of patients with K-line (-) cervical ossification of the longitudinal ligament (OPLL) compared with laminoplasty alone. We sought to elucidate the factors that are significantly associated with a better outcome after PDF for K-line (-) OPLL., Methods: The present study included 38 patients who underwent PDF for K-line (-) OPLL and were followed up for at least 1 year after surgery. Clinical outcome was assessed using Japanese Orthopedic Association (JOA) scores for cervical myelopathy and the recovery rate was calculated. Patients who belonged to the upper quartile of all the patients according to rank order of the JOA score recovery rate were considered to have a good outcome. The correlations between good outcome, patient factors and imaging assessments were analyzed statistically., Results: Univariate analyses showed that postoperative conversion of K-line from (-) to (+) (p = 0.004), no increase in the sagittal vertical axis from the center of gravity of the head to C7 (p = 0.07), and a lower grade of preoperative intramedullary T2-signal intensity (p = 0.03) were candidates for the association. Stepwise logistic regression analysis revealed that postoperative K-line conversion from (-) to (+) is an independent factor that is significantly associated with a better surgical outcome (p = 0.04)., Conclusion: Postoperative K-line conversion from (-) to (+) is a factor independently associated with a better surgical outcome. These slides can be retrieved under Electronic Supplementary material.

OBJECTIVE Fusion surgery with instrumentation is a widely accepted treatment for cervical spine pathologies. The authors propose a novel technique for subaxial cervical fusion surgery using paravertebral foramen screws (PVFS). The authors consider that PVFS have equal or greater biomechanical strength than lateral mass screws (LMS). The authors' goals of this study were to conduct a biomechanical study of PVFS, to investigate the suitability of PVFS as salvage fixation for failed LMS, and to describe this novel technique. METHODS The authors harvested 24 human cervical spine vertebrae (C3-6) from 6 fresh-frozen cadaver specimens from donors whose mean age was 84.3 ± 10.4 years at death. For each vertebra, one side was chosen randomly for PVFS and the other for LMS. For PVFS, a 3.2-mm drill with a stopper was advanced under lateral fluoroscopic imaging. The drill stopper was set to 12 mm, which was considered sufficiently short not to breach the transverse foramen. The drill was directed from 20° to 25° medially so that the screw could purchase the relatively hard cancellous bone around the entry zone of the pedicle. The hole was tapped and a 4.5-mm-diameter × 12-mm screw was inserted. For LMS, 3.5-mm-diameter × 14-mm screws were inserted into the lateral mass of C3-6. The pullout strength of each screw was measured. After pullout testing of LMS, a drill was inserted into the screw hole and the superior cortex of the lateral mass was pried to cause a fracture through the screw hole, simulating intraoperative fracture of the lateral mass. After the procedure, PVFS for salvage (sPVFS) were inserted on the same side and pullout strength was measured. RESULTS The CT scans obtained after screw insertion revealed no sign of pedicle breaching, violation of the transverse foramen, or fracture of the lateral mass. A total of 69 screws were tested (23 PVFS, 23 LMS, and 23 sPVFS). One vertebra was not used because of a fracture that occurred while the specimen was prepared. The mean bone mineral density of the specimens was 0.29 ± 0.10 g/cm 3 . The mean pullout strength was 234 ± 114 N for PVFS, 158 ± 91 N for LMS, and 195 ± 125 N for sPVFS. The pullout strength for PVFS tended to be greater than that for LMS. However, the difference was not quite significant (p = 0.06). CONCLUSIONS The authors introduce a novel fixation technique for the subaxial cervical spine. This study suggests that PVFS tend to provide stronger fixation than LMS for initial applications and fixation equal to LMS for salvage applications. If placement of LMS fails, PVFS can serve as a salvage fixation technique.

Purpose: The aim of this study was to assess the potential role of diffusion tensor imaging (DTI) as a predictor of surgical outcomes in patients with cervical compressive myelopathy (CCM). Surgical decompression is often recommended for symptomatic CCM. It is important to know the prognosis of surgical outcomes and to recommend appropriate timing for surgery., Methods: We enrolled 26 patients with CCM who underwent surgery. The Japanese Orthopaedic Association (JOA) score for cervical myelopathy was evaluated before and 6 months after surgery. Surgical outcomes were regarded as good if there was a change in JOA score of three points or more, or the recovery rate of JOA score was 50% or more. The patients were examined using a 3.0 T magnetic resonance system before surgery. Measured diffusion parameters were fractional anisotropy (FA) and mean diffusivity (MD). The correlations between DTI parameters and surgical outcomes were analyzed., Results: Both change and recovery rate of JOA score moderately correlated with FA. Furthermore, the area under the receiver-operator characteristic curve based on FA for prognostic precision of surgical outcomes indicates that FA is a good predictive factor. The cut-off values of FA for predicting good surgical outcomes evaluated by change and recovery rate of JOA score were 0.65 and 0.57, respectively. Neither change nor recovery rate of JOA score correlated with MD., Conclusions: FA in spinal cord DTI can moderately predict surgical outcomes. DTI can serve as a supplementary tool for decision-making to guide surgical intervention in patients with CCM.

Study Design: Retrospective multi-center study., Objective: This study was conducted to clarify the incidence and neurological outcomes of fall-related deterioration of subjective symptoms in patients undergoing surgical treatment., Summary of Background Data: The evidence that minor trauma, including falls, increases the risk of worsening cervical myelopathy is insufficient., Methods: A retrospective analysis of patients who had undergone surgery for cervical myelopathy at 12 participating institutes was conducted. Patients who had undergone surgery for symptomatic cervical myelopathy from January 2012 to December 2013 and completed at least 1-year follow-up were included in this study. Data were collected by chart review and a questionnaire that included numbers of recalled falls during the last preoperative year and first postoperative year, circumstances of falls, and whether the patient had experienced fall-related deterioration of subjective symptoms., Results: A total of 360 eligible patients were recruited into the study. Of these, 177 (49%) reported at least one fall during the last preoperative year, and 105 (29%) experienced fall-related deterioration of subjective symptoms. Forty (11%) reported deterioration of numbness in the arms or legs, and 65 (18%) reported deterioration of motor deficits. Incidences of falls and fall-related deterioration of symptoms decreased significantly after surgery. Patients who experienced fall-related deterioration of motor deficits showed significantly worse surgical outcomes as assessed by Japanese Orthopaedic Association (JOA) score compared with those who did not experience deterioration. The optimal cut-off for preoperative JOA score in predicting an increased risk of fall-related deterioration in motor deficits was 8., Conclusion: Patients with cervical myelopathy commonly experienced preoperative fall-related deterioration of subjective symptoms, associated with significantly worse neurological outcomes. Surgical treatment significantly reduced the incidence of both falls and fall-related deterioration of subjective symptoms., Level of Evidence: 4.

Laminoplasty (LMP) is a widely accepted surgical procedure for ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. Progression of OPLL can occur in the long term after LMP. The aim of the present study was to determine whether addition of the instrumented fusion, (posterior decompression with instrumented fusion [PDF]), can suppress progression of OPLL or not. The present study included 50 patients who underwent LMP (n=23) or PDF (n=27) for OPLL of the cervical spine. We performed open door laminoplasty. PDF surgery was performed by double-door laminoplasty followed by instrumented fusion. We observed the non-ossified segment of the OPLL and measured the thickness of the OPLL at the thickest segment with pre- and postoperative sagittal CT multi-planar reconstruction images. Postoperative CT scan revealed fusion of the non-ossified segment of the OPLL was obtained in 4/23 patients (17%) in the LPM group and in 23/27 patients (85%) in the PDF group, showing a significant difference between both groups (p=0.003). Progression of the thickness of the OPLL in the PDF group (-0.1±0.4mm) was significantly smaller than in the LMP group (0.6±0.7mm, p=0.0002). The proportion of patients showing the decrease in thickness of OPLL was significantly larger in the PDF group (6/27 patients; 22%) than in the LMP group (0/23 patients; 0%, p=0.05). In conclusion, PDF surgery can suppress the thickening of OPLL., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Dropped head syndrome (DHS) is characterized by apparent neck extensor muscle weakness and difficulty extending the neck to raise the head against gravity. The aim of the present study was to elucidate possible risk factors for DHS after cervical laminoplasty. Five patients who developed DHS after cervical laminoplasty (DHS group) and twenty age-matched patients who underwent laminoplasty without DHS after surgery (control group) were compared. The surgical procedure was single-door laminoplasty with strut grafting using resected spinous processes or hydroxyapatite spacers from C3 to C6 or C7. Analyses of preoperative images including the C2-C7 angle, C7-T1 kyphosis, T1 tilt, center of gravity line from the head-C7 sagittal vertical axis (CGH-C7 SVA) were performed on lateral plain cervical spine radiographs. Preoperative T2-weighted MRI at the C5 vertebral level was used to measure the cross-sectional area of the deep extensor muscles. Widths of the lateral gutters were assessed postoperatively using CT scans of the C5 vertebral body. The average preoperative C2-C7 angle was significantly smaller in the DHS group compared with the control group. The average preoperative C7-T1 angle was significantly larger in the DHS group compared with the control group. The average preoperative CGH-C7 SVA was significantly larger in the DHS group compared with the control group. In conclusion, patients with more pronounced preoperative C2-C7 kyphosis, C7-T1 kyphosis, and CGH-C7 SVA are more likely to develop DHS following laminoplasty., (Copyright © 2016. Published by Elsevier Ltd.)

We investigated the outcome of posterior decompression and instrumented fusion (PDF) surgery for patients with K-line (-) ossification of the posterior longitudinal ligament (OPLL) of the cervical spine, who may have a poor surgical prognosis. We retrospectively analyzed the outcome of a series of 27 patients who underwent PDF without correction of cervical alignment for K-line (-) OPLL and were followed-up for at least 1 year after surgery. We had performed double-door laminoplasty followed by posterior instrumented fusion without excessive correction of cervical spine alignment. The preoperative Japanese Orthopedic Association (JOA) score for cervical myelopathy was 8.0 points and postoperative JOA score was 11.9 points on average. The mean JOA score recovery rate was 43.6%. The average C2-C7 angle was 2.2° preoperatively and 3.1° postoperatively. The average maximum occupation ratio of OPLL was 56.7%. In conclusion, PDF without correcting cervical alignment for patients with K-line (-) OPLL showed moderate neurological recovery, which was acceptable considering K-line (-) predicts poor surgical outcomes. Thus, PDF is a surgical option for such patients with OPLL., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Ossification of the posterior longitudinal ligament (OPLL) can cause severe and irreversible paralysis in not only the cervical spine but also the thoracolumbar spine. To date, however, the prevalence and distribution of OPLL in the whole spine has not been precisely evaluated in patients with cervical OPLL. Therefore, we conducted a multi-center study to comprehensively evaluate the prevalence and distribution of OPLL using multi-detector computed tomography (CT) images in the whole spine and to analyze what factors predict the presence of ossified lesions in the thoracolumbar spine in patients who were diagnosed with cervical OPLL by plain X-ray. Three hundred and twenty-two patients with a diagnosis of cervical OPLL underwent CT imaging of the whole spine. The sum of the levels in which OPLL was present in the whole spine was defined as the OP-index and used to evaluate the extent of ossification. The distribution of OPLL in the whole spine was compared between male and female subjects. In addition, a multiple regression model was used to ascertain related factors that affected the OP-index. Among patients with cervical OPLL, women tended to have more ossified lesions in the thoracolumbar spine than did men. A multiple regression model revealed that the OP-index was significantly correlated with the cervical OP-index, sex (female), and body mass index. Furthermore, the prevalence of thoracolumbar OPLL in patients with a cervical OP-index ≥ 10 was 7.8 times greater than that in patients with a cervical OP-index ≤ 5. The results of this study reveal that the extent of OPLL in the whole spine is significantly associated with the extent of cervical OPLL, female sex, and obesity., Competing Interests: The authors have declared that no competing interests exist.

Purpose: The K-line, which is a virtual line that connects the midpoints of the anteroposterior diameter of the spinal canal at C2 and C7 in a plain lateral radiogram, is a useful preoperative predictive indicator for sufficient decompression by laminoplasty (LMP) for ossification of the posterior longitudinal ligament (OPLL). K-line is defined as (+) when the peak of OPLL does not exceed the K-line, and is defined as (-) when the peak of OPLL exceeds the K-line. For patients with K-line (-) OPLL, LMP often results in poor outcome. The aim of the present study was to compare the clinical outcome of LMP, posterior decompression with instrumented fusion (PDF) and anterior decompression and fusion (ADF) for patients with K-line (-) OPLL., Methods: The present study included patients who underwent surgical treatment including LMP, PDF and ADF for K-line (-) cervical OPLL. We retrospectively compared the clinical outcome of those patients in terms of Japanese Orthopedic Association score (JOA score) recovery rate., Results: JOA score recovery rate was significantly higher in the ADF group compared with that in the LMP group and the PDF group. The JOA score recovery rate in the PDF group was significantly higher than that in the LMP group., Conclusions: LMP should not be used for K-line (-) cervical OPLL. ADF is one of the suitable surgical treatments for K-line (-) OPLL. Both ADF and PDF are applicable for K-line (-) OPLL according to indications set by each institute and surgical decisions.

Context: We report the autopsy of a 65-year-old woman who underwent a C3-C7 laminoplasty 4 years after the diagnosis of cervical spondylotic myelopathy (CSM). Her sensory disturbance, spasticity, and vesicorectal disturbance, which corresponded to long tract sign, had improved after surgery., Findings: Cross sections at the C4-C5 level showed a triangular shape because of atrophied ventral gray matter. Moreover, despite the scarce glial scar formation around the cystic cavity, regeneration of gray matter had not occurred. In the white matter, the posterior and lateral funiculi were shrunken including three to four segments., Conclusion: Pathological change of white matter did not coincide with relief of clinical symptoms in this case. These findings indicate that it may be better to operate earlier in cases of CSM, because delay may lead to irreversible histological change.

Study Design: Case report., Objective: To report a surgically treated case of cervical ossification of the posterior longitudinal ligament (OPLL), in which a spinal subarachnoid hematoma (SSAH) developed intraoperatively but was successfully treated., Summary of Background Data: Previous reports have indicated that trauma, lumbar puncture, vascular lesions such as arteriovenous malformation, neoplastic lesions, and coagulopathy can cause SSAH. To the best of our knowledge, there has been no report that describes the occurrence of SSAH during anterior decompression surgery of the cervical spine., Methods: A 52-year-old man with cervical myelopathy caused by OPLL underwent surgery for anterior decompression from C2/3 to C6/7. Immediately after the OPLL floating procedure, cerebrospinal fluid leakage and massive bleeding occurred at right edge of the OPLL at the C3-C4 level. After hemostasis, the dura mater at the C5-C6 levels bulged rapidly and became cyanotic. Intraoperative ultrasonographic images showed a high-intensity mass lesion on the ventral side of the spinal cord, indicating an intrathecal hematoma., Results: We incised the dura, found the hematoma under the intact arachnoid, and removed it. We then found that the bleeding occurred from the radicular artery along the right C4 root. After hemostasis, we performed anterior spine fusion from C2-C7. After surgery, the patient's myelopathy was improved, and no neurologic deficit related to the subarachnoid hematoma was found., Conclusion: This experience suggests that when anterior decompression surgery is performed for cervical OPLL patients, we should consider the possible occurrence of an SSAH. Intraoperative ultrasonography is a useful tool for detecting SSAHs.

Study Design: Case report., Objective: To describe the usefulness of simulated surgery for evaluation of a patient with neurofibromatosis type-1 (NF-1) who had severe cervicothoracic kyphoscoliosis and an anomalous vertebral artery (VA)., Summary of Background Data: Several surgical procedures have been used in the treatment of cervicothoracic kyphoscoliosis associated with myelopathy in patients with NF-1. However, to our knowledge, there has been no report that describes a surgical procedure for NF-1 patients with anomalous VA at the cervical spine., Methods: A 45-year-old man with NF-1 developed cervical myelopathy. Preoperative examinations revealed severe cervicothoracic kyphoscoliosis, dystrophic changes of the cervical vertebrae, and the anomalous course of a VA and VA aneurysms. To assist in the preoperative planning and intraoperative navigation, we created 3-dimensional (3D) full-scale models of the patient's spine. Using a model, we performed a simulation of the planned surgery for spinal cord decompression with spinal fusion through both anterior and posterior approaches., Results: Through the simulation, we could evaluate the risk of VA injury at the process of corpectomy, and altered the surgical procedure for the spinal cord decompression with spinal fusion from a posterior approach and a bone graft alone from an anterior approach. We accomplished the surgery successfully without any neurovascular complications. After surgery, the patient experienced relief from myelopathy., Conclusion: Preoperative surgical simulation using a 3D full-scale model was useful for improving the accuracy and safety of the surgery for cervicothoracic kyphoscoliosis with NF-1.

Background: Many different surgical procedures have been employed in the treatment of fracture dislocation at the middle to lower cervical spine. However, consistent protocols and procedures have not been fully established for the surgical correction of an irreducible old cervical fracture dislocation associated with spinal deformity., Methods: We report a case of irreducible cervical fracture dislocation and kyphoscoliosis, in which surgical simulation using a three-dimensional full-scale model was useful for circumferential corrective osteotomy at the C6-C7 level. A 56-year-old man was diagnosed with an irreducible fracture dislocation at the C6-C7 level 2 months after a motor vehicle accident. He showed torticollis, and complained of severe pain in his neck and left upper arm. Radiographic examinations revealed that the C6 vertebra was translated anteriorly and laterally to the C7 vertebra. A bony union had progressed at the fracture site, showing rigid cervico-thoracic kyphoscoliosis. To assist in the preoperative planning, we created a three-dimensional, full-scale model from the patient's computed tomography data. Using the model, we performed a simulation of the planned circumferential corrective osteotomy at the C6-C7 level., Results: Through the simulation, we could evaluate the deformed bony structures around the vertebral arteries at the C6-C7 level accurately. At the time of the actual surgery, corrective osteotomy combined with spinal fusion (C5-T2) with a pedicle screw-rod system was accomplished successfully without any neurovascular complications. After surgery, the patient experienced relief from pain, and his neck posture became normal., Conclusions: Surgical simulation using a three-dimensional, full-scale model was useful for improving the accuracy and safety of circumferential corrective osteotomy of the cervical spine.

Study Design: To report a new index, the K-line, for deciding the surgical approach for cervical ossification of the posterior longitudinal ligament (OPLL)., Objective: To analyze the correlation between the K-line-based classification of cervical OPLL patients and their surgical outcome., Summary of Background Data: Previous studies showed that kyphotic alignment of the cervical spine and a large OPLL are major factors causing poor surgical outcome after laminoplasty for cervical OPLL patients. However, no report has evaluated these 2 factors in 1 parameter., Methods: The K-line was defined as a line that connects the midpoints of the spinal canal at C2 and C7. Twenty-seven patients who had cervical OPLL and underwent posterior decompression surgery were classified into 2 groups according to their K-line classification. OPLL did not exceed the K-line in the K-line (+) group and did exceed it in the K-line (-) group. By intraoperative ultrasonography, we evaluated the posterior shift of the spinal cord after the posterior decompression procedure. The Japanese Orthopedic Association scores before surgery and 1 year after surgery were evaluated, and the recovery rate was calculated., Results: Eight patients were classified as K-line (-), and 19 patients were classified as K-line (+). The mean recovery rate was 13.9% in the K-line (-) group and 66.0% in the K-line (+) group (P < 0.01). Ultrasonography showed that the posterior shift of the spinal cord was insufficient in the K-line (-) group., Conclusion: The present results demonstrate that a sufficient posterior shift of the spinal cord and neurologic improvement will not be obtained after posterior decompression surgery in the K-line (-) group. Our new index, the K-line, is a simple and practical tool for making decisions regarding the surgical approach for cervical OPLL patients.

Background: Prevention of graft dislodgement in multilevel cervical corpectomy and fusion has been an unresolved problem. Anterior plate fixation has a significant failure rate. External support with a halo-vest is uncomfortable for patients. In the present study, we report a new surgical technique of anterior pedicle screw (APS) fixation for multilevel cervical corpectomy and spinal fusion, and describe the safety and utility of the system., Method: After cervical corpectomy, the pedicles on the right side were visualised under oblique fluoroscopy. Guide wires were inserted into the pedicles from the inner wall of the excavated vertebral body until they were hidden in the pedicles. After a fibula autograft was placed, the graft was penetrated in the reverse direction by the guide wires. After drilling and tapping, cannulated screws were inserted into the pedicles through the grafted fibula along the guide wires., Findings: In 9 patients with cervical myelopathy, the surgery was accomplished with a fibula autograft using APS fixation. A total of 22 APSs were inserted, and 21 screws were placed precisely in the pedicles. There were no neurovascular complications. Patients were allowed to ambulate without a halo-vest on the second day after the surgery. Post-operatively, no dislodgement of the grated fibula occurred, and all patients improved neurologically., Conclusions: The insertion of APSs is feasible and safe. APS fixation enables us to obtain rigid fixation anteriorly, and we propose that APS fixation is an attractive option for multilevel cervical corpectomy and fusion.

Study Design: Case report., Objective: We describe the usefulness of 3-dimensional full-scale modeling for preoperative simulation of surgery in a patient with old cervical fracture-dislocation., Summary of Background Data: Many different surgical procedures have been used in the treatment of unilateral cervical fracture-dislocation. However, consistent protocols and procedures for the surgical correction of old fracture-dislocations associated with nerve root lesions have not been established., Methods: Two months after an automobile accident, a 50-year-old man developed symptoms of left C5 palsy. Four months after the accident, he was diagnosed with a fracture-dislocation at left C4-C5 facet with impingement of the left C5 root at the neural foramen. In addition, his left vertebral artery was completely occluded. Spontaneous bony fusion had progressed around the left facet and the anterior aspect of the vertebrae at C4-C5. Before surgery, a 3-dimensional full-scale model in the patient's cervical spine was made in order to simulate the planned surgical reconstruction., Results: Through this simulation, we were able to accurately evaluate the deformed bony structures around the fractured C4-C5 facet. During the actual surgery, all the planned procedures were successfully achieved, including anterior release, insertion of pedicle screws at left C4 and C5, unroofing of the left C5 root, reduction of the displaced facet with the pedicle screw-rod system, and spinal fusion at C4-C5. After surgery, the patient's left C5 palsy was dramatically relieved and the spinal fusion went on to successful healing., Conclusion: The surgical simulation made possible by the 3-dimensional full-scale model appeared to simplify the surgical procedure and may enhance the safety of the complex spinal reconstruction.

The authors report the case of a 62-year-old woman who suffered an accidental fall and complained of severe neck pain and right C-7 radiculopathy. A right C6-7 facet fracture-subluxation was diagnosed. Bone fragments impinged on the right C-7 nerve root at the neural foramen. The bilateral vertebral arteries (VAs) ascended at the anterior aspect of C-6 and C-5 and entered the transverse foramen at the C-4 level. Based on findings of anomalous VAs, the authors applied a pedicle screw (PS)/rod system to effect surgical correction of the deformity. Intraoperatively, they successfully performed reduction of the subluxation, decompression of the impinged nerve root, and minimum single-segment fusion involving the placement of a PS/rod system. After surgery, the patient's neurological deficit dramatically improved and spinal fusion was completed without any loss of deformity correction. Prior to surgery for cervical injuries, the possible presence of an abnormal VA course should be considered. Preoperative detection of anomalous VAs will affect decisions on the appropriate corrective surgery option in cases of cervical spine injuries.

Study Design: Case report., Objectives: To report a case with giant cell tumor (GCT) of C6 vertebra, in which three-dimensional (3-D) full-scale modeling of the cervical spine was useful for preoperative planning and intraoperative navigation., Setting: A university hospital in Japan., Case Report: A 27-year-old man with a GCT involving the C6 vertebra presented with severe neck pain. The C6 vertebra was collapsed and the tumor had infiltrated around both vertebral arteries (VAs). A single-stage operation combining anterior and posterior surgical procedures was scheduled to resect the tumor and stabilize the spine. To evaluate the anatomic structures within the surgical fields, we produced a 3-D full-scale model from the computed tomography angiography data. The 3-D full-scale model clearly showed the relationships between the destroyed C6 vertebra and the deviations in the courses of both VAs. Using the model, we were able to identify the anatomic landmarks around the VAs during anterior surgery and to successfully resect the tumor. During the posterior surgery, we were able to determine accurate starting points for the pedicle screws. Anterior iliac bone graft from C5 to C7 and posterior fixation with a rod and screw system from C4 to T2 were performed without any complications. Postoperatively, the patient experienced relief of his neck pain., Conclusion: The 3-D full-scale model was useful for simultaneously evaluating the destruction of the vertebral bony structures and the deviations in the courses of the VAs during surgery for GCT involving the cervical spine.