Is there a difference in range of motion, neck pain, and outcomes in patients with ossification of posterior longitudinal ligament versus those with cervical spondylosis, treated with plated laminoplasty?

Development of a mouse model of chronic ventral spinal cord compression: Neurobehavioral, radiological, and pathological changes

Objectives

The main objective of this study was to establish a mouse model of spinal ligament ossification to simulate the chronic spinal cord compression observed in patients with ossification of the posterior longitudinal ligament (OPLL). The study also aimed to examine the mice's neurobiological, radiological, and pathological changes.

Methods

In the previous study, a genetically modified mouse strain was created using Crispr-Cas9 technology, namely, Enpp1 flox/flox /EIIa-Cre (C57/B6 background), to establish the OPLL model. Wild-type (WT) mice without compression were used as controls. Functional deficits were evaluated through motor score assessment, inclined plate testing, and gait analysis. The extent of compression was determined using CT imaging. Hematoxylin and eosin staining, luxol fast blue staining, TUNEL assay, immunofluorescence staining, qPCR, and Western blotting were performed to evaluate levels of apoptosis, inflammation, vascularization, and demyelination in the study.

Results

The results demonstrated a gradual deterioration of compression in the Enpp1 flox/flox /EIIa-Cre mice group as they aged. The progression rate was more rapid between 12 and 20 weeks, followed by a gradual stabilization between 20 and 28 weeks. The scores for spinal cord function and strength, assessed using the Basso Mouse Scale and inclined plate test, showed a significant decline. Gait analysis revealed a noticeable reduction in fore and hind stride lengths, stride width, and toe spread. Chronic spinal cord compression resulted in neuronal damage and activated astrocytes and microglia in the gray matter and anterior horn. Progressive posterior cervical compression impeded blood supply, leading to inflammation and Fas-mediated neuronal apoptosis. The activation of Bcl2 and Caspase 3 was associated with the development of progressive neurological deficits (p < 0.05).

Conclusions

The study presents a validated model of chronic spinal cord compression, enabling researchers to explore clinically relevant therapeutic approaches for OPLL.

Comparative study of preoperative sagittal alignment between patients with multisegment cervical ossification of the posterior longitudinal ligament and cervical spondylotic myelopathy

BACKGROUND CONTEXT

Preoperative sagittal alignment is of great significance in the development of spinal deformities, degenerative diseases, preoperative planning, postoperative clinical evaluation, and functional recovery. However, few reports have focused on the difference in preoperative sagittal alignment between patients with ossification of the posterior longitudinal ligament (OPLL) and patients with cervical spondylotic myelopathy (CSM).

PURPOSE

To compare preoperative sagittal alignment between patients with multisegment cervical OPLL and multilevel CSM.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

A total of 243 patients were included in this study.

OUTCOME MEASURES

The outcome measures were the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS) score, number of hand actions in 10 seconds, hand-grip strength, C2 to C7 Cobb angle, C2 to C5 Cobb angle, C5 to C7 Cobb angle, C2 to C7 sagittal vertical axis, C7 slope, T1 slope, K-line, K-line tilt, and range of motion (ROM).

METHODS

The outcome measures were calculated in the OPLL group and CSM group and the data were analyzed using the unpaired t-test, χ² test, and one-way analysis of variance.

RESULTS

A total of 243 patients (136 men, 107 women; mean age, 59.1±10.6 years) underwent surgical treatment from September 2013 to December 2021. In total, 123 patients were diagnosed with multisegment cervical OPLL, including continuous type (n=39), segmental type (n=38), and mixed type (n=46). The remaining 120 patients had multisegment CSM. The disease course in the OPLL group was significantly shorter than that in the CSM group (p<.05). Among the above preoperative measurements, the JOA score, number of hand actions in 10 seconds, hand-grip strength, and VAS score were not significantly different between the two groups (p>.05). The C2 to C7 Cobb angle was significantly larger in the OPLL than CSM group (17.7°±9.2° and 14.9°±9.3°, respectively; p< .05), as was the C5 to C7 Cobb angle (10.0°±6.3° and 7.5°±6.1°, respectively; p<.05). The ROM was significantly smaller in the OPLL than CSM group (33.1°±8.1° and 40.1°±10.9°, respectively; p<.001). Within the OPLL group, the ROM was significantly smaller in the continuous type than in the segmental type (p<.05).

CONCLUSION

Patients with multisegment cervical OPLL have greater lordotic preoperative sagittal alignment and smaller preoperative ROM than patients with CSM.

Association Between Deep Posterior Cervical Paraspinal Muscle Morphology and Clinical Features in Patients With Cervical Ossification of the Posterior Longitudinal Ligament

STUDY DESIGN

A retrospective observational study.

OBJECTIVE

To clarify the association of the paraspinal muscle area and composition with clinical features in patients with cervical ossification of the posterior longitudinal ligament (OPLL).

METHODS

Consecutive patients with cervical OPLL who underwent cervical magnetic resonance imaging (MRI) before surgery were reviewed. The cross-sectional area (CSA) and fatty infiltration ratio (FI%) of deep posterior cervical paraspinal muscles (multifidus [MF] and semispinalis cervicis [SCer]) were examined. We assessed the association of paraspinal muscle measurements with the clinical characteristics and clinical outcomes, such as Neck Disability Index (NDI) score. Moreover, we divided the patients into 2 groups according to the extent of the ossified lesion (segmental and localized [OPLL-SL] and continuous and mixed [OPLL-CM] groups) and compared these variables between the 2 groups.

RESULTS

49 patients with cervical OPLL were enrolled in this study. The FI% of the paraspinal muscles was significantly associated with the number of vertebrae (ρ = 0.283, p = 0.049) or maximum occupancy ratio of OPLL (ρ = 0.397, p = 0.005). The comparative study results indicated that the NDI score was significantly worse (OPLL-SL, 22.9 ± 13.7 vs. OPLL-CM, 34.4 ± 13.7) and FI% of SCer higher (OPLL-SL, 9.1 ± 1.7% vs. OPLL-CM, 11.1 ± 3.7%) in the OPLL-CM group than those in the OPLL-SL group.

CONCLUSIONS

Our results suggest that OPLL severity may be associated with fatty infiltration of deep posterior cervical paraspinal muscles, which could affect neck disability in patients with cervical OPLL.

Technical Nuances of Cervical Laminoplasty: Supplemental Manuscript to Operative Video

STUDY DESIGN

Operative video and supplemental manuscript.

OBJECTIVE

The technical nuances of open-door laminoplasty are described. Potential complications of open-door laminoplasty and strategies for their minimization are discussed.

SUMMARY OF BACKGROUND DATA

Cervical laminoplasty may be indicated in patients with cervical myelopathy due to cervical stenosis in the setting of spondylosis, ossification of the posterior longitudinal ligament, congenital stenosis, and traumatic central cord syndrome.

METHODS

A video illustrates the nuances of the surgical technique for cervical laminoplasty.

RESULTS

Myelopathic patients with preserved lordotic sagittal profile, central stenosis involving several levels, and minimal to no axial neck pain are ideal candidates for laminoplasty.

CONCLUSIONS

Cervical laminoplasty provides more stability compared with laminectomy alone and a better range of motion compared with laminectomy with posterior spinal fusion. Understanding the nuances of laminoplasty may help surgeons to avoid complications.

Enhancing the Biofidelity of an Upper Cervical Spine Finite Element Model within the Physiologic Range of Motion and Its Effect On the Full Ligamentous Neck Model Response

Contemporary finite element neck models are developed in a neutral posture; however, evaluation of injury risk for out-of-position impacts requires neck model repositioning to non-neutral postures, with much of the motion occurring in the upper cervical spine (UCS). Current neck models demonstrate a limitation in predicting the intervertebral motions within the UCS within the range of motion (ROM), while recent studies have highlighted the importance of including the tissue strains resulting from repositioning FE neck models to predict injury risk. In the current study, the ligamentous cervical spine from a contemporary neck model (GHBMC M50 v4.5) was evaluated in flexion, extension and axial rotation by applying moments from 0 to 1.5 Nm in 0.5 Nm increments, as reported in experimental studies and corresponding to the physiologic loading of the UCS. Enhancements to the UCS model were identified, including the C0-C1 joint-space and alar ligament orientation. Following geometric enhancements, an analysis was undertaken to determine the UCS ligament laxities, using a sensitivity study followed by an optimization study. The ligament laxities were optimized to UCS-level experimental data from the literature. The mean percent difference between UCS model response and experimental data improved from 55% to 23% with enhancements. The enhanced UCS model was integrated with a ligamentous cervical spine (LS) model and assessed with independent experimental data. The mean percent difference between the LS model and the experimental data improved from 46% to 35% with the integration of the enhanced UCS model.

Factors contributing to neck pain in patients with degenerative cervical myelopathy: A prospective multicenter study

PURPOSE

Although the understanding of the mechanisms of low back pain due to spinopelvic sagittal imbalance has strengthened, the understanding of the mechanisms of neck pain remains insufficient. Thus, this study aimed to identify the factors associated with preoperative and postoperative neck pain in patients with degenerative cervical myelopathy who underwent laminoplasty.

METHODS

In this prospective multicenter study, we prospectively enrolled patients who were scheduled for laminoplasty for degenerative cervical myelopathy. The associations between different variables and the Numerical Pain Rating Scale (NRS) scores for neck pain were investigated using univariate and multiple linear regression models.

RESULTS

In total, 92 patients were included in the current study. The univariate analysis showed that age, sex, cervical lordosis in neutral and extension, and thoracic kyphosis were significantly associated with the preoperative NRS score for neck pain; moreover, preoperative cervical lordosis in extension and range of motion and postoperative cervical lordosis in neutral, flexion, and extension were significantly associated with the postoperative NRS Scale score for neck pain. Stepwise multiple regression analysis showed that the independent factors contributing to preoperative neck pain were preoperative cervical lordosis in extension, sex, and age. The independent preoperative predictor and contributor to postoperative neck pain were preoperative cervical lordosis in extension and postoperative cervical lordosis in extension, respectively.

CONCLUSIONS

Cervical lordosis in extension showed significant association with neck pain in patients with degenerative cervical myelopathy. Therefore, when performing laminoplasty for patients with a low cervical lordosis in extension, attention should be paid to residual postoperative neck pain.

Impacts of postoperative changes of segmental mobility on neurological improvement after laminoplasty for cervical ossification of the posterior longitudinal ligament

Several studies have demonstrated that the dynamic factor at the mobile segment affects the severity of myelopathy in patients with cervical ossification of the posterior longitudinal ligament (C-OPLL), and posterior decompression supplemented with posterior instrumented fusion at the mobile segment provides good neurological improvement. However, there have been few reports of changes in range of motion at the mobile segment (segmental ROM) after laminoplasty (LP). The aim of this study was thus to retrospectively investigate changes in segmental ROM after LP and the impacts of these changes on neurological improvement in patients with C-OPLL.A total of 51 consecutive patients who underwent LP for C-OPLL since May 2010 and were followed for at least 2 years after surgery were included in this study. Neurological status was assessed using the Japanese Orthopaedic Association (JOA) score before surgery and at 2-year follow-up. Segmental ROM at the responsible level for myelopathy was measured preoperatively and at 2-year follow-up using lateral flexion-extension radiographs of the cervical spine.The mean JOA score improved significantly from 10.7 points preoperatively to 13.5 points at 2 years after surgery (mean recovery rate, 45.0%). The mean segmental ROM decreased significantly from 6.5 degrees before surgery to 3.2 degrees at 2 years after surgery. In the good clinical outcome group (recovery rate of the JOA score ≥50%; n = 22), the mean segmental ROM decreased significantly from 5.8 degrees preoperatively to 3.0 degrees postoperatively. It also decreased significantly from 7.1 degrees to 3.4 degrees in the poor clinical outcome group (recovery rate of the JOA score <50%; n = 29).This study showed that segmental ROM was stabilized after LP in most patients with C-OPLL. Neither preoperative nor postoperative segmental ROM showed significant differences between the good and poor clinical outcome groups and neither a postoperative increase nor decrease of segmental ROM significantly affected the recovery rate of the JOA score.

Risk Factors for Axial Symptoms After Anterior Surgery Treating for Multilevel Cervical Disorder with kyphosis

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to investigate the risk factors associated with axial symptoms (AS) after anterior surgery in treatment of multilevel cervical disorder with kyphosis based on subgroup of follow-up time.

SUMMARY OF BACKGROUND DATA

Although many scholars reported on AS after cervical surgery, the risk factors associated with AS are controversial. Few studies have investigated the risk factors of AS after anterior cervical surgery treating multilevel cervical disorder with kyphosis.

METHODS

Totally, 103 patients who suffered from multilevel cervical disorder with kyphosis receiving anterior surgery from July 2015 to June 2017 were reviewed for clinical and radiological outcomes. These data were collected at the time of before surgery, 1 week, 3 months, 6 months, 1 year, and 2 years after surgery. Data were performed to compare between the patients with and without AS.

RESULTS

In our study, the occurrence of AS was 46.6%, 34.0%, 20.4%, 12.6%, and 10.7% at the time of 1 week, 3 months, 6 months,1 year, and 2 years after surgery, respectively. Our findings showed that patients with smoking, disease duration, preoperative Modic changes (Mcs), post-operative Cobb angle of C2-7, cervical range of motion (ROM) and T1 slope, and change of Cobb angle of C2-7, cervical ROM and T1 slope were associated with AS within 1 year after surgery. However, patients with smoking and preoperative Mcs were found to be risk factors associated with AS at at any follow-up.

CONCLUSION

In the present study, many factors were related to AS during 1-year after surgery. What's more, patients with smoking and preoperative Mcs were associated with AS at any follow-up. We hope this article can provide a reference for spinal surgeons to predict which patients were susceptible to suffer from AS after anterior surgery in treatment of multilevel cervical disorder with kyphosis.Level of Evidence: 3.

Neurological improvement is associated with neck pain attenuation after surgery for cervical ossification of the posterior longitudinal ligament

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.

Effects of occipital-atlas stabilization in the upper cervical spine kinematics: an in vitro study

This study compares upper cervical spine range of motion (ROM) in the three cardinal planes before and after occiput-atlas (C0–C1) stabilization. After the dissection of the superficial structures to the alar ligament and the fixation of C2, ten cryopreserved upper cervical columns were manually mobilized in the three cardinal planes of movement without and with a screw stabilization of C0–C1. Upper cervical ROM and mobilization force were measured using the Vicon motion capture system and a load cell respectively. The ROM without C0–C1 stabilization was 19.8° ± 5.2° in flexion and 14.3° ± 7.7° in extension. With stabilization, the ROM was 11.5° ± 4.3° and 6.6° ± 3.5°, respectively. The ROM without C0–C1 stabilization was 4.7° ± 2.3° in right lateral flexion and 5.6° ± 3.2° in left lateral flexion. With stabilization, the ROM was 2.3° ± 1.4° and 2.3° ± 1.2°, respectively. The ROM without C0–C1 stabilization was 33.9° ± 6.7° in right rotation and 28.0° ± 6.9° in left rotation. With stabilization, the ROM was 28.5° ± 7.0° and 23.7° ± 8.5° respectively. Stabilization of C0–C1 reduced the upper cervical ROM by 46.9% in the sagittal plane, 55.3% in the frontal plane, and 15.6% in the transverse plane. Also, the resistance to movement during upper cervical mobilization increased following C0–C1 stabilization.

[Effect of modified lateral mass screws implantation strategy on axial symptoms in cervical expansive open-door laminoplasty]

Objective

To investigate the effect of modified lateral mass screws implantation strategy on axial symptoms in cervical expansive open-door laminoplasty.

Methods

A clinical data of 166 patients, who underwent cervical expansive open-door laminoplasty between August 2011 and July 2016 and met the selection criteria, was retrospective analyzed. Among them, 81 patients were admitted before August 2014 using the traditional mini-plate placement and lateral mass screws implantation strategy (control group), and 85 patients were admitted after August 2014 using modified lateral mass screws implantation strategy (modified group). There was no significant difference in the gender composition, age, clinical diagnosis, disease duration, diseased segment, and preoperative Japanese Orthopaedic Association (JOA) score, pain visual analogue scale (VAS) score, Neck Disability Index (NDI), cervical curvature and range of motion, spinal canal diameter and cross-sectional areas, and Pavlov's value between the two groups ( P>0.05). The operation time, intraoperative blood loss, the number of facet joints penetrated by lateral mass screws, effectiveness evaluation indexes (JOA score and improvement rate, VAS score, NDI), imaging evaluation indexes (cervical curvature and range of motion, spinal canal diameter and cross-sectional areas, Pavlov's value, and lamina open angle), and complications were recorded and compared between the two groups.

Results

The modified group had shorter operation time and lower intraoperative blood loss than the control group ( P<0.05). There were 121 (29.9%, 121/405) and 10 (2.4%, 10/417) facet joints penetrated by lateral mass screws in control and modified groups, respectively; and the difference in incidence was significant ( χ ²=115.797, P=0.000). Eighteen patients in control group had 3 or more facet joints penetrated while no patients in modified group suffered 3 or more facet joint penetrated. The difference between the two groups was significant ( P=0.000). All patients were followed up, the follow-up time was (28.7±4.9) months in modified group and (42.4±10.7) months in control group, showing significant difference ( t=10.718, P=0.000). The JOA score, VAS score, and NDI at last follow-up of the two groups were significantly improved compared with preoperative ( P<0.05); there was no significant difference in JOA score and improvement rate and VAS score between the two groups ( P>0.05), but the NDI was significantly lower in modified group than in control group ( P<0.05). There were significant differences in cervical curvature and range of motion, spinal canal diameter, Pavlov's value, and cross-sectional areas at last follow-up when compared with those before operation in both groups ( P<0.05). There was no significant difference in the above indicators and lamina open angle between the two groups ( P>0.05). The modified group has a relative lower axial symptom rate (23/85, 27.1%) than the control group (27/81, 33.3%), but the difference was not significant ( Z=-1.446, P=0.148). There was no significant differences between the two groups in the incidences of C ₅ nerve root palsy, cerebrospinal fluid leakage, wound infection, and lung or urinary tract infection ( P>0.05).

Conclusion

In the cervical expansive open-door laminoplasty, the modified lateral mass screws implantation strategy can effectively reduce the risk of lateral mass screw penetrated to the cervical facet joints, and thus has a positive significance in avoiding the axial symptoms caused by facet joint destruction.

Associations between Clinical Symptoms and Degree of Ossification in Patients with Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multi-Institutional Cross-Sectional Study

This study aimed to clarify whether ossification predisposition influences clinical symptoms including pain, restriction of activities of daily living, and quality of life in patients with cervical ossification of the posterior longitudinal ligament (OPLL). Cervical ossification predisposition potentially causes neurologic dysfunction, but the relationship between clinical symptoms and radiologic severity of OPLL has not yet been investigated. Data were prospectively collected from 16 institutions across Japan. We enrolled 239 patients with cervical OPLL. The primary outcomes were patient-reported outcomes, including visual analog scale (VAS) pain scores and other questionnaires. Whole-spine computed tomography images were obtained, and correlations were investigated between clinical symptoms and radiologic findings, including the distribution of OPLL, the sum of the levels where OPLL was present (OP-index), and the canal narrowing ratio (CNR) grade. The cervical OP-index was Grade 1 in 113 patients, Grade 2 in 90, and Grade 3 in 36. No significant correlations were found between radiologic outcomes and VAS pain scores. The cervical OP-index was associated with lower extremity function, social dysfunction, and locomotive function. The CNR grade was not correlated with clinical symptoms, but Grade 4 was associated with lower extremity dysfunction. Thickness and extension of ossified lesions may be associated with lower extremity dysfunction in cervical OPLL.

Factors associated with postoperative axial symptom after expansive open-door laminoplasty: retrospective study using multivariable analysis

PURPOSE

The aim of the present study was to investigate the factors associated with axial symptom using multivariable analysis.

METHODS

The authors retrospectively assessed 249 patients treated by open-door laminoplasty. The patients were classified into two groups: axial symptom and no axial symptom group. The possible factors included demographic variables (age, sex, BMI, smoking, heart disease, diabetes, preoperative neck pain, preoperative JOA scores, preoperative NDI, course of disease and pathogenesis) and surgical and radiological variables [operation time, intraoperative blood loss, collar wear time, preoperative cervical curvature, postoperative cervical curvature, T1 slope, preoperative and postoperative C2 sagittal vertical axis (C2 SVA)].

RESULTS

The prevalence of axial symptom was 34.9% (89/249). The collar wear time, preoperative and postoperative C2 SVA were risk factors for axial symptom. A cutoff value of 22.6 mm for preoperative C2 SVA and 3.5 weeks for collar wear time predicted the development of axial symptom.

CONCLUSIONS

The longer collar wear time, larger preoperative and postoperative C2 SVA were positively correlated with the higher incidence of axial symptom.

Comparison of three fixation modalities for unilateral open-door cervical laminoplasty: a systematic review and network meta-analysis

Three fixation modalities including suture suspensory, anchor, and titanium plate are used extensively in unilateral open-door cervical laminoplasty. Nevertheless, up to now no systematic review and network meta-analysis have been published, and the differences in efficacy and safety of the three fixation modalities are still unclear. The purpose of this study is to compare the effectiveness and safety of the three fixation modalities including suture suspensory, anchor, and titanium plate in unilateral open-door cervical laminoplasty. Randomized controlled trials and cohort studies which compared the three interventions in unilateral open-door cervical laminoplasty were identified using the following databases: PubMed, Cochrane Library, Embase, Web of science, China National Knowledge Infrastructure, Chinese Science and Technology Periodical Database, and Wanfang data. Network meta-analysis was performed using R 3.4.3 software and STATA version 14.0. The results revealed that compared with suture suspensory, titanium plate and anchor showed the same effects in Japanese Orthopedic Association Scores, operative time, and blood loss. However, titanium plate showed superiority in postoperative range of motion of cervical spine, incidence of axial symptoms, and C5 paralysis; in terms of cervical curvature, titanium plate also showed better effectiveness than suture suspensory, but similar as anchor. Our network meta-analysis suggests that titanium plate is preferable to suture suspensory or anchor with more range of motion and lower incidence of axial symptoms and C5 paralysis. However, considering the limitations of this research, high-quality trials are needed in the future to evaluate the outcomes.

Clinical characteristics in patients with ossification of the posterior longitudinal ligament: A prospective multi-institutional cross-sectional study

Ossification of the posterior longitudinal ligament (OPLL) can occur throughout the entire spine and can sometimes lead to spinal disorder. Although patients with OPLL sometimes develop physical limitations because of pain, the characteristics of pain and effects on activities of daily living (ADL) have not been precisely evaluated in OPLL patients. Therefore, we conducted a multi-center prospective study to assess whether the symptoms of cervical OPLL are different from those of cervical spondylosis (CS). A total of 263 patients with a diagnosis of cervical OPLL and 50 patients with a diagnosis of CS were enrolled and provided self-reported outcomes, including responses to the Japanese Orthopaedic Association (JOA) Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), JOA Back Pain Evaluation Questionnaire (JOABPEQ), visual analog scale (VAS), and SF-36 scores. The severity of myelopathy was significantly correlated with each domain of the JOACMEQ and JOABPEQ. There was a negative correlation between the VAS score for each domain and the JOA score. There were significantly positive correlations between the JOA score and the Mental Health, Bodily Pain, Physical Functioning, Role Emotional, and Role Physical domains of the SF-36. One-to-one matching resulted in 50 pairs of patients with OPLL and CS. Although there was no significant between-group difference in scores in any of the domains of the JOACMEQ or JOABPEQ, the VAS scores for pain or numbness in the buttocks or limbs were significantly higher in the CS group; however, there was no marked difference in low back pain, chest tightness, or numbness below the chest between the two study groups. The scores for the Role Physical and Body Pain domains of the SF-36 were significantly higher in the OPLL group than in the CS group, and the mean scores for the other domains was similar between the two groups. The results of this study revealed that patients with OPLL were likely to have neck and low back pain and restriction in ADL. No specific type of pain was found in patients with OPLL when compared with those who had CS.

Cervical rotation before and after hinge-door cervical laminoplasty for cervical spondylotic myelopathy

Background:

Hinge-Door Cervical laminoplasty is commonly performed procedure in patients with cervical spondylotic myelopathy. Most available studies have established restriction of flexion and extension motion post laminoplasty but the literature on post-laminoplasty axial rotation is sparse.

Objective:

To study the axial neck rotation on either side following hinge door cervical laminoplasty.

Materials and Methods:

Twenty consecutive patients of cervical spondylotic myelopathy planned for cervical laminoplasty were included in the study. Preoperative and postoperative radiological data was recorded for each patient and analysed by an experienced neuroradiologist. The clinical and radiological follow-up was recorded at 6 months post surgery. All patients underwent standard hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra.

Results:

There were 13 men and 7 women with a mean age of 60.5 years, age range 58-70 years. The mean preop C1 C2 rotation was 46.5 degrees and mean post-operative C1-C2 rotation was 44.3 degrees. The average subaxial cervical spine rotation was 11.66 degrees preoperatively and 12.47 degrees postoperatively. The global cervical spine rotation was 80.95 degrees preoperatively and 76.82 degrees postoperatively. There is no significant change in segmental, subaxial and global cervical spine rotation following hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra.

Conclusion:

Cervical laminoplasty preserves cervical ROM and is a motion-preserving surgery as far as axial rotation is concerned.

In vivo three-dimensional kinematics of the cervical spine during maximal active head rotation

Objective

The aim of this study was to measure the movement of the cervical spine in healthy volunteers and patients with cervical spondylosis (CS) and describe the actual motion of the cervical spine using a three-dimensional (3D) CT reconstruction method. The results can enrich current biomechanical data of cervical spine and help to find the differences between the noted two groups.

Materials and methods

20 healthy volunteers underwent CT examination ranging from the clivus of the occiput (Oc) to the top of first thoracic vertebrae (T1) in a neutral position with left or right maximal axial rotation, while 26 CS patients received the same CT scan procedures in the neutral position with left and right maximum rotation. Subsequently, the three-dimensional images of the occiput and every cervical vertebrae (C1-C7) were reconstructed using medical software. 3 virtual non-collinear markers were placed on the prominent structures of foramen magnum and every cervical vertebrae. Then, the 3D orthogonal spatial coordinates were defined with these anatomical markers to represent the orientation and position of every vertebra. Segmental relative motions were calculated using Cardan angles in the 3D spatial coordinates. Finally, the differences between the two groups were analyzed with statistical software SPSS.

Results

The cervical spine exhibited complicated 3D movements, which could be adequately described using the three-dimensional CT reconstruction method. Reliability analysis of the 3D CT reconstruction method showed inter-rater ICC of 0.90–0.99 and intra-rater ICC of 0.91–0.98, suggesting very good consistency. Besides, the rotation at the upper cervical spine (Oc-C2) took up at least 60% of the total cervical rotation. The coupled lateral bending movement of the upper cervical spine was opposite to the major motion, while the movement of the lower cervical spine followed the same direction as that of the major motion. Oc to C5 segments were all coupled with the back-extension movement. The relative translations of all adjacent segments in each direction were minimal. CS patients showed a significant decrease in the movement of the C4-C5 segment compared with healthy volunteers.

Conclusion

The motion of the cervical spine was complicated and three-dimensional. The CT reconstruction method employed here was good at describing such movement. The 3D CT reconstruction method exhibited high reproducibility when measuring cervical spine movement. CS patients and healthy volunteers showed significant differences in the movement of some segments.

A Systematic Review of Classification Systems for Cervical Ossification of the Posterior Longitudinal Ligament

DESIGN

Systematic review.

OBJECTIVE

To conduct a systematic review to (1) summarize various classification systems used to describe cervical ossification of the posterior longitudinal ligament (OPLL) and (2) evaluate the diagnostic accuracy of various imaging modalities and the reliability of these classification systems.

METHODS

A search was performed to identify studies that used a classification system to categorize patients with OPLL. Furthermore, studies were included if they reported the diagnostic accuracy of various imaging modalities or the reliability of a classification system.

RESULTS

A total of 167 studies were deemed relevant. Five classification systems were developed based on X-ray: the 9-classification system (0.60%); continuous, segmental, mixed, localized or focal, circumscribed and others (92.81%); hook, staple, bridge, and total types (2.40%); distribution of OPLL (2.40%); and K-line classification (4.19%). Six methods were based on computed tomography scans: free-type, contiguous-type, and broken sign (0.60%); hill-, plateau-, square-, mushroom-, irregular-, or round-shaped (5.99%); rectangular, oval, triangular, or pedunculate (1.20%); centralized or laterally deviated (1.80%); plank-, spindle-, or rod-shaped (0.60%); and rule of nine (0.60%). Classification systems based on 3-dimensional computed tomography were bridging and nonbridging (1.20%) and flat, irregular, and localized (0.60%). A single classification system was based on magnetic resonance imaging: triangular, teardrop, or boomerang. Finally, a variation of methods was used to classify OPLL associated with the dura mater (4.19%).

CONCLUSIONS

The most common method of classification was that proposed by the Japanese Ministry of Health, Labour and Welfare. Other important methods include K-line (+/-), signs of dural ossification, and patterns of distribution.

Ossification of posterior longitudinal ligament and fluorosis

Objective

Ossification of posterior longitudinal ligament (OPLL) is a progressive disease that causes spinal canal compromise and serious neurological sequelae in advanced cases. The incidence of OPLL in the Asiatic population is 2%-3%, but the incidence is more in the background of fluorosis. Our aim was to study the association of OPLL with fluorosis by comparing urine fluoride levels and to study the types of OPLL.

Materials and Methods

Thirty consecutive patients with OPLL, observed on cervical skiagram, and confirmed by the computed tomography (CT) of the cervical spine, underwent a 24-h urine fluoride level assessment by the ion-selective electrode method. Due consent of all the patients was obtained and the data was collected. Thirty patients with a normal cervical radiograph were taken as a control group and their 24-h urine fluoride levels were compared with the test group. The 24-h urine fluoride level above 1.6 mg/L was taken as the diagnostic parameter of fluorosis. Imaging analysis of the study group focused on the subtype of OPLL, the mass occupying ratio, the sagittal cervical angle, the signs of dural penetration, and the spinal levels involved. Urinary fluoride levels were correlated with the presence of OPLL and different types of OPLL.

Results

Of the 30 patients with OPLL, 25 were males and 5 were females. The most common presentation was myelopathy. Continuous type of OPLL was seen in 11 (36.6%), segmental in 8 (26.6%), focal in 5 (16.6%), and mixed variant in 6 (20%) patients. 24-h urinary fluoride levels ranged from 0.26 mg/L to 12.2 mg/L. 18 (60%) of the patients in the study group were found to have urinary fluoride levels above 1.6 mg/L and only 1 patient (4%) of the control group had the urine fluoride level >1.6 mg/L. This difference was statistically significant. Patients with continuous and mixed types of OPLL had a higher mean urine fluoride level than those with a segmental and focal type of OPLL. The continuous variant of OPLL had a statistically significant occupancy ratio when compared to the other three variants, and the high mass occupancy ratio of the OPLL was directly associated with the presence of dural penetration.

Conclusion

Fluorosis is associated with a higher incidence of OPLL. Higher urinary fluoride levels correlate with the severe forms of OPLL.

A novel revision surgery for treatment of cervical ossification of the posterior longitudinal ligament after initial posterior surgery: preliminary clinical investigation of anterior controllable antidisplacement and fusion

BACKGROUND

Cervical ossification of the posterior longitudinal ligament (OPLL) is a progressive disease. Posterior decompression surgery is reported to be an effective and comparatively safe procedure with few complications for treatment of patients with myelopathy caused by OPLL. However, some patients require revision surgery because of late neurological deterioration due to OPLL progression or kyphotic changes in cervical alignment. This study reports preliminary clinical results of anterior controllable antidisplacement and fusion (ACAF), a novel revision surgery after initial posterior surgery for OPLL.

METHODS

From January 2017 to June 2018, ten patients with cervical OPLL who underwent ACAF revision surgery after initial posterior surgery were included in this study. The mean age was 62.1 ± 8.0 years (52-78), and the mean interval between initial posterior surgery and revision was 78.0 ± 48.2 months (5-180). The Japanese Orthopaedic Association (JOA) scales, Neck Disability Index (NDI), visual analog scale (VAS), and surgical complications were recorded.

RESULTS

The mean surgery time was 179.3 ± 41.8 min (120-240), and the mean blood loss was 432.5 ± 198.3 ml (225-850). The patients were followed up for at least 12 months. The JOA scores improved from 8.7 ± 2.8 to 13.4 ± 2.4; the mean improvement rate was 59.9% ± 16.1%. Postoperative NDI and VAS scores were 13.3 ± 3.7 and 2.0 ± 1.6, respectively, and were significantly improved compared to those before the procedure (P < 0.05). Cervical lordosis improved from 3.8 ± 4.3° to 17 ± 4.6° after revision surgery. There was only one instance of cerebrospinal fluid (CSF) leakage; no instances of postoperative hematoma, C5 root palsy, or hoarseness occurred.

CONCLUSIONS

The present study demonstrates that excellent postoperative outcomes can be achieved with the ACAF technique for revision treatment of OPLL. Though further study is required to confirm the conclusion, this novel technique has the potential to serve as an alternative surgical technique for revision treatment of OPLL.

Radiological analysis of minimal safe distance and optimal screw angle to avoid facet violation in open-door laminoplasty using precontoured plate

PURPOSE

This study aimed to present radiologic analysis of minimal safe distance (MSD) and optimal screw angle (OSA) that enables to fix screws in a lateral mass safely without facet joint violation in open-door laminoplasty using a plate.

METHODS

A retrospective analysis was made of 22 patients (male: 17; female: 5), average age 62 years. Seventy-nine lateral mass screws were fixed among a total of 158 screws. MSD that doesn't allow 5-mm screws to violate a facet joint was measured for C3-C7 and a comparative analysis was performed. If the MSD is not secured, the OSA to be given to the cephalad direction is calculated to avoid violation of the facet joint.

RESULTS

The screws violating inferior facet joints accounted for 34.1% of the screws fixed in inferior lateral mass. Joint surface to distal mini-screw distances were 3.18 ± 1.46 mm and 4.75 ± 1.71 mm in groups of facet joint violation and non-facet violation (FV), respectively ( p = 0.001). When 5-mm screws were inserted into a lateral mass, MSD was 4.39 ± 0.83 mm. The average MSD of C3, C4, and C5 was 4.05 ± 0.78 mm, 4.10 ± 0.70 mm, and 4.26 ± 0.74 mm, respectively. There was no significant differences among levels ( p > 0.05). The average MSD of C6 and C7 was 4.92 ± 0.81 mm and 4.80 ± 0.96 mm, respectively, showing significant differences from those of C3, C4, and C5 ( p < 0.05). If 6 mm of the MSD isn't secured, OSA showed in the cephalad direction of 11.5° for 5 mm and 22° for 4 mm approximately.

CONCLUSION

We suggest that mini-screw on lateral mass can be fixed safely without FV, if they are fixed at MSD of 6 mm from a joint surface. Facet joint violation doesn't occur if an OSA is given in the cephalad direction in case of not enough MSD for mini-screws.

Impact of Cervical Sagittal Alignment on Axial Neck Pain and Health-related Quality of Life After Cervical Laminoplasty in Patients With Cervical Spondylotic Myelopathy or Ossification of the Posterior Longitudinal Ligament: A Prospective Comparative Study

STUDY DESIGN

This is prospective observational study.

OBJECTIVE

To prospectively investigate the correlation among axial neck pain; a newly developed patient-based quality of life outcome measure, the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ); and cervical sagittal alignment after open-door laminoplasty for cervical myelopathy.

SUMMARY OF BACKGROUND DATA

Many studies have focused on postoperative axial neck pain after laminoplasty. However, the correlation among cervical sagittal alignment, neck pain, and JOACMEQ has not been investigated.

MATERIALS AND METHODS

In total, 57 consecutive patients treated by open-door laminoplasty for cervical myelopathy were included (mean age, 63.7 y; 15 women and 42 men) and divided into 2 groups according to diagnosis [cervical spondylotic myelopathy (CSM) group: 35 patients, and ossification of the posterior longitudinal ligament (OPLL) group: 22 patients]. JOA score, a subdomain of cervical spine function (CSF) in the JOACMEQ, and the visual analog scale for axial neck pain were assessed preoperatively and 12 months postoperatively. Radiographic cervical sagittal parameters were measured by C2 sagittal vertical axis (C2 SVA), C2-C7 lordosis, C7 sagittal slope (C7 slope), and range of motion.

RESULTS

C2 SVA values in both groups shifted slightly anteriorly between preoperative and 12-month postoperative measurements (CSM: +19.7±10.9 mm; OPLL: +22.1±13.4 mm vs. CSM: +23.2±16.1 mm; OPLL: +28.7±15.4 mm, respectively). Postoperative axial neck pain in the OPLL group showed strong negative correlations with C2 SVA and C7 slope. Strong negative correlations were found between axial neck pain and CSF in both the preoperative CSM and OPLL groups (CSM: r=-0.45, P=0.01; OPLL: r=-0.61, P<0.01) and between axial neck pain and CSF in the postoperative OPLL group (r=-0.51, P=0.05).

CONCLUSIONS

This study demonstrated a significant negative correlation between neck pain and CSF in both the CSM and OPLL groups preoperatively and in the OPLL group postoperatively. Radiographic cervical sagittal alignment did not significantly correlate with preoperative or postoperative axial neck pain.

Efficacy of Laminoplasty in Patients with Cervical Kyphosis

Background

The efficacy of laminoplasty in patients with cervical kyphosis is controversial. The purpose of this study was to investigate the impact of the initial pathogenesis on the clinical outcomes of laminoplasty in patients with cervical kyphosis.

Material/Methods

A total of 137 patients with cervical spondylotic myelopathy (CSM) or ossification of the posterior longitudinal ligament (OPLL) underwent laminoplasty from April 2013 to May 2015. The patients were divided into the following 4 groups: lordosis with CSM (LC), kyphosis with CSM (KC), lordosis with OPLL (LO), and kyphosis with OPLL (KO). The clinical outcome measures included the visual analogue scale (VAS) and modified Japanese Orthopedic Association (mJOA) scores, the range of motion (ROM), and the cervical global angle (CGA).

Results

The mean VAS and mJOA scores improved significantly in all groups after surgery. The changes in VAS and mJOA scores were significantly smaller, and the JOA recovery rate was significantly lower, in the KC group than in the LC and KO groups. The mean change in the CGA was greatest in the KC group (>8° towards kyphosis). The preoperative ROM was negatively correlated with the change in CGA and the JOA recovery rate in the KO and KC groups.

Conclusions

We found that laminoplasty is suitable for patients with cervical lordosis and those with mild cervical kyphosis and OPLL, but is not recommended for patients with kyphosis and CSM, particularly those with a large ROM preoperatively.

A Novel Anterior Revision Surgery for the Treatment of Cervical Ossification of Posterior Longitudinal Ligament: Case Report and Review of the Literature

PURPOSE

A 62-year-old blind man with severe ossification of the posterior longitudinal ligament was presented. The patient underwent posterior laminectomy and fixation. After surgery, the patient was not satisfied with the recovery of his upper limbs although his Japanese Orthopedic Association (JOA) score had increased from 9 to 12 points. Because the tactile sensation of his hands was especially important to his daily life, the patient asked for further treatment after 6 months. This report describes the novel revision surgery we invented and the outcome in the patient after the surgery.

METHODS

We performed the revision surgery using an anterior approach from C3 to C7 with a novel technique, anterior controllable antedisplacement and fusion (ACAF). The patient was followed up for 6 months. The clinical data, including JOA score and radiologic images, were collected and analyzed.

RESULTS

After the revision surgery, the patient had improved sensation in both hands, and his JOA score increased to 14 points. Satisfactory decompression was assessed by magnetic resonance imaging after operation. Bone fusion was confirmed by computed tomography 3 months after operation. No specific complications related to this surgery were observed.

CONCLUSIONS

The application of such an operative procedure in revision surgery for OPLL has not been reported earlier and might be an alternative choice for patients with an unsatisfactory outcome from previous posterior surgery.

The Role of Dynamic Magnetic Resonance Imaging in Cervical Spondylotic Myelopathy

Dynamic spinal cord compression has been investigated for several years, but until the advent of open MRI, the use of dynamic MRI (dMRI) did not gain popularity. Several publications have shown that cervical cord compression is both static and dynamic. On many occasions the evaluation of cervical spondylotic myelopathy (CSM) is straightforward, but patients are frequently encountered with a significantly worse clinical examination than would be suggested by radiological images. In this paper, we present an extensive review of the literature in order to describe the importance of dMRI in various settings and applications. A detailed literature review was performed in the Medline and Pubmed databases using the terms “cervical spondylotic myelopathy”, “dynamic MRI”, “kinetic MRI”, and “myelomalalcia” for the period of 1980-2016. The study was limited to English language, human subjects, case series, retrospective studies, prospective reports, and clinical trials. Reviews, case reports, cadaveric studies, editorials, and commentaries were excluded. The literature search yielded 180 papers, 19 of which met inclusion criteria. However, each paper had evaluated results and outcomes in different ways. It was not possible to compile them for meta-analysis or pooled data evaluation. Instead, we evaluated individual studies and present them for discussion. We describe a number of parameters evaluated in 2661 total patients, including dynamic changes to spinal cord and canal dimensions, transient compression of the cord with changes in position, and the effects of position on the intervertebral disc. dMRI is a useful tool for understanding the development of CSM. It has found several applications in the diagnosis and preoperative evaluation of many patients, as well as certain congenital dysplasias and Hirayama disease. It is useful in correlating symptoms with the dynamic changes only noted on dMRI, and has reduced the incidence of misdiagnosis of myelopathy.

Impact of wedge-shaped resection of the posterior bony arch on postoperative outcomes after open door laminoplasty in the cervical spine: a 2-year follow-up study

BACKGROUND CONTEXT

Open door laminoplasty (ODLP) can also lead to significant postoperative motion restriction that further increases over time, for which one of the possible factors is the bony impingement between neighboring posterior bony arches. Previously, we reported this phenomenon and modified technique of ODLP, wedge-shaped resection of the posterior bony arch that produced greater range of motion (ROM) of the cervical spine and less posterior neck pain compared with conventional ODLP (cODLP) in 1-year follow-up time, but no longer follow-up outcomes of the surgical technique has been reported.

PURPOSE

The study aimed to thoroughly evaluate the impact of posterior bony impingement following ODLP on postoperative cervical motion and related outcomes, and to compare postoperative outcomes of conventional ODLP (cODLP with those of modified ODLP (mODLP) in 2-year follow-up times.

STUDY DESIGN

This is a retrospective comparative study.

PATIENT SAMPLE

A total of 145 patients who underwent cODLP or mODLP and were followed up for at least 2 years were classified into two groups: Group A (cODLP, 79 patients) and Group B (mODLP, 66 patients).

OUTCOME MEASURES

The primary outcome measure was ROM of the cervical spine. Secondary outcome measures included (1) patient satisfaction, (2) radiological outcomes, including the rate of bony impingement and spontaneous fusion, and bone regrowth of the resection site, (3) clinical outcomes based on pain intensity and scores on the 12-item short-form health survey (SF-12) and neck disability index (NDI), (4) surgical outcomes, and (5) surgery-related complications.

METHODS

We compared baseline data in both groups. To evaluate the impact of our surgical modification on postoperative outcome after ODLP, we compared the outcome measures in 2-year follow-up times. No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

RESULTS

The ROM of the cervical spine was significantly greater in Group B 2 years after surgery than in Group A (p=.001). Patient satisfaction (p=.02) at 2 years after surgery and pain intensity of the posterior neck at 1 (p=.01) and 2 years (p<.01) after surgery were better in Group B than in Group A. Radiological evidence of posterior bony impingement and spontaneous fusion between ODLPsegments were definitely fewer less in Group B than in Group A (p<.001 and<0.001, respectively). The mean value of bone regrowth was 1.2 mm (range, 0-3 mm). The NDI and SF-12 scores did not differ significantly between groups. Surgical outcomes and postoperative complications were similar between groups.

CONCLUSIONS

These results indicate that posterior bony impingement can be a factor in ROM restriction after cODLP surgery and that wedge-shaped resection during ODLP can be a reliable option for preserving cervical ROM and improving postoperative clinical and radiological outcomes.

A Meta-Analysis of Cervical Laminoplasty Techniques: Are Mini-Plates Superior?

STUDY DESIGN

Meta-analysis and systematic review of literature.

OBJECTIVE

In the late 1990s, spinal surgeons experimented by using maxillofacial fixation plates as an alternative to sutures, anchors, and local spinous process autografts to provide a more rigid and lasting fixation for laminoplasty. This eventually led to the advent of laminoplasty mini-plates, which are currently used. The objective is to compare laminoplasty techniques with plate and without plate with regard to functional outcome results.

METHODS

Qualitative and quantitative analyses were performed to evaluate the currently available studies in an attempt to justify the use of a plate in laminoplasty.

RESULTS

The principal finding of this study was that there was no statistically significant difference in clinical outcome between the 2 different techniques of laminoplasty.

CONCLUSION

There is not enough evidence in the literature to support one technique over the other, and hence, there is no evidence to support change in practice (using or not using the plate in laminoplasty). A randomized controlled trial will give a better comparison between the 2 groups.

Wedge-Shaped Resection of the Posterior Bony Arch During Open Door Laminoplasty to Prevent Postoperative Motion Limitation

STUDY DESIGN

Prospective randomized double-arm noninferiority study.

OBJECTIVE

To evaluate an additional surgical procedure (wedge-shaped resection of the cranial portion of the posterior bony arch) during open-door laminoplasty (ODLP), and to compare the outcomes with those of conventional ODLP surgery.

SUMMARY OF BACKGROUND DATA

In clinical practice, spine surgeons sometimes encounter patients who show bony impingement on lateral radiographs after ODLP; bony impingement may lead to reduced motion of the cervical spine and posterior neck pain. However, this problem has not been well studied, and no methods have been developed to prevent it.

METHODS

Of total 79 patients, 75 were enrolled and randomly assigned to either group A (additional procedure in ODLP, n = 38) or group B (ODLP alone, n = 37). The primary outcome measure was range of motion (ROM) of the cervical spine. Secondary endpoints included clinical outcomes based on pain intensity, 12-item short form health survey (SF-12), and modified Japanese Orthopedic Association scale; presence of bony impingement on dynamic lateral radiographs; surgical outcomes; and surgery-related complications.

RESULTS

ROM of the cervical spine was significantly greater at 6 months (P = 0.04) and 1 year (P = 0.02) postoperative in group A than in group B. Pain intensity at the posterior neck was significantly lower 1 year after surgery in group A than in group B (P = 0.03). In lateral radiographs 1 year after surgery, the presence of posterior bony impingement was 0% in group A and 32.4% in group B (P <0.01). Clinical outcomes and surgery-related complications were similar between groups.

CONCLUSION

Performing wedge-shaped resection of the cranial portion of the posterior bony arch in ODLP surgery can lead to better outcomes than ODLP alone in terms of preservation of cervical ROM, prevention of posterior bony impingement, and amelioration of posterior neck pain.

LEVEL OF EVIDENCE

2.

Effect of Preoperative Sagittal Balance on Cervical Laminoplasty Outcomes

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To clarify how preoperative global sagittal imbalance influences outcomes in patients with cervical compression myelopathy undergoing cervical laminoplasty.

SUMMARY OF BACKGROUND DATA

The influence of sagittal balance on outcomes of cervical laminoplasty remains uncertain.

METHODS

The authors retrospectively reviewed data of 106 patients who underwent double-door cervical laminoplasty between 2004 and 2011 and investigated the influence of the C7 sagittal vertical axis (SVA) on outcome scores. Primary outcomes used were Japanese Orthopedic Association (JOA) scores, Numerical Rating Scale for neck or arm pain, the Short Form 36 Health Survey (physical and mental component summary scores ), and the Neck Disability Index (NDI).

RESULTS

Ninety-two patients with complete data were eligible for inclusion. The preoperative C7 SVA was ≤5 cm in 64 patients (69.6%) and > 5 cm in 28 (30.4%). We compared each parameter by the magnitude of spinal sagittal balance (preoperative C7 SVA > 5 cm vs. C7 SVA ≤ 5 cm) after adjusting for age via the least square mean analysis because the average age was significantly higher in patients with C7 SVA > 5 cm. As for the radiographic parameters, both C2-7 SVA and C7 SVA were larger in patients when the C7 SVA was > 5 cm. Numerical Rating Scale for postoperative arm pain, postoperative JOA scores, and both pre- and postoperative physical component summary and NDI were worse in patients with C7 SVA > 5 cm; however, the JOA score recovery rate and changes in physical component summary and NDI were not significantly different.

CONCLUSION

Postoperative functional outcome scores were significantly lower in patients with C7 SVA > 5 cm, although the improvement after cervical laminoplasty was not greatly affected. The involvement of global sagittal balance and cervical regional alignment should be considered in evaluating surgical outcomes for patients undergoing cervical laminoplasty.

LEVEL OF EVIDENCE

4.

Optimal area of lateral mass mini-screws implanted in plated cervical laminoplasty: a radiography anatomy study

PURPOSE

Lateral mass mini-screws used in plated cervical laminoplasty might penetrate into facet joints. The objective is to observe this complication incidence and to identify the optimal areas for 5- and 7-mm-long mini-screws to implant on lateral mass.

METHODS

47 patients who underwent plated cervical laminoplasty were included. The optimal area for mini-screws implanting was set according to pre-operative 3D CT reconstruction data. Then, each posterior-lateral mass surface was divided into three regions: 7-mm region, 5-mm region, and dangerous area. The mini-screw implanted region was recorded. Post-operative CT images were used to identify whether the mini-screws penetrated into facet joints.

RESULTS

235 mini-plates and 470 lateral mass mini-screws were used in the study. 117 (24.9%) mini-screws penetrated 88 (37.4%) facet joints. The 5-mm-long mini-screw optimal area occupied the upper 72, 65, 65, 64, and 65 % area of the posterior-lateral mass surface for C3-7, while the 7-mm-long mini-screw optimal area encompassed the upper 54, 39, 40, 33, and 32 %. Only 7-mm-long mini-screws were used to fix the plate to the lateral mass. 4 of 240 mini-screws in 7-mm region, 67 of the 179 mini-screws in 5-mm region, and 46 of the 51 mini-screws in dangerous region penetrated into the facet joint. The differences in the rate of facet joint penetration related to region were statistically significant (P < 0.001).

CONCLUSIONS

The facet joint destruction by mini-screws was not a rare complication in plated cervical laminoplasty. The optimal areas we proposed may help guide the mini-screw implantation positions.

Safety and efficacy of cervical laminoplasty using a piezosurgery device compared with a high-speed drill

BACKGROUND

Piezosurgery is a relatively new osteotomy technique using microvibrations of scalpels at ultrasonic frequencies to perform safe and effective osteotomies without damage to adjacent soft tissue, which is widely used in spinal, oral, and maxillofacial surgery. We hypothesized that such a device could also be useful in cervical laminoplasty. The purpose of this study was to compare the safety and efficacy of a piezosurgery device with those of a highspeed drill in cervical laminoplasty.

METHODS

A prospectively randomized clinical study was designed. Forty-two consecutive patients were enrolled in the study. All patients underwent modified expansive open-door laminoplasty and were randomly divided into 2 groups according to the instrument for transection of the lamina, using high-speed drill (drill group) or piezosurgery device (piezosurgery group). The operation time, intraoperative blood loss, and postoperative drainage were recorded. Japanese Orthopedic Association (JOA) score and visual analogue scale (VAS) as clinical assessments were quantified.

RESULTS

No significant difference was observed in the operation time between the 2 groups. In the piezosurgery group, there were less loss of the intraoperative blood and postoperative drainage compared with the drill group. However, clinical results (VAS and JOA scores) showed no significant difference between both groups during the all follow-up periods.

CONCLUSION

The piezosurgery is a useful instrument and at least as safe and efficacious as the conventional high-speed drill in cervical laminoplasty.

Multivariate Analysis of Factors Associated With Axial Symptoms in Unilateral Expansive Open-Door Cervical Laminoplasty With Miniplate Fixation

Retrospective case-control study.Unilateral expansive open-door cervical laminoplasty with miniplate fixation is an efficient and increasing popular surgery for multilevel cervical spondylotic myelopathy. Axial symptoms are the most frequent complaints after cervical laminoplasty. But the mechanisms have not been fully clarified yet.The objective of this study is to compare the clinical and radiologic data between patients with or without axial symptoms and to investigate the factors associated with axial symptoms by multivariate analysis in cervical laminoplasty with miniplate fixation.A total of 129 patients who underwent cervical laminoplasty with miniplate fixation were comprised from August 2009 to March 2014. Patients were grouped according to whether they suffered from postoperative axial symptoms (PA) or not (NA). The clinical data including gender, age, duration of symptoms, diagnosis type, medical comorbidity, operative level, blood loss, operative time, pre- and post-Japanese Orthopedic Association (JOA) score, JOA recovery rates, and other complications were recorded. The radiologic data including cervical canal diameter, C2-7 Cobb angle, cervical range of motion (ROM), cross-sectional area, open angle, hinge union, and facet joint destroyed would be measured according to X-ray plain and CT scan images. The univariate analysis and multivariate logistic regression analysis were performed.There were 39 patients in PA group and 90 patients in NA group. Both groups gained significant JOA improvement postoperatively (P < 0.05). The preoperative neck pain (P = 0.048), negative change of cervical ROM (P = 0.018), and facet joints destroyed (P = 0.022) were significant different between the 2 groups. There were no significant differences for other clinical and radiography parameters between the groups (P > 0.05). The multivariate analysis showed that the negative change of cervical ROM (OR = 1.062, P = 0.047) and facet joints destroyed (OR = 0.661, P = 0.024) were related to axial symptoms.The change of cervical ROM and facet joints destroyed by miniscrews might be associated with axial symptoms after cervical laminoplasty with miniplate fixation. Cervical spine surgeons should carefully operate to decrease the injury of posterior musculature structure and protect the facet joints.

Impact of dynamic alignment, motion, and center of rotation on myelopathy grade and regional disability in cervical spondylotic myelopathy

OBJECT

Cervical stenosis is a defining feature of cervical spondylotic myelopathy (CSM). Matsunaga et al. proposed that elements of stenosis are both static and dynamic, where the dynamic elements magnify the canal deformation of the static state. For the current study, the authors hypothesized that dynamic changes may be associated with myelopathy severity and neck disability. This goal of this study was to present novel methods of dynamic motion analysis in CSM.

METHODS

A post hoc analysis was performed of a prospective, multicenter database of patients with CSM from the AOSpine North American study. One hundred ten patients (34%) met inclusion criteria, which were symptomatic CSM, age over 18 years, baseline flexion/extension radiographs, and health-related quality of life (HRQOL) questionnaires (modified Japanese Orthopaedic Association [mJOA] score, Neck Disability Index [NDI], the 36-Item Short Form Health Survey Physical Component Score [SF-36 PCS], and Nurick grade). The mean age was 56.9 ± 12 years, and 42% of patients were women (n = 46). Correlations with HRQOL measures were analyzed for regional (cervical lordosis and cervical sagittal vertical axis) and focal parameters (kyphosis and spondylolisthesis between adjacent vertebrae) in flexion and extension. Baseline dynamic parameters (flexion/extension cone relative to a fixed C-7, center of rotation [COR], and range of motion arc relative to the COR) were also analyzed for correlations with HRQOL measures.

RESULTS

At baseline, the mean HRQOL measures demonstrated disability and the mean radiographic parameters demonstrated sagittal malalignment. Among regional parameters, there was a significant correlation between decreased neck flexion (increased C2–7 angle in flexion) and worse Nurick grade (R = 0.189, p = 0.048), with no significant correlations in extension. Focal parameters, including increased C-7 sagittal translation overT-1 (slip), were significantly correlated with greater myelopathy severity (mJOA score, Flexion R = −0.377, p = 0.003; mJOA score, Extension R = −0.261, p = 0.027). Sagittal slip at C-2 and C-4 also correlated with worse HRQOL measures. Reduced flexion/extension motion cones, a more posterior COR, and smaller range of motion correlated with worse general health SF-36 PCS and Nurick grade.

CONCLUSIONS

Dynamic motion analysis may play an important role in understanding CSM. Focal parameters demonstrated a significant correlation with worse HRQOL measures, especially increased C-7 sagittal slip in flexion and extension. Novel methods of motion analysis demonstrating reduced motion cones correlated with worse myelopathy grades. More posterior COR and smaller range of motion were both correlated with worse general health scores (SF-36 PCS and Nurick grade). To our knowledge, this is the first study to demonstrate correlation of dynamic motion and listhesis with disability and myelopathy in CSM.

Clinical and radiography results of mini-plate fixation compared to suture suspensory fixation in cervical laminoplasty: A five-year follow-up study

OBJECTIVES

Lamina closure is the most common reason for failure of unilateral open-door laminoplasty. Mini-plate fixation was designed to solve such problem. We assessed the clinical outcomes and radiography results of mini-plate fixation by comparing it with suture suspension fixation.

PATIENTS AND METHODS

This prospective study enrolled 57 patients with multi-segment cervical spondylotic myelopathy between January 2008 and March 2010. Thirty-four patients underwent laminoplasty with mini-plate fixation (mini-plate group) whereas 23 patients underwent laminoplasty with suture suspension fixation (suture group). The neurological function was measured with the Japanese Orthopedic Association (JOA) score. Cervical range of motion (ROM), C2-7 angle, and the spinal canal expansive parameters (anteroposterior diameter, Pavlov's ratio, cross-sectional area, and open angles) were evaluated.

RESULTS

The mean follow-up time was 64 (60-82) months. There were no significant differences in preoperative JOA scores (p=0.191), postoperative JOA scores (p=0.700), preoperative cervical ROM (p=0.315) and preoperative C2-7 angle (p=0.074) between the two groups. Both groups had significant postoperative JOA improvement (p<0.05). The mini-plate group had larger cervical ROM (p=0.041) and C2-7 angle (p=0.040) than the suture group at the final follow-up. Both groups showed significant improvement in the spinal canal expansive parameters immediately after the surgery. In the suture group, the parameters, such as anteroposterior diameter, Pavlov's ratio, cross-sectional area, and open angles, decreased along with time, mainly within the first 6 months following the operation. In the mini-plate group, these parameters remained unchanged. The spinal canal expansive parameters between the 2 groups were not significantly different immediately following the operation, but were significantly different at the final follow-up (p<0.05). Three patients in the suture group displayed neurological deterioration due to lamina reclosure.

CONCLUSIONS

Laminoplasty by mini-plate fixation preserved more cervical ROM and better cervical alignment, maintained cervical spine canal expansive stability and effectively avoided lamina reclosure for a long-term follow-up.

Cervical laminoplasty developments and trends, 2003-2013: a systematic review

OBJECT

Despite extensive clinical experience with laminoplasty, the efficacy of the procedure and its advantages over laminectomy remain unclear. Specific clinical elements, such as incidence or progression of kyphosis, incidence of axial neck pain, postoperative cervical range of motion, and incidence of postoperative C-5 palsies, are of concern. The authors sought to comprehensively review the laminoplasty literature over the past 10 years while focusing on these clinical elements.

METHODS

The authors conducted a literature search of articles in the Medline database published between 2003 and 2013, in which the terms "laminoplasty," "laminectomy," and "posterior cervical spine procedures" were used as key words. Included was every single case series in which patient outcomes after a laminoplasty procedure were reported. Excluded were studies that did not report on at least one of the above-mentioned items.

RESULTS

A total of 103 studies, the results of which contained at least 1 of the prespecified outcome variables, were identified. These studies reported 130 patient groups comprising 8949 patients. There were 3 prospective randomized studies, 1 prospective nonrandomized alternating study, 15 prospective nonrandomized data collections, and 84 retrospective reviews. The review revealed a trend for the use of miniplates or hydroxyapatite spacers on the open side in Hirabayashi-type laminoplasty or on the open side in a Kurokawa-type laminoplasty. Japanese Orthopaedic Association (JOA) scoring was reported most commonly; in the 4949 patients for whom a JOA score was reported, there was improvement from a mean (± SD) score of 9.91 (± 1.65) to a score of 13.68 (± 1.05) after a mean follow-up of 44.18 months (± 35.1 months). The mean preoperative and postoperative C2-7 angles (available for 2470 patients) remained stable from 14.17° (± 0.19°) to 13.98° (± 0.19°) of lordosis (average follow-up 39 months). The authors found significantly decreased kyphosis when muscle/posterior element-sparing techniques were used (p = 0.02). The use of hardware in the form of hydroxyapatite spacers or miniplates did not influence the progression of deformity (p = 0.889). An overall mean (calculated from 2390 patients) of 47.3% loss of range of motion was reported. For the studies that used a visual analog scale score (totaling 986 patients), the mean (cohort size-adjusted) postoperative pain level at a mean follow-up of 29 months was 2.78. For the studies that used percentages of patients who complained of postoperative axial neck pain (totaling 1249 patients), the mean patient number-adjusted percentage was 30% at a mean follow-up of 51 months. The authors found that 16% of the studies that were published in the last 10 years reported a C-5 palsy rate of more than 10% (534 patients), 41% of the studies reported a rate of 5%-10% (n = 1006), 23% of the studies reported a rate of 1%-5% (n = 857), and 12.5% reported a rate of 0% (n = 168).

CONCLUSIONS

Laminoplasty remains a valid option for decompression of the spinal cord. An understanding of the importance of the muscle-ligament complex, plus the introduction of hardware, has led to progress in this type of surgery. Reporting of outcome metrics remains variable, which makes comparisons among the techniques difficult.

Effect of preservation of the C-6 spinous process and its paraspinal muscular attachment on the prevention of postoperative axial neck pain in C3-6 laminoplasty

OBJECT

Axial neck pain after C3-6 laminoplasty has been reported to be significantly lesser than that after C3-7 laminoplasty because of the preservation of the C-7 spinous process and the attachment of nuchal muscles such as the trapezius and rhomboideus minor, which are connected to the scapula. The C-6 spinous process is the second longest spinous process after that of C-7, and it serves as an attachment point for these muscles. The effect of preserving the C-6 spinous process and its muscular attachment, in addition to preservation of the C-7 spinous process, on the prevention of axial neck pain is not well understood. The purpose of the current study was to clarify whether preservation of the paraspinal muscles of the C-6 spinous process reduces postoperative axial neck pain compared to that after using nonpreservation techniques.

METHODS

The authors studied 60 patients who underwent C3-6 double-door laminoplasty for the treatment of cervical spondylotic myelopathy or cervical ossification of the posterior longitudinal ligament; the minimum follow-up period was 1 year. Twenty-five patients underwent a C-6 paraspinal muscle preservation technique, and 35 underwent a C-6 nonpreservation technique. A visual analog scale (VAS) and VAS grading (Grades I-IV) were used to assess axial neck pain 1-3 months after surgery and at the final follow-up examination. Axial neck pain was classified as being 1 of 5 types, and its location was divided into 5 areas. The potential correlation between the C-6/C-7 spinous process length ratio and axial neck pain was examined.

RESULTS

The mean VAS scores (± SD) for axial neck pain were comparable between the C6-preservation group and the C6-nonpreservation group in both the early and late postoperative stages (4.1 ± 3.1 vs 4.0 ± 3.2 and 3.8 ± 2.9 vs 3.6 ± 3.0, respectively). The distribution of VAS grades was comparable in the 2 groups in both postoperative stages. Stiffness was the most prevalent complaint in both groups (64.0% and 54.5%, respectively), and the suprascapular region was the most common site in both groups (60.0% and 57.1%, respectively). The types and locations of axial neck pain were also similar between the groups. The C-6/C-7 spinous process length ratios were similar in the groups, and they did not correlate with axial neck pain. The reductions of range of motion and changes in sagittal alignment after surgery were also similar.

CONCLUSIONS

The C-6 paraspinal muscle preservation technique was not superior to the C6-nonpreservation technique for preventing postoperative axial neck pain.

Modified Open-door Laminoplasty Using Hydroxyapatite Spacers and Miniplates

Objective

Cervical laminoplasty has been widely accepted as one of the major treatments for cervical myelopathy and various modifications and supplementary procedures have been devised to achieve both proper decompression and stability of the cervical spine. We present the retrospectively analyzed results of a modified unilateral open-door laminoplasty using hydroxyapatite (HA) spacers and malleable titanium miniplates.

Methods

From June 2008 to May 2012, among patients diagnosed with cervical spondylotic myelopathy and ossification of posterior longitudinal ligament, the patients who received laminoplasty were reviewed. Clinical outcome was assessed using Frankel grade and Japanese Orthopaedic Association score. The radiologic parameters were obtained from plain films, 3-dimensional computed tomography and magnetic resonance images.

Results

A total of 125 cervical laminae were operated in 38 patients. 11 patients received 4-level laminoplasty and 27 patients received 3-level laminoplasty. Postoperatively, the mean Frankel grade and JOA score were significantly improved from 3.97 to 4.55 and from 12.76 to 14.63, respectively (p<0.001). Radiologically, cervical curvature was worsened from 19.09 to 15.60 (p=0.025). The percentage of range of motion preservation was 73.32±22.39%. The axial dimension of the operated spinal canal was increased from 1.75 to 2.70 cm² (p<0.001).

Conclusion

In the presenting study, unilateral open-door laminoplasty using HA spacers and miniplates appears to be a safe, rapid and easy procedure to obtain an immediate and rigid stabilization of the posterior elements of the cervical spine. This modified laminoplasty method showed effective expansion of the spinal canal and favorable clinical outcomes.

In vivo 3D kinematic changes in the cervical spine after laminoplasty for cervical spondylotic myelopathy

Object

Cervical laminoplasty is an effective procedure for decompressing the spinal cord at multiple levels, but restriction of neck motion is one of the well-known complications of the procedure. Although many authors have reported on cervical range of motion (ROM) after laminoplasty, they have focused mainly on 2D flexion and extension on lateral radiographs, not on 3D motion (including coupled motion) nor on precise intervertebral motion. The purpose of this study was to clarify the 3D kinematic changes in the cervical spine after laminoplasty performed to treat cervical spondylotic myelopathy.

Methods

Eleven consecutive patients (6 men and 5 women, mean age 68.1 years, age range 57–79 years) with cervical spondylotic myelopathy who had undergone laminoplasty were included in the study. All patients underwent 3D CT of the cervical spine in 5 positions (neutral, 45° head rotation left and right, maximum head flexion, and maximum head extension) using supporting devices. The scans were performed preoperatively and at 6 months after laminoplasty. Segmental ROM from Oc–C1 to C7–T1 was calculated both in flexion-extension and in rotation, using a voxel-based registration method.

Results

Mean C2–7 flexion-extension ROM, equivalent to cervical ROM in all previous studies, was 45.5° ± 7.1° preoperatively and 35.5° ± 8.2° postoperatively, which was a statistically significant 33% decrease. However, mean Oc–T1 flexion-extension ROM, which represented total cervical ROM, was 71.5° ± 8.3° preoperatively and 66.5° ± 8.3° postoperatively, an insignificant 7.0% decrease. In focusing on each motion segment, the authors observed a statistically significant 22.6% decrease in mean segmental ROM at the operated levels during flexion-extension and a statistically insignificant 10.2% decrease during rotation. The most significant decrease was observed at C2–3. Segmental ROM at C2–3 decreased 24.2% during flexion-extension and 21.8% during rotation. However, a statistically insignificant 37.2% increase was observed at the upper cervical spine (Oc–C2) during flexion-extension. The coupling pattern during rotation did not change significantly after laminoplasty.

Conclusions

In this first accurate documentation of 3D segmental kinematic changes after laminoplasty, Oc–T1 ROM, which represented total cervical ROM, did not change significantly during either flexion-extension or rotation by 6 months after laminoplasty despite a significant decrease in C2–7 flexion-extension ROM. This is thought to be partially because of a compensatory increase in segmental ROM at the upper cervical spine (Oc–C2).