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Few researchers have verified the clinical efficacy and safety of the modified unilateral extrapedicular approach (mUEP) applied to the percutaneous kyphoplasty (PKP) in comparative studies with other puncture techniques. Compared with the bilateral transpedicular approach (BTP), whether mUEP PKP is a preferred treatment for lumbar osteoporotic vertebral compression fracture (OVCF) remains unclear.Patients treated by PKP for single-level lumbar OVCF in our institution from September 2019 to December 2020 were retrospectively enrolled. Patients were grouped according to the puncture techniques. Clinical and radiologic outcomes were evaluated preoperatively, postoperatively, and at follow-up. The clinical evaluation was performed by using visual analog scale for pain relief and Oswestry Disability Index for health status. Radiologic measurements contained anterior vertebral height, kyphotic angle, and bone cement distribution.In total, 76 patients with a mean follow-up duration of 16.6 months were enrolled, including 34 patients in the mUEP PK group and 42 patients in the BTP PKP group. In the mUEP group, operation time, fluoroscopy times, and injected cement volume were significantly less than that in the BTP group (P0.01). Both visual analog scale and Oswestry Disability Index scores of all patients decreased significantly after surgery (P0.01), with no significant differences between the 2 groups at each follow-up. Both mUEP PKP and BTP PKP showed significant anterior height restoration and kyphotic angle correction (P0.01), with no significant differences between the 2 groups at each follow-up. Meanwhile, the mUEP PKP reduced the incidence of intraspinal cement leakage (P0.05), and no facet joint violation was found in mUEP PKP.mUEP PKP could be clinically and radiographically equivalent to BTP PKP. However, it has advantages in reducing operation time and fluoroscopy times, lowering the risk of intraspinal cement leakage, and preventing the presence of facet joint violation. Compared with BTP PKP, the mUEP PKP seems to be an effective and alternative puncture technique for the treatment of lumbar OVCF after appropriate patient selection.

To evaluate changes in the sagittal parameters of the occipito-atlantoaxial complex after three-level anterior cervical decompression and fusion (ACDF) and identify the influential factors by comparing ACDF with a zero-profile anchored spacer (ACDF-Z) versus a cage-plate construct (ACDF-P). The cohort comprised 106 patients who underwent three-level contiguous ACDF-Z or ACDF-P for cervical radiculopathy and/or myelopathy. Standing, flexion, and extension radiographs of cervical spine were obtained preoperatively, and 3 and 12 months postoperatively. The assessed cervical sagittal parameters were the platform angle of the axis, Cobb angle, and range of motion (ROM) of C2⁃7, C0⁃1, and C1⁃2. In both the ACDF-Z and ACDF-P groups, the Cobb angle of the upper cervical spine decreased and the C0-1 ROM increased from preoperatively to 3 and 12 months postoperatively (P

Cervical focal kyphosis could often be observed in patients with cervical spondylotic myelopathy (CSM). However, the association between it and myelopathy severity remains unclear. This study aims to elucidate the association between cervical focal kyphosis and myelopathy severity before surgery. A retrospective review of 191 consecutive patients treated for CSM from 2017 to 2019 was surveyed. Seven MRI and five radiographic parameters were measured, clinical parameters were included. Patients were divided into two sagittal focal angle groups (lordosis/kyphosis) and two disc herniation severity groups (severe/non-severe). The potential risk factors of myelopathy symptoms were analysed. Significant correlations between cervical sagittal focal angles, several other imaging findings and myelopathy severity were found in both total patients (R2 = 0.51, P

Background: The pathogenesis of ankylosing spondylitis (AS) remains undetermined. Ferroptosis is a newly discovered form of regulated cell death involved in multiple autoimmune diseases. Currently, there are no reports on the connection between ferroptosis and AS. Methods: AS samples from the Gene Expression Omnibus were divided into two subgroups using consensus clustering of ferroptosis-related genes (FRGs). Weighted gene co-expression network analysis (WGCNA) of the intergroup differentially expressed genes (DEGs) and protein–protein interaction (PPI) analysis of the key module were used to screen out hub genes. A multifactor regulatory network was then constructed based on hub genes. Results: The 52 AS patients in dataset GSE73754 were divided into cluster 1 (n = 24) and cluster 2 (n = 28). DEGs were mainly enriched in pathways related to mitochondria, ubiquitin, and neurodegeneration. Candidate hub genes, screened by PPI and WGCNA, were intersected. Subsequently, 12 overlapping genes were identified as definitive hub genes. A multifactor interaction network with 45 nodes and 150 edges was generated, comprising the 12 hub genes and 32 non-coding RNAs. Conclusions: AS can be divided into two subtypes according to FRG expression. Ferroptosis might play a regulatory role in AS. Tailoring treatment according to the ferroptosis status of AS patients can be a promising direction.

Spinal cord injury (SCI) is a serious trauma; however, the mechanisms underlying the role of insulin-like growth factor 1 (IGF-1) in autophagy following SCI remain to be elucidated. The present study aimed to investigate the therapeutic effect of IGF-1 on SCI and to determine whether IGF-1 regulates autophagy via the PI3K/Akt/mTOR signaling pathway. SH-SY5Y neuroblastoma cells were assigned to the H2O2, IGF-1 and control groups to investigate subsequent neuron injury in vitro. An MTT assay was performed to evaluate cell survival. In addition, Sprague-Dawley rats were randomly assigned to SCI, SCI + IGF-1 and sham groups, and Basso-Beatlie-Bresnahan scores were assessed to determine rat neurological function. Western blotting was used to analyze the autophagy level and the activation of the PI3K/Akt/mTOR signaling pathway. Cell survival was increased significantly in the IGF-1 group compared with the control group in vitro (P

Background Metal allergy is frequently seen. Orthopedic metal implants, such as external fixators or other stainless implants, contain chromium, nickel, and molybdenum, which can cause type IV hypersensitivity. Case summary A patient diagnosed with open comminuted tibiofibular fracture was treated with external fixation surgery, and she showed contact dermatitis and eczema-like symptoms 2 weeks postoperatively. She was then diagnosed as allergic to several metals by patch test and subsequently treated with traditional Chinese medicine (TCM), both orally and externally for 1 month. TCM treatment significantly alleviated the hypersensitive symptoms and made the patient bear the external fixator for 2 months until bone union. Conclusion TCM therapy may be an effective treatment for external fixation-induced metal allergy and contact dermatitis.

To investigate the adjacent segment kinematics, including the instantaneous axis of rotation (IAR) and range of motion (ROM), after anterior cervical discectomy and fusion (ACDF), and to compare between ACDF with zero-profile anchored spacer (ACDF-Z) and ACDF with plate (ACDF-P).Eighty-seven patients (ACDF-Z = 63; ACDF-P = 24) were included. Flexion, extension and neutral cervical radiographs were obtained before operation and at 1-year follow-up. C2-C7 ROM, adjacent segment ROMs, and IARs were measured. Clinical evaluation was based on the Visual Analogue Scale, Neck Disability Index, and Japanese Orthopaedic Association score.After ACDF-Z, location of the superior IAR-AP reduced 1.60 mm, which represents 8% of the vertebral body (P 0.001), and location of the inferior IAR-SI reduced 2.19 mm, 17% of the vertebral body (P = 0.02). After ACDF-P, location of the superior IAR-AP increased 0.8 mm, which means 6% of the vertebral body (P = 0.008), location of the inferior IAR-AP increased 3.34 mm, 22% of the vertebral body (P = 0.03), and location of the inferior IAR-SI reduced 3.14 mm, 25% of the vertebral body (P = 0.002). C2-C7 ROM significantly decreased after both ACDF-Z and ACDF-P (P 0.001). Neither ACDF-Z nor ACDF-P significantly affected the adjacent segment ROMs (P 0.05).Both ACDF-Z and ACDF-P significantly impacted cervical kinematics, although both procedures obtained satisfactory clinical results in the treatment of cervical spondylosis. After both ACDF-Z and ACDF-P, C2-C7 ROM decreased significantly, while adjacent segment ROMs were preserved. ACDF-Z and ACDF-P impact the location of adjacent segment IAR-SI in similar way, while impact the location of adjacent segment IAR-AP in diverse ways. These slides can be retrieved under Electronic Supplementary Material.

Objective This meta-analysis was conducted to evaluate the therapeutic effects in clinical and radiologic outcomes of a self-locking stand-alone cage (SSC) and cage-with-plate (CP) for multilevel anterior cervical discectomy and fusion (ACDF). Methods A systematic search was performed for all comparative studies reported up to August 2018. Operative time, hospital stay, intraoperative blood loss, Japanese Orthopedic Association score, Neck Disability Index (NDI), cervical and segmental Cobb angle, intervertebral height, fusion rate, incidence of subsidence, dysphagia, and adjacent segment degeneration were analyzed with the RevMan 5.3.3 software. Results A total of 15 studies were included. There was no difference regarding preoperative or postoperative Japanese Orthopedic Association score, Neck Disability Index, segmental Cobb angle and intervertebral height, preoperative cervical Cobb angle, fusion rate, incidence of subsidence, and adjacent segment degeneration between the SSC and CP group (P > 0.05). However, the SSC group had shorter operative time (mean difference [MD], −11.35; 95% confidence interval [CI], −16.24 to −3.66) and hospital stay (MD, −0.64; 95% CI, −1.21 to −0.06), less intraoperative blood loss (MD, −13.22; 95% CI, −19.03 to −7.41) and postoperative cervical Cobb angle (MD, −0.70; 95% CI, −1.35 to −0.06), and lower incidence of dysphagia significantly (odds ratio, −0.57; 95% CI, 0.40–0.82) (P Conclusions ACDF with SSC and CP in multilevel cervical spondylosis achieved similar clinical relief. Although CP maintained better cervical lordosis, SSC contributed to less surgical pain and fewer complications. ACDF with SSC is safe and efficient in treating multilevel cervical spondylosis.

Study Design: Prospective cohort study. Objective: To evaluate whether pre-existing adjacent spinal canal stenosis (SCS) is associated with short-term outcomes after lumbar fusion surgery. Methods: We included patients with lumbar spinal stenosis treated surgically between July 2015 and December 2017 at 4 centers. All patients had the same pathology, with L4-S1 as the culprit sections. Patients were divided into 2 groups based on the cerebrospinal fluid occlusion sign on MRI at the adjacent L3/4 level. Patients without SCS (grade 0) and with mild SCS (grade 1) were classified into the non-stenosis (NS) and mild stenosis (MS) groups, respectively. All patients underwent PLIF and completed at least 1-year follow-up. The incidence of adjacent segment degeneration (ASDeg) and clinical outcomes were compared between the 2 groups. Results: A total of 308 patients (NS, 156; MS, 152) met the inclusion criteria. The incidence of ASDeg in the NS group (n = 40, 25.6%) was significantly lower than that in the MS group (n = 74, 48.7%; P < .001). The most frequent type of ASDeg in the 2 groups was the SCS-aggravated type. No significant difference was observed in adjacent segment disease incidence between the 2 groups ( P = .243). The NS group had better outcomes according to the clinical function scores ( P < .05). Conclusions: The cerebrospinal fluid occlusion sign on MRI is valuable for evaluating the adjacent segment with pre-existing degeneration. Patients with mild SCS in adjacent segments were more likely to have ASDeg, and the most frequent type of ASDeg was the SCS-aggravated type at early follow-up.

Background The motion path of instantaneous center of rotation (ICR) is a crucial kinematic parameter to dynamically characterize cervical spine intervertebral patterns of motion; however, few studies have evaluated the effect of cervical disc degeneration (CDD) on ICR motion path. The purpose of this study was to investigate the effect of CDD on the ICR motion path of degenerated and adjacent segments. Method A validated nonlinear three-dimensional finite element (FE) model of a healthy adult cervical spine was used. Progressive degeneration was simulated with six FE models by modifying intervertebral disc height and material properties, anterior osteophyte size, and degree of endplate sclerosis at the C5–C6 level. All models were subjected to a pure moment of 1 Nm and a compressive follower load of 73.6 N to simulate physical motion. ICR motion paths were compared among different models. Results The normal FE model results were consistent with those of previous studies. In degenerative models, average ICR motion paths shifted significantly anterior at the degenerated segment (β = 0.27 mm; 95% CI: 0.22, 0.32) and posterior at the proximal adjacent segment (β = −0.09 mm; 95% CI: −0.15, −0.02) than those of the normal model. Conclusion CDD significantly affected ICR motion paths at the degenerated and proximal adjacent segments. The changes at adjacent segments may be a result of compensatory mechanisms to maintain the balance of the cervical spine. Surgical treatment planning should take into account the restoration of ICR motion path to normal. These findings could provide a basis for prosthesis design and clinical practice.

BACKGROUND: In the craniocervical junction, the ligaments between the anterior foramen magnum and the anterior arch of the atlas are not well defined, and ossification of the ligaments in this region has rarely been reported. Characterizing the anatomy and ossification of these ligaments may help in the diagnosis and treatment of disorders in this region. QUESTIONS/PURPOSES: (1) What is the prevalence of an unrecognized ossification at the craniocervical junction in patients with cervical spine disorders, and what are the patient characteristics associated with this ossification? (2) Do patients with this ossification have a greater risk of ossification of other structures at the craniocervical junction or cervical spine? (3) Is there an unreported ligament at this ossified site? METHODS: We conducted a retrospective study of 578 hospitalized patients who underwent CT for cervical spine disorders between January 2016 and July 2020. Based on the inclusion criteria, 11% (66 of 578) were excluded because of a cervical or craniocervical tumor, deformity, infection, fracture or dislocation, or prior surgery, leaving 89% (512 of 578) for analysis. These 512 patients had diagnoses of cervical radiculopathy, cervical myelopathy, cervical spondylotic amyotrophy, cervical spinal cord injury without a radiographic abnormality, or axial neck pain. Their mean age was 57 years (range 22-90 years), and 60% of the patients were men. Patient characteristics including age, gender, and diagnosis were retrieved from a longitudinally maintained institutional database. CT images were used to assess the presence of a previously unrecognized ossification and ossification of other structures in the craniocervical junction and cervical spine, including the posterior longitudinal ligament, anterior longitudinal ligament, nuchal ligament, ligamentum flavum, transverse ligament, and apical ligament, as well as diffuse idiopathic skeletal hyperostosis (DISH). The association between these structures was also assessed. This unreported ossification was called the capped dens sign. It was defined and graded from 1 to 3. Grade 3 was defined as the typical capped dens sign. Cervical spine MRI was used to assess whether there was an unreported structure in the same region as where the capped dens sign was detected on CT images. In the database of a recent study, there were 33 patients younger than 41 years. Nine percent (three of 33) were excluded because they did not have cervical spine MRI. MRIs of the remaining 30 patients were assessed. Their mean age was 35 years (range 22-40 years), and 58% were men. All cervical spine CT images and MRIs were reviewed by one senior spine surgeon and one junior spine surgeon twice with a 2-week interval. Blinding was accomplished by removing identifying information from the radiographs and randomly assigning them to each examiner. Any discrepancy with respect to the grade of the capped dens sign was adjudicated by a third blinded senior spine surgeon. Intrarater and interrater reliabilities were assessed by calculating weighted kappa statistics. No ligament or membrane was reported at this site. MRI is not sensitive to identify thin tissue in this region, especially when severe degeneration has occurred. A cadaveric study was conducted to discover a potential ligament between the inferior margin of the foramen magnum and the anterior arch of the atlas, as prompted by the newly discovered ossification in the clinical analysis of this study. Six embalmed human cadaveric craniocervical regions (three male and three female cadavers; median age 56 years, range 45-78 years) were dissected by a senior anatomist and a senior anatomy technician. A mid-sagittal section of the craniocervical junction was created, allowing us to explore the interval between the anterior foramen magnum and anterior arch of the atlas. A histologic analysis was conducted in two of the six cadavers (a male cadaver, 45 years; and a female cadaver, 51 years). Slides were made with 4-µm sections and stained with hematoxylin and eosin. RESULTS: A novel capped dens sign was detected in 39% (198 of 512) of the patients and the most typical capped dens sign was detected in 19% (96 of 512) of patients. The prevalence of this sign was the highest in patients with cervical spondylotic amyotrophy (12 of 25 patients). The prevalence of ossification of the anterior longitudinal ligament, ligamentum nuchae, and apical ligament, as well as DISH, was higher in patients with a capped dens sign than in those without (p = 0.04, p < 0.001, p < 0.001, and p = 0.001, respectively). The capped dens sign was identified in 69% (18 of 26) of the patients with DISH. A thin and short band-like structure or osteophyte was detected on MRI in 87% (26 of 30), in the same region as the capped dens sign. In the cadaveric study, an unreported, distinct ligamentous structure was identified at this ossified site. It originated from the posterosuperior rim of the anterior arch of the atlas to the inferior margin of the foramen magnum, which we called the inter-atlanto-occipital ligament. It was found in all six dissected craniocervical junctions. The histologic analysis revealed dense connective tissue. CONCLUSION: More than one-third of the patients in this series demonstrated CT evidence of a previously unrecognized ossification in the craniocervical junction, which we called the capped dens sign. Anatomic evidence of this sign, which was a previously unidentified ligament, was also newly discovered in this region. This study was conducted among Asian patients and specimens. Further studies among diverse ethnic groups may be needed to generalize the results. An additional well-designed prospective study will be needed to provide further evidence regarding the potential pathophysiology and clinical relevance of the capped dens sign. Furthermore, the cadaveric analysis in this study was only a preliminary report of the ligament; further biomechanical research is needed to investigate its function. CLINICAL RELEVANCE: Knowledge of this novel ligament may improve the diagnosis and treatment of craniocervical stability and dislocation. Ossification of this ligament is correlated with age, cervical spondylotic amyotrophy, and DISH. We wonder whether patients with cervical degenerative disorders who also have a capped dens sign may be at risk for the formation of osteophytes of an uncovertebral joint, which may result in palsy of the upper limb muscles. The capped dens sign may be the craniocervical manifestation of DISH. This possible association between the capped dens sign and DISH should be considered when performing surgery on patients with the capped dens sign.

BACKGROUND Self-locking stand-alone cages (MC+) and cage-with-pate fixation system are 2 different surgical methods used in anterior cervical discectomy and fusion (ACDF), but few systematic comparative studies comparing the 2 methods in treating multilevel cervical spondylotic myelopathy (MCSM) have been published. MATERIAL AND METHODS Sixty-two patients with MCSM who underwent multilevel ACDF were enrolled and completed at least a 3-year postoperative follow-up. The operative time, intra-operative blood loss, and clinical and radiological results were compared between the MC+ self-locking cages group and the cage-with-plate fixation group. Clinical parameters, including VAS for neck pain, Japanese Orthopedic Association (JOA) score, and neck disabled index (NDI), were evaluated. Surgical results according to Odom's criteria and postoperative dysphagia status, C5 nerve root palsy, and loosening of the instrumentation were recorded. Postoperative radiological results, including fusion rates, fusion segmental Cobb's angle (FSC), cervical lordosis, fusion segmental height (FSH), cage subsidence, and adjacent segment degeneration, were assessed. RESULTS The VAS score, JOA score, and NDI score were significantly improved in both groups. However, the patients in the cage-with-plate group were more likely to have neck pain at the last follow-up. The cervical lordosis, FSC, and FSH showed significant correction immediately after surgery. The loss of the cervical lordosis and FSH were higher in the MC+ group. CONCLUSIONS We found that use of MC+ cages is safe and effective in treating MCSM, but for patients who require strong postoperative stabilization and maintaining the cervical alignment better, the cage-with-plate fixation may best.

Purpose To determine how center of rotation (COR) changes and what affects changes in COR after cervical arthroplasty. Methods A systematic literature review of in vivo clinical studies comparing the location of the COR before and after cervical arthroplasty with different artificial prostheses was performed. Meta-analysis was performed using a fixed effects model where appropriate. Results A systematic review of the PubMed, EMBASE, and Cochrane Library databases was conducted. We initially identified 267 studies, of which 14 involved in vivo kinematics studies evaluating COR following cervical arthroplasty. We found that at the last follow-up, the COR location shifted anteriorly in patients from 4 studies including 85 segments, superiorly in patients from 4 studies including 98 segments, anterior-superiorly in patients from 4 studies including 290 segments, and anterior-inferiorly in patients from 1 study including 272 segments after cervical arthroplasty. The COR location showed no significant change in patients from 5 studies including 106 segments after cervical arthroplasty. Changes in COR showed a certain trend after cervical arthroplasty with different types of prostheses. Conclusions Prosthesis design affects changes in COR after cervical arthroplasty. If a constrained or semiconstrained prosthesis is chosen (2-piece implant, ball-and-socket, or ball-in-trough design), the COR location tends to shift anteriorly and/or superiorly, whereas if a nonconstrained prosthesis is chosen (3-piece implant, mobile nucleus design), the COR tends to keep the same location as preoperation. In addition, the position of the prosthesis in the intervertebral space also can affect changes in COR after cervical arthroplasty.

Background The center of rotation (COR), instantaneous center of rotation (ICR), instantaneous axis of rotation, instantaneous helical axis, finite helical axis, and helical axis of motion are important kinematic parameters for evaluating the quality of intervertebral motion of the cervical spine (QIMC). These parameters embody different concepts and are calculated using various methods. In this review, the distinctions and connections between these kinematic parameters are analyzed according to the concepts, research, and measurement techniques to provide a theoretic basis for future research and new research directions. Methods The PubMed/MEDLINE databases were searched for studies published in English related to the concepts, research, and calculation of these parameters. The included studies were classified according to the different research or calculation methods, and the proportion of each study type was calculated and analyzed. Results Forty articles were selected. The methods for analyzing the QIMC include in vivo and in vitro studies and finite element analysis. The primary methods for calculating these parameters include the method of perpendicular bisectors and the finite helical axis method. Conclusions COR was the simplest but not the most accurate parameter to evaluate the QIMC. Conversely, instantaneous helical axis/helical axis of motion were the most accurate, but relatively complex parameters to evaluate the QIMC. ICR showed dynamic changes during flexion-extension motion, but not the three-dimensional kinematic motion of the cervical spine. These parameters were equivalent only in certain situations but cannot be substituted for each other in the clinic. A dynamic radiographic in vivo study was the most convenient and frequently used research method to calculate COR, but failed to describe the dynamic movement. The method of perpendicular bisectors was widely used to calculate the COR or ICR. Therefore, a combination of new research and calculation methods to simply and effectively evaluate the QIMC requires further investigation.

BACKGROUND CONTEXT The coordination of the alignment between the lower extremities and cervical spine helps to achieve balance and horizontal gaze during standing and walking. Malalignment in any segment can disturb the global balance, causing compensation in another segment. Knee flexion contracture (KFC) can cause spine inclination with increased C7 tilt or C7 SVA (sagittal vertical axis). Cervical alignment and the posterior muscles are essential for maintaining the horizontal gaze which is closely related to neck tension (NT). PURPOSE This study aimed to determine whether KFC can affect cervical alignment and its potential effects on the posterior muscles and NT. DESIGN A prospective pilot study was carried out in preoperative (pre-op) and postoperative (post-op) phases. PATIENT SAMPLE This study included 22 consecutive patients with KFC and 12 control subjects in our department who agreed to participate from between August 1, 2018 and February 28, 2019 in our department. OUTCOME MEASURES Visual analog scale (VAS) and neck disability index (NDI) were used. The sagittal alignment parameters and cervical range of motion (ROM) were measured on radiographic images, and included the C0–C2 lordosis (C0–2L), C2–C7 lordosis (C2–7L), C2 SVA, C7 SVA, T1 slope, thoracic kyphosis, lumbar lordosis (LL), pelvic tilt, sacral slope, and knee flexion angle (KA). Surface electromyography-based flexion-relaxation ratio (FRR) and ultrasound-based shear wave elastography (SWE) were performed. METHODS The control group was matched for age, sex, and body mass index with the KFC group. Patients in the KFC group underwent arthroscopic surgery to correct knee alignment. Comparisons between pre-op and post-op phases were performed using paired sample t tests, comparisons between KFC and control groups were performed using independent samples t tests. The correlation analysis between the parameters was performed using Spearman analysis. Funding for this study was provided by the National Natural Science Foundation of China (60,000 USD), Beijing Municipal Administration of Hospitals Incubating Program (50,000 USD), and Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (20,000 USD). There were no conflicts of interest associated with this study. RESULTS The average follow-up time for this pilot study was 11.4±1.5 days. Pre-op, the KFC group had higher KA, T1S, C7 SVA, C2 SVA, C0–2L, SWE, VAS, and NDI compared with the control group, but all of these parameters were decreased significantly post-op. The LL, FRR of splenius capitis (FRRsc), and ROM of the KFC group pre-op were lower than the control group, and all of these were increased significantly post-op. There were no differences in pelvic tilt, sacral slope, C2–7 L, or TK between the KFC and control groups, or in FRR of splenius capitis (FRRutr) between pre-op and post-op phases. KA had strong correlations with LL (r=−0.83), which correlated well with C7 SVA (r=−0.75). C7 SVA correlated strongly with C2 SVA (r=0.79), which also correlated strongly with C0–2 L (r=0.76). C0–2 L correlated well with FRRsc (r=−0.65) and SWEsc (r=0.72), and both of them correlated well with VAS (r=−0.54, r=0.71) and NDI (r=−0.57, r=0.76). ROM correlated well with FRRsc (r=0.71), SWEsc (r=−0.74), VAS (r=−0.66), and NDI (r=−0.66). CONCLUSIONS KFC may cause spine inclination and craniocervical malalignment, leading to NT and ROM reduction. The results of this pilot study may be helpful in guiding further studies concerning KFC and NT.

OBJECT The aims of this study were 1) to establish the standard parameters of alignment and total and segmental range of motion (ROM) of the cervical spine in the asymptomatic population, and 2) to identify factors that influence cervical ROM and alignment. METHODS The authors measured 636 standard cervical lateral, flexion, and extension plain radiographs of 212 asymptomatic volunteers. The relationship between cervical alignment and total ROM was assessed with simple linear regression. Multivariate linear regression was used to determine the effect of the influential factors on cervical alignment and total and segmental ROM. RESULTS The mean value for C2–7 cervical alignment was 21.40° ± 12.15°, and the mean value for total ROM was 63.59° ± 15.37°. Sex was a significant factor in cervical alignment, total ROM, and segmental ROM for C2–3 and C5–6 (p < 0.05). Age had a significant negative association with both the total ROM and all of the segmental ROM measurements (p < 0.05). Cervical disc degeneration at the level of interest had a significant negative association with C4–5, C5–6, and C6–7 ROM (p < 0.05). CONCLUSIONS Cervical alignment in female subjects was 2.47° lower than that in male subjects. Total ROM was 3.86° greater in female than in male subjects and decreased 6.46° for each decade of aging. Segmental ROM decreased 1.28° for each decade of aging and 2.26° for each category increase in disc degeneration at the level of interest.

Background Multi-level cervical degeneration of the spine is a common clinical pathology that is often repaired by anterior cervical discectomy and fusion (ACDF). The aim of this study was to investigate the kinematics of the cervical spine after hybrid surgery compared with 2-level ACDF. Material/Methods Five freshly frozen, unembalmed whole human cadavers were used including 3 males and 2 females with a mean age of 51±8 years. After evaluating the intact spine for range of motion (ROM), sagittal alignment and instantaneous center of rotation (ICR), each cadaver underwent 4 consecutive surgeries: 2-level artificial disc replacement (ADR) from C4 to C6 (ADR surgery); 2-level ACDF from C4 to C6 (ACDF surgery); hybrid C4–5 ACDF and C5–6 ADR (ACDF+ADR surgery); and hybrid C4–5 ADR and C5–6 ACDF (ADR+ACDF surgery). The ROM and ICR of adjacent intact segments (C3–4; C6–7), and whole sagittal alignment were revaluated. Results Two-level ACDF resulted in increased ROM at C3–4 and C6–7 compared with intact spine. ROM was significantly different to intact spine using ACDF surgery at C3–C4 and C6–C7 and ROM was increased with ACDF+ADR surgery at C6–C7 (all P

Background Understanding the biomechanical effects of cervical disc degeneration (CDD) on the cervical spine is fundamental for understanding the mechanisms of spinal disorders and improving clinical treatment. While the biomechanical effects of CDD on segmental flexibility and the posterior facets have been reported, a clear understanding of the effect of the motion loading method on facet joint forces after CDD is still lacking. Therefore, the objective of this study was to determine the effect of the motion loading method on facet joint forces after CDD. Methods A three-dimensional nonlinear finite element (FE) model of the cervical spine (C3–C7) was developed and validated to represent normal conditions. This normal model was modified to create six degenerative models simulating mild, moderate, and severe grades of disc degeneration at C5–C6. While under a follower compressive preload (73.6 N), a 1-Nm moment was applied to all models to determine range of motion (ROM). A displacement load was applied to all degenerative models under the same follower load, making the C5–C6 degeneration segment motion same to the ROM of C5–C6 in normal model, and facet joint forces were computed. Results Compared with the normal model, ROM of the C5–C6 degenerative segments dramatically declined in all postures with increasing degenerative pathologies in the disc. The ROM in the adjacent normal segments of the degenerative segments also declined, with the exception of C4–C5 during extension. Under a 1-Nm moment load, there were not obvious changes in facet joint forces in the C5–C6 degenerative segment with increasing grades of degeneration, but facet joint forces in the adjacent normal segments did increase. Under a displacement load, the facet joint forces of the C5–C6 degenerative segment increased with increasing grades of degeneration. Conclusions Facet joint forces were positively correlated with the ROM of the degenerative segment, demonstrating that the motion loading method had a significant effect on facet joint forces after CDD. Loading conditions must be strictly controlled in future finite element analysis studies to improve the comparability between models built by different units.

To investigate the effect of osteoporosis and intervertebral disc degeneration on the endplate cartilage injury in rats.A total of 48 female Sprague Dawley rats (3 months) were randomly divided into Groups A, B, C and D with 12 rats in each group. Osteoporosis and intervertebral disc degeneration composite model, simple degeneration model and simple osteoporosis model were prepared in Groups A, B and C respectively. After modeling, four rats of each group at 12th, 18th and 24th week were sacrificed. Intervertebral height of cervical vertebra C6/C7 was measured. Micro-CT was used to image the endplate of cephalic and caudal cartilage at C6/C7 intervertebral disc. Abraded area rate of C6 caudal and C7 cephalic cartilage endplate was calculated, and then C6/C7 intervertebral disc was routinely embedded and sectioned, stained with safranin O to observe histological changes microscopically.At 12, 18 and 24 weeks, intervertebral disc height of C6/C7 were (0.58±0.09) mm, (0.53±0.04) mm and (0.04±0.06) mm in Group A rats, (0.55±0.05) mm, (0.52±0.07) mm and (0.07±0.05) mm in Group B rats. At 24th week, intervertebral disc height of Group A rats was significantly lower than that of Group B rats (P0.05); intervertebral disc height of Groups A and B rats at each time point were significantly lower than that of Groups C and D (P0.05). There was no significantly statistical difference of intervertebral disc height between Groups C and D (P0.05). At 12 and 18 weeks, the abraded rate of C6 caudal and C7 cephalic cartilage endplate in Group A rats were significantly higher than that in Groups B, C and D rats (P0.05); the abraded rate in Group B was significantly higher than that in Groups C and D (P0.05). Microscopic observation of CT showed that ventral defects in C6 caudal or C7 cephalic cartilage endplate in Groups A and B appeared after 12 weeks of modeling; obvious cracks were found in front of the C6 and C7 vertebral body, and cartilage defect shown the trend of "repairing" at 18 and 24 weeks after modeling.Intervertebral disc degeneration and osteoporosis can cause damage to the cartilage endplate. Co-existence of these two factors can induce more serious damage to the endplate, which has possitive correlation with intervertebral disc degeneration. Osteoporosis plays a certain role in intervertebral disc degeneration process, and accelerates the degeneration of intervertebral disc in a specific time window.

We located the instantaneous center of rotation (ICR) for the cervical spine at various ages and investigated age-related changes. We evaluated the impact of cervical disc degeneration on the ICR using a scoring system based on plain radiographs. Flexion, extension, and neutral lateral radiographs were obtained from 680 asymptomatic subjects (363 men, 317 women; ages 20–79 years) divided into six 10-year-age groups. The ICRs from C3/C4 to C6/C7 were determined from the radiographs using MIMICS software. A scoring system determined from lateral radiographs quantitatively assessed degeneration of cervical intervertebral discs. ICRs were compared among groups to analyze age-related changes and the relation between degenerative changes and ICR location. In asymptomatic subjects, the ICR was located approximately at the superior half of the lower vertebral body height and the posterior half of its width. The ICR at the C5/C6 level was located more anterior and higher in patients >50 years than in younger subgroups (P

Study design In a radiographic study, postoperative segmental alignment was compared between 2 cohorts of 20 consecutive patients operated with a Bryan Cervical Disc Prosthesis. In group 2, patients with severe preoperative kyphosis were excluded for disc replacement surgery and the surgical technique was slightly altered to avoid asymmetric overdrilling of the posterior part of the cranial endplate of the caudal vertebral body. Objective The aim was to investigate whether this change in patient inclusion criteria and modification of the surgical technique had an influence on postoperative segmental alignment and whether postoperative kyphosis is related to the mechanical properties and/or the design of the prosthesis. Summary of background data Several research groups reported segmental kyphosis after treatment of degenerative disc disease with the Bryan Cervical Disc Prosthesis. Methods On the basis of lateral radiographs, the disc insertion angle (as a postoperative estimate for the intraoperative angle of approach) and the angle of the functional spinal unit (FSU) and disc angle (both as measures for segmental alignment) were calculated. Results In group 1, 80% of the patients had a kyphotic FSU angle and 40% had a kyphotic disc angle preoperatively. At follow-up, 65% of the patients had a kyphotic FSU angle, whereas 55% had a kyphotic disc angle. In group 2, 40% of the patients had a kyphotic FSU angle and 5% had a kyphotic disc angle preoperatively. At follow-up, 40% of the patients had a kyphotic FSU angle, whereas 5% had a kyphotic disc angle. Due to the change in patient inclusion criteria, there was a significant difference in preoperative FSU angle between groups 1 and 2; however, no significant difference in preoperative disc angle was found. Owing to the change in surgical technique, the disc insertion angle was significantly different between both the groups. A difference in postoperative FSU angle, however, nonsignificant, between both the groups was observed. There was a significant difference in postoperative disc angle between both the groups; group 1 showed significantly more kyphosis of the shells, than group 2. Conclusions This study shows that segmental malalignment with the Bryan Disc can be reduced and is therefore not device related. Proper patient selection and a modified surgical technique can prevent this adverse outcome.

Degeneration of intervertebral discs and facet joints is one of the most frequently encountered spinal disorders. In order to describe and quantify degeneration and evaluate a possible relationship between degeneration and biomechanical parameters, e.g., the intervertebral range of motion and intradiscal pressure, a scoring system for degeneration is mandatory. However, few scoring systems for the assessment of degeneration of the cervical spine exist. Therefore, two separate objective scoring systems to qualitatively and quantitatively assess the degree of cervical intervertebral disc and facet joint degeneration were developed and validated. The scoring system for cervical disc degeneration consists of three variables which are individually scored on neutral lateral radiographs: "height loss" (0-4 points), "anterior osteophytes" (0-3 points) and "endplate sclerosis" (0-2 points). The scoring system for facet joint degeneration consists of four variables which are individually scored on neutral computed tomography scans: "hypertrophy" (0-2 points), "osteophytes" (0-1 point), "irregularity" on the articular surface (0-1 point) and "joint space narrowing" (0-1 point). Each variable contributes with varying importance to the overall degeneration score (max 9 points for the scoring system of cervical disc degeneration and max 5 points for facet joint degeneration). Degeneration of 20 discs and facet joints of 20 patients was blindly assessed by four raters: two neurosurgeons (one senior and one junior) and two radiologists (one senior and one junior), firstly based on first subjective impression and secondly using the scoring systems. Measurement errors and inter- and intra-rater agreement were determined. The measurement error of the scoring system for cervical disc degeneration was 11.1 versus 17.9% of the subjective impression results. This scoring system showed excellent intra-rater agreement (ICC = 0.86, 0.75-0.93) and excellent inter-rater agreement (ICC = 0.78, 0.64-0.88). Surgeons as well as radiologists and seniors as well as juniors obtained excellent inter- and intra-rater agreement. The measurement error of the scoring system for cervical facet joint degeneration was 20.1 versus 24.2% of the subjective impression results. This scoring system showed good intra-rater agreement (ICC = 0.71, 0.42-0.89) and fair inter-rater agreement (ICC = 0.49, 0.26-0.74). Both scoring systems fulfilled the criteria for recommendation proposed by Kettler and Wilke. Our scoring systems can be reliable and objective tools for assessing cervical disc and facet joint degeneration. Moreover, the scoring system of cervical disc degeneration was shown to be experience- and discipline-independent. ispartof: European Spine Journal vol:18 issue:3 pages:358-369 ispartof: location:Germany status: published

To analyze the percutaneous kyphoplasty (PKP) data statistically to predict the bone cement volume (CV).Retrospective analysis of 93 patients with 154 vertebrae of osteoporotic vertebra compressed fracture, who received PKP from January 2012 to December 2013 in Beijing Tian Tan Hospital, Capital Medical University. All procedures were bilateral and non-high-pressure polymethyl methacrylate injection. The balloon volume (BV), balloon peak pressure (Pmax), CV and the ratio of Pmax to BV (P/BV) were documented. The data was analyzed by correlation analysis and linear regression analysis to reveal the correlation between BV and CV.Seven vertebrae had bone cement leakage, no intraspinal leakage, no neuro-deficit. Visual analogue scale was 0-2 of all patients on 3 d postoperation. The data of 147 vertebrae without leakage: BV was 2.1-6.3 ml, Pmax was 130-359 psi, CV was 2.8-8.5 ml, and the ratio of Pmax to BV (P/BV) was 25-263 psi/ml. The data analysis showed there was no high correlation between BV and CV as one group (R0.75). However if divided the data into three groups by the value of P/BV, group A (P/BV100), group B (100≤P/BV200), group C (P/BV≥200), there was high correlation and linear relationship between BV and CV in each group (R0.75, P0.01). CV was 0.9-1.1 times of BV in group A; CV was 1.4-1.6 times of BV in group B; and CV was 2.0-2.2 times of BV in group C.CV is predictable by the BV and the ratio of Pmax to BV. It can reduce the rate of the leakage, and also can prevent the unsatisfactory results by insufficient bone cement volume.

To investigate the upper-extremity abduction, and lifting limitations and associated factors after anterior cervical decompression and fusion.A total of 117 patients who underwent anterior cervical decompression and fusion for cervical spondylosis were assessed retrospectively. Their upper-extremity abduction and lifting capacity after operation and manual muscle test grade for deltoid muscle strength and its sensory status were recorded. In addition, spinal cord function (Japanese Orthopaedic Association and Neck Disability Index scores) and C4-5 intervertebral height (radiographs) were assessed. Finally, high signal and ossification of posterior longitudinal ligament were observed by T2 magnetic resonance imaging and computed tomography, respectively.Seven individuals had a decrease in muscle strength, with 2 patients also exhibiting sensory defect. Six individuals had bilateral weakness of deltoid and biceps brachii and 1 of unilateral. After 8-16 months of follow-up, the abduction function and lift capacity were restored. The manual muscle test grade recovered to 5 and 4 degrees, respectively, in 6 and 1 patients. Two patients remained with sensory defect. The mean recovery time 19.7 days on average, and Japanese Orthopaedic Association scores significantly improved. Among the 117 patients, less than 2-level decompression showed upper-extremity function limitations in 1 of 67 (1.5%), whereas more than a 3-level decompression resulted in greater rate in 6 of 50 (12%), a significant difference (P0.05). No significant difference was obtained in C4-5 intervertebral heights, as well as for rates of C3-5 high signal area in magnetic resonance imaging.The rate of upper-extremity abduction and lifting limitation after anterior cervical decompression and fusion is low, indicating a good prognosis after active treatment.

Ossification of the posterior longitudinal ligament of the cervical spine (OPLL) is characterized by the replacement of ligament tissues with ectopic bone formation, and this result is strongly affected by genetic and local factors. Two single nucleotide polymorphisms (SNPs) of rs2273073 (T/G) and rs235768 (A/T) of bone morphogenetic protein 2 (BMP2) gene which are associated with OPLL have been reported in our previous report. In this study, we confirmed the connection in 18 case samples analysis of BMP2 gene in OPLL patients; additionally, it was also shown from the OPLL patients with ligament tissues that enchondral ossification and expression of BMP2 were significantly higher compared with the non-OPLL patients by histological examination, immunohistochemistry and Western blotting analysis. To investigate the underlying mechanism, we studied the effect of SNPs in cell model. The C3H10T1/2 cells with different BMP2 gene variants were constructed and then subjected to uniaxial cyclic stretch (0.5 Hz, 10% stretch). In the presence of mechanical stress, the expression of BMP2 protein in C3H10T1/2 cells transfected by BMP2 (rs2273073 (T/G)) and BMP2 (rs2273073 (T/G), rs235768 (A/T)) were significantly higher than the corresponding static groups (P