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Background Lateral lumbar interbody fusion (LLIF) is widely used in degenerative lumbar spine surgery. Previous studies of radiographic investigations after LLIF have assessed the anterior interbody fusion rate, the changes in the segmental lumbar lordosis, efficacy of indirect neural decompression, and remodeling of the ligamentum flavum hypertrophy and spinal canal dimension, and so on. The purpose of this study was to evaluate the radiological changes in the degenerated facet joints following LLIF with bilateral percutaneous pedicle screw (PPS) fixation, focusing on spontaneous fusion. Methods We retrospectively analyzed 31 patients (79 surgical levels) who underwent two- or three-level LLIF with PPS fixation without direct posterior decompression and bone grafting. We assessed the fusion rate and characteristics of the facet joints’ fusion process on the preoperative, immediately postoperative, 12-month, and at least 2-year computed tomography (CT) images. On average, the last follow-up CT was performed after 30.2 months. Multivariate logistic regression analysis investigated factors related to spontaneous facet joint fusion postoperatively. Results The fusion rates of the interbody and facet joints were 32.9% (26/79) and 19.0% (15/79) after 12-months and 79.7% (63/79) and 58.2% (46/79) at the final CT follow-up, respectively. Of the 46 cases with spontaneous facet fusion, three cases fused posteriorly only. Concomitant anterior interbody fusion was seen in 43/46 (93.5%) cases. Facet fusion started in a ring shape from the outermost joint edges, exposing subchondral bone without cartilage covering, and progressed to the central thicker cartilage regions. Multivariate analysis established that concomitant anterior interbody fusion (adjusted odds ratio [aOR]: 12.10, P = 0.0035) and preoperative facet joint osteoarthritis of Weishaupt Grade ≧ 1 (aOR: 4.770, P = 0.0068) were significant contributing factors to postoperative spontaneous facet fusion. Conclusions Our study shows that spontaneous facet fusion frequently occurs after LLIF and may be an indicator of the inherent structural stability of the LLIF construct.

BACKGROUND: The finite element method (FEM) is an efficient and powerful tool for studying human spine biomechanics. OBJECTIVE: In this study, a detailed asymmetric three-dimensional (3D) finite element (FE) model of the upper cervical spine was developed from the computed tomography (CT) scan data to analyze the effect of ligaments and facet joints on the stability of the upper cervical spine. METHODS: A 3D FE model was validated against data obtained from previously published works, which were performed in vitro and FE analysis of vertebrae under three types of loads, i.e. flexion/extension, axial rotation, and lateral bending. RESULTS: The results show that the range of motion of segment C1–C2 is more flexible than that of segment C2–C3. Moreover, the results from the FE model were used to compute stresses on the ligaments and facet joints of the upper cervical spine during physiological moments. CONCLUSION: The anterior longitudinal ligaments (ALL) and interspinous ligaments (ISL) are found to be the most active ligaments, and the maximum stress distribution is appear on the vertebra C3 superior facet surface under both extension and flexion moments.

Background: Lumbar facet joint is an important element of spinal “three-joint complex”. Whether there is a relationship between strange structure of facet joint and adolescent lumbar disc herniation (ALDH) is nonetheless controversial, and the current research is mainly centered on adults. Objective: To find out the normal lumbar facet joints between 13 and 18 years old to provide anatomical basis for early diagnosis and therapy of lumbar disc herniation. Methods: CT imaging information of 32 sufferers with lumbar disc herniation aged from 13 to 18 years old in Inner Mongolia have been collected as the ALDH group, and 62 wholesome subjects in the equal period had been chosen as the normal group. Uncooked records of continuous scanning lumbar tomography pix were imported into MIMICS 21.0 for evaluation and size in DICOM format. The parameters include facet joint height, facet joint width, et al. Results: 1. The left and right transverse angle of L5S1 segment in the ALDH group were (52.41 ± 9.2) ° and (55.99 ± 10.91) ° (P

Facet joints are the important articular pillars of the spine. Several pathologies can occur in and around the facet joint, including extra ossicles, traumatic dislocation, osteoarthritis, synovial cyst, axial spondyloarthritis, rheumatoid arthritis, calcium pyrophosphate deposition disease, septic arthritis, and malignant and benign neoplasms. Imaging is the mainstay to detect and characterize these diseases. In this review, we discuss the anatomy and function of facet joints, imaging techniques, and the imaging findings of several facet joint diseases. This information may be helpful to radiologists to make the correct diagnosis and optimize the management of patients with facet joint diseases.

Purpose Adjacent segment disease (ASD) requiring revision surgery is the most serious complication that can occur in patients undergoing posterior lumbar interbody fusion (PLIF) surgery. This study aimed to determine the risk factors for surgical ASD requiring revision surgery after PLIF with screw fixation surgery. We especially focused on paraspinal muscle, facet joint, and disc degeneration. Methods Among the patients who underwent PLIF with screw fixation due to degenerative spinal disease from January 2010 to December 2019, patients who underwent revision surgery for the development of ASD were enrolled. To evaluate the risk factors for surgical ASD, we selected a control group. Each patient in the control group was matched by age, sex, fusion level, number of fused segments, secondary MRI follow-up interval, and follow-up duration with a patient in the surgical ASD group. The radiographic and demographic data were compared between the surgical ASD and control groups. Results There were statistically significant differences between the two groups in radiological parameters of preoperative facet degeneration, facet effusion, facet angle, and fatty degeneration of the multifidus muscle. Multivariable logistic regression analysis revealed that preoperative facet effusion (odds ratio [OR] 6.48), preoperative facet angle (OR 1.24), and progression of fatty degeneration in the multifidus muscle (OR 1.07) were significant risk factors for surgical ASD. Conclusions Preexisting high-grade adjacent facet effusion, sagittally oriented facet joint angle, and progressive fatty degeneration of the multifidus muscle are associated with the development of surgical ASD after PLIF surgery.

The study aimed to develop a grading scale for evaluating degenerative changes in uncovertebral joints (UVJs) found on computed tomography (CT) scans, and assess the intra- and inter-rater reliability of this scale. The study included 50 subjects (average age 55.12 ± 13.76 years) referred for CT examinations due to cervical complaints. Three researchers developed a reading protocol using a semiquantitative grading scale of UVJ degenerative changes. CTs were read and reread several times to refine the protocol. Subsequently, the reader read and reread 20 CTs (C3-C7 bilateral, altogether 200 UVJs) 2 weeks apart in order to assess the intra-rater reliability. The second reader, after the training, read the same 20 CTs (yet, C4-C6 bilateral, altogether 120 UVJs) in order to assess the inter-rater reliability. The additional 30 CTs were evaluated to analyze the prevalence and associations between the studied parameters. The final grading scale included joint space narrowing, osteophyte, subchondral sclerosis, subchondral cyst, hypertrophy, cortical erosion, and vacuum phenomenon. The intra-rater agreement ranged from very good in joint space narrowing (k = 0.757), osteophyte grade (k = 0.748), subchondral cyst (k = 0.716), hypertrophy (k = 0.728), vacuum phenomenon (k = 0.712) to good (k = 0.544) in subchondral sclerosis, and fair in cortical erosion (k = 0.36). For the overall UVJ degeneration grade, the intra-rater agreement was very good (k = 0.616) and the inter-rater reliability was good (k = 0.468). 77.6% of the evaluated UVJs exhibited some degenerative changes. Our grading scale is the first to evaluate UVJs presenting good-very good intra-rater and inter-rater reliability which can be utilized in further clinical studies and assess degenerative changes in UVJs.

Purpose Surgical treatment of thoracolumbar A3-fractures usually comprises posterior fixation—in neutral position or distraction—potentially followed by subsequent anterior support. We hypothesized that additional posterior compression in circumferential stabilization may increase stability by locking the facets, and better restore the sagittal profile. Methods Burst fractures Type A3 were created in six fresh frozen cadaver spine segments (T12–L2). Testing was performed in a custom-made spinal loading simulator. Loads were applied as pure bending moments of ± 3.75 Nm in all six movement axes. We checked range of motion, neutral zone and Cobb’s angle over the injured/treated segment within the following conditions: Intact, fractured, instrumented in neutral alignment, instrumented in distraction, with cage left in posterior distraction, with cage with posterior compression. Results We found that both types of instrumentation with cage stabilized the segment compared to the fractured state in all motion planes. For flexion/extension and lateral bending, flexibility was decreased even compared to the intact state, however, not in axial rotation, being the most critical movement axis. Additional posterior compression in the presence of a cage significantly decreased flexibility in axial rotation, thus achieving stability comparable to the intact state even in this movement axis. In addition, posterior compression with cage significantly increased lordosis compared to the distracted state. Conclusion Among different surgical modifications tested, circumferential fixation with final posterior compression as the last step resulted in superior stability and improved sagittal alignment. Thus, posterior compression as the last step is recommended in these pathologies.

As the leading cause of disability worldwide, low back pain is commonly caused by biomechanical and catabolic disruptions to key structures of the spine, such as intervertebral discs and facet joints. To date, accurate, noninvasive detection of microdestruction within these tissues remains an elusive goal. Here, we report an

Background Compression-extension injury with unilateral facet joint fracture is one of the most devastating injuries of subaxial cervical spine. However, it is not yet clear which fixation technique represents the optimal choice in surgical management. This study aims to assess the construct stability at the operative level (C4/C5 cervical spine) following anterior cervical discectomy and fusion (ACDF) alone and combined fixation techniques (posterior-anterior fixations). Methods A previously validated three-dimensional C2-T1 finite element model were modified to simulate surgical procedures via the anterior-only approach (ACDF) and combined cervical approach [(transarticular screw, lateral mass screw, unilateral pedicle screw, bilateral pedicle screw) + ACDF, respectively] for treating compression-extension injury with unilateral facet joint fracture at C4/C5 level. Construct stability (range of rotation, axial compression displacement and anterior shear displacement) at the operative level was comparatively analyzed. Results In comparison with combined fixation techniques, a wider range of motion and a higher maximum von Mises stress was found in single ACDF. There was no obvious difference in range of motion among transarticular screw and other posterior fixations in the presence of anterior fixation. In addition, the screws inserted by transarticular screw technique had high stress concentration at the middle part of the screw but much less than 500 MPa under different conditions. Furthermore, the variability of von Mises stress in the transarticular screw fixation device was significantly lower than ACDF but no obvious difference compared with other posterior fixations. Conclusions Of the five fixation techniques, ACDF has proven poor stability and high structural stress. Compared with lateral and pedicle screw, transarticular screw technique was not worse biomechanically and less technically demanding to acquire in clinical practice. Therefore, our study suggested that combined fixation technique (transarticular screw + ACDF) would be a reasonable treatment option to acquire an immediate stabilization in the management of compression-extension injury with unilateral facet joint fracture. However, clinical aspects must also be regarded when choosing a reconstruction method for a specific patient.

Objectives To assess the effects of filgotinib on inflammatory and structural changes at various spinal locations, based on MRI measures in patients with active AS in the TORTUGA trial. Methods In the TORTUGA trial, patients with AS received filgotinib 200 mg (n = 58) or placebo (n = 58) once daily for 12 weeks. In this post hoc analysis, spine MRIs were evaluated using the Canada–Denmark (CANDEN) MRI scoring system to assess changes from baseline to week 12 in total spine and subscores for inflammation, fat, erosion and new bone formation (NBF) at various anatomical locations. Correlations were assessed between CANDEN inflammation and clinical outcomes and Spondyloarthritis Research Consortium of Canada (SPARCC) MRI scores and between baseline CANDEN NBF and baseline BASFI and BASMI scores. Results MRIs from 47 filgotinib- and 41 placebo-treated patients were evaluated. There were significantly larger reductions with filgotinib vs placebo in total spine inflammation score and most inflammation subscores, including posterolateral elements (costovertebral joints, transverse/spinous processes, soft tissues), facet joints and vertebral bodies. No significant differences were observed for corner or non-corner vertebral body inflammation subscores, spine fat lesion, bone erosion or NBF scores. In the filgotinib group, the change from baseline in the total inflammation score correlated positively with the SPARCC spine score. Baseline NBF scores correlated with baseline BASMI but not BASFI scores. Conclusions Compared with placebo, filgotinib treatment was associated with significant reductions in MRI measures of spinal inflammation, including in vertebral bodies, facet joints and posterolateral elements. Trial registration ClinicalTrials.gov (https://clinicaltrials.gov), NCT03117270.

The structure of spinal motion segments and spinal vasculature is complicated. Visualizing the three-dimensional (3D) structure of the spine may provide guidance for spine surgery. However, conventional imaging techniques fail to simultaneously obtain 3D images of soft and hard tissues, and achieving such coimaging states of the spine and its vascular networks remains a challenge. Synchrotron radiation micro-CT (SRμCT) provides a relatively effective and novel method of acquiring detailed 3D information. In this study, specimens of the thoracic spine were obtained from six mice. SRμCT was employed to acquire 3D images of the structure, and histologic staining was performed for comparisons with the SRμCT images. The whole spinal motion segments and the spinal vascular network were simultaneously explored at high resolution. The mean thickness of the cartilaginous end plates (CEPs) and the volume of the intervertebral discs (IVDs) were calculated. The surface of the CEPs and the facet joint cartilage (FJC) were presented as heat maps, which allowed for direct visualization of the thickness distribution. Regional division revealed heterogeneity among the ventral, central, and dorsal parts of the CEPs and between the superior and inferior parts of the facet processes. Moreover, the connections and spatial morphology of the spinal vascular network were visualized. Our study indicates that SRμCT imaging is an ideal method for high-resolution visualization and 3D morphometric analysis of the whole spinal motion segments and spinal vascular network.

Study design Retrospective longitudinal cohort study. Objective To investigate the impact of facet joint opening (FJO) on clinical outcomes after minimally invasive decompression surgery for lumbar spinal stenosis. Summary of background data Although FJOs have previously been identified as indicators of segmental spinal instability, their impact on clinical outcomes after decompression alone surgery has yet to be investigated. Methods This study included 296 patients from a single institution who underwent minimally invasive surgery for lumbar spinal stenosis and were followed up for ≥5 years. Our analysis focused on identifying FJOs at the index decompression level (d-FJO) and at multiple levels (m-FJO) (i.e., ≥3 levels within the lumbar segment) using preoperative computed tomography. Clinical outcomes including reoperations, improvement ratio for Japanese Orthopaedic Association (JOA) score, and achievement of a minimal clinically important difference (MCID) in visual analogue scale (VAS) scores for low back pain (LBP) or leg pain at 5 years were compared between patients with and without d-FJO or m-FJO. Results There were 129 (44%) and 62 (21%) patients with d-FJO (more common with lateral olisthesis) and m-FJO (less common with spondylolisthesis), respectively. Reoperations were more common in patients with d-FJO than in those without (16% vs. 5%). On Cox proportional hazards analysis, d-FJO was identified as a predictor for revision at the index decompression level [hazard ratio (HR) 4.04, p = 0.03], whereas m-FJO was a predictor for revision at other lumbar levels (HR 3.71, p = 0.03). Patients with m-FJO had slightly lower rates of achieving MCID in VAS scores for LBP (34% vs. 52%, p = 0.03) and poorer improvement ratio forJOA scores (74% vs. 80%, p = 0.03) than those without. Conclusion FJO at both index decompression level and multiple level were predictors of poor outcomes; patients with FJOs require careful surgical planning or special follow-up.Level of Evidence: 3.

Objectives To investigate the occurrence of facet joint ankylosis in the spine of patients with radiographic axial spondyloarthritis (r-axSpA) using low dose computed tomography (ldCT), and to examine the association between facet joint ankylosis and functional impairment. Methods A group of 126 patients with r-axSpA was selected from Incheon Saint Mary's axSpA observational cohort and whole spine ldCT data were examined. Facet joint (right and left, C2–S1) ankylosis was scored from 0–46 (total). The presence of facet joint ankylosis was assessed by two readers, each blinded to the patient data. The inter-reader reliability of facet joint ankylosis scoring was assessed using intraclass correlation coefficients (ICCs). The CT Syndesmophyte Score (CTSS) was assessed. Lumbar spinal mobility was evaluated using the modified Schober test. Functional impairment was measured using the Bath AS functional index (BASFI). Results The ICCs of ankylosed facet joint scores at the cervical, thoracic, lumbar and whole spine were 0.84, 0.88, 0.92 and 0.90, respectively. Facet joint ankylosis was most common in the thoracic spine. Scores for the whole spine correlated positively with the ASDAS, mSASSS and the syndesmophyte score. Multivariate analysis revealed that facet joint ankylosis was significantly associated with decreased lumbar motion. For both readers, the scores for the whole spine were independently associated with BASFI after adjusting for syndesmophyte score and disease activity. Conclusions Facet joint ankylosis in patients with r-axSpA was associated with functional impairment and spinal mobility. Facet joints should be incorporated into a structural damage assessment method.

Background We describe the minimally invasive, facet-sparing postero-lateral approach to the thoracic spine for a ventral dural repair in a patient with intracranial hypotension secondary to a spontaneous dural breach. Methods We performed a minimally invasive approach using a short paramedian posterior skin incision followed by a 10 × 10 mm targeted trans-laminar approach, to achieve a microsurgical repair of a symptomatic ventral dural defect causing severe disability. Conclusion The facet-sparing postero-lateral approach is safe and effective in the surgical management of thoracic dural tears, even in the most anterior ones, and avoids the traditional costotransversectomy.

In this study, we used a previously developed osteometry-based method to calculate available range of motion in presacral intervertebral joints in artiodactyls. We have quantified all three directions of intervertebral mobility: sagittal bending (SB), lateral bending (LB), and axial rotation (AR). This research covers 10 extant families of artiodactyls from 33 genera and 39 species. The cervical region in artiodactyls is the most mobile region of the presacral vertebral column in SB and LB. Mobility is unevenly distributed throughout the joints of the neck. The posterior neck joints (C4-C7) are significantly more mobile (on average by 2.5-3.5°) to anterior joints (C2-C4) and to the neck-thorax joint (C7-T1) in SB and LB. An increase in the relative length of the cervical region in artiodactyls is accompanied by an increase in the bending amplitudes (SB: Pearson r = 0.781; LB: r = 0.884). Animals with the most mobile necks (representative of Giraffidae and Camelidae) are 2-3 times more mobile in SB and LB compared to species with the least mobile necks. The thoracic region in artiodactyls, as in other mammals, is characterized by the greatest amplitudes of AR due to the tangential orientation of the zygapophyseal articular facets. The lowest AR values in the thoracic region are typical for the heaviest artiodactyls-Hippopotamidae. The highest AR values are typical for such agile runners as cervids, musk deer, pronghorn, as well as large and small antelopes. SB mobility in the posterior part of the thoracic region can be used by artiodactyls during galloping. The highest values of SB aROM in the posterior part of the thoracic region are typical for small animals with high SB mobility in the lumbar region. The lumbar region in mammals is adapted for efficient SB. Both the cumulative and average SB values in the lumbar region showed correspondence to the running type employed by an artiodactyl. The greatest SB amplitudes in the lumbar region are typical for small animals, which use saltatorial and saltatorial-cursorial running. An increase in body size also corresponds to a decrease in lumbar SB amplitudes. The lowest SB amplitudes are typical for species using the so-called mediportal running. Adaptation to endurance galloping in open landscapes is accompanied by a decrease in lumbar SB amplitudes in artiodactyls. The consistency of the approach used and the wide coverage of the studied species make it possible to significantly expand and generalize the knowledge of the biomechanics of the vertebral column in artiodactyls.

The ligamentum flavum (LF), the inter- and supraspinous ligament (ISLSSL) and the intertransverse ligament (ITL) are relevant spinal structures for segmental stability. The biomechanical effect of degeneration and aging on their biomechanical properties remains largely unknown.The aim of this study was to assess the material properties of the ITL, ISLSSL and LF and to correlate parameters of biomechanical function with LF-thickness, intervertebral disc (IVD) degeneration and age.Biomechanical cadaveric study.MRI- and CT-scans of 50 human lumbar segments (Th12-L5) were used to assess the ISL (acc. to Keorochana), the grade of IVD degeneration (acc. to Pfirrmann) and to quantify LF-thickness. The ITL, ISLSSL and LF were resected in the neutral position of the spinal segment with a specifically developed method to conserve initial strain. Ramp to failure testing was performed (0.5 mm/s) to record initial tension, slack length, stiffness and ultimate strength. The relationship between the biomechanical characteristics and age and radiological parameters were analyzed. There are no study-specific conflicts of interest and no external funding was received for this study.With aging, a significant reduction in initial tension (r=-0.5, p.01) and ultimate strength (r=-0.41, p.01) of the LF was observed, while the effect on LF-stiffness and the characteristics of the other ligaments was non-significant. IVD-degeneration was correlated with a significant reduction in stiffness (r=-0.47, p=.001; r=-0.36, p=.01) and ultimate strength (r=-0.3, p=.04; r=-0.36, p=.01) of the LF and ISLSSL respectively and a significant reduction in initial tension (r=-0.4, p.01) of the LF. For the ITL, no significant correlation was observed. Comparing Pfirrman 2 to 5, this reduction was 40% to 80% for stiffness 60% to 70% for ultimate strength and 88% for initial tension of the LF. ISLSSL-stiffness between Kerorochana grade A and D differed significantly (p=.03), while all other comparisons were non-significant (p.05). LF-thickness did not correlate with the biomechanical properties of the LF (p.05).Aging is primarily related to biomechanical changes to the LF. IVD-degeneration is related to a relevant reduction in stiffness and ultimate strength of the LF and ISLSSL, with a similar trend for the ITL. The ISL-specific Keorochana grading system provides only minimal biomechanical information and LF-thickness does not provide biomechanical information.Patient age and the degenerative state of the IVD can be used to evaluate the biomechanical characteristics of the dorsal spinal ligaments, which can be helpful in selecting the optimal surgical procedure (e.g. in decompression surgery) for a specific situation.

Background An incidental dural tear is a well-known complication during spine surgery. A rare consequence is a postoperative nerve root herniation. The purpose of this report is to describe a case of such a herniation with entrapment in the facet gap joint and to present the first MR images of this rare surgical complication. Case presentation We report a case of a patient who underwent lumbar decompression surgery and afterwards suffered a sudden intractable sciatica. Postoperative MRI showed a new facet joint gap effusion. During revision surgery an entrapped nerve root was found in the facet joint gap. In retrospective, the herniated nerve root is visible on postoperative MRI. Conclusion This case report highlights a rare complication during spine surgery. This finding is important as signs suggestive for nerve root herniation can easily be overlooked on MRI. Furthermore, this represents the first MRI documentation of this complication.

The vertebrate skeleton is composed of articulated bones. Most of the articulations are classically described using mechanical joints, except the intervertebral joint. The aim of this study was to identify a joint model with the same mechanical features as the cervical joints. On the neck vertebrae, six articular surfaces participate in the joint: the cranial part of the centrum and the facets of the two prezygapophyses of a vertebra articulate on the caudal part of the centrum and the two articular facets of the postzygapophyses of the previous vertebra. We used the intervertebral joints of the birds neck to identify the mechanical joint representing intervertebral linkage. This link was described in the literature as a joint allowing two or three rotations and no translation. These features correspond to the rotule à doigt (RAD) joint, a ball and socket joint with a pin. We compared the RAD joint to the postaxial intervertebral joints of the avian neck and found it a suitable model to determine the geometrical features involved in the joint mobility. The difference in the angles of virtual axes linking the geometrical center of the centrum to the zygapophysis surfaces determines the mean dorsoventral flexion of the joint. It also helps to limit longitudinal rotation. The orientation of the zygapophysis surfaces determines the range of motion in both dorsoventral and lateral flexion. The overall system prevents dislocation. The model was validated on 13 joints of a vulture neck and 11 joints of a swallow neck and on one joint (C6-C7) in each of three mammal species: the wolf (Canis lupus), mole (Talpa europaea), and human (Homo sapiens). The RAD mechanical joint was found in all vertebral articulations. This validation of the model on different species shows that the RAD intervertebral joint model makes it possible to extract the parameters that guide and limit the mobility of the cervical spine from the complex shape of the vertebrae and to compare them in interspecific studies.

Objective To directly compare robotic-versus fluoroscopy-guided percutaneous pedicle screw (PPS) placement in thoracolumbar spine trauma with a focus on clinically acceptable pedicle screw accuracy and facet joint violation (FJV). Methods A retrospective chart review assessed 37 trauma patients undergoing percutaneous thoracic and/or lumbar fixation. Postoperative computed tomography images were reviewed by authors blinded to surgical technique who assessed pedicle screw trajectory accuracy and FJV frequency. Results Seventeen patients underwent placement of 143 PPS with robotic assistance (robot group), compared with 20 patients receiving 149 PPS using fluoroscopy assistance (control group). Overall, the robot cohort demonstrated decreased FJV frequency of 2.8% versus 14.8% in controls (P = 0.0003). When further stratified by level of surgery (i.e., upper thoracic, lower thoracic, lumbar spine), the robot group had FJV frequencies of 0%, 3.2%, and 3.7%, respectively, compared with 17.7% (P = 0.0209), 14.3% (P = 0.0455), and 11.9% (P = 0.2340) in controls. The robot group had 84.6% clinically acceptable screw trajectories compared with 81.9% in controls (P = 0.6388). Within the upper thoracic, lower thoracic, and lumbar regions, the robot group had acceptable screw trajectories of 66.7%, 87.1%, and 90.7%, respectively, compared with 58.8% (P = 0.6261), 91.1% (P = 0.5655), and 97.6% (P = 0.2263) in controls. Conclusions There was no significant difference in clinically acceptable screw trajectory accuracy between robotic versus fluoroscopy-guided PPS placement. However, the robot cohort demonstrated a statistically significantly decreased FJV overall and specifically within the thoracic spine region. Use of robotic technology may improve radiographic outcomes for a subset of patients or spine surgeries.

One-in-five people suffer from chronic low back pain (LBP). The incidence of this disease has doubled since 1950s and affects not only the elderly, but also the young population. However, the mechanism of LBP is still unknown. A possible location where the LBP may develop is the facet joint and it has been revealed that the intervertebral disc (IVD) nucleotomy may be a trigger for LBP. The aim of the present study was to investigate the influence of IVD nucleotomy on the load sharing in the spinal facet joint under the loading scenarios of different postures. Finite element (FE) models of the intact and nucleotomised L4 – L5 spinal segments were generated from the clinical CT images. Seven human postures, including upright, 5° extension, 5° flexion, ± 6° lateral bending and ± 2° axial rotation, were simulated. The resultant forces in the fact joint were compared between the intact and the nucleotomised cases. It was revealed that the IVD nucleotomy significantly increased the forces in the facet joints under the loading scenarios of upright, 5° extension and 5° flexion. The IVD nucleotomy increased the force in the ipsilateral facet joint but decreased the force on the contralateral side under the loading scenarios of ± 2° axial rotation. However, the IVD nucleotomy made little influence on the resultant forces in both facet joints in the postures of ± 6° lateral bending. In conclusion, the IVD nucleotomy can cause an increase in the overall force in the facet joint, and thus may serve as a possible explanation for the LBP and a main contributing factor for the pain complaints.

Objective Pathology of the facet and sacroiliac (SI) joints contributes to 15% to 45% and 10% to 27% of lower back pain cases, respectively. Although tissue engineering may offer novel treatment options to patients suffering from cartilage degeneration in these joints, the tribological characteristics of the facet and SI joints have not been studied in either the human or relevant large animal models, which hinders the development of joint-specific cartilage implants. Design Cartilage was isolated from the knee, cervical facet, thoracic facet, lumbar facet, and SI joints of 6 skeletally mature Yucatan minipigs ( Sus scrofa). Tribological characteristics were assessed via coefficient of friction testing, interferometry, and immunohistochemistry for lubricin organization. Results Compared with the knee, the coefficient of friction was higher by 43% in the cervical facet, 77% in the thoracic facet, 37% in the lumbar facet, and 28% in the SI joint. Likewise, topographical features of the facet and SI joints varied significantly, ranging from a 114% to 384% increase and a 48% to 107% increase in global and local surface roughness measures, respectively, compared with the knee. Additionally, the amount of lubricin in the SI joint was substantially greater than in the knee. Statistical correlations among the various tribological parameters revealed that there was a significant correlation between local roughness and coefficient of friction, but not global roughness or the presence of lubricin. Conclusion These location-specific tribological characteristics of the articular cartilages of the spine will need to be taken into consideration during the development of physiologically relevant, functional, and durable tissue-engineered replacements for these joints.

Objective To explore the kinematic biomechanical changes and symmetry in the left and right sides of the facet joints of lumbar spine segments under different functional loads. Methods Participants (n = 10) performing standing flexion and extension movements were scanned using computed tomography (CT) and dual fluoroscopy imagine system. Instantaneous images of the L3–S1 vertebrae were captured, and by matching a three‐dimensional CT model with contours from dual fluoroscopy images, in vivo facet joint movements were reproduced and analyzed. Translations and rotations of lumbar vertebral (L3 and L4) facet joints of data were compared for different loads (0, 5, 10 kg). The participants performed flexion and extension movements in different weight‐bearing states, the translations and angles changes were calculated respectively. Results From standing to extension, there were no statistical differences in rotation angles for the facet joint processes of different vertebral segment levels under different weight loads (P > 0.05). Mediolateral axis and cranio‐caudal translations under different weight loads were not statistically different for vertebral segment levels (P > 0.05). Anteroposterior translations for L3 (1.4 ± 0.1 mm) were greater than those for L4 (1.0 ± 0.1 mm) under the different load conditions (P = 0.04). Bilaterally, mediolateral, anteroposterior, and cranio‐caudal translations of the facet joints under different weights (0, 10 kg) for each segment level (L3 and L4) were symmetric (P > 0.05). From flexion to standing, there were no statistical differences in rotation angles for different weights (0, 5, 10 kg) for each level (L3 and L4) (P > 0.05). There were no statistical differences between mediolateral, anteroposterior, and cranio‐caudal translations at each segment level (L3 and L4) under different loads (P > 0.05). Under the condition of no weight (0 kg), L3 mediolateral translations on the left side (1.7 ± 1.6 mm) were significantly greater (P = 0.03) than those on the right side (1.6 ± 1.6 mm). Left side (1.0 ± 0.7 mm) L4 mediolateral translations were significantly smaller (P = 0.03) than those on the right side (1.1 ± 0.7 mm). There were no statistical differences between different weights for either anteroposterior and cranio‐caudal translations (P > 0.05). There were no statistical differences for mediolateral, anteroposterior, and cranio‐caudal translations for 10 kg (P > 0.05). Conclusion Lumbar spine facet joint kinematics did not change significantly with increased loads. Anteroposterior translations for L3 were greater than those for L4 of the vertebral segments are related to the coronal facet joint surface. Changes in facet surface symmetry indicates that the biomechanical pattern between facet joints may change., At present, many studies on facet joint movement patterns are based on the analysis of morphological data collected by imaging methods such as computed tomography (CT) and magnetic resonance imaging (MRI), cadaver specimens, and animal models. But these methods do not reflect true and accurate physiological data under weight‐bearing conditions. Using computed tomography (CT) and dual fluoroscopy imagine system (DFIS), in vivo facet joint movements were exactly reproduced and analyzed. The data collected are of great significance for studying the mechanisms of the lower lumbar spine to delay disease progression, exploration of pathogenesis of the lumbar degenerative disease, and guidance of surgical operation.

Introduction Radiofrequency ablation (RFA) is a demonstrated safe and effective treatment for chronic low back pain. RFA delivers high density electrical current near lumbar medial branch nerve. The success of RFA is contingent upon creating a lesion that overlaps the sensory nerve supplying the affected facet joint(s). Both bipolar-RFA and V-shaped active tip cannulas increase lesion size in experimental models. We describe successful application of concomitant bipolar and V-shaped lesions in a single patient with chronic low back pain caused by lumbar spondylosis. Case presentation An 81-year-old male with atrial fibrillation on chronic warfarin anticoagulation was previously treated with conventional monopolar lumbar facet RFA resulting in a 75% decrement in pain intensity exceeding eight months. Nine months after the procedure, his pain returned with similar pretreatment character and was unresponsive to additional physical therapy and acetaminophen. We elected to use a V-shaped cannula to maximize lesion diameter and lengthen intervals between anticoagulant abstinence to minimize the risk. Intraoperatively, a grounding-pad malfunction compelled us to convert to bipolar-RFA by placing a second adjacent V-shaped cannula, eliminating grounding-pad requirement. Bilateral bipolar medial branch RFA of L3–L4, L4–L5, L5–S1 nerves was performed between these two cannulas without further incident. The patient had sustained analgesia that lasted over twelve months resultant from treatment. Conclusions We herein describe a technique of combined bipolar-RFA utilizing proximally adjacent V-shaped cannulas. Both bipolar and V-shaped cannulas create larger lesions in experiments. While both techniques purport theoretical advantages, the clinical superiority of a combined technique warrants continued clinical investigation.

Study design Analytical biomechanical study using a finite-element (FE) model. Objective We investigated the effects of paraspinal muscle volume to the physiological loading on the lower lumbar vertebral column using a FE model. Summary of background data The FE model analysis can measure the physiological load on the lumbar vertebral column. Which changes as the surrounding environment changes. In this study, our FE model consisted of the sacrum, lumbar spine (L3-L5), intervertebral discs, facet joints, and paraspinal muscles. Methods Three-dimensional FE models of healthy lumbar spinal units were reconstructed. The physiological loads exerted on the lumbar vertebra column were evaluated by applying different paraspinal muscle volumes (without muscles, 50%, 80%, and 100% of healthy muscle volume). Results As the paraspinal muscle volume increased, the loads exerted on the vertebral column decreased. The mean load on the intervertebral disc was 1.42 ± 0.75 MPa in the model without muscle, 1.393 ± 0.73 MPa in the 50% muscle volume model, 1.367 ± 0.71 MPa in the 80% muscle volume model, and 1.362 ± 0.71 MPa in the 100% muscle volume model. The mean loads exerted on the posterior column of lumbar spine were 11.79 ± 4.70 MPa in the model without muscles, 11.57 ± 4.57 MPa in the model with 50% muscle volume, and 11.13 ± 4.51 MPa in the model with 80% muscle volume, and 10.92 ± 4.33 MPa in the model with 100% muscle volume. The mean pressure on the vertebral body in the model without paraspinal muscle, and with 50%, 80%, and 100% paraspinal muscle volume were 14.02 ± 2.82, 13.82 ± 2.62, 13.65 ± 2.61, and 13.59 ± 2.51 MPa, respectively. Conclusion Using FEM, we observed that the paraspinal muscle volume decreases pressure exerted on the lumbar vertebral column. Based on these results, we believe that exercising to increase paraspinal muscle volume would be helpful for spinal pain management and preventing lumbar spine degeneration.Level of Evidence: N/A.

BackgroundLumbar interbody fusion is a standard technique for treating degenerative lumbar disorders involving instability. Due to its invasiveness, a minimally invasive technique, extraforaminal lumbar interbody fusion (ELIF), was introduced. On surgically approaching posterolaterally, the posterior muscles and spinal canal are barely invaded. Despite its theoretical advantage, ELIF is technically demanding and has not been popularised. Therefore, we developed a microendoscopy-assisted ELIF (mELIF) technique which was designed to be safe and less invasive. Here, we aimed to report on the surgical technique and clinical results.MethodsUsing a posterolateral approach similar to that of lateral disc herniation surgery, a tubular retractor, 16 or 18 mm in diameter, was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was cleaned. A cage and local bone graft were inserted into the disc space. All disc-related procedures were performed under microendoscopy. The spinal canal was not invaded. Bilateral percutaneous screw-rod constructs were inserted and fixed.ResultsFifty-five patients underwent the procedure. The Oswestry Disability Index and visual analogue scale scores greatly improved. Over 90% of the patients obtained excellent or good results based on Macnab’s criteria. There were neither major adverse clinical effects nor the need for additional surgery.ConclusionsmELIF is minimally invasive because the spinal canal and posterior muscles are barely invaded. It produces good clinical results with fewer complications. This technique can be applied in most single-level spondylodesis cases, including those involving L5/S1 disorders.

Background Facet tropism (FT) refers to the difference in the orientation of facet joints with respect to each other in the sagittal plane. FT leads to unequal biomechanical forces on facet joint and intervertebral disc during rotation and other physiologic movements. Most of the studies have reported the incidence of FT in the lumbar spine to vary between 40% and 70%, with L4-5 level being the most commonly afflicted level. The objective of this study was to find the association between FT and various lumbar and cervical degenerative disorders. Methods A systematic search of PubMed was performed with the keywords “facet tropism” and “facet asymmetry.” Data for meta-analysis were extracted from the studies to obtain pooled impact of FT on lumbar disc herniation (LDH) and lumbar degenerative spondylolisthesis (LDS). Results Eighty-two articles were included in the systematic review and 18 studies had the required data to be included in the meta-analysis. The pooled standard mean difference between FT angles in patients with or without LDH was 0.31 with (P = 0.04). The pooled odds ratio for FT in patients with LDH was 3.27 with (P = 0.02). Subgroup analysis showed that there is no significant difference in the L3/4, L4/5, and L5S1 subgroups. The pooled standard mean difference between FT angles in patients with or without LDS was 0.54 (P = 0.009). Conclusions FT is significantly associated with LDH and LDS along with various other lumbar and cervical degenerative diseases.

Objective To evaluate the effect of inserting epidemiological information into lumbar spine imaging reports on subsequent nonsurgical and surgical procedures involving the thoracolumbosacral spine and sacroiliac joints. Design Analysis of secondary outcomes from the Lumbar Imaging with Reporting of Epidemiology (LIRE) pragmatic stepped-wedge randomized trial. Setting Primary care clinics within four integrated health care systems in the United States. Subjects 238,886 patients ≥18 years of age who received lumbar diagnostic imaging between 2013 and 2016. Methods Clinics were randomized to receive text containing age- and modality-specific epidemiological benchmarks indicating the prevalence of common spine imaging findings in people without low back pain, inserted into lumbar spine imaging reports (the “LIRE intervention”). The study outcomes were receiving 1) any nonsurgical lumbosacral or sacroiliac spine procedure (lumbosacral epidural steroid injection, facet joint injection, or facet joint radiofrequency ablation; or sacroiliac joint injection) or 2) any surgical procedure involving the lumbar, sacral, or thoracic spine (decompression surgery or spinal fusion or other spine surgery). Results The LIRE intervention was not significantly associated with subsequent utilization of nonsurgical lumbosacral or sacroiliac spine procedures (odds ratio [OR] = 1.01, 95% confidence interval [CI] 0.93–1.09; P = 0.79) or any surgical procedure (OR = 0.99, 95 CI 0.91–1.07; P = 0.74) involving the lumbar, sacral, or thoracic spine. The intervention was also not significantly associated with any individual spine procedure. Conclusions Inserting epidemiological text into spine imaging reports had no effect on nonsurgical or surgical procedure utilization among patients receiving lumbar diagnostic imaging.

Background The treatment of unilateral CFD in patients without neurologic deficits remains controversial, especially in the choice of the best surgical approach. Our objective is to determine the way spine surgeons from Latin America manage this condition. Methods A survey regarding management and surgical strategies was conducted by the AO Spine Latin American Trauma Study Group considering the treatment of unilateral CFD. Results All AO Spine Latin American Trauma Study Group members were sent a link to the survey, among whom 285 replied, with 197 respondents answering all the questions. Nonsurgical management was considered by 25% of the surgeons. The majority stated that magnetic resonance imaging is necessary (65%) to treat this type of patient. A posterior approach was preferred by 44%, an anterior approach by 29%, and a combined approach by 25%, while 2.2% did not answer. Traction was not used by the majority of respondents (62%). In the setting of an anterior disk herniation, the majority of surgeons preferred to employ an anterior (45%) or combined (44%) approach versus an isolated posterior approach (only 0.5%). Comparing early versus late cervical trauma, fewer surgeons adopted an isolated anterior approach with the latter (29% vs. 15%). Conclusions Wide variations exist in the management of unilateral CFD by Latin American surgeons, with early injuries generally treated using either an anterior or posterior approach and treated early but after an MRI, while a combined approach is used more commonly with late injuries. Either an anterior or combined approach is used when disk herniation is present.

Objective This report analyzes the significance of osteophytes in the overall pathologic scheme in patients with single-level or multilevel cervical spinal degeneration. Methods From January 2010 to December 2018, 249 patients with cervical spondylosis were surgically treated. The alterations in ventral compression caused by disc bulges, osteophytes, and ligament buckling (disc-osteophye-ligament [DOL] complex) at single or multiple levels were evaluated after surgical treatment that involved only spinal fixation and did not involve any kind of bone or soft tissue decompression. Delayed (≥1 year after surgery) postoperative imaging was available in 165 patients and these patients formed the study group. Forty-five patients underwent facet distraction arthrodesis (group A), 106 patients underwent only-fixation involving transarticular screw insertion (group B), and 14 patients underwent hybrid fixation that involved both intra-articular spacers and transarticular fixation techniques (group C) as the surgical treatment. Results The size of the DOL complex at the segments that underwent fixation was reduced in 136 patients. The size of the DOL complex or its related dural or neural compression did not increase in any of the cases evaluated. Reduction in the size of DOL was more pronounced in patients in group A in both immediate postoperative and delayed images and in patients in group C at spinal levels at which facet distraction was performed using facet distraction spacers. Conclusions Spinal stabilization reduces the size of osteophytes. Facet distraction spacers are more effective in reduction of the size of DOL in both immediate and delayed postoperative periods.

Objective By observing the 3D anatomy of normal adult cervical facet joints, using the picture archiving and communication system to measure its 3D parameters and discussing its clinical significance, the aim of this study was to provide a reliable morphological basis for the design and manufacture of lower cervical facet joint interface distractors. Methods We selected 200 patients who underwent cervical spine 3D spiral computed tomography (CT) examination in the imaging department of our hospital from September 2019 to May 2020 and whose spiral CT images showed no cervical spinal canal stenosis, cervical disc herniation, obvious bone hyperplasia, or infection. The anterior and posterior diameters of the facet joints on both sides of the cervical spine, the space between the joints, and the left and right diameters were measured on the sagittal, cross-sectional and coronal planes after reconstruction with 3D spiral CT. Results The anterior and posterior diameters of the facet joints of the cervical spine, the space between the joints, and the left and right diameters all increased from top to bottom along the cervical spine. The 3D parameters of the C2-3~C6-7 segments were significantly different between the male and female groups. Conclusion The anteroposterior diameter, joint space interval, and left and right diameter of cervical facet joints are different in each segment and between the sexes. The lower cervical facet joint interface fusion device designed according to the measurement results can fully meet the needs of most patients.

Tumor necrosis factor receptor-associated factor 6 (TRAF6), a regulator of NF-κB signaling, has been discovered recently to be probably related to osteoarthritis, while the function of TRAF6 in lumbar facet joint osteoarthritis(FJOA)still remains unknown. The aim of this study was to probe the specific function of TRAF6 in chondrocytes and its connection with the pathophysiology of FJOA. We found upregulation of TRAF6 in FJOA cartilage by western blot analysis. In vitro, we stimulated immortalized human chondrocytes by LPS to establish the cells apoptosis model. Western blot analysis demonstrated that levels of TRAF6 and cleaved caspase-3/8 in the chondrocyte injury model increased significantly. Knockdown of TRAF6 suppressed the expression of matrix metallopeptidase-13 (MMP-13) and interleukin-6 (IL-6) induced by LPS, and alleviated cell apoptosis. Meanwhile, western blot and immunofluorescent staining demonstrated that IκBα degradation and p65 nuclear transportation were also inhibited, revealing that knockdown of TRAF6 suppressed activation of the NF-κB pathway in LPS-induced chondrocytes apoptosis model. Collectively, our findings suggest that TRAF6 plays a crucial role in FJOA development by regulating NF-κB signaling pathway. Knockdown of TRAF6 may supply a potential therapeutic strategy for FJOA.

OBJECTIVEFacet cysts may represent a sign of intrinsic facet disease and instability, increasing the importance of less-invasive approaches that limit tissue dissection and improve visualization. The authors developed an intraoperative cyst-dyeing technique, involving the injection of indigo carmine from the facet joint into the cyst, as an adjunct during decompression. This study aimed to evaluate the clinical outcomes and perioperative complication rates of microendoscopic spinal decompression for lumbar spinal stenosis (LSS) and lumbar foraminal stenosis (LFS), caused by facet cysts and to elucidate the efficacy of the cyst-dyeing method in microendoscopic surgery for facet cysts.METHODSForty-eight consecutive patients who underwent surgical treatment with microendoscopic decompression for symptomatic LSS or LFS caused by facet cysts from 2011 to 2018 were reviewed. These patients were divided into two groups: a group that did not receive dye (N), with the patients undergoing surgery from April 2011 to May 2015; and a group that received dye (D), with patients undergoing surgery from June 2015 to March 2018. The authors evaluated the operative time, blood loss, perioperative complications, visual analog scale scores for low-back and leg pain, and Japanese Orthopaedic Association scores. Surgical outcome was evaluated 2 years postoperatively and was compared between groups D and N.RESULTSThe clinical outcomes were generally excellent or good. Group N consisted of 36 patients and group D of 12 patients. Comparing the clinical results, it was found that the cyst-dyeing method reduced the perioperative complication rate, including reduction in dural tears to 0%, and shortened the average operative time by approximately 40 minutes.CONCLUSIONSIn this study, the authors demonstrated that the clinical outcomes of microendoscopic spinal decompression in patients with LSS or LFS caused by facet-joint cysts are generally favorable. Additionally, the adjunctive cyst-dyeing method effectively delineated the cystic and dural boundaries, facilitating safer and more effective cyst separation and neural decompression. Microendoscopic surgery combined with this novel facet cyst-dyeing method is a safe and effective minimally invasive technique for facet-joint cysts.

Objective To develop a thermochromic tissue-mimicking phantom (TTMP) with an embedded 3D-printed bone mimic of the lumbar spine to evaluate MRgFUS ablation of the facet joint and medial branch nerve. Materials and methods Multiple 3D-printed materials were selected and characterized by measurements of speed of sound and linear acoustic attenuation coefficient using a through-transmission technique. A 3D model of the lumbar spine was segmented from a de-identified CT scan, and 3D printed. The 3D-printed spine was embedded within a TTMP with thermochromic ink color change setpoint at 60 °C. Multiple high energy sonications were targeted to the facet joints and medial branch nerve anatomical location using an ExAblate MRgFUS system connected to a 3T MR scanner. The phantom was dissected to assess sonication targets and the surrounding structures for color change as compared to the expected region of ablation on MR-thermometry. Results The measured sound attenuation coefficient and speed of sound of gypsum was 240 Np/m-MHz and 2471 m/s, which is the closest to published values for cortical bone. Following sonication, dissection of the TTMP revealed good concordance between the regions of color change within the phantom and expected areas of ablation on MR-thermometry. No heat deposition was observed in critical areas, including the spinal canal and nerve roots from either color change or MRI. Conclusion Ablated regions in the TTMP correlated well with expected ablations based on MR-thermometry. These findings demonstrate the utility of an anatomic spine phantom in evaluating MRgFUS sonication for facet joint and medial branch nerve ablations.

Background The long-term outcome of facet joint replacement (FJR) still is to be proven. Methods We present a prospective case series of 26 (male-to-female ratio of 1:1; mean age: 61 years) patients undergoing FJR with a follow-up of at least 1 year (range: 12–112; mean: 67 months). Visual analog scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), and the 12-Item Short Form Health Survey (SF-12) were applied pre- and postoperatively (after 3, 6, and 12 months) as well as at the last follow-up (N = 24). Using X-rays of the lumbar spine (N = 20), the range of motion (ROM) and disk height in the indicator and adjacent levels were assessed. Results FJR was performed at L3/L4 (N = 7), L4/L5 (N = 17), and L5/S1 (N = 2). Mean VAS (mm) for back pain decreased from 71 to 18, mean VAS for right leg pain from 61 to 7, and from 51 to 3 for the left leg. Mean ODI dropped from 51 to 22% (for all p Conclusions In selected cases, long-term results of FJR show good outcome concerning pain, quality of life, preservation of lumbar spine motion, and protection of adjacent level.

Background and Objective Learning a new technique in neurosurgery is a big challenge especially for trainees. In recent years, simulations and simulators got into the focus as a teaching tool. Our objective is to propose a simulator for placement of cortical bone trajectory (CBT) screws to improve results and reduce complications.Methods We have created a platform consisting of a sawbone navigated with a 3D fluoroscope to familiarize our trainees and consultants with CBT technique and later implement it in our department. Objective Structured Assessment of Technical Skills (OSATS) and Physician Performance Diagnostic Inventory Scale (PPDI) were obtained before and after the use of the simulator by the five participants in the study. Patients who were operated on after the implementation of the technique were retrospectively reviewed.Results During the simulation, there were 4 cases of pedicle breach out of 24 screws inserted (16.6%). After having completed simulation, participants demonstrated an improvement in OSATS and PPDI (p = 0.039 and 0.042, respectively). Analyzing the answers to the different items of the tests, participants mainly improved in the knowledge (p = 0.038), the performance (p = 0.041), and understanding of the procedure (p = 0.034). In our retrospective series, eight patients with L4–L5 instability were operated on using CBT, improving their Oswestry Disability Index (ODI) score (preoperative ODI 58.5 [SD 16.7] vs. postoperative ODI 31 [SD 13.4]; p = 0.028). One intraoperative complication due to a dural tear was observed. In the follow-up, we found a case of pseudoarthrosis and a facet joint violation, but no other complications related to misplacement, pedicle fracture, or hardware failure.Conclusion The simulation we have created is useful for the implementation of CBT. In our study, consultants and trainees have valued very positively the learning obtained using the system. Moreover, simulation facilitated the learning of the technique and the understanding of surgical anatomy. We hope that simulation helps reducing complications in the future.

BACKGROUND CONTEXT A few studies have already investigated the influences of functional structures of the cervical spine on its biomechanical behavior. In most studies, this has been done by measuring the range of motion. However, this parameter lacks of qualitative information about the overall kinematic behavior, such as coupled motions or translations. These data are essential for future development of cervical implants and surgical techniques. PURPOSE An investigation of the influences of cervical structures on the kinematic behavior of the cervical spine under in vivo conditions is almost impossible due to ethical reasons. Therefore, an in vitro study was conducted which allowed the analysis of these influences using three-dimensional helical axes. STUDY DESIGN/SETTING An in vitro test applying pure moments on mono-segmental specimens was designed in order to investigate the influences of a series of structures on the kinematic behavior of the cervical spine using three-dimensional helical axes. METHODS In this study we extracted motion segments C2–C3, C4–C5, and C6–C7 from 6 human cadaveric specimens with an average age of 48 years. The specimens were carefully selected using X-ray images. For the in vitro experiments, seven states were defined. The first state represented the intact state of each specimen. The remaining six states correspond with the subsequent resection of the following structures in the given order: interspinous ligament, ligamentum flavum, facet capsule, vertebral arch, posterior longitudinal ligament, and anterior longitudinal ligament. Each state was tested using a well-established spine tester. Each test sequence included 3.5 quasi-static motion cycles in all three bending directions using pure moments of 1 Nm. All motions were recorded using a motion tracking device and six reflective markers which were attached to the specimens. The recordings were then used to calculate the 3D helical axes, which were matched with the X-ray images. Due to the small number of specimens, qualitative results, such as the helical axes, were analyzed using descriptive statistics. RESULTS In general, the overall range of motion was increased in all loading directions due to the resection steps. The least change in the kinematic behavior of the cervical spine was observed during flexion/extension. For lateral bending and axial rotation the greatest change in the pattern of the helical axes was observed during the resection of the vertebral arch. For some specimens, however, typical patterns regarding the orientation of the helical axes remained until the last state. For lateral bending, it could be observed that the deviation in the axes’ orientation increased whereas for axial rotation it decreased. CONCLUSION Resection of the cervical ligaments are much less crucial than the removal of guiding structures such as the facet joint. Furthermore, coupled motions not only result from the orientations of the articular surfaces of the facet joints but also from the overall shape of the cervical vertebrae including the uncinate processes. CLINICAL SIGNIFICANCE It is well-known that coupled motions play a substantial role in cervical kinematics. However, the influences of cervical structures on the overall kinematic behavior of the cervical spine are not yet fully understood. Knowledge of these influences could help to reduce or even prevent iatrogenic degeneration after surgical intervention. Furthermore, the data provided by this study can be helpful for future developments of cervical implants as well as finite element models for more advanced numerical investigations.

Study design Clinical case series. Objective The aim of this study was to propose a novel posterior ligament-bone injury classification and severity (PLICS) score system that can be used to reflect the severity of subaxial cervical fracture dislocations (SCFDs) and predict the failure of anterior-only surgery; and to measure the intraobserver and interobserver reliability of this system. Summary of background data The approach selection for SCFDs is controversial. Although the anterior approach is familiar for most surgeons, postoperative hardware failure and/or delayed cervical deformity is a nonnegligible complication. Methods Ten patients were randomly selected for intraobserver reliability evaluation on two separate occasions, one month apart. Another 30 patients were randomly selected, and the interobserver reliability was measured by comparing results of each case between each reviewer and averaging. To analyze the difference in the PLICS score, 354 patients fulfilled the follow-up were divided into stable and unstable groups according to whether radiologically stable was observed during follow-up. Results For the intraobserver reliability, the mean intraclass correlation coefficient for the 10 reviewers was 0.931. For the interobserver reliability, the mean interobserver correlation coefficient for the three elements was 0.863. Among 16 patients with PLICS score ≥7, two patients in the stable group manifested with severe injury of the posterior ligamentous complex (PLC); extremely unstable lateral mass fractures with or without severe injury of PLC were detected in the 14 patients of the unstable group. Conclusion The proposed PLICS score system showed excellent intraobserver and interobserver reliability. When a PLICS score is >7 or 7 accompanied by extremely unstable lateral mass fractures, the risk of postoperative failure after an anterior-only reconstruction is high and supplemental posterior strengthening can be considered.Level of Evidence: 4.

Purpose We present an organized hospital plan for the management of Coronavirus disease (COVID-19) patients requiring emergency surgical interventions. To introduce a multidisciplinary approach for the management of COVID-19-infected patients and to report the first operated patient in the Corona unit. Methods A detailed presentation of the hospital plan for a separate Corona unit with its intensive care unit and operating rooms. Description of the management of the first spine surgery case treated in this unit. Results The Corona unit showed a practical approach for the management of an emergency cervical spine fracture-dislocation with acute paralysis. The patient is 92-year-old female. The mechanism of injury was a simple fall during the stay in the internal medicine department where the patient was treated in the referring hospital. The patient had no other injuries and was awake and oriented. The patient did not have the clinical symptom of COVID-19, and the test result of COVID-19 done in the referring hospital was not available on admission in our emergency room. Education of the medical staff and organization of the operating theatre facilitated the management of the patient without an increased risk of spreading the infection. Conclusions The current COVID-19 pandemic requires an extra-ordinary organization of the medical and surgical care of the patients. It is possible to manage an infected or a potentially infected patient surgically, but a multidisciplinary plan is necessary to protect other patients and the medical staff.

Objective Thoracic spinal pain is common, and patients with this type of pain have limited therapeutic options. The cohort in this study received diagnostic intra-articular zygapophysial joint injections leading to thermal neurotomy to the medial branch nerves to demonstrate improved pain as well as physical and psychological function. Design A consecutive cohort from 2012 to 2018 with retrospective analysis of prospectively gathered data. Setting A private multidisciplinary pain clinic with referrals from primary care. Results Forty-six complete data sets from 39 patients were found using a pre-procedure and 3-month post-procedure questionnaire. Further follow-up results were found for the dual primary outcomes of duration of ≥50% relief using a numeric rating scale (NRS) for the entire group. The group was then divided into three subgroups of T1/2–T3/4, T4/5–T8/9, and T9/10–T12/L1. Success rates of 63% for ≥3 months of ≥50% relief and 46% for ≥6 months of ≥50% relief were found, for an average duration of 7.8 months. Group mean change in the NRS was 6.7, decreasing to 4.3 (P36% improvement in scores. Conclusion This cohort demonstrates that there is a pragmatic diagnostic and therapeutic option available for patients with thoracic zygapophysial joint pain that can achieve 50–100% of pain relief in 63% of patients with improved physical and psychological function.

Study design Cross-sectional study. Objective The aim of this study was to evaluate the actual prevalence of degenerative spinal changes and their association with age in a cohort of professional soccer players. Summary of background data Presently, there are data that athletes have more degenerative changes than nonathletes; however, the research examining the prevalence of degenerative spinal conditions among professional elite soccer players is scarce. Methods Professional male soccer players were included in the study (n = 40, average age 26,6 ± 4,5 years, average height 18 ± 0.07 m, weight 76.7 ± 7.1 kg). Lumbosacral spine MRI scanning at the L1-S1 level has been performed. Two radiologists with at least 7 years of experience of working with athletes evaluated all images independently of each other. Results 92.5% (n = 37) of soccer players had ≥1 spinal degenerative condition. Thirty-five percent (n = 14) of players had three to five, and 50% (n = 20) had six or more conditions. The average age of players who had six or more conditions was significantly higher than those who had zero to five or three to five conditions-28.1 ± 4.8 years versus 25.1 ± 3.6 years (P = 0.029), and 24.8 ± 3.6 years, respectively.Kruskal-Wallis test has shown no association between the number of degenerative conditions and weight (P = 0.98) as well as body mass index (P = 0.99). The age was associated with degenerative changes (P = 0.008).Disc desiccation was the most common pathologic condition, which was found in 82.5% of athletes. Facet joint arthropathy and spondylosis were present in 70, and 50% of the studied lumbar spine MRI scans, respectively. The spondylolysis prevalence of 20% was noted. Conclusion Elite professional soccer players demonstrate a high prevalence of asymptomatic degenerative lumbar spinal degenerative changes, which are significantly associated with age. These conditions might lead to the development of symptomatic lower back pain, given the high-intensity exercise required in professional soccer. It is presently unclear what measures might be applied for the primary prevention of these degenerative spinal conditions.Level of Evidence: 4.

Background: In the absence of any exclusive classification for dorsal FJA, there is a lot of confusion while labelling grade 1 FJA in thoracic spine based on decreased FJ space. Purpose: The purpose of this study was to know the facet joint space measurements in thoracic spine of asymptomatic and symptomatic participants and to comment whether the lower cut-off of 2 mm used in lumbar FJA classification can be safely applied in thoracic spine too. Materials and Methods: This cross-sectional study was done from December 1, 2018 to November 30, 2019. Patients above 18 years of age in this study who underwent CT thorax for causes unrelated to dorsal spinal pain were included. IBM SPSS Statistics v 26 was used for statistical analysis. Results: We measured and analysed 1512 thoracic facet joints in 63 patients (30 females and 33 males) in both axial and sagittal plane on CT scan. Mean age of the entire sample was 59.19 ± 15.19 years, ranging from 33 to 97 years and a standard error of mean 1.365 years. Overall mean thoracic facet joint space was measured to be 1.270 mm ± 0.3416 mm, ranging from 0 to 3.1 mm and a standard error of mean 0.0088 mm and a variance of 0.117 mm. The median was 1.300 mm while mode was 1.1 mm. Conclusion: The popular lumbar FJA classification by Weishupt et al. cannot be applied in its present form in thoracic spine, without the modification in parameters of grade 1 FJA. The lower cut-off of normal thoracic facet joint space probably lies around 1 mm. MeSH Terms: Zygapophyseal joints, dorsal, thoracic, facet joint, arthritis, classification

Background Context The contribution of anatomical structures to the stability of the spine is of great relevance for diagnostic, prognostic and therapeutic evaluation of spinal pathologies. Although a plethora of literature is available, the contribution of anatomical structures is still not well understood. Purpose We aimed to quantify the biomechanical relevance of each of the passive spinal structure trough deliberate biomechanical test series using a stepwise reduction approach on cadavers. Study design Biomechanical cadaveric study. Methods Fifty lumbar spinal segments originating from 22 human lumbar cadavers were biomechanically tested in a displacement-controlled stepwise reduction study: the intertransverse ligaments, the supraspinous and interspinous ligaments, the facet joint capsules (FJC), the facet joints (FJ), the ligamentum flavum (LF), the posterior longitudinal ligament (PLL), and the anterior longitudinal ligament were subsequently reduced. In the intact state and after each transection step, the segments were physiologically loaded in flexion, extension, axial rotation (AR), lateral bending (LB) and with anterior (AS), posterior (PS) and lateral shear (LS). Thirty-two specimens with only minor degeneration, representing a reasonably healthy subpopulation, were selected for the here presented evaluation. Quantitative values for load and spinal level dependent contribution patterns for the anatomical structures were derived. Results Small variability between of the contribution patterns are observed. The intervertebral disc (IVD) is exposed to about 67% of the applied load in LB and during shear loading, but less by load in flexion, extension and AR (less than 35%). The FJ&FJC are the main stabilizers in AR with 49%, but provide only 10% of the stability in extension. Beside the IVD, the LF and the PLL contribute mainly in flexion (22% and 16%, respectively), while the ALL plays a major role during extension (40%) and also contributes during LB (15%). The contribution of the intertransverse ligaments and the supraspinous and interspinous ligaments are very small in all loading directions ( Conclusion The IVD takes the main load in LB and absorbs shear loading, while the FJ&FJC stabilize AR. The ALL resists extension while LF and PLL stabilize flexion. With the small variability of contribution patterns, suggesting distinct adaptation of the structures to one another, the biomechanical characteristics of one structure have to be put in context of the whole spinal segment. CLINICAL SIGNIFICANCE The novel information on load distribution helps predict the biomechanical consequences of surgical procedures in more detail.

Objectives This study aims to evaluate whether ultrasound (US)- guided facet joint injection reduces pain and improves mobility in patients with failed back surgery syndrome (FBSS). Patients and methods This retrospective study included 27 patients (8 males, 19 females; mean age 43.6±11.5 years; range, 31 to 54 years) who underwent US-guided facet injections for FBSS between January 2017 and January 2019. Patients’ medial records were assessed. Pain rating scores were evaluated with the Numeric Rating Scale (NRS). Functional status was assessed with Oswestry Disability Index (ODI) version 2.0. Lumbar flexion degree was noted. After injection (lidocaine-betamethasone mixture), patients were reevaluated at first and sixth months. The study data were analyzed with Wilcoxon signed-rank test. Results Successful facet joint injections were achieved without any complications in all patients. The median duration of time after surgery was 7.8±1.3 months. Mean duration of pain was 6.7±5.7 months. There was a significant decrease in NRS values between baseline and sixth month comparison (7.0 at baseline and 6.0 at sixth month, p=0.006). Baseline-first month and first-sixth months comparisons were not significant (p=0.165 and p=0.106, respectively). For ODI, no significant change was observed between baseline-first month, first-sixth months, and baseline-sixth month comparisons (p=0.109, p=0.857, and p=0.095, respectively). For lumbar flexion, all comparisons resulted in significant increase (50.0° for baseline, 60.0° at first month, and 70.0° at sixth month; p

In this paper, we develop and validate an osteometry‐based mechanistic approach to calculation of available range of motion (aROM) in presacral intervertebral joints in sagittal bending (SB), lateral bending (LB), and axial rotation (AR). Our basic assumption was the existence of a mechanistic interrelation between the geometry of zygapophysial articular facets and aROM. Trigonometric formulae are developed for aROM calculation, of which the general principle is that the angle of rotation is given by the ratio of the arc length of motion to the radius of this arc. We tested a number of alternative formulae against available in vitro data to identify the most suitable geometric ratios and coefficients for accurate calculation. aROM values calculated with the developed formulae show significant correlation with in vitro data in SB, LB, and AR (Pearson r = 0.900) in the reference mammals (man, sheep, pig, cow). It was found that separate formulae for different zygapophysial facet types (radial (Rf), tangential (Tf), radial with a lock (RfL)) give significantly greater accuracy in aROM calculation than the formulae for the presacral spine as a whole and greater accuracy than the separate formulae for different spine regions (cervical, thoracic, lumbar). The advantage of the facet‐specific formulae over the region‐specific ones shows that the facet type is a more reliable indicator of the spine mobility than the presence or absence of ribs. The greatest gain in calculation accuracy with the facet‐specific formulae is characteristic in AR aROM. The most important theoretical outcome is that the evolutionary differentiation of the zygapophysial facets in mammals, that is the emergence of Tf joints in the rib cage area of the spine, was more likely associated with the development of AR rather than with SB mobility and, hence, with cornering rather than with forward galloping. The AR aROM can be calculated with the formulae common for man, sheep, pig, and cow. However, the SB aROM of the human spine is best calculated with different coefficient values in the formulae than those for studied artiodactyls. The most suitable coefficient values indicate that the zygapophysial articular facets tend to slide past each other to a greater extent in the human thoracolumbar spine rather than in artiodactyls. Due to this, artiodactyls retain relatively greater facet overlap in extremely flexed and extremely extended spine positions, which may be more crucial for their quadrupedal gallop than for human bipedal locomotion. The SB, LB, and AR aROMs are quite separate in respect of the formulae structure in the cervical region (radial facet type). However, throughout the thoracolumbar spine (tangential and radial with lock facets), the formulae for LB and AR are basically similar differing in coefficient values only. This means that, in the thoracolumbar spine, the greater the LB aROM, the greater the AR aROM, and vice versa. The approach developed promises a wide osteological screening of extant and extinct mammals to study the sex, age, geographical variations, and disorders.

Facet joint osteoarthritis is prevalent in young patients with adolescent idiopathic scoliosis (AIS) and might contribute to back pain. Toll‐like receptors (TLR) have been linked to cartilaginous tissue degeneration but their involvement in facet joint osteoarthritis in AIS patients is still unknown. We compared baseline gene expression levels of TLRs ‐1, ‐2, ‐4, and ‐6 in scoliotic and non‐scoliotic chondrocytes and found higher expression levels in scoliotic chondrocytes with significantly higher TLR2 levels. Furthermore, TLR expression correlated strongly and significantly with inflammatory and catabolic markers in scoliotic but not in non‐scoliotic chondrocytes. TLR activation with a synthetic TLR2/6 agonist resulted in a robust induction and release of pro‐inflammatory and catabolic factors which exacerbated proteoglycan loss in scoliotic but not in non‐scoliotic cartilage. We also detected a higher abundance of alarmins including S100A8/9 and biglycan in scoliotic cartilage. Finally, the small‐molecule antagonists Sparstolonin B and o‐Vanillin reduced catabolism following induction with naturally occurring alarmins and the synthetic TLR2/6 agonist. The high baseline expression, robust responsiveness and strong and significant correlation with proteases and pro‐inflammatory cytokines suggest that TLRs are key regulators of facet joint degeneration in AIS. Blocking their activity could therefore potentially modify disease progression.

A tenosynovial giant cell tumor is a benign proliferative disease, mostly arising from the synovial membrane of tendon sheaths, bursae, and joints. Axial skeleton involvement is very rare, but it is often found in the cervical spine. Spinal tenosynovial giant cell tumors often arise at the facet joints; a completely extra-articular spinal tenosynovial giant cell tumor is rare. We report an extremely rare case of tenosynovial giant cell tumor in the upper cervical spine that extended from the posterior atlanto-occipital membrane rather than the facet joint. Herein, the clinical and radiological findings will be reviewed to better our understanding of the characteristics of spinal tenosynovial giant cell tumors, and to help improve their diagnosis despite their non-typical locations of origin.

Background Low back pain is the leading cause of years lost to disability worldwide. Approximately 15% to 45% of chronic low back pain is due to facet joint arthropathy. Currently, no large-scale retrospective studies have investigated long-term clinical predictors of success in individuals receiving radiofrequency ablation (RFA) of the medial branches for facet joint arthropathy. Objective To determine the clinical factors associated with success and failure of RFA of lumbar facet joints at 1-year follow-up. Methods Clinical data were gathered from 500 consecutive patients with an International Classification of Diseases (ICD)-10 diagnosis of lumbar spondylosis. VAS pain scores for patients undergoing lumbar medial branch RFA procedures were recorded at multiple time points, up to the 1-year follow-up visit. A responder was defined as having ≥30% improvement in VAS score from the pre-procedural VAS score. For our primary analysis, regression analysis was conducted to identify associations between responder status and patient characteristics, including age, gender, body mass index (BMI), hormone use, opiate dose, and smoking history at multiple time points, up to the 1-year follow-up visit. Results A total of 500 patients were included in the study. At the 1-year post-RFA follow-up visit, responder status was associated with a lower rate of prior opioid use (43.22% vs. 55.76%, odds ratio 0.60 [95% confidence interval (CI) 0.40 to 0.92], P = 0.018), lower pre-procedural opioid consumption in oral morphine equivalents (10.16 ± 16.02 vs. 14.67 ± 20.65, β -4.50 [95% CI -8.57 to -0.44], P = 0.030), and a higher pre-VAS pain score (6.36 ± 2.17 vs. 5.85 ± 2.17, β 0.50 [95% CI 0.06 to 0.95], P = 0.028). There were no significant associations between responder status and age, gender, BMI, hormone use, and smoking history at the 1-year follow-up visit. Conclusions Our results suggest that patients prescribed opioids, particularly at higher dosages, may find less pain relief 1 year following RFA for facetogenic pain. Additionally, patients with higher pre-procedural VAS pain scores may be more likely to have a positive response at 1 year.

Background The rationale of only fixation without any kind of bone, ligament, disc, or osteophyte decompression as a treatment for single- or multiple-level cervical spinal degeneration was analyzed. The concept was based on the understanding that muscle weakness–related spinal instability is the cause of spinal degeneration, and spinal stabilization is the treatment. Materials and Methods During the period June 2012 to June 2019, 215 patients with single- or multiple-level cervical spinal degeneration who presented with symptoms of radiculopathy and/or myelopathy were treated. Age range of patients was 35–76 years. The series included 194 men and 21 women. Patients with acute symptoms and disc herniation, prolapse, or extrusion were excluded from the analysis. Only spinal stabilization by deploying facet screw fixation techniques was done in all cases. No decompression by resection of any bone, soft tissue, disc, or osteophyte was done. The minimum follow-up was 6 months. Results Postoperative clinical outcome was measured using Japanese Orthopaedic Association score, Goel clinical grade, and visual analog scale score. In addition, 2 specialist neurosurgeons were recruited to assess clinical outcome. Clinical assessments and videos were used to document the outcome. There were no significant complications. Varying degree of clinical recovery was seen in all patients. None of the patients in the series underwent reoperation for persistence or recurrence of symptoms. Conclusions Instability of spinal segments forms the basis of spinal degeneration. Stabilization forms the basis of surgical treatment. The role of decompression needs to be re-evaluated.

Background The purpose of this study was to compare the incidence of facet joint violation (FJV) after placement of percutaneous pedicle screws (PPSs) in 2 cohorts of patients who underwent surgery in a single position or dual position following lateral lumbar interbody fusion (LLIF) (extreme lateral interbody fusion [XLIF]). Methods We reviewed 82 patients who underwent combined XLIF surgery and PPS fixation for the treatment of degenerative lumbar spinal disorders. Patient demographics were compared between 2 groups: those who remained in the lateral decubitus position for PPS fixation (SP group) and those who were turned to the prone position (DP group). Postoperative axial computed tomography scans were evaluated independently for FJV according to the following classification: grade 0, no impingement; grade 1, screw head in contact/suspected to be in contact with the facet joint; and grade 2, screw clearly invaded the facet joint. Results A total of 349 screws were graded. Using the consensus grades, the incidence of FJV was 13.2% (46/349), but the incidence of FJV did not differ significantly according to the position of the patient during PPS insertion (SP group; 15.4%, DP group; 10.8%, P = 0.204). Conclusions Although the incidence of FJV after PPS insertion did not differ between the prone and lateral decubitus positions, grade 2 FJV was observed only in the SP group. To avoid FJV, the surgeon should pay close attention to the facet joints when inserting PPSs with the patient in a lateral decubitus position.

To explore 1) whether the degree of facet joint distraction during single-segment anterior cervical discectomy and fusion for cervical spondylotic radiculopathy affects functional outcome and 2) whether the degree of facet joint distraction is related to cervical sagittal parameters.This study retrospectively analyzed data from 72 patients with single-segment cervical spondylotic radiculopathy from January 2013 to December 2018. Lateral cervical radiographs were performed preoperatively and 12 months postoperatively. Disc height, interfacet distance, and segmental angle were measured from the lateral cervical radiographs to evaluate facet joint distraction, and cervical sagittal parameters were measured. The outcome measures included visual analog scale (VAS) and Neck Disability Index scores.Sixty-eight patients were included. ΔInterfacet distance was statistically significant in relation to ΔVAS score (P0.01). In a receiver operating characteristic curve analysis, less than the mean ΔVAS score for all patients was set as a positive result, and the critical value of Δinterfacet distance was 0.7 mm (P = 0.024, area under the curve = 0.659, sensitivity = 46.8%, specificity = 78.8%). According to the critical value determined by the receiver operating characteristic curve, all patients were divided into the appropriate distraction group or the excessive distraction group. There was a significant difference in VAS scores between the 2 groups (P0.05).After undergoing single-segment ACDF for the treatment of cervical spondylotic radiculopathy, patients with an interfacet distance of 0.7 mm or more had worse VAS pain scores. However, this was not related to the improvement in postoperative Neck Disability Index scores; changes in the interfacet distance were not associated with changes in the cervical sagittal parameters.