Cervical Spine Segments Research Articles

Unilateral biportal endoscopic posterior cervical foraminotomy for cervical radiculopathy

To investigate the clinical efficacy of posterior unilateral biportal endoscopic(UBE) cervical discectomy for cervical radiculopathy under general anesthesia. A retrospective analysis of 35 patients with cervical disc herniation uderwent posterior UBE cervical discectomy under general anesthesia from March 2021 to March 2023 was performed, including 17 males and 18 females, with an average age of (56.00±7.79) years old ranging from 42 to 69 years old. The non-operative treatment time was 6 to 27 weeks with an average of(16.03±4.56) weeks. MRI showed lateral cervical disc herniation in 19 cases and foraminal cervical disc herniation in 8 cases. The pathological segments distribution was as follows L4,5 in 5 cases, C5,6 in 12 cases C6,7 in 18 cases. CT/MRI was performed 1 to 3 d after surgery to evaluate the decompression, and the visual analogue scale(VAS), the Japanese Orthopedic Association(JOA) score, the stability of cervical spine surgery segment and the change of intervertebral height were recorded. All 35 patients successfully completed the operation, and the operation time was (55.88±5.02) min, the hospital stay after surgery (3.53±0.74) d. All 35 patients were followed up from 12 to 24 months with an average of (14.53±2.32) months. The VAS of preoperative, postoperative 1 day and 12 months were (7.000±0.875), (2.540±0.611), (2.143±0.772), respectively, the VAS at each time point before and after surgery were statistically significant(P<0.05). The JOA scores of preoperative, postoperative 1 day and 12 months were (11.660±0.533), (16.430±0.655), (16.540±0.611), respectively. The intervertebral height of the lesion segment at preoperative and 12 months was (6.206±0.493) mm and (6.147±0.497) mmm, respectively, and the difference was not statistically significant(P>0.05). None of the patients had cervical spine segment instability before or after surgery. According to the modified Macnab criteria, the clinical efficacy was evaluated at 12 months after operation, 32 cases were excellent, 2 cases were good, and 1 case was good. UBE cervical discectomy is a minimally invasive, safe and effective surgical method for the treatment of single-segment cervical disc herniation, which may be an alternative to the treatment of cervical foraminal herniation, but due to the small sample size and short follow-up time, its long-term efficacy needs to be further observed.

Cervical spine motion during videolaryngoscopic intubation using a Macintosh-style blade with and without the anterior piece of a cervical collar: a randomized controlled trial.

Applying a cervical collar during videolaryngoscopic intubation can increase the lifting force required to achieve adequate glottic view, potentially increasing cervical spine motion. We aimed to compared cervical spine motion during videolaryngoscopic intubation between applying only the posterior piece (posterior-only group) and applying both the anterior and posterior pieces (anterior-posterior group) in patients wearing a cervical collar. We conducted a dingle-centre, parallel-group, randomized controlled trial in 102 patients (each group, N = 51). We used a videolaryngoscope (AceScope™, Ace Medical, Seoul, Republic of Korea) with a Macintosh-style blade (AceBlade™, Ace Medical, Seoul, Republic of Korea) for videolaryngoscopic intubation. In each group (posterior-only vs anterior-posterior), we measured cervical spine motion during intubation, defined as change in cervical spine angle (calculated as cervical spine angle at intubation minus that before intubation) at three cervical spine segments on lateral cervical spine radiographs. The differences in mean cervical spine motion during intubation between the posterior-only and anterior-posterior groups were 1.2° (98.3% confidence interval [CI], -0.7 to 3.0), 1.0° (98.3% CI, -0.6 to 2.6), and -0.3° (98.3% CI, -2.2 to 1.7) at the occiput-C1, C1-C2, and C2-C5 segments, respectively. Mean (standard deviation) cervical spine angles at the occiput-C1, C1-C2, and C2-C5 segments in the posterior-only vs anterior-posterior groups were 10.8° (4.2) vs 9.6° (3.3) (P = 0.13), 5.6° (3.0) vs 4.7° (3.5) (P = 0.14), and 1.2° (3.7) vs 1.5° (4.3) (P = 0.74), respectively. Intubation times were shorter in the posterior-only group (median [interquartile range], 23 [19-28] sec vs 33 [20-47] sec; P = 0.003). In patients wearing a cervical collar, the differences in mean cervical spine motions during intubation between applying only the posterior piece and applying both the anterior and posterior pieces were approximately 1°. Intubation times were significantly shorter without the anterior piece of a cervical collar. These findings can be referred to when removal of the anterior piece of a cervical collar is considered to address difficult videolaryngoscopic intubation conditions. CRIS.nih.go.kr ( KCT0008151 ); first submitted 17 January 2023.

“Normal” Cervical Spine Radiographs and Computed Tomography Scans in the Emergency Department: Beware of Posttraumatic Instability of the Mobile Segment of the Lower Cervical Spine

The NEXUS criteria have been introduced in the 1990s to assist emergency department physicians to decide whether to perform radiographic work-up following cervical whiplash injury. Four criteria have been described on these profile radiographs of the cervical spine including angulation between cervical endplates, 3-mm listhesis, posterior facet joints overlap, and widened interspinous space. Although these criteria could help to detect patients suffering from unstable trauma of the mobile segment if the lower cervical spine, the radiographic signs may be so subtle that even specifically trained physicians like spine surgeons and neuroradiologists may miss them, especially during after-hour shifts. Hence, we present the striking case of a young female patient whose radiographs displayed slight but abnormal signs of lower cervical spine instability, but was nonetheless discharged home with dynamic X-rays of the cervical spine to be performed in a delayed setting. We hope that these striking features will help us remind the importance of radiologic semiology of posttraumatic unstable cervical spine.

Diagnostic efficacy of tract-specific diffusion tensor imaging in cervical spondylotic myelopathy with electrophysiological examination validation.

This study aimed to investigate the effectiveness of tract-specific diffusion tensor imaging (DTI) metrics in identifying the responsible segments for neurological dysfunction in cervical spondylotic myelopathy (CSM). The study encompassed nineteen participants diagnosed with CSM, including 10 males and 9 females. Additionally, a control group consisting of ten healthy caregivers (5 males and 5 females) were recruited with no symptoms and no compressions on magnetic resonance imaging (MRI). All participants underwent a comprehensive physical examination, MRI assessment, and DTI examination conducted by a senior chief physician. Several parameters were collected from the MR images, including the aspect ratio (defined as the anteroposterior diameter / the transverse diameter of the corresponding segment's spinal cord), transverse ratio (defined as the transverse diameter of the corresponding segment's spinal cord / the transverse diameter of the spinal cord at C2/3), and T2 high signal of the spinal cord. Furthermore, quantitative DTI metrics, such as axial diffusivity (AD), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA), were calculated using automatic region-of-interest (ROI) analysis for both whole spinal cord column and dorsal column. Receiver operating characteristic (ROC) curves were constructed to evaluate the diagnostic efficacy of the aspect ratio, transverse ratio, and DTI parameters. The area under the curve (AUC), sensitivity, and specificity were calculated. Intraoperative spinal cord electrophysiological examination was performed as the objective measure of spinal cord function during surgery. As determined by electrophysiological examination, neurological dysfunction was found in 2 patients due to C3/4 compression, in 10 patients due to C4/5 compression, in 6 patients due to C5/6 compression, and in 1 patient due to C6/7 compression. The modified Japanese Orthopedic Association scale (mJOA) was 12.71 ± 1.55 in the CSM group, with 4.87 ± 0.72 for sensory nerve function and 5.05 ± 1.35 for motor nerve function. For the control group, none of the volunteers had neurological dysfunction. T2 high signal was found at the most stenotic segment in 13 patients of the CSM group. Considering all the cervical segments, the aspect ratio (AUC = 0.823, P = 0.001, Sensitivity = 68.42%, Specificity = 82.47%) was more capable of determining the responsible segment than transverse ratio (AUC = 0.661, P = 0.027, Sensitivity = 68.42%, Specificity = 67.01%). AD, MD, and RD were significantly higher while FA was significantly lower in the responsible segment than in the irresponsible segment (P < 0.05). The AUC of DTI-Dorsal column parameters (AD, MD, RD, FA) was larger than the corresponding parameters of the DTI (Whole spinal cord). AD of DTI-Dorsal Column possessed the greatest efficacy (AUC = 0.823, sensitivity = 84.21%, specificity = 77.32%) to determine the responsible segment, larger than AD of DTI-Whole spinal cord (AUC = 0.822, P = 0.001, Sensitivity = 89.47%, Specificity = 77.32%), aspect ratio (AUC = 0.823, P = 0.001, Sensitivity = 68.42%, Specificity = 82.47%) and transverse ratio (AUC = 0.661, P = 0.027, Sensitivity = 68.42%, Specificity = 67.01%). Subgroup analysis revealed that the diagnostic efficacy of DTI and MRI parameters was influenced by cervical spine segment. When considering all cervical segments, AD from the DTI-Dorsal Column exhibited the most significant potential in identifying responsible segments. This potential was found to be superior to that of DTI-Whole spinal cord, aspect ratio, the most stenotic segment, T2 high signals, transverse ratio, motor nerve dysfunction, and sensory nerve dysfunction. The diagnostic effectiveness of both DTI and MRI parameters was notably influenced by the specific cervical spine segment.

Middle- and Long term postoperative Outcomes in Patients undergone a dorsal cervical stabilization in the highest 3 segments of cervical spine

Middle- and Long term postoperative Outcomes in Patients undergone a dorsal cervical stabilization in the highest 3 segments of cervical spine

Implantation of Surgical Paddle Electrodes Using Percutaneous Biportal-Endoscopic Technique for Spinal Cord Stimulation: An Anatomical Feasibility Study in Human Cadavers

BACKGROUND: Spinal cord stimulation is a technique in which different types of electrodes are placed in the spinal epidural space for neuromodulation. Surgical paddle electrodes (SEs) are usually implanted by a surgeon by performing open surgery with laminectomy. Recent advances in endoscopic spine surgery provide another option for minimally invasive SE implantation. OBJECTIVES: This anatomical study aims to examine the feasibility of implanting SEs in thoracic and cervical spine segments, discussing the specific advantages and disadvantages compared with previously reported methods. STUDY DESIGN: Laboratory study with Institutional Review Board No B2023-056. METHODS: Four fresh adult cadavers (2 women, 2 men) were operated on in this study. The posterior unilateral biportal endoscopic surgical approach, the accessibility to the intraspinal epidural space, and the technical possibilities and limitations of implantation of SEs were evaluated, as well as the surgical duration and complications. RESULTS: All the planned steps of the operation were successfully accomplished in all 4 cadavers. A total of 8 electrodes were successfully implanted through the working portal. Among them, 4 were located in the cervical segment and 4 in the thoracic segment. The proper position of the electrodes was also verified by fluoroscopy. No rupture of dura occurred during the operation. Except for the first cadaver, the duration of surgery did not exceed 1 hour. LIMITATIONS: Anatomical study on human cadavers, the quantity of cadavers, and the steep learning curve. CONCLUSIONS: The results of this anatomical study show that the SEs can be satisfactorily implanted in cervical and thoracic segments using the unilateral biportal endoscopic technique. KEY WORDS: Surgical paddle electrodes, spinal cord stimulation, unilateral biportal endoscopic technique, anatomical feasibility, anatomical study, cadavers, cervical, thoracic

Smoothed Particle Hydrodynamics to Model Spinal Canal Occlusion of a Finite Element Functional Spinal Unit Model under Compression

&lt;div&gt;Compressive impacts on the cervical spine can result in bony fractures. Bone fragments displaced into the spinal canal produce spinal canal occlusion, increasing the potential for spinal cord injury (SCI). Human body models (HBMs) provide an opportunity to investigate SCI but currently need to be improved in their ability to model compression fractures and the resulting material flow. Previous work to improve fracture prediction included the development of an anisotropic material model for the bone (hard tissues) of the vertebrae assessed in a functional spinal unit (FSU) model. In the FSU model, bony failure was modeled with strain-based element erosion, with a limitation that material that could occlude the spinal canal during compression was removed when an element was eroded. The objective of this study was to implement a multi-physics modeling approach, using smoothed particle hydrodynamics (SPH) with element erosion, to simulate the movement of fractured material during central compression of a C5-C6-C7 cervical spine segment and assess spinal canal occlusion. The calculated maximum occlusion in the original model was 11.1%. In contrast, the enhanced model with SPH had a maximum occlusion of 79.0%, in good agreement with the average experimental maximum occlusion of 69.0% for age-matched specimens. The SPH implementation to preserve fractured material volume enabled the assessment of spinal canal occlusion.&lt;/div&gt;

192 Effect of Helmet on Cervical Spine Biomechanics in Rear Impact Scenario (Whiplash)

INTRODUCTION: Rear impact (whiplash) is a common scenario has been studied previously by subjecting the head-neck complex under postero-anterior acceleration. There is a lack of studies investigating the effect of helmet on cervical spine biomechanics despite its common use in military and competitive automotive environments. METHODS: We developed a finite element model of the head-neck complex simulating the three spinal columns with layered intervetebral discs and ligaments. This was then validated against a cadaver (head to T1) model which was fixated to a sled on linear rails with a rear pendulum that simulated rear impact scenario. Standard-issue US Military Combat helmets in small, medium, large sizes were modeled and mounted on the finite element model. 1.8 m/s and 2.6 m/s velocity profiles were simulated and the range of motion at each functional spinal unit from C2-3 to C7-T1 was measured. RESULTS: Segmental motions were measured over 120 ms for all scenarios. 2.6 m/s vector resulted in peak acceleration of 3.5 g, and 1.8 m/s resulted in 2.5 g. Helmet use increased the range of motion at all segments from C2-3 to C7-T1. The greatest range of motion occurred at C5-6, followed by C6-7 and C7-T1. Greatest percentage increase in motion occurred at C2-3 followed by C5-6. Increasing helmet size resulted in increasing motion at all spinal segments. CONCLUSIONS: Helmet use, although protective for the cranium, significantly increases the motion at all spinal segments, especially C2-3 and C5-7, in a rear impact scenario (whiplash). Increasing helmet size results in greater motion change at all cervical spine segments. This is important to consider when designing the helmet and determining the need for additional head-mounted gear in both military and competitive automotive environments.

Effectiveness of Manual Therapy Versus Electrotherapy in Patients with Neck Pain Due to Poor Posture –A non-randomized trial

Background: Neck pain has become increasingly common in families and individuals. Due to prolong bending of cervical spine the following structure are compromised shoulders , scapular, thoracic spine that leads to flexion deformity of upper segment and extension deformity of lower cervical spine. The overuse of the muscles causes muscular imbalances.&#x0D; Objective: The main objective of this study was to determine the comparative effectiveness of manual therapy versus electrotherapy in patients with neck pain due to poor posture.&#x0D; Methodology: The data was collected from different Physiotherapy Clinics of Lahore. The study was completed in four months after the approval. The sample size was 40 participants. The participant’s male and females patients, age range 18-45 years. Numeric Pain rating score of 3 from last 3 months with forward head posture were included. In group a manual therapy (Post-isometric stretching, Jones technique) were used. .A portable digital TENS model BE-660 was used with frequency 80Hz, intensity level 6(strong but comfortable) in Group B. Outcome was assessed using Numeric pain rating, Goniometry and Neck disability index (NDI). The data was analyzed using SPSS Version 16. Paired t test and independent sample t test was used for within and between group analysis.&#x0D; Results: In group A 6(30%) were underweight and 2(10%) were overweight whereas in group B 10(50%) were under weight and 1(5%) was obese with a mean age of 29.5±8.23. This study showed that study variables were not statistically significant at the time of baseline. In both groups, pre post mean difference of pain, neck disability index, neck flexion (and neck extension was statistically significant. The mean value of pain and neck disability index of both groups were statistically significant at the end of study&#x0D; Conclusion: The current study shown that both treatment strategies including manual therapy and electrotherapy play a significant role in treating the patients with chronic neck pain due to poor posture.&#x0D; Key words: Manual therapy, Electrotherapy, Patients, Neck pain, Posture, Exercise, Neck disability, Range of Motion

Assessment of value of protraction angle and functional disorders of motion segments of cervical spine in bus drivers

Introduction: Cervical segment is a part of the spine which is the most exposed to stress and dysfunction. Aim: The aim of the study is to analyze the body posture of bus drivers and, especially, functional assessment of cervical spine mobility segments. Material and methods: The study included a group of 40 people, consisting of professionally active drivers working in public transport, 20 of whom were the men under 40, and the remaining 20 were the men over 40. The study used the original study card. Results: There was dependence between the subjects' length of service and the appearance of hand numbness. There was dependence between protraction angle and length of service. Most of the study subjects (67.5%) report the presence of back pain syndromes. Among the study subjects, 45.0% declare that they do sports / physical activity improving their condition. In the case of rectus abdominis muscle strength, the majority of the surveyed (60.0%) cannot sit unassisted. Conclusions: The bus driver is exposed to a lot of stress every day, resulting, i.a. from the responsibility he bears for passengers in the vehicle, as well as from heavy traffic, which leads to changes in myofascial tensioning, resulting in the incidence of pain.

Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Background: Anterior cervical fusion (ACF) has become a standard treatment approach to effectively alleviate symptoms in patients with cervical spondylotic myelopathy and radiculopathy. However, alteration of cervical sagittal alignment may accelerate degeneration at segments adjacent to the fusion and thereby compromise the surgical outcome. It remains unknown whether changes in T1 tilt, an important parameter of cervical sagittal alignment, may cause redistribution of biomechanical loading on adjacent segments after ACF surgery. Objective: The objective was to examine the effects of T1 tilt angles on biomechanical responses (i.e.range of motion (ROM) and intradiscal VonMises stress) of the cervical spine before and after ACF. Methods: C2-T1 FE models for pre- and postoperative C4-C6 fusion were constructed on the basis of our previous work. Varying T1 tilts of -10°, -5°, 0°, 5°, and 10° were modeled with an imposed flexion-extension rotation at the T1 inferior endplate for the C2-T1 models. The flexion-extension ROM and intradiscal VonMises stress of functional spinal units were compared between the pre- and postoperative C2-T1 FE models of different T1 tilts. Results: The spinal segments adjacent to ACF demonstrated higher ROM ratios after the operation regardless of T1 tilt. The segmental ROM ratio distribution was influenced as T1 tilt varied and loading conditions, which were more obvious during displacement-control loading of extension. Regardless of T1 tilt, intradiscal VonMises stress was greatly increased at the adjacent segments after the operation. As T1 tilt increased, intradiscal stress at C3-C4 decreased under 30° flexion and increased under 15° extension. The contrary trend was observed at the C6-C7 segment, where the intradiscal stress increased with the increasing T1 tilt under 30° flexion and decreased under 15° extension. Conclusion: T1 tilt change may change biomechanical loadings of cervical spine segments, especially of the adjacent segments after ACF. Extension may be more susceptible to T1 tilt change.

Prevalence, clinical presentation and MRI of intervertebral disc herniations in cats.

The aims of this study were to evaluate the prevalence and to describe the clinical and diagnostic imaging features of the different types of feline intervertebral disc herniation (IVDH). Medical records and imaging studies were retrospectively reviewed for cats diagnosed with IVDH between January 2008 and October 2020. Information obtained from the clinical records included signalment, clinical presentation, the presence of spinal hyperaesthesia and neurolocalisation. Diagnostic imaging findings, including type (ie, intervertebral disc extrusion [IVDE], intervertebral disc protrusion [IVDP] or acute non-compressive nucleus pulposus extrusion (ANNPE), site and number of IVDHs, were recorded. The association between breed, age, sex, duration and severity of neurological signs, the presence of spinal pain and MRI features was evaluated. Forty-three cats were included. A total of 50 IVDHs were identified: 39 cats were diagnosed with a single IVDH and four with multiple IVDHs. The most common type of IVDH was ANNPE (n = 22), followed by IVDP (n = 19) and IVDE (n = 9). Neuroanatomical localisation included L4-S3 (n = 19/43), T3-L3 (n = 18/43) and C1-C5 (n = 6/43). Cats with a single IVDH were statistically significantly associated with a diagnosis of ANNPE (P = 0.023) compared with cats with multiple IVDHs affected by IVDP (P = 0.004). Males were more commonly affected by IVDE (P = 0.020) and females by ANNPE (P = 0.020). Cats with IVDP had a longer duration of clinical signs (P <0.001) than cats with ANNPE and demonstrated milder neurological deficits (P = 0.005). IVDEs were statistically significantly associated with spinal hyperaesthesia (P = 0.013), while ANNPEs were not (P = 0.014). ANNPE, IVDP and IVDE are each associated with distinctive clinical scenarios. Thoracolumbar and mid-to-caudal lumbar regions are the most affected, followed by the cranial cervical spine segment.

Kinematics of a cervical disc prosthesis implanted above or below one- and two-level fusions

BackgroundThe theoretical advantages of hybrid constructs over multi-level fusion have been illustrated in clinical and biomechanical studies. However, there is no biomechanical data on hybrid constructs using load control analyses. There is also no clear data on whether there is a biomechanical difference if the arthroplasty is below or above a 1- or 2-level fusion. This work investigated the effect on segmental motion of having a cervical total disc arthroplasty implanted above or below a 1- or 2-level fusion. MethodsSegmental motions of 16 C2-T1 cervical spine specimens were measured as the specimens were tested to 1.5Nm in axial rotation and in flexion-extension under compressive preload. Tests were conducted on intact specimens, and then after arthroplasty with a 1-level and 2-level fusion. 8 specimens were in test Group 1, where the hybrid configuration had a total disc arthroplasty above a 1- or 2-level fusion. The arthroplasty was below the 1- and 2-level fusion in Group 2. Load control and displacement control analyses were conducted to determine the effect of the hybrid configurations on segmental motion. ResultsIn load control, compensatory motion increases were found at all non-instrumented cervical spine segments in flexion-extension and axial rotation. Flexion-extension and axial rotation ranges of motion at the total disc arthroplasty level were less than 1° different than intact.In displacement control, there was no consistent pattern of compensatory motion. Range of motion at the arthroplasty level was within 3.5° of intact. ConclusionsThe total disc arthroplasty segmental level in a hybrid construct has similar amounts of motion as intact. This may shield the arthroplasty level and adjacent levels from supra-physiological motion and loading. These results suggest that a hybrid construct may be protective of adjacent segments, whether the total disc arthroplasty is above or below the fusion.

Technical Notes for Establishing a Cervical Fusion Model in Goats Based on Distinctive Anatomy.

Goat is an adequate experimental model for cervical spine testing. However, studies on the anatomy of the cervical spine in goats are limited, and there is no uniform standard for establishing a single-segment anterior cervical discectomy and fusion (ACDF) model in goats. To address this issue, we investigated the cervical spine anatomy of goats and provided a technical basis for establishing a single-segment ACDF model in goats. We measured the imaging anatomical parameters using Mimics Medical 20.0 software. We then performed histological analysis of the cervical spine segment 2-3 (C2-3) segment of six goat cervical spine specimens. Based on the measurements and histological analysis, the fusion cage was designed to be wedge-shaped, the length of the plate was 25 mm, and the length of the screw was 15 mm. Based on the anatomical characteristics of goats, we believed that the C2-3 segment of goats was most suitable for a single-segment ACDF model in goats, and the decompression should be performed medial to the pterygoid joint on both sides, the thickness of the removed endplate was ∼0.6 mm, the cage implanted in the anterior two-thirds of the intervertebral space could maximize the contact area of the cage-endplate interface, and the location of the midline spur could position the implantation of the internal fixtures. Radiological examination at 12 weeks postoperatively suggested that the internal fixtures were in place and new bone formation was visible. These results demonstrated that these technical notes based on anatomical features were practical and could minimize damage to animals.

Is Cervical Stabilization Exercise Immediately Effective in Patients with Chronic Neck Pain and Upper Cervical Spine Dysfunction? Randomized Controlled Trial.

Purpose: To compare the effectiveness of a single exercise session with manual therapy techniques in the segments of the upper cervical spine (C0–1, C1–2 and C2–3), against a single exercise session in patients with chronic neck pain and mobility deficits in the upper cervical spine. Methods: A single-blind randomized controlled trial was performed. Fifty-eight patients were recruited (29 for the manual therapy and exercise group and 29 for the exercise group) who presented chronic neck pain and upper cervical spine dysfunction. The exercise focused on the deep muscles. The manual therapy combined manipulations and mobilizations with these exercises. Cervical range of motion, flexion-rotation test, pressure pain threshold and pain intensity were measured by a blind evaluator before and after the intervention. Results: Compared to pre-intervention, after intervention, the exercise group was significantly lower in terms of the range of motion, flexion-rotation test, and pressure pain threshold (p < 0.05). The manual therapy and exercise group improved in upper cervical flexion, the flexion-rotation test and intensity of pain (p < 0.05). Conclusions: It may be necessary to normalize the mobility of the upper cervical spine before cervical stabilization training, in patients with chronic neck pain and mobility deficits in the upper cervical spine.

The Effect of Axial Compression and Distraction on Cervical Facet Cartilage Apposition During Shear and Bending Motions

During cervical spine trauma, complex intervertebral motions can cause a reduction in facet joint cartilage apposition area (CAA), leading to cervical facet dislocation (CFD). Intervertebral compression and distraction likely alter the magnitude and location of CAA, and may influence the risk of facet fracture. The aim of this study was to investigate facet joint CAA resulting from intervertebral distraction (2.5 mm) or compression (50, 300 N) superimposed on shear and bending motions. Intervertebral and facet joint kinematics were applied to multi rigid-body kinematic models of twelve C6/C7 motion segments (70 ± 13 year, nine male) with specimen-specific cartilage profiles. CAA was qualitatively and quantitatively compared between distraction and compression conditions for each motion; linear mixed-effects models (α = 0.05) were applied. Distraction significantly decreased CAA throughout all motions, compared to the compressed conditions (p < 0.001), and shifted the apposition region towards the facet tip. These observations were consistent bilaterally for both asymmetric and symmetric motions. The results indicate that axial neck loads, which are altered by muscle activation and head loading, influences facet apposition. Investigating CAA in longer cervical spine segments subjected to quasistatic or dynamic loading may provide insight into dislocation and fracture mechanisms.

Establishment of finite element model of anterior cervical transpedicular system for reconstruction of cervical stability after subtotal resection of two segments of lower cervical spine

To establish the fixation model of anterior cervical transpedicular system (ACTPS) after subtotal resection of two segments of lower cervical spine(C3-C7) in order to provide a finite element modeling method for anterior cervical reconstruction. The CT data of the cervical segment (C1-T1) of a 30-year-old adult healthy male volunteer was collected. Used Mimics 10.0, Rapidform XOR3, HyperMesh 10.0, CATIA5V19 and ANSYS 14.0 to establish the three-dimensional nonlinear complete model of lower cervical spine(C3-C7) as the intact group. The number of units and nodes of the complete model were recorded. After the effectiveness of the complete model was verified, the C5 and C6 vertebral subtotal resection was performed, and the ACTPS model was established as the ACTPS group. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C3 in intact group and ACTPS group, the range of motion(ROM)and stress distribution in states of flexion extension, lateral flexion, rotation was compared between two groups. There were 85 832 elements and 23 612 nodes in the complete model of lower cervical spine(C3-C7) which was established in this experiment. The stress distribution of ACTPS internal fixation model was relatively uniform. Comparing with the intact group, the overall range of motion in ACTPS group was decreased in flexion extension, lateral flexion and rotation directions, and the corresponding compensation of adjacent C3,4 segment was increased slightly. The stress distribution of ACTPS fixation system is uniform, there is no stress concentration area at the joint of screw and titanium plate, and the fracture risk of internal fixation is low. It is suitable for stability reconstruction after anterior decompression of two or more cervical segments.

How to reconstruct the lordosis of cervical spine in patients with Hirayama disease? A finite element analysis of biomechanical changes focusing on adjacent segments after anterior cervical discectomy and fusion

PurposeTo compare the biomechanical changes of adjacent segments between patients with Hirayama disease and non-pathological people after anterior cervical discectomy and fusion (ACDF) operation, and to explore the optimal degree of local lordosis reconstruction during surgery.MethodsA young male volunteer was recruited to establish a three-dimensional finite element model of the lower cervical spine based on the CT data. By adjusting the bony structures and simulating the operation process, the models of non-pathological individuals before and after ACDF, patients with Hirayama disease before and after ACDF, and different local lordosis angles were established. Then, the postoperative range of motion (RoM) and stress of the adjacent segments under flexion, extension, left bending, right bending, left rotation and right rotation were recorded and compared.ResultsThe RoM and stress of all segments of lower cervical spine in patients with Hirayama disease are higher than those in non-pathological individual, and this trend still exists after ACDF surgery. When the local lordosis angle is under physiological conditions, the RoM and stress of the adjacent segments are minimum.ConclusionCompared with non-pathological people, Hirayama disease patients have differences in cervical biomechanics, which may lead to cervical hypermobility and overload. After ACDF, the possibility of adjacent segments degeneration is greater than that of non-pathological people. When the operation maintains the physiological local lordosis angle, it can slow down the degeneration.

Anatomical assessment of the biomechanical factors isolated influence on the process of disc material displacements beyond the of intervertebral space within the cervical spine segment in the structure of dorsopathies

<h3>АКТУАЛЬНОСТЬ</h3> Дорсопатии шейного отдела позвоночника относятся к наиболее распространенным болезням опорно-двигательного аппарата. Боль в шее нередко ассоциируют с дегенеративно-дистрофическим поражением позвоночника, но это не всегда так. Использование методов нейровизуализации и статистической обработки данных в оценке патогенетических факторов формирования грыжевых выпячиваний межпозвонковых дисков (МПД) является наиболее рациональным. В нашем исследовании инициирована попытка описания биомеханических процессов в структуре дорсопатий шейного отдела позвоночника. <h3>ЦЕЛЬ ИССЛЕДОВАНИЯ</h3> Изучение изолированного влияния биомеханических факторов на процесс формирования смещений дискового материала (выпячивания) за пределы пространства МПД шейного отдела позвоночника. <h3>МАТЕРИАЛ И МЕТОДЫ</h3> Объектом исследования явилась случайная выборка, состоящая из 124 исследований с применением магнитно-резонансной томографии (МРТ) шейного отдела позвоночника различных пациентов. Все исследования были разделены на 9 групп в соответствии с типами шеи: короткая толстая, короткая промежуточная, короткая тонкая, средняя толстая, средняя промежуточная, средняя тонкая, длинная толстая, длинная промежуточная, длинная тонкая (1—9-я соответственно). <h3>РЕЗУЛЬТАТЫ</h3> Биомеханические факторы оказывают изолированное влияние на формирование грыжевых выпячиваний шейного отдела позвоночника. Главным критерием оценки эффективности рычага позвоночно-двигательного сегмента является значение <i>tg α</i>, которое определяется как отношение ¹/₂ высоты диска на уровне переднего края позвонков в сагиттальной плоскости и отрезка, соединяющего середину расстояния между межпозвонковыми суставами, и передний край МПД. Полученные данные свидетельствуют, что эффективность рычага позвоночно-двигательного сегмента C_V—C_VI и C_VI—C_VII оказывает наибольшее влияние на процесс формирования выпячиваний МПД в молодом возрасте. <h3>ЗАКЛЮЧЕНИЕ</h3> Исследование продемонстрировало достоверное влияние биомеханического фактора на формирование грыжевых выпячиваний МПД в шейном отделе позвоночника у молодых людей; при этом очевидно, что у лиц старшего возраста механический фактор оказывает наименьшее воздействие, что, вероятно, обусловлено возрастными и дегенеративными изменениями МПД. Предложенный способ оценки влияния механического фактора на формирование грыжевых выпячиваний МПД позволяет прогнозировать развитие дорсопатий шейного отдела у лиц молодого возраста, а также при дальнейшем изучении может быть использован при моделировании послеоперационных осложнений оперативного лечения на шейном отделе с применением имплантов. Внедрение в повседневную практику МРТ способа оценки влияния рычага 2 рода на процесс формирования смещения дискового материала позволит увеличить информативность исследования и персонализировать лечебный процесс, разработать индивидуальный комплекс превентивных медицинских мероприятий.

Biomechanical analysis of the cervical spine segment as a method for studying the functional and dynamic anatomy of the human neck

BackgroundTraditionally, dynamic and functional anatomy, in particular the dynamic anatomy of the neck, is studied on cadaveric material. However, the development of in vivo visualization technologies and in silico modeling has made it possible to expand these possibilities. Despite significant progress in the study of dynamic and functional anatomy of the neck by means of in silico methods, the issues of validating the developed models and taking into account the pronounced nonlinearity of soft tissues as well as local anisotropy remain open. The aim of this study was to develop a virtual dynamic anatomical model of the human neck and reproduce the dynamic processes in the cervical spine from this model using the finite element method. Materials and methodsReverse engineering was used to generate a dynamic anatomical model of the neck from CT data (both male, 24 and 22 years old). Two segments of the cervical spine (C3-C5, C2-T1) were isolated from the resulting model for finite element analysis. Finite element mesh generation and contact interactions were performed using the HyperMesh software (Altair Engineering Inc, Troy, Michigan, USA). The anisotropic hyperelastic Holzapfel-Gasser-Ogden model was used to describe the material behavior of the fibrous rings of the disc. Material modeling and finite element analysis were performed using Abaqus CAE 6.14 software (Simulia, Johnston, Rhode Island, USA). ResultsA technique for creating a virtual dynamic anatomical model of the neck was elaborated and implemented. The model includes 79 major anatomical structures of the neck segmented from radiological data. A finite element analysis of the cervical spine was performed. The results of finite element analysis of the C3-C5 segment under axial load were compared with in vitro data. The proposed model shows nonlinear deformation of the disc under static loading; the model predicted displacement values agree well with the experimental ones. The displacement of the С3-С5 central vertebra with an axial load of 800 N reaches a value of 0.65 mm. For the segment C2-T1, data on intradiscal pressure, stress plots and displacements during flexion were obtained. The maximum stress value of 10.036 MPa is observed in the C3-C4 disc. ConclusionSimulation results using the proposed methodology are in good agreement with experimental data. The generated biomechanical models allow describing dynamic phenomena in the cervical spine and obtaining a wide range of quantitative properties of anatomical objects, which are otherwise inaccessible to classical methods for studying dynamic and functional anatomy.