On cervical zygapophysial joint pain after whiplash

Efficient 2D Neck Model for Simulation of the Whiplash Injury Mechanism

Whiplash injuries, mainly located in the neck, are one of the most common injuries resulting from road collisions. These injuries can be particularly challenging to detect, compromising the ability to monitor patients adequately. This work presents the development and validation of a computationally efficient model, called Efficient Neck Model-2D (ENM-2D), capable of simulating the whiplash injury mechanism. ENM-2D is a planar multibody model consisting of several bodies that model the head and neck with the same mass and inertia properties of a male occupant model in the 50th percentile. The damping and non-linear spring parameters of the kinematic joints were identified through a multiobjective optimization process, solved sequentially. The TNO-Human Body Model (TNO-HBM), a validated occupant model for rear impact, was simulated, and its responses were used as a reference for validation purposes. The root mean square (RMS) of the deviations of angular positions of the bodies were used as objective functions, starting from the bottom vertebra to the top, and ending in the head. The sequence was repeated until it converged, ending the optimization process. The identified ENM-2D model could simulate the whiplash injury mechanism kinematics and accurately determine the injury criteria associated with head and neck injuries. It had a relative deviation of 8.3% for the head injury criteria and was 12.5 times faster than the reference model.

Quantitative cervical spine injury responses in whiplash loading with a numerical method of natural neural reflex consideration

BACKGROUND AND OBJECTIVE

Neural reflex is hypothesized as a regulating step in spine stabilizing system. However, neural reflex control is still in its infancy to consider in the previous finite element analysis of head-neck system for various applications. The purpose of this study is to investigate the influences of neural reflex control on neck biomechanical responses, then provide a new way to achieve an accurate biomechanical analysis for head-neck system with a finite element model.

METHODS

A new FE head-neck model with detailed active muscles and spinal cord modeling was established and globally validated at multi-levels. Then, it was coupled with our previously developed neuromuscular head-neck model to analyze the effects of vestibular and proprioceptive reflexes on biomechanical responses of head-neck system in a typical spinal injury loading condition (whiplash). The obtained effects were further analyzed by comparing a review of epidemiologic data on cervical spine injury situations.

RESULT

The results showed that the active model (AM) with neural reflex control obviously presented both rational head-neck kinematics and tissue injury risk referring to the previous experimental and epidemiologic studies, when compared with the passive model (PM) without it. Tissue load concentration locations as well as stress/strain levels were both changed due to the muscle activation forces caused by neural reflex control during the whole loading process. For the bony structures, the AM showed a peak stress level accounting for only about 25% of the PM. For the discs, the stress concentrated location was transferred from C2-C6 in the PM to C4-C6 in the AM. For the spinal cord, the strain concentrated locations were transferred from C1 segment to around C4 segment when the effects of neural reflex control were implemented, while the gray matter and white matter peak strains were reduced to 1/3 and 1/2 of the PM, respectively. All these were well correlated with epidemiological studies on clinical cervical spine injuries.

CONCLUSION

In summary, the present work demonstrated necessity of considering neural reflex in FE analysis of a head-neck system as well as our model biofidelity. Overall results also verified the previous hypothesis and further quantitatively indicated that the muscle activation caused by neural reflex is providing a protection for the neck in impact loading by decreasing the strain level and changing the possible injury to lower spinal cord level to reduce injury severity.

Advanced magnetic resonance imaging of chronic whiplash patients: a clinical practice-based feasibility study

BACKGROUND

Whiplash injury is common following road traffic crashes affecting millions worldwide, with up to 50% of the injured developing chronic symptoms and 15% having a reduced working capability due to ongoing disability. Many of these patients receive treatment in primary care settings based upon clinical and diagnostic imaging findings. Despite the identification of different types of injuries in the whiplash patients, clinically significant relationships between injuries and chronic symptoms remains to be fully established. This study investigated the feasibility of magnetic resonance imaging (MRI) techniques including quantitative diffusion weighted imaging and measurements of cerebrospinal fluid (CSF) flow as novel non-invasive biomarkers in a population of healthy volunteers and chronic whiplash patients recruited from a chiropractic clinic for the purpose of improving our understanding of whiplash injury.

METHODS

Twenty chronic whiplash patients and 18 healthy age- and gender matched control subjects were included [mean age ± SD (sex ratio; females/males), case group: 37.8 years ± 9.1 (1.22), control group: 35.1 years ± 9.2 (1.25)]. Data was collected from May 2019 to July 2020. Data from questionnaires pertaining to the car crash, acute and current symptoms were retrieved and findings from clinical examination and MRI including morphologic, diffusion weighted and phase-contrast images were recorded. The apparent diffusion coefficient and fractional anisotropy were calculated, and measurement and analysis of CSF flow was conducted. Statistical analyses included Fisher's exact test, Mann Whitney U test and analysis of variance between groups.

RESULTS

The studied population was described in detail using readily available clinical tools. No statistically significant differences were found between the groups on MRI.

CONCLUSIONS

This study did not show that MRI-based measures of morphology, spinal cord and nerve root diffusion or cerebrospinal fluid flow are sensitive biomarkers to distinguish between chronic whiplash patients and healthy controls. The detailed description of the chronic whiplash patients using readily available clinical tools may be of great relevance to the clinician. In the context of feasibility, clinical practice-based advanced imaging studies with a technical setup similar to the presented can be expected to have a high likelihood of successful completion.

Sensorimotor performance in acute-subacute non-specific neck pain: a non-randomized prospective clinical trial with intervention

Background

The assessment of cervical spine kinematic axial rotation performance is of great importance in the context of the study of neck sensorimotor control. However, studies addressing the influence of the level of provocation of spinal pain and the potential benefit of passive manual therapy mobilizations in patients with acute-subacute non-specific neck pain are lacking.

Methods

A non-randomized prospective clinical trial with an intervention design was conducted. We investigated: (1) the test-retest reliability of kinematic variables during a fast axial head rotation task standardized with the DidRen laser test device in 42 Healthy pain-free Control Participants (HCP) (24.3 years ±6.8); (2) the differences in kinematic variables between HCP and 38 patients with Acute-subacute Non-Specific neck Pain (ANSP) assigned to two different groups according to whether their pain was localized in the upper or lower spine (46.2 years ±16.3); and (3) the effect of passive manual therapy mobilizations on kinematic variables of the neck during fast axial head rotation.

Results

(1) Intra-class correlation coefficients ranged from moderate (0.57 (0.06-0.80)) to excellent (0.96 (0.91-0.98)). (2) Kinematic performance during fast axial rotations of the head was significantly altered in ANSP compared to HCP (age-adjusted) for one variable: the time between peaks of acceleration and deceleration (p<0.019). No significant difference was observed between ANSP with upper vs lower spinal pain localization. (3) After the intervention, there was a significant effect on several kinematic variables, e.g., ANSP improved peak speed (p<0.007) and performance of the DidRen laser test (p<0.001), with effect sizes ranging from small to medium.

Conclusion

(1) The DidRen laser test is reliable. (2) A significant reduction in time between acceleration and deceleration peaks was observed in ANSP compared to HCP, but with no significant effect of spinal pain location on kinematic variables was found. (3) We found that neck pain decreased after passive manual therapy mobilizations with improvements of several kinematic variables.

Trial registration

Registration Number: NCT 04407637

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04876-4.

Consensus practice guidelines on interventions for cervical spine (facet) joint pain from a multispecialty international working group

BACKGROUND

The past two decades have witnessed a surge in the use of cervical spine joint procedures including joint injections, nerve blocks and radiofrequency ablation to treat chronic neck pain, yet many aspects of the procedures remain controversial.

METHODS

In August 2020, the American Society of Regional Anesthesia and Pain Medicine and the American Academy of Pain Medicine approved and charged the Cervical Joint Working Group to develop neck pain guidelines. Eighteen stakeholder societies were identified, and formal request-for-participation and member nomination letters were sent to those organizations. Participating entities selected panel members and an ad hoc steering committee selected preliminary questions, which were then revised by the full committee. Each question was assigned to a module composed of 4-5 members, who worked with the Subcommittee Lead and the Committee Chairs on preliminary versions, which were sent to the full committee after revisions. We used a modified Delphi method whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chairs, who incorporated the comments and sent out revised versions until consensus was reached. Before commencing, it was agreed that a recommendation would be noted with >50% agreement among committee members, but a consensus recommendation would require ≥75% agreement.

RESULTS

Twenty questions were selected, with 100% consensus achieved in committee on 17 topics. Among participating organizations, 14 of 15 that voted approved or supported the guidelines en bloc, with 14 questions being approved with no dissensions or abstentions. Specific questions addressed included the value of clinical presentation and imaging in selecting patients for procedures, whether conservative treatment should be used before injections, whether imaging is necessary for blocks, diagnostic and prognostic value of medial branch blocks and intra-articular joint injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for designating a block as positive, how many blocks should be performed before radiofrequency ablation, the orientation of electrodes, whether larger lesions translate into higher success rates, whether stimulation should be used before radiofrequency ablation, how best to mitigate complication risks, if different standards should be applied to clinical practice and trials, and the indications for repeating radiofrequency ablation.

CONCLUSIONS

Cervical medial branch radiofrequency ablation may provide benefit to well-selected individuals, with medial branch blocks being more predictive than intra-articular injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of false-negatives (ie, lower overall success rate). Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

Consensus practice guidelines on interventions for cervical spine (facet) joint pain from a multispecialty international working group

Background

The past two decades have witnessed a surge in the use of cervical spine joint procedures including joint injections, nerve blocks and radiofrequency ablation to treat chronic neck pain, yet many aspects of the procedures remain controversial.

Methods

In August 2020, the American Society of Regional Anesthesia and Pain Medicine and the American Academy of Pain Medicine approved and charged the Cervical Joint Working Group to develop neck pain guidelines. Eighteen stakeholder societies were identified, and formal request-for-participation and member nomination letters were sent to those organizations. Participating entities selected panel members and an ad hoc steering committee selected preliminary questions, which were then revised by the full committee. Each question was assigned to a module composed of 4–5 members, who worked with the Subcommittee Lead and the Committee Chairs on preliminary versions, which were sent to the full committee after revisions. We used a modified Delphi method whereby the questions were sent to the committee en bloc and comments were returned in a non-blinded fashion to the Chairs, who incorporated the comments and sent out revised versions until consensus was reached. Before commencing, it was agreed that a recommendation would be noted with >50% agreement among committee members, but a consensus recommendation would require ≥75% agreement.

Results

Twenty questions were selected, with 100% consensus achieved in committee on 17 topics. Among participating organizations, 14 of 15 that voted approved or supported the guidelines en bloc, with 14 questions being approved with no dissensions or abstentions. Specific questions addressed included the value of clinical presentation and imaging in selecting patients for procedures, whether conservative treatment should be used before injections, whether imaging is necessary for blocks, diagnostic and prognostic value of medial branch blocks and intra-articular joint injections, the effects of sedation and injectate volume on validity, whether facet blocks have therapeutic value, what the ideal cut-off value is for designating a block as positive, how many blocks should be performed before radiofrequency ablation, the orientation of electrodes, whether larger lesions translate into higher success rates, whether stimulation should be used before radiofrequency ablation, how best to mitigate complication risks, if different standards should be applied to clinical practice and trials, and the indications for repeating radiofrequency ablation.

Conclusions

Cervical medial branch radiofrequency ablation may provide benefit to well-selected individuals, with medial branch blocks being more predictive than intra-articular injections. More stringent selection criteria are likely to improve denervation outcomes, but at the expense of false-negatives (ie, lower overall success rate). Clinical trials should be tailored based on objectives, and selection criteria for some may be more stringent than what is ideal in clinical practice.

Equine Cervical Pain and Dysfunction: Pathology, Diagnosis and Treatment

Simple Summary

Neck pain and dysfunction in the horse is becoming an increasingly important topic among riders, trainers and veterinarians. Some horses may present for a subtle performance decline, while others may show dramatic, dangerous behavior. It is important to recognize how to carefully evaluate the horse in an effort to understand the different types of pain that may be contributing to the different behaviors. The musculoskeletal and nervous systems may both play a role in the development of clinical signs. Recognizing that there are many diagnostic options as well as several treatments choices is important. This synopsis covers the disease processes that may contribute to the development of neck pain and dysfunction in the horse, as well as several possible diagnostic and treatment options.

Abstract

Interest in the cervical spine as a cause of pain or dysfunction is increasingly becoming the focus of many equine practitioners. Many affected horses are presented for poor performance, while others will present with dramatic, sometimes dangerous behavior. Understanding and distinguishing the different types of neck pain is a starting point to comprehending how the clinical presentations can vary so greatly. There are many steps needed to systematically evaluate the various tissues of the cervical spine to determine which components are contributing to cervical pain and dysfunction. Osseous structures, soft tissues and the central and the peripheral nervous system may all play a role in these various clinical presentations. After completing the clinical evaluation, several imaging modalities may be implemented to help determine the underlying pathologic processes. There are multiple treatment options available and each must be carefully chosen for an individual horse. Provided is a synopsis of the current knowledge as to different disease processes that can result in cervical pain and dysfunction, diagnostic approaches and treatment strategies. Improving the knowledge in these areas will ideally help to return horses to a state of well-being that can be maintained over time and through the rigors of their job or athletic endeavors.

Magnetic Resonance Spectroscopy Assessment of Brain Metabolite Concentrations in Individuals With Chronic Whiplash-associated Disorder: A Cross-sectional Study

OBJECTIVES

Pathophysiologic mechanisms underpinning ongoing pain in whiplash-associated disorder (WAD) are not well understood, however, alterations in brain morphology and function have been observed in this population and in other chronic pain conditions. This study investigated metabolite profiles of brain regions in people with chronic WAD compared with controls.

MATERIALS AND METHODS

Thirty-eight individuals with chronic WAD (mean [SD] age, 39.5 [11.3] years, 23 female individuals) and 16 pain-free controls (38.9 [12.7] years, 11 female individuals) underwent multivoxel brain magnetic resonance spectroscopy. At the anterior cingulate cortex (ACC), primary motor cortex (1MC), and somatosensory cortex (SSC), ratios of metabolite concentrations were calculated for N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myo-inositol (Ins), and glutamate/glutamine (Glx). Chronic WAD group participants completed clinical questionnaires and cold and pressure pain threshold assessment. Data were analyzed with hypothesis testing and Spearman correlations (P≥0.05), with Benjamini-Hochberg corrections (5% false discovery rate).

RESULTS

No group differences were observed for NAA:Cr, NAA:Cho, Cr:Cho, Glx:NAA, Glx:Cr, Glx:Cho, Ins:NAA, Ins:Cr, Ins:Cho or Ins:Glx for left or right ACC, 1MC, or SSC following correction for multiple comparisons. No significant correlations were observed between metabolite ratios and any clinical variable.

DISCUSSION

These results suggest that ongoing pain and disability in this population may not be underpinned by metabolite aberrations in the brain regions examined. Further research is required to progress our understanding of cortical contributions to neurophysiologic mechanisms in chronic WAD.

Human Pelvis Bayesian Injury Probability Curves From Whole Body Lateral Impact Experiments

Injury criteria are used in military, automotive, and aviation environments to advance human safety. While injury risk curves (IRCs) for the human pelvis are published under vertical loading, there is a paucity of analysis that describe IRCs under lateral impact. The objective of the present study is to derive IRCs under this mode. Published data were used from 60 whole-body postmortem human surrogate (PMHS) tests that used repeated testing protocols. In the first analysis, from single impact tests, all injury data points were considered as left censored and noninjury points were considered as right censored, while repeated testing results were treated as interval censored data. In the second analysis, injury data were treated uncensored. Peak force was used as the response variable. Age, total body mass, gender, and body mass index (BMI) were used as covariates in different combinations. Bayesian survival analysis model was used to derive the IRCs. Plus-minus 95% credible intervals (CI) and their normalized CI sizes (NCIS) were obtained. This is the first study to develop IRCs in whole body PMHS tests to describe the human pelvic tolerance under lateral impact using Bayesian models.

Small fibre pathology in chronic whiplash-associated disorder: A cross-sectional study

BACKGROUND

Mechanisms underpinning ongoing symptoms in chronic whiplash associated-disorder (WAD) are not well understood. People with chronic WAD can exhibit sensory dysfunction consistent with small nerve fibre pathology, including thermal hypoaesthesia and hyperalgesia. This study investigated small fibre structure and function in chronic WAD.

METHODS

Twenty-four people with chronic WAD (median [IQR] age 49 [15] years, 16 females) and 24 pain-free controls (50 [17] years, 16 females) were recruited. Intraepidermal nerve fibre density (IENFD) and dermal innervation were assessed by skin biopsy. This was performed at (a) the lateral index finger on the primary side of pain and (b) superior to the lateral malleolus on the contralateral side. Quantitative sensory testing was performed over the hand.

RESULTS

The WAD group exhibited lower IENFD at the finger (WAD: median [IQR] 4.5 [4.9] fibres/mm; control 7.3 [3.9]; p = .010), but not the ankle (WAD: mean [SD] 7.3 [3.7] fibres/mm; control 9.3 [3.8]; p = .09). Dermal innervation was lower in the WAD group at the finger (WAD: median [IQR] 3.7 [2.8] nerve bundles/mm² ; controls: 4.9 [2.1]; p = .017) but not the ankle (WAD: median [IQR] 2.1 [1.9] nerve bundles/mm² ; controls: 1.8 [1.8]; p = .70). In the WAD group, hand thermal and light touch detection were impaired, and heat pain thresholds were lowered (p ≤ .037).

CONCLUSIONS

Findings suggest small fibre structural and functional deficits in chronic WAD, implicating potential involvement of small fibre pathology.

SIGNIFICANCE

Our study found decreased intraepidermal nerve fibre density, reduced dermal innervation, thermal hypoaesthesia and hypersensitivity in people with chronic WAD, suggestive of small fibre pathology. This observation of peripheral nervous system pathology in chronic whiplash provides novel insights on mechanisms underpinning symptoms and challenges commonly held beliefs regarding this condition.

Biomechanical comparison of noncontiguous cervical disc arthroplasty and noncontiguous cervical discectomy and fusion in the treatment of noncontinuous cervical degenerative disc disease: a finite element analysis

Background

Biomechanical characteristics of noncontinuous ACDF and noncontinuous CDA in the treatment of noncontinuous cervical degenerative disc disease were still unclear. The aim of this research is to compare the differences between these two kinds of treatment methods and to verify the effectiveness of Prodisc-C in noncontinuous CDA.

Methods

Eight FEMs of the cervical spine (C2–C7) were built based on CT images of 8 mild CDDD volunteers. In the arthroplasty group, we inserted Prodisc-C at C3/4 and C5/6. In the fusion group, CoRoent® Contour and NuVasive® Helix ACP were implanted at C3/4 and C5/6. Initial loads of 75 N were used to simulate the head weight and muscle forces. The application of 1.0 N m moment on the top on the C2 vertebra was used to create motion in all directions. Statistical analyses were performed using STATA version 14.0 (Stata Corp LP, College Station, Texas, USA). Statistical significance was set at P < 0.05.

Results

The IDPs in C2/3 (P < 0.001, P = 0.005, P < 0.001, P < 0.001), C4/5 (P < 0.001), and C6/7 (P < 0.001) of the intact group were significantly less than that in the fusion group in flexion, extension, lateral bending, and axial rotation, respectively. In addition, the IDPs in C2/3 (P < 0.001, P = 0.001, P < 0.001, P < 0.001), C4/5 (P < 0.001), and C6/7 (P < 0.001) of the arthroplasty group were significantly less than that in the fusion group in flexion, extension, lateral bending, and axial rotation, respectively. Contact forces of facet joints in C2/3 (P = 0.010) in the arthroplasty group was significantly less than that in the intact group. Contact forces of facet joints in C2/3 (P < 0.001), C4/5 (P < 0.001), and C6/7 (P < 0.001) in the arthroplasty group was significantly less than that in the fusion group. Contact forces of facet joints in C2/3 (P < 0.001), C4/5 (P < 0.001), and C6/7 (P < 0.001) in the intact group were significantly less than that in the fusion group.

Conclusions

Noncontinuous CDA could preserve IDP and facet joint forces at the adjacent and intermediate levels to maintain the kinematics of cervical spine near preoperative values. However, noncontinuous ACDF would increase degenerative risks at adjacent and intermediate levels. In addition, the application of Prodisc-C in noncontinuous CAD may have more advantages than that of Prestige LP.

Cervical Discs as a Source of Neck Pain. An Analysis of the Evidence

OBJECTIVESBACKGROUND

Objectives To determine the extent and strength of evidence that supports the belief that cervical intervertebral discs are a source of neck pain.

DESIGN

Design The evidence from anatomical, laboratory, experimental, diagnostic, and treatment studies was summarized and analyzed for concept validity, face validity, content validity, and construct validity.

RESULTS

Results Evidence from basic sciences shows that cervical discs have a nociceptive innervation, and experimental studies show that they are capable of producing neck pain. Disc stimulation has been developed as a diagnostic test but has rarely been used in a disciplined fashion. The prevalence of cervical disc pain has not been properly established but appears to be low. No treatment has been established that reliably achieves complete relief of neck pain in substantial proportions of patients.

CONCLUSIONS

Conclusions Basic science evidence supports the concept of cervical disc pain, but epidemiologic and clinical evidence to vindicate the clinical application of the concept is poor or lacking.

Biomechanical effects on the intermediate segment of noncontiguous hybrid surgery with cervical disc arthroplasty and anterior cervical discectomy and fusion: a finite element analysis

BACKGROUND CONTEXT

Surgery for cervical degenerative disc disorder (CDDD) at two noncontiguous segments is infrequent. Few studies have explored the biomechanical effects on the intermediate adjacent segment of anterior cervical discectomy and fusion (ACDF) or cervical disc arthroplasty (CDA) in this situation. No study has examined biomechanical differences between ACDF and hybrid surgery (HS) constructs for noncontiguous CDDD. Differences in the biomechanical changes between the intermediate and adjacent segments are unknown.

PURPOSE

This study was conducted to compare the biomechanical changes resulting from noncontiguous ACDFs and HS.

STUDY DESIGN

A finite element analysis study.

METHODS

A finite element model of a healthy cervical spine (C2-C7) was constructed. Three surgical models were developed: (1) ACDF at C3/4 and C5/6 (FF), (2) ACDF at C3/4 and CDA at C5/6 (FA) and (3) CDA at C3/4 and ACDF at C5/6 (AF). A 75-N follower load with 1.0 N·m moments was applied to the top of the C2 vertebra in the intact model to simulate flexion, extension, lateral bending, and axial rotation. Surgical models achieved identical motion angles of the intact model in each direction following the displacement-control protocols.

RESULTS

The FF model required much higher moments than did the AF and FA models to achieve the same amount of motion. In the FF model, the motion contributions of the unfused segments were unevenly increased. The magnitude of the increased motion in the intermediate segment was larger than those in the supra- or infra-adjacent segments. The facet contact force (FCF) and intradiscal pressure (IDP) at the intermediate segment were also more susceptible to impact. In the FA and AF models, the motion contributions of the untreated levels were evenly changed, and the intermediate segment did not experience additive motion, FCF, or IDP. The segment adjacent to the level of ACDF had greater FCF and IDP than did the segment adjacent to the level of CDA in the two HS constructs.

CONCLUSIONS

HS constructs resulted in less altered biomechanics and kinematics of the untreated levels and showed no additive biomechanical effects on the intermediate segments compared with ACDF at noncontiguous levels. However, the effects were associated with the relative location of the ACDF and CDA levels.

CLINICAL SIGNIFICANCE

This study provides a biomechanical rationale for the use of HS to treat patients with noncontiguous CDDD.

Radiofrequency Denervation Improves Health-Related Quality of Life in Patients with Thoracic Zygapophyseal Joint Pain

Objective

To describe a practical approach for the diagnosis and treatment of thoracic zygapophyseal joint pain and to present preliminary clinical data on the effects of this treatment approach on health-related quality of life.

Design

An observational study.

Setting

Specialist outpatient pain clinic in northern Sweden.

Subjects

Patients with long-term thoracic pain.

Methods

We describe a method of radiofrequency denervation of thoracic zygapophyseal joints. We compared health-related quality of life between patients who underwent radiofrequency denervation of thoracic zygapophyseal joints and patients who underwent radiofrequency denervation for lumbar and cervical zygapophyseal joint pain.

Results

Treatment according to the Spine Intervention Society Guidelines was performed on the lumbar region in 178 patients and in the cervical region in 55 patients. Another 82 patients were treated in the thoracic region with our proposed technique. A survival plot of improvements in health-related quality of life revealed that all three treatments were effective in 65% or more of patients. The improvement in health-related quality of life was maintained for 12 or more months after treatment in 47% to 51% of patients.

Conclusions

Our results suggest that radiofrequency denervation of thoracic zygapophyseal joint pain is as effective as radiofrequency denervation, the standard treatment, for lumbar and cervical zygapophyseal joint pain. If these results can be confirmed by other centers, radiofrequency denervation is likely to become more widely available for the treatment of thoracic zygapophyseal joint pain.

Biomechanics following skip-level cervical disc arthroplasty versus skip-level cervical discectomy and fusion: a finite element-based study

Background

Moderately increased motion at the intermediate segment (IS) after skip-level fusion may accelerate disc degeneration. However, limited biomechanical data are available that examine the effects on the IS following cervical disc arthroplasty (CDA). The purpose of this study is to investigate the biomechanical changes in the IS of the cervical spine after skip-level fusion or skip-level arthroplasty.

Methods

A finite element model of a healthy cervical spine (C2-C7) was constructed. Two surgical models were developed: (1) skip-level fusion at C3/4 and C5/6 and (2) skip-level arthroplasty at C3/4 and C5/6. A 75-N follower load and 1.0-N·m moments were applied to the top of the C2 vertebra to produce flexion, extension, lateral bending and axial rotation in the intact model. The end-points in each direction corresponding to the intact model were applied to the surgical models under displacement-control protocols.

Results

The ranges of motion (ROMs) of the fusion model were markedly decreased at the operated levels, while the corresponding ROMs of the arthroplasty model were similar to those of the intact spine in all directions. In the fusion model, the ROMs of the IS (C4/5) were markedly increased in all directions. The ROMs in the arthroplasty model were similar to those in the intact spine, and the ROMs of untreated segments were evenly increased. In the fusion model, the intradiscal pressure and facet contact force at were C4/5 remarkably increased and unevenly distributed among the unfused segments. In the arthroplasty model, the IS did not experience additive stress.

Conclusion

The IS does not experience additive ROM or stress in the intervertebral disc or facet joints after skip-level arthroplasty, which has fewer biomechanical effects on the IS than does skip-level fusion. This study provides a biomechanical rationale for arthroplasty in treating patients with skip-level cervical degenerative disc disease.

Tissue loading and microstructure regulate the deformation of embedded nerve fibres: predictions from single-scale and multiscale simulations

Excessive deformation of nerve fibres (axons) in the spinal facet capsular ligaments (FCLs) can be a cause of pain. The axons are embedded in the fibrous extracellular matrix (ECM) of FCLs, so understanding how local fibre organization and micromechanics modulate their mechanical behaviour is essential. We constructed a computational discrete-fibre model of an axon embedded in a collagen fibre network attached to the axon by distinct fibre-axon connections. This model was used to relate the axonal deformation to the fibre alignment and collagen volume concentration of the surrounding network during transverse, axial and shear deformations. Our results showed that fibre alignment affects axonal deformation only during transverse and axial loading, but higher collagen volume concentration results in larger overall axonal strains for all loading cases. Furthermore, axial loading leads to the largest stretch of axonal microtubules and induces the largest forces on axon's surface in most cases. Comparison between this model and a multiscale continuum model for a representative case showed that although both models predicted similar averaged axonal strains, strain was more heterogeneous in the discrete-fibre model.

Influence of morphological variations on cervical spine segmental responses from inertial loading

OBJECTIVES

The objective of this study was to investigate the influence of morphological variations in osteoligamentous lower cervical spinal segment responses under postero-anterior inertial loading.

METHODS

A parametric finite element model of the C5-C6 spinal segment was used to generate models. Variations in the vertebral body and facet depth (anteroposterior), posterior process length, intervertebral disc height, facet articular process height and slope, segment orientation ranging from lordotic to straight, and segment size were parameterized. These variations included male-female differences. A Latin hypercube sampling method was used to select parameter values for model generation. Forces and moments associated with the inertial loading were applied to the generated model segments. The 7 parameters were grouped as local or global depending on the number of spinal components involved in the shape variation. Four output responses representing overall segmental and soft tissue responses were analyzed for each model variation: response angle of the segment, anterior longitudinal ligament stretch, anterior capsular ligament stretch, and facet joint compression in the posterior region. Pearson's correlation coefficient was used to compute the correlations of these output responses with morphological variations.

RESULTS

Fifty models were generated from the parameterized model using a Latin hypercube sampling technique. Variation in response angle among the models was 4° and was most influenced by change in the combined dimension of vertebral body and facet depth, followed by size of the segment. The maximum anterior longitudinal ligament stretch varied between 0.1 and 0.3 and was strongly influenced by the change in the segment orientation. The anterior facet joint region sustained tension, whereas the posterior region sustained compression. For the anterior capsular ligament stretch, the most influential global variation was segment orientation, whereas the most influential local variations were the facet height and facet angle parameters. In the case of posterior facet joint compression, segment orientation was again most influential, whereas among the local variations, the facet angle had the most influence.

CONCLUSION

Shape variations in the intervertebral disc influenced segmental rotation and ligament responses; however, the influence of shape variations in the facet joint was confined to capsular ligament responses. Response angle was most influenced by the vertebral body depth variations, explaining greater segmental rotations in female spines. Straighter spine segments sustained greater posterior facet joint compression, which may offer an explanation for the higher incidence of whiplash-associated disorders among females, who exhibit a straighter cervical spine. The anterior longitudinal ligament stretch was also greater in straighter segments. These findings indicate that the morphological features specific to the anatomy of the female cervical spine may predispose it to injury under inertial loading.

Collagen organization regulates stretch-initiated pain-related neuronal signals in vitro: Implications for structure-function relationships in innervated ligaments

Injury to the spinal facet capsule, an innervated ligament with heterogeneous collagen organization, produces pain. Although mechanical facet joint trauma activates embedded afferents, it is unclear if, and how, the varied extracellular microstructure of its ligament affects sensory transduction for pain from mechanical inputs. To investigate the effects of macroscopic deformations on afferents in collagen matrices with different organizations, an in vitro neuron-collagen construct (NCC) model was used. NCCs with either randomly organized or parallel aligned collagen fibers were used to mimic the varied microstructure in the facet capsular ligament. Embryonic rat dorsal root ganglia (DRG) were encapsulated in the NCCs; axonal outgrowth was uniform and in all directions in random NCCs, but parallel in aligned NCCs. NCCs underwent uniaxial stretch (0.25 ± 0.06 strain) corresponding to sub-failure facet capsule strains that induce pain. Macroscopic NCC mechanics were measured and axonal expression of phosphorylated extracellular signal-regulated kinase (pERK) and the neurotransmitter substance P (SP) was assayed at 1 day to assess neuronal activation and nociception. Stretch significantly upregulated pERK expression in both random and aligned gels (p < 0.001), with the increase in pERK being significantly higher (p = 0.013) in aligned than in random NCCs. That increase likely relates to the higher peak force (p = 0.025) and stronger axon alignment (p < 0.001) with stretch direction in the aligned NCCs. In contrast, SP expression was greater in stretched NCCs (p < 0.001) regardless of collagen organization. These findings suggest that collagen organization differentially modulates pain-related neuronal signaling and support structural heterogeneity of ligament tissue as mediating sensory function. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:770-777, 2018.

Lateral atlantoaxial joint meniscoid volume in individuals with whiplash associated disorder: A case-control study

BACKGROUND

Lateral atlantoaxial (LAA) joints are established sources of nociceptive input in chronic whiplash associated disorder (WAD). These joints contain intra-articular meniscoids that may be damaged in whiplash trauma. LAA joint meniscoid morphology has not been investigated comprehensively in a chronic WAD population, and it is unclear whether morphological differences exist compared to a pain-free population.

OBJECTIVES

This study examined LAA joint meniscoid volume in individuals with chronic WAD who report pain in a distribution consistent with LAA joint pain.

DESIGN

Case-control study.

METHOD

Fourteen individuals with chronic WAD with pain in an LAA joint distribution (mean [SD] age 38.1 [10.8] years; six female) and 14 age- and sex-matched pain-free controls (38.0 [10.5] years) underwent cervical spine magnetic resonance imaging. LAA joint images were inspected for meniscoids; meniscoid volume was calculated in mm³ and as a percentage of articular cavity volume. Symptom duration, location and intensity were recorded. Data were analysed using paired t-tests, Wilcoxon signed-rank testing, Spearman's rank testing, linear and logistic regression (α < 0.05).

RESULTS

Ventral and dorsal meniscoids (n = 112) were found in each LAA joint. Greater dorsal meniscoid volume as a percentage of articular cavity volume was associated with higher pain intensity (odds ratio 1.48, p = 0.03; likelihood ratio test chi-square₂ = 6.64, p = 0.04), however no significant differences existed between meniscoid volumes of WAD and control participants.

CONCLUSIONS

Findings indicate a potential link between dorsal LAA joint meniscoid volume and pain, suggesting larger meniscoid size may have pathoanatomical significance in WAD.

The biomechanical impact of facet tropism on the intervertebral disc and facet joints in the cervical spine

BACKGROUND CONTEXT

Facet tropism is defined as the angular difference between the left and the right facet orientation. Facet tropism was suggested to be associated with the disc degeneration and facet degeneration in the lumbar spine. However, little is known about the relationship between facet tropism and pathologic changes in the cervical spine and the mechanism behind.

PURPOSE

This study was conducted to investigate the biomechanical impact of facet tropism on the intervertebral disc and facet joints.

STUDY DESIGN

A finite element analysis study.

METHODS

The computed tomography (CT) scans of a 28-year-old male volunteer was used to construct the finite element model. First, a symmetrical cervical model from C2 to C7 was constructed. The facet orientations at each level were simulated using the data from our previously published study. Second, the facet orientations at the C5-C6 level were altered to simulate facet tropism with respect to the sagittal plane. The angular difference of the moderate facet tropism model was set to be 7 degrees, whereas the severe facet tropism model was set to be 14 degrees. The inferior of the C7 vertebra was fixed. A 75 N follower loading was applied to simulate the weight of the head. A 1.0 N⋅m moments was applied on the odontoid process of the C2 to simulate flexion, extension, lateral bending, and axial rotation.

RESULTS

The intradiscal pressure (IDP) at the C5-C6 level of the severe facet tropism model increased by 49.02%, 57.14%, 39.06%, and 30.67%, under flexion, extension, lateral bending, and axial rotation moments, in comparison with the symmetrical model. The contact force of the severe facet tropism model increased by 35.64%, 31.74%, 79.26%, and 59.47% from the symmetrical model under flexion, extension, lateral bending, and axial rotation, respectively.

CONCLUSIONS

Facet tropism with respect to the sagittal plane at the C5-C6 level increased the IDP and facet contact force under flexion, extension, lateral bending, and axial rotation. The results suggested that facet tropism might be the anatomic risk factor of the development of cervical disc degeneration or facet degeneration. Future clinical studies are in need to verify the biomechanical impact of facet tropism on the development of degenerative changes in the cervical spine.

A Nociceptive Role for Integrin Signaling in Pain After Mechanical Injury to the Spinal Facet Capsular Ligament

Integrins modulate chemically-induced nociception in a variety of inflammatory and neuropathic pain models. Yet, the role of integrins in mechanically-induced pain remains undefined, despite its well-known involvement in cell adhesion and mechanotransduction. Excessive spinal facet capsular ligament stretch is a common injury that induces morphological and functional changes in its innervating afferent neurons and can lead to pain. However, the local mechanisms underlying the translation from tissue deformation to pain signaling are unclear, impeding effective treatment. Therefore, the involvement of the integrin subunit β1 in pain signaling from facet injury was investigated in complementary in vivo and in vitro studies. An anatomical study in the rat identified expression of the integrin subunit β1 in dorsal root ganglion (DRG) neurons innervating the facet, with greater expression in peptidergic than non-peptidergic DRG neurons. Painful facet capsule stretch in the rat upregulated the integrin subunit β1 in small- and medium-diameter DRG neurons at day 7. Inhibiting the α2β1 integrin in a DRG-collagen culture prior to its stretch injury prevented strain-induced increases in axonal substance P (SP) in a dose-dependent manner. Together, these findings suggest that integrin subunit β1-dependent pathways may contribute to SP-mediated pain from mechanical injury of the facet capsular ligament.

The Interface of Mechanics and Nociception in Joint Pathophysiology: Insights From the Facet and Temporomandibular Joints

Chronic joint pain is a widespread problem that frequently occurs with aging and trauma. Pain occurs most often in synovial joints, the body's load bearing joints. The mechanical and molecular mechanisms contributing to synovial joint pain are reviewed using two examples, the cervical spinal facet joints and the temporomandibular joint (TMJ). Although much work has focused on the macroscale mechanics of joints in health and disease, the combined influence of tissue mechanics, molecular processes, and nociception in joint pain has only recently become a focus. Trauma and repeated loading can induce structural and biochemical changes in joints, altering their microenvironment and modifying the biomechanics of their constitutive tissues, which themselves are innervated. Peripheral pain sensors can become activated in response to changes in the joint microenvironment and relay pain signals to the spinal cord and brain where pain is processed and perceived. In some cases, pain circuitry is permanently changed, which may be a potential mechanism for sustained joint pain. However, it is most likely that alterations in both the joint microenvironment and the central nervous system (CNS) contribute to chronic pain. As such, the challenge of treating joint pain and degeneration is temporally and spatially complicated. This review summarizes anatomy, physiology, and pathophysiology of these joints and the sensory pain relays. Pain pathways are postulated to be sensitized by many factors, including degeneration and biochemical priming, with effects on thresholds for mechanical injury and/or dysfunction. Initiators of joint pain are discussed in the context of clinical challenges including the diagnosis and treatment of pain.

Classification and Treatment of Chronic Neck Pain: A Longitudinal Cohort Study

BACKGROUND AND OBJECTIVES

Neck pain exerts a steep personal and socioeconomic toll, ranking as the fourth leading cause of disability. The principal determinant in treatment decisions is whether pain is neuropathic or nonneuropathic, as this affects treatment at all levels. Yet, no study has sought to classify neck pain in this manner.

METHODS

One hundred participants referred to an urban, academic military treatment facility with a primary diagnosis of neck pain were enrolled and followed up for 6 months. Pain was classified as neuropathic, possible neuropathic, or nonneuropathic using painDETECT and as neuropathic, mixed, or nociceptive by s-LANSS (self-completed Leeds Assessment of Neuropathic Symptoms and Signs pain scale) and physician designation. Based on previous studies, the intermediate possible neuropathic pain category was considered to be a mixed condition. The final classification was based on a metric combining all 3 systems, slightly weighted toward physician's judgment, which is considered the reference standard.

RESULTS

Fifty percent of participants were classified as having possible neuropathic pain, 43% as having nonneuropathic pain, and 7% with primarily neuropathic pain. Concordance was high between the various classification schemes, ranging from a low of 62% between painDETECT and physician designation for possible neuropathic pain, to 83% concordance between s-LANSS and the 2 other systems for neuropathic pain. Individuals with neuropathic pain reported higher levels of baseline disability, were more likely to have a coexisting psychiatric illness, and underwent surgery more frequently than other pain categories, but were also more likely to report greater reductions in disability after 6 months.

CONCLUSIONS

Although pure neuropathic pain comprised a small percentage of our cohort, 50% of our population consisted of mixed pain conditions containing a possible neuropathic component. There was significant overlap between the various classification schemes.

The Role of Exercise and Patient Education in the Noninvasive Management of Whiplash

Synopsis The majority of people with whiplash-associated disorder do not have neurological deficit or fracture and are therefore largely managed with nonsurgical interventions such as exercise, patient education, and behavioral-based interventions. To date, clinical guidelines, systematic reviews, and the results of high-quality randomized controlled trials recommend exercise and patient education as the primary interventions for people in both acute and chronic stages after injury. However, the relatively weak evidence and small effect sizes in individual trials have led authors of some systematic reviews to reach equivocal recommendations for either exercise or patient education, and led policy makers and funders to question whether the more expensive intervention (exercise) should be funded at all. Physical therapists, one of the most commonly consulted professionals treating individuals with whiplash-associated disorder, need to look beyond the evidence for insights as to what role patient education and exercise should play in the future management of whiplash. This clinical commentary therefore will review the evidence for exercise, patient education, and behavioral-based interventions for whiplash and provide clinical insight as to the future role that exercise and patient education should play in the management of this complex condition. Possible subgroups of patients who may best respond to exercise will be explored using stratification based on impairments, treatment response, and risk/prognostic factors. J Orthop Sports Phys Ther 2017;47(7):481-491. Epub 16 Jun 2017. doi:10.2519/jospt.2017.7138.

Stretch-induced network reconfiguration of collagen fibres in the human facet capsular ligament

Biomaterials can display complex spatial patterns of cellular responses to external forces. Revealing and predicting the role of these patterns in material failure require an understanding of the statistical dependencies between spatially distributed changes in a cell's local biomechanical environment, including altered collagen fibre kinematics in the extracellular matrix. Here, we develop and apply a novel extension of network science methods to investigate how excessive tensile stretch of the human cervical facet capsular ligament (FCL), a common source of chronic neck pain, affects the local reorganization of collagen fibres. We define collagen alignment networks based on similarity in fibre alignment angles measured by quantitative polarized light imaging. We quantify the reorganization of these networks following macroscopic loading by describing the dynamic reconfiguration of network communities, regions of the material that display similar fibre alignment angles. Alterations in community structure occur smoothly over time, indicating coordinated adaptation of fibres to loading. Moreover, flexibility, a measure of network reconfiguration, tracks the loss of FCL's mechanical integrity at the onset of anomalous realignment (AR) and regions of AR display altered community structure. These findings use novel network-based techniques to explain abnormal collagen fibre reorganization, a dynamic and coordinated multivariate process underlying tissue failure.

Immunohistochemical investigation of nerve fiber presence and morphology in elderly cervical spine meniscoids

BACKGROUND CONTEXT

Innervation of anatomical structures is fundamental to their capacity to generate nociceptive impulses. Cervical spine meniscoids are hypothesized to be contributors to neck pain; however, their innervation is not comprehensively understood.

PURPOSE

This study aimed to examine the presence and morphology of nerve fibers within cervical spine meniscoids and adjacent joint capsules.

STUDY DESIGN

This is a cross-sectional study.

PATIENT SAMPLE

The sample consists of cervical hemispines of 12 embalmed cadavers (mean [standard deviation] age 82.9 [6.5] years, six female, six left). Either the right or the left half of the cervical spine (hemispine) of each cadaver was included in the sample. So six left sides and six right sides of the cadaver cervical spines made up the 12 hemispines that formed the sample.

METHODS

Cervical spine meniscoids and adjacent joint capsules were excised from lateral atlantoaxial and cervical zygapophyseal (C2-C3 to C6-C7) joints (n=67), then paraffin embedded. Meniscoids were sectioned sagittally (5 µm), slide mounted, and immunohistochemistry was performed using primary antibodies to neurofilament heavy (NF-H) and pan-neurofilament (Pan-NF) to identify nerve tissue. The study was supported by institutional graduate student funding. The authors have no conflicts of interest to declare.

RESULTS

Seventy-seven meniscoids (23 lateral atlantoaxial, 54 cervical zygapophyseal) were extracted and processed (154 sections in total). Sixty-four individual nerve fiber bundles were identified (26 NF-H positive, 38 Pan-NF positive) from 14 meniscoids. Nerves immunoreactive to both NF-H and Pan-NF were identified in 13 of 77 meniscoids (10 of 14 lateral atlantoaxial joint) from 11 joints (eight cadavers). Nerves were always located in joint capsules except three exclusively Pan-NF immunoreactive nerve fiber bundles from two adipose meniscoids.

CONCLUSIONS

The low nerve prevalence in elderly cervical spine meniscoids, with nerves only found in two adipose type meniscoids, suggests these structures may play a minimal role in cervical nociception generation in this demographic. The joint capsules, which were more frequently innervated, appear to be more likely generators of nociception in the elderly. Joint capsule nerves were mostly NF-H positive, indicating potential Aδ-fiber presence.

Morphology of Cervical Spine Meniscoids in Individuals With Chronic Whiplash-Associated Disorder: A Case-Control Study

Study Design Case-control study. Background Cervical spine meniscoids are thought to contribute to neck pain and hypomobility in individuals with chronic whiplash-associated disorder (WAD); however, their morphology has not been studied in a clinical population. Objectives To investigate cervical spine meniscoid morphology in individuals with chronic WAD. Methods Twenty volunteers with chronic WAD (mean ± SD age, 39.3 ± 11.0 years; 10 female) and 20 age- and sex-matched controls (age, 39.1 ± 10.6 years) underwent cervical spine magnetic resonance imaging. Lateral atlantoaxial and zygapophyseal joints (C2-3 to C6-7) were inspected for meniscoids. Length of meniscoid protrusion was measured and composition (adipose/fibrous/fibroadipose) assessed. Data were analyzed using Wilcoxon signed-rank tests and linear and logistic regression (P<.05). Results Meniscoids were identified in the chronic WAD (n = 317) and control (n = 296) groups. At the lateral atlantoaxial joints, median meniscoid length was greater in the control group (ventral, 6.07 mm; dorsal, 7.24 mm) than the WAD group (ventral, 5.01 mm; P = .06 and dorsal, 6.48 mm; P<.01). At the dorsal aspect of zygapophyseal joints, meniscoids were more frequently fibrous in the chronic WAD group (odds ratio = 2.38, P<.01; likelihood ratio test: χ²₂, 9.02; P = .01). Conclusion In individuals with chronic WAD, lateral atlantoaxial meniscoids were shorter and dorsal cervical zygapophyseal meniscoids were more fibrous, suggesting alterations in meniscoid composition. This may have pathoanatomical implications in chronic WAD. J Orthop Sports Phys Ther 2016;46(10):902-910. Epub 3 Sep 2016. doi:10.2519/jospt.2016.6702.

Cervical Spine Involvement in Mild Traumatic Brain Injury: A Review

Background. There is a lack of scientific evidence in the literature on the involvement of the cervical spine in mTBI; however, its involvement is clinically accepted. Objective. This paper reviews evidence for the involvement of the cervical spine in mTBI symptoms, the mechanisms of injury, and the efficacy of therapy for cervical spine with concussion-related symptoms. Methods. A keyword search was conducted on PubMed, ICL, SportDiscus, PEDro, CINAHL, and Cochrane Library databases for articles published since 1990. The reference lists of articles meeting the criteria (original data articles, literature reviews, and clinical guidelines) were also searched in the same databases. Results. 4,854 records were screened and 43 articles were retained. Those articles were used to describe different subjects such as mTBI's signs and symptoms, mechanisms of injury, and treatments of the cervical spine. Conclusions. The hypothesis of cervical spine involvement in post-mTBI symptoms and in PCS (postconcussion syndrome) is supported by increasing evidence and is widely accepted clinically. For the management and treatment of mTBIs, few articles were available in the literature, and relevant studies showed interesting results about manual therapy and exercises as efficient tools for health care practitioners.

Functional anatomy of the spine

Among other important features of the functional anatomy of the spine, described in this chapter, is the remarkable difference between the design and function of the cervical spine and that of the lumbar spine. In the cervical spine, the atlas serves to transmit the load of the head to the typical cervical vertebrae. The axis adapts the suboccipital region to the typical cervical spine. In cervical intervertebrtal discs the anulus fibrosus is not circumferential but is crescentic, and serves as an interosseous ligament in the saddle joint between vertebral bodies. Cervical vertebrae rotate and translate in the sagittal plane, and rotate in the manner of an inverted cone, across an oblique coronal plane. The cervical zygapophysial joints are the most common source of chronic neck pain. By contrast, lumbar discs are well designed to sustain compression loads, but rely on posterior elements to limit axial rotation. Internal disc disruption is the most common basis for chronic low-back pain. Spinal muscles are arranged systematically in prevertebral and postvertebral groups. The intrinsic elements of the spine are innervated by the dorsal rami of the spinal nerves, and by the sinuvertebral nerves. Little modern research has been conducted into the structure of the thoracic spine, or the causes of thoracic spinal pain.

Cervical zygapophysial (facet) joint pain: effectiveness of interventional management strategies

Diagnostic facet joint nerve blocks have been utilized in the diagnosis of cervical facet joint pain in patients without disk herniation or radicular pain due to a lack of reliable noninvasive diagnostic measures. Therapeutic interventions include intra-articular injections, facet joint nerve blocks and radiofrequency neurotomy. The diagnostic accuracy and effectiveness of facet joint interventions have been assessed in multiple diagnostic accuracy studies, randomized controlled trials (RCTs), and systematic reviews in managing chronic neck pain. This assessment shows there is Level II evidence based on a total of 11 controlled diagnostic accuracy studies for diagnosing cervical facet joint pain in patients without disk herniation or radicular pain utilizing controlled diagnostic blocks. Due to significant variability and internal inconsistency regarding prevalence in a heterogenous population; despite 11 studies, evidence is determined as Level II. Prevalence ranged from 36% to 67% with at least 80% pain relief as the criterion standard with a false-positive rate ranging from 27% to 63%. The evidence is Level II for the long-term effectiveness of radiofrequency neurotomy and facet joint nerve blocks in managing cervical facet joint pain. There is Level III evidence for cervical intra-articular injections.

Modulation of Cervical Facet Joint Nociception and Pain Attenuates Physical and Psychological Features of Chronic Whiplash: A Prospective Study

OBJECTIVE

To investigate changes in clinical (physical and psychological) features of individuals with chronic whiplash-associated disorder who had previously undergone cervical radiofrequency neurotomy at the time point when the effects of radiofrequency neurotomy had dissipated and pain returned.

DESIGN

Prospective cohort observational trial of consecutive patients.

SETTING

Tertiary spinal intervention centre in Calgary, Alberta, Canada.

PATIENTS

A total of 53 consecutive individuals with chronic whiplash-associated disorder.

METHODS

Individuals underwent radiofrequency neurotomy and were assessed before radiofrequency neurotomy, at 1 and 3 months postprocedure, and then after the return of pain (approximately 10 months postprocedure).

MAIN OUTCOME MEASUREMENTS

Quantitative sensory tests (pressure; thermal pain thresholds; brachial plexus provocation test), nociceptive flexion reflex, and motor function (cervical range of movement; craniocervical flexion test) were measured. Self-reported disability, psychological distress, pain catastrophization, and posttraumatic stress disorder symptoms also were measured.

RESULTS

Upon the return of pain after radiofrequency neurotomy, levels of disability increased (P < .0001), and were no different to those before radiofrequency neurotomy (P = .99). There also was a significant deterioration in quantitative sensory testing measures and reduced cervical range of motion after the return of pain (all P < .05); all approaching values were recorded before radiofrequency neurotomy (P > .22). There were no significant changes in pressure hyperalgesia (P > .054) or craniocervical flexion test performance (P > .07) after the return of pain. Psychological distress and pain catastrophizing increased significantly after the return of pain (P < .01), and again were no different than measures taken prior to radiofrequency neurotomy (P > .13). However, there was no difference in number or severity of posttraumatic stress symptoms after the return of pain (P > .30).

CONCLUSIONS

Physical and psychological features of chronic whiplash-associated disorder are modulated dynamically with cervical radiofrequency neurotomy. These findings indicate that peripheral nociception is involved in the manifestations of chronic whiplash-associated disorder in this cohort of individuals.

Morphology and morphometry of lateral atlantoaxial joint meniscoids

The lateral atlantoaxial joints contain folds of synovium termed meniscoids that may potentially contribute to cervical spine pain; however, the anatomy of these structures has not been comprehensively investigated. The purpose of this study was to explore the morphology and morphometry of lateral atlantoaxial joint meniscoids. Twelve cadaveric hemi-spines (6 female; 6 left; mean 81.5 years, SD 7.3) were obtained for dissection and disarticulation of the lateral atlantoaxial joints. Meniscoids were identified and measurements made of surface area, length, and surrounding articular cartilage degeneration. Tissue was sectioned sagittally, stained with hematoxylin and eosin, and examined by light microscopy. Data were analyzed descriptively and using nonparametric techniques. Ventral and dorsal meniscoids (24 in total) were found in each joint, and could be classified histologically into adipose (32%), fibrous (41%), and fibroadipose (27%) meniscoids. No significant associations were found between meniscoid size and age, histology, cartilage degeneration, or joint position. Meniscoid length in males was significantly greater than in females (P = 0.04). Fibrous meniscoids were noted to be associated with articular cartilage degeneration, and adipose and fibroadipose meniscoids with intact cartilage (P = 0.05). Fibrous meniscoids tended to be located dorsally (78%), whereas adipose meniscoids were mostly located ventrally (86%). Distinct patterns in lateral atlantoaxial joint meniscoid morphology were observed, including the association of fibrous meniscoid composition with dorsal joint position and articular cartilage degeneration. The clinical significance of these patterns remains uncertain, and further research is needed to examine these structures across the lifespan and in cervical pathology.

The anatomy and morphometry of cervical zygapophyseal joint meniscoids

PURPOSE

Meniscoids are folds of synovial membrane that project into the articular cavities of zygapophyseal joints throughout the cervical spine. These structures have been implicated in musculoskeletal neck pain; however, their anatomy has not been extensively investigated. The purpose of this study was to explore the morphometry and composition of the cervical zygapohyseal joint meniscoids.

METHODS

Twelve adult cadaveric hemi-spines were dissected and their C2-3 to C6-7 zygapophyseal joints disarticulated (six female; six left; mean 81.5 years, SD 7.3 years). Meniscoids were identified and their surface area, protrusion length and articular cartilage degeneration measured. Specimens were then sectioned sagittally, stained with haematoxylin and eosin, and examined with a light microscope. Data were analysed descriptively and using non-parametric hypothesis testing (significance p < 0.05).

RESULTS

Meniscoids were identified in 86% of zygapophyseal joints examined; 50% contained both ventral and dorsal meniscoids, 7% contained a ventral meniscoid only and 29% contained a dorsal meniscoid only. Meniscoids were classified as adipose (4%), fibrous (74%), or fibroadipose (22%) based upon histological composition. There were no significant associations between meniscoid size (surface area or protrusion length) and gender, position in joint, spinal level, or articular degeneration. Increased articular degeneration was associated with fibrous meniscoid classification.

CONCLUSIONS

The morphological patterns observed, such as the association of fibrous meniscoids with cartilage degeneration, may provide insight into the significance of the zygapophyseal joint meniscoids in neck pathology. Further investigation is needed to explore the morphological qualities of these structures in a pathological population.

In vivo cervical facet joint capsule deformation during flexion-extension

STUDY DESIGN

Nonrandomized controlled cohort.

OBJECTIVE

To characterize subaxial cervical facet joint kinematics and facet joint capsule (FJC) deformation during in vivo, dynamic flexion-extension. To assess the effect of single-level anterior arthrodesis on adjacent segment FJC deformation.

SUMMARY OF BACKGROUND DATA

The cervical facet joint has been identified as the most common source of neck pain, and it is thought to play a role in chronic neck pain related to whiplash injury. Our current knowledge of cervical facet joint kinematics is based on cadaveric mechanical testing.

METHODS

Fourteen asymptomatic controls and 9 C5-C6 arthrodesis patients performed full range of motion flexion-extension while biplane radiographs were collected at 30 Hz. A volumetric model-based tracking process determined 3-dimensional vertebral position with submillimeter accuracy. FJC fibers were modeled and grouped into anterior, lateral, posterior-lateral, posterior, and posterior-medial regions. FJC fiber deformations (total, shear, and compression-distraction) relative to the static position were determined for each cervical motion segment (C2-C3 through C6-C7) during flexion-extension.

RESULTS

No significant differences in the rate of fiber deformation in flexion were identified among motion segments (P = 0.159); however, significant differences were observed among fiber regions (P < 0.001). Significant differences in the rate of fiber deformation in extension were identified among motion segments (P < 0.001) and among fiber regions (P = 0.001). The rate of FJC deformation in extension adjacent to the arthrodesis was 45% less than that in corresponding motion segments in control subjects (P = 0.001).

CONCLUSION

In control subjects, FJC deformations are significantly different among vertebral levels and capsule regions when vertebrae are in an extended orientation. In a flexed orientation, FJC deformations are different only among capsule regions. Single-level anterior arthrodesis is associated with significantly less FJC deformation adjacent to the arthrodesis when the spine is in an extended orientation.

LEVEL OF EVIDENCE

4.

An early intervention programme had no detectable influence on the health status of people with musculoskeletal injuries following road traffic crashes: comparative study

OBJECTIVE

To compare the health status of people with minor injuries from road traffic crashes that are exposed to an early, active intervention programme (intervention group) with those receiving usual care (control group) over a 12 month period.

DESIGN

Prospective comparative study using sequential cohorts.

SUBJECTS

People presenting to hospital emergency departments with mild to moderate musculoskeletal injuries following road traffic crashes.

MAIN OUTCOME MEASURES

Physical Component Score (PCS) and Mental Component Score (MCS) of the Short Form 36 (SF-36) health status measure; Hospital Anxiety and Depression Scale (HADS) and the Functional Rating Index (FRI) recorded immediately post-crash, at 6 months and at 12 months after injury.

RESULTS

There were 95 participants allocated to the control group and 98 allocated to the intervention group. Participants were enrolled at a mean of 9.3 days following the crash. There were no significant differences in baseline health measures between the groups. Apart from a small improvement in anxiety for the intervention group, there were no significant differences in health status between the groups. Twenty percent of participants in the intervention group received treatment from external healthcare providers that was inconsistent with the recommendations of the intervention programme.

CONCLUSIONS

The intervention programme failed to result in a clinically significant improvement in health outcomes compared with usual care. There is some evidence to suggest that the intervention had some psychological benefits, as evidenced by the small improvement in anxiety levels. Limited adherence, frequent use of co-interventions, or other factors (such as intervention content or intensity) may have reduced its effect.

Cervical spine injury biomechanics: Applications for under body blast loadings in military environments

BACKGROUND

While cervical spine injury biomechanics reviews in motor vehicle and sports environments are available, there is a paucity of studies in military loadings. This article presents an analysis on the biomechanics and applications of cervical spine injury research with an emphasis on human tolerance for underbody blast loadings in the military.

METHODS

Following a brief review of published military studies on the occurrence and identification of field trauma, postmortem human subject investigations are described using whole body, intact head-neck complex, osteo-ligamentous cervical spine with head, subaxial cervical column, and isolated segments subjected to differing types of dynamic loadings (electrohydraulic and pendulum impact devices, free-fall drops).

FINDINGS

Spine injuries have shown an increasing trend over the years, explosive devices are one of the primary causal agents and trauma is attributed to vertical loads. Injuries, mechanisms and tolerances are discussed under these loads. Probability-based injury risk curves are included based on loading rate, direction and age.

INTERPRETATION

A unique advantage of human cadaver tests is the ability to obtain fundamental data to delineate injury biomechanics and establish human tolerance and injury criteria. Definitions of tolerances of the spine under vertical loads based on injuries have implications in clinical and biomechanical applications. Primary outputs such as forces and moments can be used to derive secondary variables such as the neck injury criterion. Implications are discussed for designing anthropomorphic test devices that may be used to predict injuries in underbody blast environments and improve the safety of military personnel.

An anatomical and immunohistochemical characterization of afferents innervating the C6-C7 facet joint after painful joint loading in the rat

STUDY DESIGN

This study used retrograde neuronal tracing and immunohistochemistry to identify neurons innervating the C6-C7 facet joint and those expressing calcitonin gene-related peptide (CGRP) in the dorsal root ganglion (DRG) of rats after painful cervical facet joint injury.

OBJECTIVE

The objective of this study was to characterize the innervation of the C6-C7 facet joint after painful joint injury in the rat.

SUMMARY OF BACKGROUND DATA

The cervical facet joint is a source of neck pain, and its loading can initiate persistent pain. CGRP is a nociceptive neurotransmitter; peptidergic afferents have been identified in the facet joint's capsule. Although studies suggest that facet joint injury alters CGRP expression in joint afferents, the distribution of neurons innervating the C6-C7 facet joint and their expression of CGRP after a painful joint injury have not been investigated.

METHODS

Holtzman rats (Harlan Sprague-Dawley, Indianapolis, IN) received an intra-articular injection of cholera toxin subunit B in the C6-C7 facet joints. After injection, subgroups underwent either a painful joint distraction or sham procedure. Mechanical sensitivity was assessed, and immunohistochemical techniques were used to quantify CGRP expression and cholera toxin subunit B labeling in the C5-C8 DRGs.

RESULTS

Facet joint distraction-induced (P ≤ 0.0002) hypersensitivity. Neurons labeled by the joint injection were identified in the C5-C8 DRGs. Significantly, more (P ≤ 0.0001) cholera toxin subunit B-positive neurons were identified in the C7 DRG than any other level. At C7, 54.4% ± 15.3% of those neurons were also CGRP-positive, whereas only 41.5% ± 5.4% of all neurons were CGRP-positive; this difference was significant (P = 0.0084).

CONCLUSION

The greatest number of afferents from the C6-C7 facet joint has cell bodies in the C7 DRG, implicating this level as the most relevant for pain from this joint. In addition, peptidergic afferents seem to have an important role in facet joint-mediated pain.

Treatment of post-traumatic pain, and autonomic and muscular dysfunction by ganglion impar block and medial branch block of the facet joints: A case report

Introduction Patients exposed to whiplash trauma are at risk of developing pain and dysfunction of the neck and shoulder. Although rarely discussed in the literature, some patients also develop autonomic dysfunction. Case presentation A previously healthy 41-year-old woman was involved in a "head-on" car crash. During the following 3 years she developed severe and complex post-traumatic pain syndrome, which consisted of neck pain, lumbar pain, sensory-motor dysfunction, and myoclonic muscular contractions. Despite pharmacotherapy, physiotherapy, and rehabilitation, her condition worsened, resulting in severe disability. Fourteen years after the car crash, an interventional pain therapy program was started, which consisted of sympathetic ganglion impar block and medial branch blocks of facet joints at different levels. These treatment strategies ultimately normalized her sensory-motor dysfunction, reduced her autonomic dysfunction, and stopped the myoclonic muscular contractions. Conclusion This case highlights a possible interaction between the pain-generating facet joints, the somatosensory nervous system, and the autonomic/sympathetic nervous systems. The case also highlights the importance of identifying autonomic dysfunction in patients with persisting pain syndromes. Implications This complex case shows that many clinical phenomena cannot be explained using our present knowledge of pain mechanisms. We hope that readers who have observed similar cases can learn from our case, and are encouraged to publish their observations.

Somatic symptoms beyond those generally associated with a whiplash injury are increased in self-reported chronic whiplash. A population-based cross sectional study: the Hordaland Health Study (HUSK)

BACKGROUND

Chronic whiplash leads to considerable patient suffering and substantial societal costs. There are two competing hypothesis on the etiology of chronic whiplash. The traditional organic hypothesis considers chronic whiplash and related symptoms a result of a specific injury. In opposition is the hypothesis that chronic whiplash is a functional somatic syndrome, and related symptoms a result of society-induced expectations and amplification of symptoms. According to both hypotheses, patients reporting chronic whiplash are expected to have more neck pain, headache and symptoms of anxiety and depression than the general population. Increased prevalence of somatic symptoms beyond those directly related to a whiplash neck injury is less investigated. The aim of this study was to test an implication derived from the functional hypothesis: Is the prevalence of somatic symptoms as seen in somatization disorder, beyond symptoms related to a whiplash neck injury, increased in individuals self-reporting chronic whiplash? We further aimed to explore recall bias by comparing the symptom profile displayed by individuals self-reporting chronic whiplash to that among those self-reporting a non-functional injury: fractures of the hand or wrist. We explored symptom load, etiologic origin could not be investigated in this study.

METHODS

Data from the Norwegian population-based "Hordaland Health Study" (HUSK, 1997-99); N = 13,986 was employed. Chronic whiplash was self-reported by 403 individuals and fractures by 1,746. Somatization tendency was measured using a list of 17 somatic symptoms arising from different body parts and organ systems, derived from the research criteria for somatization disorder (ICD-10, F45).

RESULTS

Chronic whiplash was associated with an increased level of all 17 somatic symptoms investigated (p<0.05). The association was moderately strong (group difference of 0.60 standard deviation), only partly accounted for by confounding. For self-reported fractures symptoms were only slightly elevated. Recent whiplash was more commonly reported than whiplash-injury a long time ago, and the association of interest weakly increased with time since whiplash (r = 0.016, p = 0.032).

CONCLUSIONS

The increased prevalence of somatic symptoms beyond symptoms expected according to the organic injury model for chronic whiplash, challenges the standard injury model for whiplash, and is indicative evidence of chronic whiplash being a functional somatic syndrome.