Cervical helical axis characteristics and its center of rotation during active head and upper arm movements—comparisons of whiplash-associated disorders, non-specific neck pain and asymptomatic individuals

Concurrent Validity of Cervical Movement Tests Using VR Technology-Taking the Lab to the Clinic

Reduced cervical range of motion (ROM) and movement velocity are often seen in people with neck pain. Objective assessment of movement characteristics is important to identify dysfunction, to inform tailored interventions, and for the evaluation of the treatment effect. The purpose of this study was to investigate the concurrent validity of a newly developed VR technology for the assessment of cervical ROM and movement velocity. VR technology was compared against a gold-standard three-dimensional optical motion capture system. Consequently, 20 people, 13 without and 7 with neck pain, participated in this quantitative cross-sectional study. ROM was assessed according to right/left rotation, flexion, extension, right/left lateral flexion, and four diagonal directions. Velocity was assessed according to fast cervical rotation to the right and left. The correlations between VR and the optical system for cervical ROM and velocity were excellent, with intraclass correlation coefficient (ICC) values > 0.95. The mean biases between VR and the optical system were ≤ 2.1° for the ROM variables, <12°/s for maximum velocity, and ≤3.0°/s for mean velocity. In conclusion, VR is a useful assessment device for ROM and velocity measurements with clinically acceptable biases. It is a feasible tool for the objective measurement of cervical kinematics in the clinic.

Reliability of Shoulder Helical Axes During Intransitive and Transitive Upper Limb Tasks

Shoulder complex stability can be estimated in vivo through the analysis of helical axes (HAs) dispersion during upper limb movements. The study aimed at investigating test-retest reliability of shoulder HAs dispersion parameters during upper limb tasks. Twenty healthy volunteers performed 2 intransitive (shoulder flexion and rotation) and one transitive (combing) tasks with the dominant and nondominant upper limbs during 2 recording sessions at 1-week distance. Kinematics was detected through an optoelectronic system. Mean distance and mean angle (MA) were adopted as HAs dispersion indexes. Reliability was excellent for mean distance (intraclass correlation coefficient [ICC]: .91) and MA (ICC: .92) during dominant flexion, and good for MA (ICC: .90) during nondominant flexion. Moderate reliability was found for HAs parameters during rotation (ICCs from .70 to .59), except for MA during dominant rotation where reliability was poor. Reliability was good for mean distance (ICC: .83) and moderate for MA (ICC: .67) during the dominant combing task, whereas no reliability was found during the nondominant combing task. HAs dispersion parameters revealed high reliability during simple intransitive tasks with the dominant limb. Reliability decreased with the increase in task complexity due to the increase in movement variability. HAs dispersion technique could be used to assess shoulder complex stability in patients after rehabilitation or surgery.

Effect of non-specific neck pain on the path of the instantaneous axis of rotation of the neck during its flexion-extension movement

Non-specific neck pain is a common musculoskeletal disorder with a high prevalence and involves impaired joint movement pattern. Therefore, this study aimed to compare the trajectory of the instantaneous axis of rotation(IAR) in flexion-extension movements of the neck between people with and without nonspecific neck pain, using functional data analysis techniques. Furthermore, possible relationships between neck kinematics and perceived pain and disability were explored. Seventy-three volunteers participated in this cross-sectional study. They were allocated in a non-specific pain group (PG, n = 28) and a control group (CG, n = 45). A cyclic flexion-extension movement was assessed by a video photogrammetry system and numerical and functional variables were computed to analyze IAR trajectory during movement. Moreover, to explore possible relationships of these variables with pain and neck disability, a visual analogue scale (VAS) and the neck disability index (NDI) were used. The instantaneous axis of rotation trajectory during the flexion-extension cyclic movement described a path like Greek letter rho both in the CG and the PG, but this trajectory was shorter and displaced upward in the PG, compared to the CG. A reduction of the displacement range and a rise in the vertical position of the IAR were related to VAS and NDI scores. Non-specific neck pain is associated with a higher location of the instantaneous axis of rotation and a decrease in length of the path traveled during the flexion-extension movement. This study contributes to a better description of neck movement in people with non-specific neck pain, which would help to plan an individualized treatment.

Perceived pain and disability but not fear of movement are associated with altered cervical kinematics in people with acute neck pain following a whiplash injury

OBJECTIVES

To determine if measures of cervical kinematics are altered in people with acute whiplash associated disorders (WAD) and secondarily, to examine whether kinematic variables are associated with self-reported outcomes.

METHODS

We recruited people with acute WAD within 15 days after a motor vehicle collision and asymptomatic control participants. All participants performed active neck movements at a self-determined velocity. Maximal range of motion (ROM), peak and mean velocity of movement, smoothness of movement, and cervical joint position error were assessed. Moreover, self-reported measures of perceived pain and disability, pain catastrophising, and fear of movement were obtained.

RESULTS

Sixty people participated: 18 with acute WAD (mean age [SD] 38.7 [12.0]) and 42 as asymptomatic controls (mean age [SD] 38.4 [10.2]). Participants with acute WAD showed significantly decreased ROM in all movement directions (p < 0.0001). All participants with acute WAD showed a reduction in the mean and peak velocity of movement in all directions (p < 0.0001) and the number of velocity peaks was significantly higher (i.e., reduced smoothness of movement) in those with acute WAD in all directions (p < 0.0001). Repositioning acuity following cervical rotation was not significantly different between groups. Neck pain-related disability showed the largest number of significant associations with kinematic features, while fear of movement was not associated with measures of cervical kinematics.

CONCLUSIONS

Participants with acute WAD presented with altered cervical kinematics compared to asymptomatic participants. Several measures of cervical kinematics were associated with the level of pain and disability in people with acute WAD but not their fear of movement.

Cervical spine and muscle adaptation after spaceflight and relationship to herniation risk: protocol from 'Cervical in Space' trial

Background

Astronauts have a higher risk of cervical intervertebral disc herniation. Several mechanisms have been attributed as causative factors for this increased risk. However, most of the previous studies have examined potential causal factors for lumbar intervertebral disc herniation only. Hence, we aim to conduct a study to identify the various changes in the cervical spine that lead to an increased risk of cervical disc herniation after spaceflight.

Methods

A cohort study with astronauts will be conducted. The data collection will involve four main components: a) Magnetic resonance imaging (MRI); b) cervical 3D kinematics; c) an Integrated Protocol consisting of maximal and submaximal voluntary contractions of the neck muscles, endurance testing of the neck muscles, neck muscle fatigue testing and questionnaires; and d) dual energy X-ray absorptiometry (DXA) examination. Measurements will be conducted at several time points before and after astronauts visit the International Space Station. The main outcomes of interest are adaptations in the cervical discs, muscles and bones.

Discussion

Astronauts are at higher risk of cervical disc herniation, but contributing factors remain unclear. The results of this study will inform future preventive measures for astronauts and will also contribute to the understanding of intervertebral disc herniation risk in the cervical spine for people on Earth. In addition, we anticipate deeper insight into the aetiology of neck pain with this research project.

Trial registration

German Clinical Trials Register, DRKS00026777. Registered on 08 October 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05684-0.

Head kinematics in patients with neck pain compared to asymptomatic controls: a systematic review

BACKGROUND

Neck pain is one of the most common musculoskeletal disorders encountered by healthcare providers. A precise assessment of functional deficits, including sensorimotor control impairment, is regarded necessary for tailored exercise programmes. Sensorimotor control can be measured by kinematic characteristics, such as velocity, acceleration, smoothness, and temporal measures, or by assessing movement accuracy. This systematic review aims to identify movement tasks and distinct outcome variables used to measure kinematics and movement accuracy in patients with neck pain and present their results in comparison to asymptomatic controls.

METHODS

Electronic searches were conducted in MEDLINE, PEDro, Cochrane Library and CINAHL databases from inception to August 2020. Risk of bias of included studies was assessed. Movement tasks and specific outcome parameters used were collated. The level of evidence for potential group differences in each outcome variable between patients with neck pain and controls was evaluated.

RESULTS

Twenty-seven studies examining head kinematics and movement accuracy during head-aiming, functional and unconstrained movement tasks of the head were included. Average Risk of Bias of included studies was moderate. In total, 23 different outcome variables were assessed. A strong level of evidence for an increased movement time and for an increased number of errors during head aiming tasks was found. Moderate evidence was found in traumatic neck pain for a decreased mean velocity, peak acceleration, and reaction time, and for point deviation and time on target during head aiming tasks. Moderate evidence was found for decreased acceleration during unconstrained movements, too. Results on the remaining movement task and outcome variables showed only limited, very limited or even conflicting level of evidence for patients with neck pain to differ from controls.

CONCLUSIONS

Sensorimotor control in NP in the way of kinematic and movement accuracy characteristics of head motion was examined in head aiming, functional or unconstrained movement tasks. The results from this review indicate that for some characteristics that describe sensorimotor control, patients with NP differ from healthy controls.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42020139083.

Effectiveness of Specific Neck Exercise for Nonspecific Neck Pain; Usefulness of Strategies for Patient Selection and Tailored Exercise-A Systematic Review With Meta-Analysis

OBJECTIVE

Specific neck exercises (SNE) targeting deep cervical flexors and extensors are commonly used for the treatment of nonspecific neck pain (NSNP). However, whether SNE are more effective than alternative exercise interventions (AEI) remains unclear. Furthermore, it has been postulated that SNE may be most effective when they are tailored and targeted to patients with evidence of motor control dysfunction, yet this notion also remains unproven. The objectives of this study were to compare the effectiveness of SNE with that of AEI for reducing pain and disability in people with NSNP and to assess whether the effectiveness of SNE is increased when the exercises are tailored and provided to patients with evidence of motor control dysfunction.

METHODS

For this systematic review with meta-analysis, Medline, Web of Science, Scopus, and Physiotherapy Evidence Database were searched. Eligibility criteria included randomized controlled trials evaluating the effectiveness of SNE against that of AEI in people with NSNP. Meta-analysis included subgroup analyses to determine the effect of exercise tailoring and participant selection criteria on the effectiveness of SNE.

RESULTS

Twelve studies were included. Meta-analysis revealed greater effectiveness of SNE in the short to medium term for reducing pain (pooled standardized mean difference [SMD] = -0.41; 95% CI = -0.76 to -0.06; P = .02) and disability (pooled SMD = -0.41; 95% CI = -0.78 to -0.04; P = .03) but no differences in the long term for pain (pooled SMD = -1.30; 95% CI = -3.35 to 0.75; P = .21) and disability (pooled SMD = -1.81; 95% CI = -4.29 to 0.67; P = .15), although evidence was limited for the latter. The effectiveness of SNE was not superior in studies that included only participants with motor control dysfunction or when exercises were tailored to each participant. Overall, the studies were of low quality. Grading of Recommendations Assessment, Development and Evaluation revealed low certainty, serious risk of bias, and inconsistency of findings for short- to medium-term effects and very low certainty, serious risk of bias, and very serious inconsistency for long-term effects.

CONCLUSION

The preferential use of SNE may be recommended to achieve better short- to medium-term outcomes, although the low quality of evidence affects the certainty of these findings. Currently used strategies for selecting patients and tailoring SNE are not supported by the evidence and therefore cannot be recommended for clinical practice.

IMPACT

SNE are more effective than AEI for reducing pain and disability in patients with NSNP in the short to medium term, but overall evidence is of low quality, affecting the certainty of the findings. Tests of muscle dysfunction (mostly the craniocervical flexion test) currently used in studies to select patients and tailor SNE do not result in greater effectiveness of these exercises.

LAY SUMMARY

Evidence suggests SNE are more effective than other forms of exercise, although evidence is overall of low quality. Use of the craniocervical flexion test in isolation to select participants and/or tailor SNE cannot be recommended.

Analysis and evaluation of the systems used for the assessment of the cervical spine function: a systematic review

Neck injuries and pathologies are widespread and cause disability. Clinicians use different tools to measure the cervical spine' mobility to diagnose different disorders. There are many reliable assessment methods for this purpose, but their benefits have not been deeply investigated and compared, as well as their measurement results. This review aims to summarise the advantages, accuracy, and reliability, of measurement tools and devices used in studies or trails related to the neck and cervical spine evaluation, to evidence the use of inertial sensors and compare them, to highlight the best assessment systems and their characteristics. A literature review has been performed in a range of five years, to obtain information about cervical spine evaluation. Studies that met the established inclusion criteria were selected and classified according their pathology studied, objectives and methodologies followed when evaluating the cervical spine functionality. Studies were described chronologically highlighting the tools employed, where the motion capture systems and cervical range of motion devices stood out as the most used and reliable methods. Cervical spine assessment studies employing systems with inertial sensors as an accurate method, is not evidenced in the sample. However, they are widely tested and different studies validate these systems for their clinical area use, obtaining high reliability and repeatability. Thereby, this review argues that inertial sensors have proven to be a portable, and easy to use tool for the evaluation of neck and its related pathologies, with a great accuracy level.

Dispersion of shoulder helical axes during upper limb movements after muscle fatigue

Shoulder complex control of motion is influenced by neuromuscular function and can be quantified through the analysis of helical axes (HAs) dispersion. Muscle fatigue is a variable able to influence neuromuscular control, altering muscle activation timing and proprioception. The aim of the study was to describe shoulder complex HAs dispersion after muscle fatigue during upper limb movements of young healthy subjects. Thirty healthy right-handed volunteers (age 23.2 ± 2.6 years) were asked to perform a test made up of 15 humerothoracic flexion and rotation movements using both upper limbs in two different recording sessions. After each session, muscles of the tested movement were fatigued in isometric condition at dominant side. After fatigue, subjects repeated the test. Kinematics was recorded by an optoelectronic system and HAs dispersion was computed using Mean Distance (MD) and Mean Angle (MA) for the entire Range of Motion (RoM) and in portions of RoM. After fatigue of shoulder flexion muscles, greater MD (p = 0.001) and MA (p = 0.019) were found on the dominant side. After fatigue of shoulder rotation muscles, greater MD and MA were found on the dominant (p = 0.002 for MD; p = 0.047 for MA) and non-dominant (p = 0.038 for MD; p = 0.019 for MA) sides. Independently of fatigue, greater MA was found in portions of RoM with higher external resistance torque in flexion and rotation tasks. Muscle fatigue increases shoulder complex HAs dispersion, probably due to alteration in neuromuscular control. This data should be considered when exercise involving upper arms are proposed to subjects undergoing fatigue.

Dispersion of knee helical axes during walking in young and elderly healthy subjects

Knee joint rotation center displacement can be estimated in vivo through the analysis of helical axis (HAs) dispersion. HAs can be analyzed during walking, providing information on joint stability. The study aim was to describe knee HAs dispersion during walking in dominant and non-dominant legs of young and elderly healthy subjects. Twenty young (YG: age 23.3 ± 2.4 years) and twenty elderly (EG: age 69.3 ± 4.6 years) healthy subjects were asked to walk on a treadmill at a self-selected speed with reflective markers placed bilaterally on thighs and shanks to detect HAs dispersion and knee kinematics with an optoelectronic system. HAs dispersion was described during the following four phases of gait cycle: (1) flexion from 95% of the previous gait cycle to 10% of the subsequent gait cycle, (2) extension from 10% to 40%, (3) flexion from 40% to 75% and (4) extension from 75% to 95% of the gait cycle. Mean Distance (MD) and Mean Angle (MA) were used as HAs dispersion indexes during each gait phase. Participants showed greater MD and MA in sagittal and frontal planes during the first and second phases. EG revealed higher MD (p = 0.001) and MA (p < 0.001) during the first phase and higher MA (p = 0.001) during the fourth phase in both dominant and non-dominant legs on the sagittal plane. HAs dispersion could be related to the amount of forces acting on knee (first two phases) and knee degeneration (elderly). These results may be used as reference data in further studies on HAs dispersion in presence of knee pathologies or after knee surgery or rehabilitation.

Instantaneous helical axis estimation of glenohumeral kinematics: The impact of rotator cuff pathology

The rotator cuff is theorized to contribute to force couples required to produce glenohumeral kinematics. Impairment in these force couples would theoretically result in impaired ball-and-socket kinematics. Although less frequently used than traditional kinematic descriptors (e.g., Euler angles, joint translations), helical axes are capable of identifying alterations in ball-and-socket kinematics by quantifying the variability (i.e., dispersion) in axis orientation and position during motion. Consequently, assessing glenohumeral helical dispersion may provide indirect evidence of rotator cuff function. The purpose of this exploratory study was to determine the extent to which rotator cuff pathology is associated with alterations in ball-and-socket kinematics. Fifty-one participants were classified into one of five groups based on an assessment of the supraspinatus using diagnostic imaging: asymptomatic healthy, asymptomatic tendinosis, asymptomatic partial-thickness tear, asymptomatic full-thickness tear, symptomatic full-thickness tear. Glenohumeral kinematics were quantified during coronal plane abduction using a biplane x-ray system and described using instantaneous helical axes. The degree to which glenohumeral motion coincided with ball-and-socket kinematics was described using the angular and positional dispersion about the optimal helical axis and pivot, respectively. No statistically significant difference was observed between groups in angular dispersion. However, symptomatic individuals with a full-thickness supraspinatus tear had significantly more positional dispersion than asymptomatic individuals with a healthy supraspinatus or tendinosis. These findings suggest that symptomatic individuals with a full-thickness supraspinatus tear exhibit impaired ball-and-socket kinematics, which is believed to be associated with a disruption of the glenohumeral force couples.

Eccentric exercise and delayed onset muscle soreness reduce the variability of active cervical movements

People with acute neck pain commonly present with restricted neck movement. However, it is unknown whether the presence of acute pain affects the quality of neck movement, specifically neck movement variability. We examined the effects of acute neck muscle soreness induced via eccentric exercise in healthy volunteers, on the variability of neck movement by examining changes in parameters of the helical axis during active neck movements. An experimental, single-arm repeated measures study recruited 32 healthy participants, male and female, aged between 18 and 55 years. Repetitive active neck movements (flexion-extension, bilateral lateral flexion and bilateral rotation) were performed at different speeds, either at full range of motion (RoM) or restricted to 45° RoM at baseline, pre-exercise (T0), immediately following eccentric neck exercise (T1), 24 h (T2) and 48 h post-exercise (T3). The mean distance (MD) and mean angle (MA) parameters of the helical axis were extracted to quantify movement variability. MD, measured during movements performed at full RoM, reduced significantly at T2 compared to T0 (P = 0.001) regardless of direction or speed of movement. MA was significantly lower at T2 and T3 compared to T1 (P = 0.029 and P = 0.033, respectively). When RoM was restricted to 45°, significantly lower MD values were observed at T3 compared to T1 (P = 0.034), and significantly lower MA values were measured at T3 compared to T0, T1 and T2 (all P < 0.0001). This study uniquely demonstrates that neck movement variability is reduced immediately after, 24 h and 48 h after eccentric exercise, indicating that acute neck muscle soreness modifies the quality of neck movement.

Análisis de Flexo-extensión del Cuello Mediante el Uso de Visión Artificial

En el tratamiento del dolor cervical se emplean equipos y técnicas que no miden la intensidad del dolor del paciente, sino que únicamente permiten observar los daños estructurales de dicha región. Sin embargo, la evaluación de éste dolor se puede llevar a cabo al analizar las variables cinemáticas de los tres movimientos de la articulación cervical: flexo-extensión, flexo-lateral y rotación. En este trabajo estudiaremos la fiabilidad de la técnica de fotogrametría, mediante el uso de una cámara de bajo costo, denominado Kinect V1. La cámara Kinect adquirirá los parámetros cinemáticos del movimiento de flexo-extensión de la articulación del cuello y, técnicas de visión artificial y de procesamiento de imágenes de profundidad/color del sensor Kinect serán empleadas para obtener las trayectorias de los marcadores anatómicos y técnicos. Se utilizará un filtro de Kalman para corregir el seguimiento continuo de las trayectorias de los marcadores técnicos y, consecuentemente, las coordenadas espaciales de cada marcador. Los datos fueron obtenidos de siete sujetos de prueba, entre hombres y mujeres, físicamente sanos. Las edades de los sujetos están comprendidas entre 17 y 40 años. Asociados a las coordenadas de cada marcador técnico, calculamos los parámetros cinemáticos de velocidad angular, aceleración angular y desplazamiento angular, para obtener los parámetros de fiabilidad y correlación entre pruebas. Esto último se realizó al analizar el error estándar medio, el índice de correlación múltiple y los índices de correlación de Pearson, empleados para análisis clínico. El alto índice de correlación entre los ensayos realizados nos permite ratificar la fiabilidad de nuestra metodología.

Paths of the cervical instantaneous axis of rotation during active movements-patterns and reliability

The instantaneous helical axis (IHA) is a characteristic of neck movement that is very sensitive to changes in coordination and that has potential in the assessment of functional alterations. For its application in the clinical setting, normative patterns must be available, and its reliability must be established. The purpose of this work is to describe the continuous paths of the IHA during cyclic movements of flexion-extension (FE), lateral bending (LB), and axial rotation (AR) and to quantify their reliability. Fifteen healthy volunteers participated in the study; two repetitions were made on the same day (by different operators) and over an 8-day interval (by the same operator) to evaluate the inter-operator and inter-session reliability, respectively. The paths described by the IHA suggest a sequential movement of the vertebrae in the FE movement, with a large vertical displacement (mean, 10 cm). The IHA displacement in LB and AR movements are smaller. The paths described by the IHAs have a very high reliability for FE movement, although it is somewhat lower for LB and RA movements. The standard error of measurement (SEM) is less than 0.5 cm. These results show that the paths of the IHA are reliable enough to evaluate changes in the coordination of intervertebral movement. Graphical abstract A video photogrammetry system is used to record the cyclic movements of the neck, from which the continuous trajectories of the associated instantaneous helical axis (IHA) are calculated. We have analyzed the movements of flexion-extension (FE), lateral flexion (LB), and axial rotation (AR) for a sample of 15 healthy subjects. The measurements have been repeated with two different operators (in the same session) and in two separate sessions (same operator). IHA displacement patterns have been obtained in each movement, and the reliability of the measurement of such IHA trajectories has been estimated.

Helical axis analysis to quantify humeral kinematics during shoulder rotation

Information pertaining to the helical axis during humeral kinematics during shoulder rotation may be of benefit to better understand conditions such as shoulder instability. The aim of this study is to quantify the behavior of humeral rotations using helical axis (HA) parameters in three different conditions. A total of 19 people without shoulder symptoms participated in the experiment. Shoulder kinematics was measured with an optoelectric motion capture system. The subjects performed three different full range rotations of the shoulder. The shoulder movements were analyzed with the HA technique. Four parameters were extracted from the HA of the shoulder during three different full-range rotations: range of movement (RoM), mean angle (MA), axis dispersion (MDD), and distance of their center from the shoulder (D). No significant differences were observed in the RoM for each condition between left and right side. The MA of the axis was significantly lower on the right side compared to the left in each of the three conditions. The MDD was also lower for the right side compared to the left side in each of the three conditions.The four parameters proposed for the analysis of shoulder kinematics showed to be promising indicators of shoulder instability.

Electronic measures of movement impairment, repositioning, and posture in people with and without neck pain-a systematic review

BACKGROUND

Neck pain is a major public health problem. Our objective was to describe differences in measures of movement and posture between people with and without neck pain.

METHODS

PubMed and Embase were searched before 15 February 2019 for studies comparing people with neck pain with controls using electronic measurements of neck movement and/or posture. Data were extracted on participants, device, test methods, active range of motion (RoM) and quality of motion, joint positioning sense, and posture. Study quality was assessed using the quality assessment of studies of diagnostic accuracy included in systematic reviews (QUADAS) and Guidelines for Reporting Reliability and Agreement Studies (GRRAS) guidelines.

RESULTS

Thirty-six studies were included: 24 studies included measurement of active RoM, 15 quality of motion, 12 joint positioning sense, and 5 cervical spine posture. Measurements and test methods were heterogeneous. The reporting of study populations and methods were poor, whereas devices and statistics were well described. All studies on RoM showed reduced active RoM in people with neck pain when compared with controls, 5 of 10 studies reported reduced movement speed for people with neck pain, and 5 of 9 studies reported significantly greater joint positioning error for people with neck pain compared with controls. Due to heterogeneous test parameters and methods, no conclusion regarding differences in conjunct motion, tracking a motion pattern, and measures of posture could be drawn.

CONCLUSIONS

People with neck pain appear to have reduced active RoM, movement speed, and head repositioning accuracy when compared with controls. However, quality of reviewed studies was low and better descriptions of participants and methods are required before firm conclusions can be drawn.

Dispersion of helical axes during shoulder movements in young and elderly subjects

The shoulder complex (SC) consists of joints with little congruence and its active and passive structures ensure its stability. Stability of the SC rotation centre during upper arm movements can be estimated through the analysis of Helical Axes (HAs) dispersion. The aim of this study was to describe shoulder HAs dispersion during upper limb movements performed with dominant and non-dominant arms by young and elderly subjects. Forty subjects participated in the study (20 young: age 24.8 ± 2.8 years and 20 elderly: age 71.7 ± 6.3 years). Subjects were asked to perform four cycles of 15 rotations, flexions, elevations and abductions with one arm at a time at constant speed. Reflective markers were placed on participants' arms and trunk in order to detect movements and the HAs dispersion with an optoelectronic system. Mean Distance (MD) from the HAs barycenter and Mean Angle (MA) were used as HAs dispersion indexes. Young subjects showed significant lower MD compared to the elderly during all motion ranges of rotation, flexion and elevation (p < 0.001). Moreover, the MD was lower in the dominant arm compared to the contralateral for rotation (p = 0.049) and flexion (p = 0.019). The results may be due to joint degeneration described in elderly subjects and differences in neuromuscular control of SC stability.

People With Chronic Neck Pain Walk With a Stiffer Spine

Study Design Controlled laboratory study, case-control design. Objective To evaluate spine kinematics and gait characteristics in people with nonspecific chronic neck pain. Background People with chronic neck pain present with a number of sensorimotor and biomechanical alterations, yet little is known about the influence of neck pain on gait and motions of the spine during gait. Methods People with chronic nonspecific neck pain and age- and sex-matched asymptomatic controls walked on a treadmill at 3 different speeds (self-selected, 3 km/h, and 5 km/h), either with their head in a neutral position or rotated 30°. Tridimensional motion capture was employed to quantify body kinematics. Neck and trunk rotations were derived from the difference between the transverse plane component of the head and thorax and thorax and pelvis angles to provide an indication of neck and trunk rotation during gait. Results Overall, the patient group showed shorter stride length compared to the control group (P<.001). Moreover, the patients with neck pain showed smaller trunk rotations (P<.001), regardless of the condition or speed. The difference in the amount of trunk rotation between groups became larger for the conditions of walking with the head rotated. Conclusion People with chronic neck pain walk with reduced trunk rotation, especially when challenged by walking with their head positioned in rotation. Reduced rotation of the trunk during gait may have long-term consequences on spinal health. J Orthop Sports Phys Ther 2017;47(4):268-277. Epub 3 Feb 2017. doi:10.2519/jospt.2017.6768.

Can parameters of the helical axis be measured reliably during active cervical movements?

Convex hull area (CHA) and mean angle (MA) have been proposed to describe the behaviour of the helical axis during joint kinematics. This study investigates the intra- and inter-session reliability of CHA and MA during active movements of the cervical spine. Twenty-seven healthy volunteers (19 women) aged 23 ± 2.8 years participated. Each volunteer was tested on two sessions. All participants were instructed to perform the following active movements of the cervical spine: rotation, flexion/extension and lateral bending, each performed to full range and repeated ten consecutive times. Cervical movements were registered with an electromagnetic tracking system. For each participant, each movement and each session, range of motion (ROM), CHA and MA were extracted. ROM showed high intra- and inter-session reliability during all cervical spine movements using this method. Overall, the intra- and inter-session reliability of the helical axis parameters varied depending on the movement direction and ranged from fair to almost perfect. The intra- and inter-session reliability of CHA and MA were almost perfect during rotation whereas the intra- and inter-session reliability of CHA was substantial during lateral bending and intra- and inter-session reliability of MA ranged from fair to substantial during flexion/extension and lateral bending. This is the first study to evaluate the reliability of helical axis measures during active movements of the cervical spine. The results show that CHA and MA are promising descriptors of cervical kinematics which could be applied in future studies to evaluate neck function in patients with cervical spine disorders.

Compensatory Versus Noncompensatory Shoulder Movements Used for Reaching in Stroke

Background The extent to which the upper-limb flexor synergy constrains or compensates for arm motor impairment during reaching is controversial. This synergy can be quantified with a minimal marker set describing movements of the arm-plane. Objectives To determine whether and how (a) upper-limb flexor synergy in patients with chronic stroke contributes to reaching movements to different arm workspace locations and (b) reaching deficits can be characterized by arm-plane motion. Methods Sixteen post-stroke and 8 healthy control subjects made unrestrained reaching movements to targets located in ipsilateral, central, and contralateral arm workspaces. Arm-plane, arm, and trunk motion, and their temporal and spatial linkages were analyzed. Results Individuals with moderate/severe stroke used greater arm-plane movement and compensatory trunk movement compared to those with mild stroke and control subjects. Arm-plane and trunk movements were more temporally coupled in stroke compared with controls. Reaching accuracy was related to different segment and joint combinations for each target and group: arm-plane movement in controls and mild stroke subjects, and trunk and elbow movements in moderate/severe stroke subjects. Arm-plane movement increased with time since stroke and when combined with trunk rotation, discriminated between different subject groups for reaching the central and contralateral targets. Trunk movement and arm-plane angle during target reaches predicted the subject group. Conclusions The upper-limb flexor synergy was used adaptively for reaching accuracy by patients with mild, but not moderate/severe stroke. The flexor synergy, as parameterized by the amount of arm-plane motion, can be used by clinicians to identify levels of motor recovery in patients with stroke.

Head-trunk kinematics during high-velocity-low-amplitude manipulation of the cervical spine in asymptomatic subjects: helical axis computation and anatomic motion modeling

OBJECTIVE

This study aimed to analyze the in vivo 3-dimensional kinematics of the head during cervical manipulation including helical axis (HA) computation and anatomic motion representation.

METHODS

Twelve asymptomatic volunteers were included in this study. An osteopathic practitioner performed 1 to 3 manipulations (high-velocity and low-amplitude [HVLA] multiple component technique) of the cervical spine (between C2 and C5) with the patient in the sitting position. During manipulation, head motion was collected using an optoelectronic system and expressed relative to the thorax. Motion data were processed to analyze primary and coupled motions and HA parameters. Anatomic motion representation including HA was obtained.

RESULTS

During manipulation, average maximal range of motion was 39° (SD, 6°), 21° (SD, 7°), and 8° (SD, 5°) for lateral bending (LB), axial rotation (AR), and flexion extension, respectively. For the impulse period, magnitude averaged of 8° (SD, 2°), 5° (SD, 2°), and 3° (SD, 2°), for LB, AR, and flexion extension, respectively. Mean impulse velocity was 139°/s (SD, 39°/s). Concerning AR/LB ratios, an average of 0.6 (SD, 0.3) was observed for global motion, premanipulation positioning, and impulse. Mean HA was mostly located ipsilateral to the impulse side and displayed an oblique orientation.

CONCLUSION

This study demonstrated limited range of AR during cervical spine manipulation and provided new perspectives for the development of visualization tools, which might be helpful for practitioners and for the analysis of cervical manipulation using HA computation and anatomic representation of motion.

Comparison of neck movement smoothness between patients with mechanical neck disorder and healthy volunteers using the spectral entropy method

PURPOSE

Mechanical neck disorder is one of the most common health issues. No related observations have applied spectral entropy to explore the smoothness of cervical movement. Therefore, the objectives were to ascertain whether the spectral entropy of time-series linear acceleration could extend to estimate the smoothness of cervical movement and compare the characteristics of the smoothness of cervical movement in patients with mechanical neck pain (MND) with healthy volunteers.

METHODS

The smoothness of cervical movement during cervical circumduction from 36 subjects (MND: n = 18, asymptomatic: n = 18) was quantified by the spectral entropy of time-series linear acceleration and other speed-dependent parameters, respectively.

RESULTS

Patients with MND showed significantly longer movement time, higher value in the spectral entropy and wider band response in frequency spectrum than healthy volunteers (P = 0.01).

CONCLUSIONS

The spectral entropy would be suitable to discriminate the smoothness of cervical movement between patients with MND with healthy volunteers and demonstrated patients with MND had significantly less smooth cervical movement.

Methodological analysis of finite helical axis behavior in cervical kinematics

Although a far more stable approach compared to the six degrees of freedom analysis, the finite helical axis (FHA) struggles with interpretational difficulties among health professionals. The analysis of the 3D-motion axis has been used in clinical studies, but mostly limited to qualitative analysis. The aim of this study is to introduce a novel approach for the quantification of the FHA behavior and to investigate the effect of noise and angle intervals on the estimation of FHA parameters. A simulation of body movement has been performed introducing Gaussian noise on position and orientation of a virtual sensor showing linear relation between the simulated noise and the error in the corresponding parameter. FHA axis behavior was determined by calculating the intersection points of the FHA with a number of planes perpendicular to the FHA using the Convex Hull (CH) technique. The angle between the FHA and each of the IHA was also computed and its distribution was also analyzed. Input noise has an inversely proportional relationship with the angle steps of FHA estimation. The proposed FHA quantification approach can be useful to provide new approaches to researchers and to improve insight for the clinician in order to better understand joint kinematics.

Measurement of cervical sensorimotor control: the reliability of a continuous linear movement test

BACKGROUND

Cervical sensorimotorcontrol (cSMC) is traditionally assessed by head repositioning accuracy (HRA) measurements. A disadvantage of the HRA measurements is their static character and lack of visual feedback. In 2008, Sjölander et al. developed a continuous linear movement test (CLMT). This CLMT uses several kinematic parameters, such as reduced range of motion (ROM), velocity and movement smoothness, to quantify altered sensorimotor functions.

OBJECTIVE

Investigate the inter and intra rater reliability of a CLMT.

DESIGN

Reliability study.

METHODS

Fifty asymptomatic adults were recruited. Five outcome measures were obtained: the time (t) needed to perform one movement, variation in time (var-t), ROM, peak velocity (peak-v) and Jerk index (Cj). A 3D analysis of cervical movements during the CLMT was made using ZEBRIS™. MATLAB™ was used to process data provided by the ZEBRIS™ device. These data were used to calculate ICC or κw-values, depending on the normality of the distribution, using SPSS.

RESULTS

The intra rater reliability shows slight to moderate agreement for t (ICC: 0.19-0.42 and κw: 0.42) and peak-v (κw: 0.27-0.47), moderate to substantial agreement for var-t (ICC: 0.54-0.73) and ROM (ICC: 0.43-0.65) and fair to substantial agreement for Cj (κw: 0.27-0.69). The inter rater reliability shows moderate to almost perfect agreement for t (ICC: 0.54-0.93), almost perfect agreement for var-t (κw: 0.81-0.96) and ROM (ICC: 0.86-0.95), slight to moderate agreement for peak-v (κw: -0.03-0.44) and slight to fair agreement for Cj (κw: 0.00-0.31).

CONCLUSION

Time and ROM are presently the most reliable outcome measures. However, it must be noted that the discriminant validity of the time parameters needs further investigation.

Kinetic analysis of anterior cervical discectomy and fusion supplemented with transarticular facet screws

OBJECT The clinical success rates of anterior cervical discectomy and fusion (ACDF) procedures are substantially reduced as more cervical levels are included in the fusion procedure. One method that has been proposed as an adjunctive technique for multilevel ACDF is the placement of screws across the facet joints ("transfacet screws"). However, the biomechanical stability imparted by transfacet screw placement (either unilaterally or bilaterally) has not been reported. Therefore, the purpose of this study was to determine the acute stability conferred by implementation of unilateral and bilateral transfacet screws to an ACDF construct. METHODS Eight C2-T1 fresh-frozen human cadaveric spines (3 female and 5 male; mean age 50 years) were tested. Three different instrumentation variants were performed on cadaveric cervical spines across C4-7: 1) ACDF with an intervertebral spacer and standard plate/screw instrumentation; 2) ACDF with an intervertebral spacer and standard plate/screw instrumentation with unilateral facet screw placement; and 3) ACDF with an intervertebral spacer and standard plate/screw instrumentation with bilateral facet screw placement. Kinetic ranges of motion in flexion-extension, lateral bending, and axial rotation at 1.5 Nm were captured after each of these procedures and were statistically analyzed for significance. RESULTS All 3 fixation scenarios produced statistically significant reductions (p < 0.05) in all 3 bending planes compared with the intact condition. The addition of a unilateral facet screw to the ACDF construct produced significant reductions at the C4-5 and C6-7 levels in lateral bending and axial rotation but not in flexion-extension motion. Bilateral facet screw fixation did not produce any statistically significant decreases in flexion-extension motion compared with unilateral facet screw fixation. However, in lateral bending, significant reductions at the C4-5 and C5-6 levels were observed with the addition of a second facet screw. The untreated, adjacent levels (C2-3, C3-4, and C7-1) did not demonstrate significant differences in range of motion. CONCLUSIONS The data demonstrated that adjunctive unilateral facet screw fixation to an ACDF construct provides significant gains in stability and should be considered a potential option for increasing the likelihood for obtaining a successful arthrodesis for multilevel ACDF procedures.

Validation protocol for assessing the upper cervical spine kinematics and helical axis: An in vivo preliminary analysis for axial rotation, modeling, and motion representation

Context:

The function of the upper cervical spine (UCS) is essential in the kinematics of the whole cervical spine. Specific motion patterns are described at the UCS during head motions to compensate coupled motions occurring at the lower cervical segments.

Aims:

First, two methods for computing in vitro UCS discrete motions were compared to assess three-dimensional (3D) kinematics. Secondly, the same protocol was applied to assess the feasibility of the procedure for in vivo settings. Also, this study attempts to expose the use of anatomical modeling for motion representation including helical axis.

Settings and Design:

UCS motions were assessed to verify the validity of in vitro 3D kinematics and to present an in vivo procedure for evaluating axial rotation.

Materials and Methods:

In vitro kinematics was sampled using a digitizing technique and computed tomography (CT) for assessing 3D motions during flexion extension and axial rotation. To evaluate the feasibility of this protocol in vivo, one asymptomatic volunteer performed an MRI kinematics evaluation of the UCS for axial rotation. Data processing allowed integrating data into UCS 3D models for motion representation, discrete joint behavior, and motion helical axis determination.

Results:

Good agreement was observed between the methods with angular displacement differences ranging from 1° to 1.5°. Helical axis data were comparable between both methods with axis orientation differences ranging from 3° to 6°. In vivo assessment of axial rotation showed coherent kinematics data compared to previous studies. Helical axis data were found to be similar between in vitro and in vivo evaluation.

Conclusions:

The present protocol confirms agreement of methods and exposes its feasibility to investigate in vivo UCS kinematics. Moreover, combining motion analysis, helical axis representation, and anatomical modeling, constitutes an innovative development to provide new insights for understanding motion behaviors of the UCS.

Muscle activity and head kinematics in unconstrained movements in subjects with chronic neck pain; cervical motor dysfunction or low exertion motor output?

Background

Chronic neck pain after whiplash associated disorders (WAD) may lead to reduced displacement and peak velocity of neck movements. Dynamic neck movements in people with chronic WAD are also reported to display altered movement patterns such as increased irregularity, which is suggested to signify impaired motor control. As movement irregularity is strongly related to the velocity and displacement of movement, we wanted to examine whether the increased irregularity in chronic WAD could be accounted for by these factors.

Methods

Head movements were completed in four directions in the sagittal plane at three speeds; slow (S), preferred (P) and maximum (M) in 15 men and women with chronic WAD and 15 healthy, sex and age-matched control participants. Head kinematics and measures of movement smoothness and symmetry were calculated from position data. Surface electromyography (EMG) was recorded bilaterally from the sternocleidomastoid and splenius muscles and the root mean square (rms) EMG amplitude for the accelerative and decelerative phases of movement were analyzed.

Results

The groups differed significantly with regard to movement velocity, acceleration, displacement, smoothness and rmsEMG amplitude in agonist and antagonist muscles for a series of comparisons across the test conditions (range 17 – 121%, all p-values < 0.05). The group differences in peak movement velocity and acceleration persisted after controlling for movement displacement. Controlling for differences between the groups in displacement and velocity abolished the difference in measures of movement smoothness and rmsEMG amplitude.

Conclusions

Simple, unconstrained head movements in participants with chronic WAD are accomplished with reduced velocity and displacement, but with normal muscle activation levels and movement patterns for a given velocity and displacement. We suggest that while reductions in movement velocity and displacement are robust changes and may be of clinical importance in chronic WAD, movement smoothness of unconstrained head movements is not.

Quantitative study of knee joint surface configurations using a morpho-functional approach

Several models exist in the literature to describe knee kinematics. In this paper we propose a morpho-functional approach based on the determination of a simulated kinematics of flexion/extension from a unique CT scan acquisition. We will compare this kinematics to the real one obtained from experiments on one cadaver. In parallel, we have developed quantitative tools for the assessment of the motion. As the computation of these tools depends on the bone morphology, they can describe the state of the joint, which is not classical in the literature. Both tools follow the evolution of the distances between two bones during motion. They are called the Figure of Articular Coherence and the Index of Articular Coherence. In order to verify the relevance of these tools, we have tested them to compare different surgeries of Anterior Cruciate Ligament (ACL) reconstruction.

A wearable inertial system to assess the cervical spine mobility: comparison with an optoelectronic-based motion capture evaluation

In clinical settings, the cervical range of motion (ROM) is commonly used to assess cervical spine function. This study aimed at assessing cervical spine mobility based on head and thorax kinematics measured with a wearable inertial system (WS). Sequences of imposed active head movements (lateral bending, axial rotation and flexion-extension) were recorded in ten controls and 13 patients who had undergone an arthrodesis. Orientation of the head relative to the thorax was computed in terms of 3D helical angles and compared with the values obtained using an optoelectronic reference system (RS). Movement patterns from WS and RS showed excellent concurrent validity (CMC up to 1.00), but presented slight differences of bias (mean bias<2.5°) and dispersion (mean dispersion<4.2°). ROM obtained using WS also showed some differences compared to RS (mean difference<5.7°), within the range of those reported in literature. WS enabled the observation of the same significant differences between controls and patients as RS. Moreover, ROM from WS presented good test-retest repeatability (ICC between 0.63 and 0.99 and SEM<6.2°). In conclusion, WS can provide angles and ROM comparable to those obtained with RS and relevant for the cervical assessment after treatment.

Instantaneous helical axis methodology to identify aberrant neck motion

BACKGROUND

Neck pain afflicts 30-50% of the U.S. population annually; however we currently have poor diagnostic differentiation techniques to inform individualized treatment. Planar neck kinematics has been shown to be correlated with neck pain, but neck motion is much more complex than pure planar activities. Our objective was to define a methodology for determining aberrant neck kinematics and assess it.

METHODS

We examined a complex neck kinematic activity of neck circumduction and computed the pathway of motion using the instantaneous helical axis approach in 81 patients with non-specific neck pain and in 20 non-matched symptom free subjects. Neck circumduction, or rolling of the head, represents a complex neck kinematic activity, investigating the innate coupled motion of the cervical spine at the end ranges of motion in all directions. Instance of discontinuities in the helical axis patterns, or folds, were identified and labeled as occurrences of aberrant motion.

FINDINGS

The instances of aberrant motion, or folds, which are nearly non-existent in the healthy sample group, are present in both the pre- and post-treatment neck pain patients. Following a treatment intervention of the symptomatic patients, pain and neck disability index decreased significantly (P<0.001) concomitant with a decrease in the number of folds (P=0.021).

INTERPRETATION

The present study highlights a new technique using an instantaneous helical axis approach to detect subtle abnormalities in the pathway of motion of the head about the trunk, during a neck circumduction exercise.

Three-dimensional kinematic analysis of active cervical spine motion by using a multifaceted marker device

Assessing cervical range of motion (CROM) is an important part of the clinical evaluation of patients with conditions such as whiplash syndrome. This study aimed to develop a convenient and accurate system involving multifaceted marker device (MMD)-based assessment of 3-dimensional (3D) dynamic coupled CROM and joint angular velocity. We used an infrared optical tracking system and our newly developed MMD that solved problems such as marker shielding and reflection angle associated with the optical tracking devices and enabled sequential and accurate analysis of the 3D dynamic movement of the polyaxial joint and other structurally complicated joints. The study included 30 asymptomatic young male volunteers (age, 22-27 years). The MMD consisted of 5 surfaces and 5 markers and was attached to the participant's forehead. We measured active CROM (axial rotation, flexion/extension, and lateral bending) and joint angular velocity by the MMD. The MMD was easy to use, safe for patients and operators, could be constructed economically, and generated accurate data such as dynamic coupled CROM and angular velocity.

IFOMPT 2012: a rendez-vous of hands and minds

Since its founding in Montreal, Canada in 1974, the International Federation of Orthopaedic Manipulative Physical Therapists (IFOMPT) has been providing orthopaedic and manual therapists from around the world with the highest-quality learning opportunities through a conference held every 4 years. In 2012, IFOMPT is partnering with The International Private Practitioners Association (IPPA) to host this prestigious event in Quebec City, Canada. As more than 51% of the Canadian Physiotherapy Association membership is working in private practice, this adds even greater value to this quadrennial event. This conference emulates best-evidence practice in the marriage of research and clinical excellence by pulling together some of the best and brightest hands and minds in orthopaedic physiotherapy. Through a call for proposals that equally emphasized research, clinical excellence, and the knowledge translation link between the two, the IFOMPT mandate of clinical and academic excellence has been kept at the forefront of this year's conference. Included in this supplement are the IFOMPT 2012 keynote addresses, schedule, and abstracts.

Considerations in the physical rehabilitation of patients with whiplash-associated disorders

STUDY DESIGN

Review of research identifying physical impairments in the neuromuscular system in subjects with whiplash-associated disorders.

OBJECTIVE

Review the impairments in movement and neuromuscular function toward constructing research informed exercise programs.

SUMMARY OF BACKGROUND DATA

Pain and injury to the musculoskeletal system result in loss of motion and impaired neuromuscular function which impacts on functional activities, work and quality of life. Therapeutic exercise is a mainstay of rehabilitation, but the nature of the exercises prescribed are currently various and the effect sizes of current programs for patients with whiplash-associated disorders are modest at best.

METHODS

A review was undertaken of research investigating the changes in cervical motion and neuromuscular function to better inform exercise prescription and identify areas for future research. RESULTS.: Reduced range of movement as well as pathological movement patterns (reduced acceleration and velocity, reduced smoothness and irregular axes of neck movement) have been documented in subjects with whiplash-associated disorders. In relation to neuromuscular control, changes have been demonstrated in neck muscles' spatial and temporal relationships as well as in their strength and endurance. The presence or not and the extent of changes is highly variable between individuals and appears to have some relationship to pain intensity. It appears that there is a need for specificity in exercise prescription to address particular impairments rather than the use of generic programs. High pain intensity can modify effects of a therapeutic exercise program.

CONCLUSION

Pain and injury result in reorganization of the motor control strategies of neck muscles and movement. Further research is required to determine if outcomes after a whiplash injury can be improved by using research informed, individually prescribed exercise programs matched to the individual's presentation. Research into best methods of pain management is also required to facilitate physical rehabilitation.

Toward optimal early management after whiplash injury to lessen the rate of transition to chronicity: discussion paper 5

STUDY DESIGN

Expert debate and synthesis of research to inform future management approaches for acute whiplash disorders.

OBJECTIVE

To identify a research agenda toward improving outcomes for acute whiplash-injured individuals to lessen the incidence of transition to chronicity.

SUMMARY OF BACKGROUND DATA

International figures are concordant, estimating that 50% of individuals recover from pain and disability within 3 to 6 months of a whiplash injury. The remainder report continuing symptoms up to 1 to 2 years or longer postinjury. As no management approach to date has improved recovery rates, new clinical/research directions are required for early management of whiplash-injured patients.

METHODS

A group of multidisciplinary researchers critically debated evidence and current research concerning whiplash from biological, psychological, and social perspectives toward informing future research directions for management of acute whiplash.

RESULTS

It was recognized that effective treatments for acute whiplash are constrained by a limited understanding of causes of whiplash-associated disorders. Acute whiplash presentations are heterogeneous leading to the proposal that a research priority was development of a triage system based on modifiable prognostic indicators and clinical features to better inform individualized early management decisions. Other priorities identified included researching effective early pain management for individuals presenting with moderate to high levels of pain; development of best education/information for acute whiplash; testing the efficacy of stratified and individualized rehabilitation, researching modes of delivery considering psychosocial modulators of pain and disability; and the timing, nature, and mode of delivery of cognitive-behavioral therapies. Directions were highlighted for future biomechanical research into injury prevention.

CONCLUSION

The burden of whiplash injuries, the high rate of transition to chronicity, and evidence of limited effects of current management on transition rates demand new directions in evaluation and management. Several directions have been proposed for future research, which reflect the potential multifaceted dimensions of an acute whiplash disorder.

Neck motion patterns in whiplash-associated disorders: quantifying variability and spontaneity of movement

BACKGROUND

whiplash-associated disorders have usually been explored by analyzing changes in the cervical motor system function by means of static variables such as the range of motion, whereas other behavioural features such as speed, variability or smoothness of movement have aroused less interest.

METHODS

whiplash patients (n=30), control subjects (n=29) and a group of people faking the symptoms of whiplash-associated-disorders (Simulators, n=30) performed a cyclical flexion-extension movement. This movement was recorded by means of video-photogrammetry. The computed variables were: range of motion, maxima angular velocity and acceleration, and two additional variables that quantify the repeatability of a motion and its spontaneity. Two comparisons were made: Control vs. Patients and Patients vs. Simulators. At each comparison we used ANOVA to detect differences between groups and discriminant analysis to evaluate the ability of these variables to classify individuals.

FINDINGS

comparison between Controls and Patients showed significant reductions in the range of motion, and both the maximum of angular velocity and acceleration in the Patients. The most efficient discriminant model only included the range of motion and maximum angular velocity. Comparison between Patients and Simulators showed a significant reduction in all measured variables in the Simulators. The best classification model was obtained with maximum angular velocity, spontaneity and repeatability of motion.

INTERPRETATION

our results suggest that the pathological patterns differ from those of Controls in amplitude and speed of motion, but not in repeatability or spontaneity of movement. These variables are especially useful for detecting abnormal movement patterns.

Kinematics of fast cervical rotations in persons with chronic neck pain: a cross-sectional and reliability study

Background

Assessment of sensorimotor function is useful for classification and treatment evaluation of neck pain disorders. Several studies have investigated various aspects of cervical motor functions. Most of these have involved slow or self-paced movements, while few have investigated fast cervical movements. Moreover, the reliability of assessment of fast cervical axial rotation has, to our knowledge, not been evaluated before.

Methods

Cervical kinematics was assessed during fast axial head rotations in 118 women with chronic nonspecific neck pain (NS) and compared to 49 healthy controls (CON). The relationship between cervical kinematics and symptoms, self-rated functioning and fear of movement was evaluated in the NS group. A sub-sample of 16 NS and 16 CON was re-tested after one week to assess the reliability of kinematic variables. Six cervical kinematic variables were calculated: peak speed, range of movement, conjunct movements and three variables related to the shape of the speed profile.

Results

Together, peak speed and conjunct movements had a sensitivity of 76% and a specificity of 78% in discriminating between NS and CON, of which the major part could be attributed to peak speed (NS: 226 ± 88 °/s and CON: 348 ± 92 °/s, p < 0.01). Peak speed was slower in NS compared to healthy controls and even slower in NS with comorbidity of low-back pain. Associations were found between reduced peak speed and self-rated difficulties with running, performing head movements, car driving, sleeping and pain. Peak speed showed reasonably high reliability, while the reliability for conjunct movements was poor.

Conclusions

Peak speed of fast cervical axial rotations is reduced in people with chronic neck pain, and even further reduced in subjects with concomitant low back pain. Fast cervical rotation test seems to be a reliable and valid tool for assessment of neck pain disorders on group level, while a rather large between subject variation and overlap between groups calls for caution in the interpretation of individual assessments.

In vitro 3D-kinematics of the upper cervical spine: helical axis and simulation for axial rotation and flexion extension

PURPOSE

Registration of 3D-anatomical model and kinematics data is reported to be an accurate method to provide 3D-joint simulation. We applied this approach to discrete kinematics analysis of upper cervical spine (UCS) during axial rotation (AR) and flexion extension (FE) to create anatomical models with movement simulation including helical axis.

METHODS

Kinematics and CT imaging data were sampled in ten anatomical specimens. Using technical and anatomical marker digitizing, spatial position of segments was computed for five discrete positions of AR and FE using a 3D-digitizer. Computerized tomography was used to create anatomical models and to assure kinematics and imaging data registration for simulation. Kinematics was processed using orientation vector and helical axis (HA) computation.

RESULTS

Maximal standard error on marker digitizing was 0.47 mm. Range of motion and coupled movement during AR was in agreement with previous in vitro studies. HA location and orientation have shown low variation at the occipitoaxial and atlantoaxial levels for FE and AR, respectively.

CONCLUSIONS

We developed a protocol to create UCS anatomical model simulations including three-dimensional discrete kinematics, using previously validated methods. In this study, simultaneous segmental movement simulation and display of HA variations was shown to be feasible. Although partially confirming previous results, helical axis computation showed variations of motion patterns dependent on movement, level and specimen. Further in vivo investigations are needed to confirm relevance of this method in the clinical field.

A novel method for neck coordination exercise--a pilot study on persons with chronic non-specific neck pain

BACKGROUND

Chronic neck pain is a common problem and is often associated with changes in sensorimotor functions, such as reduced proprioceptive acuity of the neck, altered coordination of the cervical muscles, and increased postural sway. In line with these findings there are studies supporting the efficacy of exercises targeting different aspects of sensorimotor function, for example training aimed at improving proprioception and muscle coordination. To further develop this type of exercises we have designed a novel device and method for neck coordination training. The aim of the study was to investigate the clinical applicability of the method and to obtain indications of preliminary effects on sensorimotor functions, symptoms and self-rated characteristics in non-specific chronic neck pain

METHODS

The study was designed as an uncontrolled clinical trial including fourteen subjects with chronic non-specific neck pain. A new device was designed to allow for an open skills task with adjustable difficulty. With visual feedback, subjects had to control the movement of a metal ball on a flat surface with a rim strapped on the subjects' head. Eight training sessions were performed over a four week period. Skill acquisition was measured throughout the intervention period. After intervention subjects were interviewed about their experience of the exercise and pain and sensorimotor functions, including the fast and slow components of postural sway and jerkiness-, range-, position sense-, movement time- and velocity of cervical rotation, were measured. At six-month follow up, self-rated pain, health and functioning was collected.

RESULTS

The subjects improved their skill to perform the exercise and were overall positive to the method. No residual negative side-effects due to the exercise were reported. After intervention the fast component of postural sway (p = 0.019) and jerkiness of cervical rotation (p = 0.032) were reduced. The follow up showed decreased disability (one out of three indices) and fear of movement, and increased general health (three out of eight dimensions).

CONCLUSION

The results support the clinical applicability of the method. The improvements in sensorimotor functions may suggest transfer from the exercise to other, non-task specific motor functions and justifies a future randomized controlled trial.