Noninvasive three-dimensional analysis of cervical spine motion in normal subjects in relation to age and sex. An experimental examination

Dynamic in vivo 3D atlantooccipital kinematics during multiplanar physiologic motions

Normal biomechanics of the upper cervical spine, particularly at the atlantooccipital joint, remain poorly characterized. The purpose of this study was to determine the intervertebral kinematics of the atlantooccipital joint (occiput-C1) during three-dimensional in vivo physiologic movements. Twenty healthy young adults performed dynamic flexion/extension, axial rotation, and lateral bending while biplane radiographs were collected at 30 images per second. Motion at occiput-C1 was tracked using a validated volumetric model-based tracking process that matched subject-specific CT-based bone models to the radiographs. The occiput-C1 total range of motion (ROM) and helical axis of motion (HAM) was calculated for each movement. During flexion/extension, the occiput-C1 moved almost exclusively in-plane (ROM: 17.9 ± 6.9°) with high variability in kinematic waveforms (6.3°) compared to the in-plane variability during axial rotation (1.4°) and lateral bending (0.9°) movements. During axial rotation, there was small in-plane motion (ROM: 4.2 ± 2.5°) compared to out-of-plane flexion/extension (ROM: 12.7 ± 5.4°). During lateral bending, motion occurred in-plane (ROM: 9.0 ± 3.1°) and in the plane of flexion/extension (ROM: 7.3 ± 2.7°). The average occiput-C1 axis of rotation intersected the sagittal and coronal planes 7 mm to 18 mm superior to the occipital condyles. The occiput-C1 axis of rotation pointed 60° from the sagittal plane during axial rotation but only 10° from the sagittal plane during head lateral bending. These novel results are foundational for future work on upper cervical spine kinematics.

Neck stiffness and range of motion for young males and females

Well characterised mechanical response of the normal head-neck complex during passive motion is important to inform and verify physical surrogate and computational models of the human neck, and to inform normal baseline for clinical assessments. For 10 male and 10 female participants aged 20 to 29, the range of motion (ROM) of the neck about three anatomical axes was evaluated in active-seated, passive-lying and active-lying configurations, and the neck stiffness was evaluated in passive-lying. Electromyographic signals from the agonist muscles, normalised to maximum voluntary contractions, were used to provide feedback during passive motions. The effect of sex and configuration on ROM, and the effect of sex on linear estimates of stiffness in three regions of the moment-angle curve, were assessed with linear mixed models and generalised linear models. There were no differences in male and female ROM across all motion directions and configurations. Flexion and axial rotation ROM were configuration dependent. The passive-lying moment-angle relationship was typically non-linear, with higher stiffness (slope) closer to end of ROM. When normalising the passive moment-angle curve to active lying ROM, passive stiffness was sex dependent only for lateral bending region 1 and 2. Aggregate moment-angle corridors were similar for males and females in flexion and extension, but exhibited a higher degree of variation in applied moment for males in lateral bending and axial rotation. These data provide the passive response of the neck to low rate bending and axial rotation angular displacement, which may be useful for computational and surrogate modelling of the human neck.

Radiographic Predictors of Subaxial Subluxation After Atlantoaxial Fusion

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to clarify preoperative radiographic predictors associated with the development of subaxial subluxation (SAS) after surgery.

BACKGROUND

The incidence of atlantoaxial fusion for atlantoaxial instability has been increasing. SAS can develop after surgery despite atlantoaxial fusion with the optimal C1-C2 angle. We hypothesized that preoperative discordant angular contribution in the upper and subaxial cervical spine is associated with the occurrence of postoperative SAS.

MATERIALS AND METHODS

Patients who underwent surgery for atlantoaxial instability with a minimum 5-year follow-up and control participants were included. The O-C2 angle, C2 slope (C2S), C2-C7 cervical lordosis (CL), and T1 slope (T1S) were measured. We focused on the angular contribution ratio in the upper cervical spine to the whole CL, and the preoperative C2/T1S ratio was defined as the ratio of C2S to T1S.

RESULTS

Twenty-seven patients (SAS=11, no-SAS=16; mean age, 60.7 y old; 77.8% female; mean follow-up duration, 6.8 y) and 23 demographically matched control participants were enrolled. The SAS onset was at 4.7 postoperative years. Preoperatively, the O-C2 angle, C2-C7 CL, and T1S were comparable between the SAS, no-SAS, and control groups. The preoperative C2S and C2/T1S ratio were smaller in the SAS group than in the no-SAS or control group (C2S, 11.0 vs. 18.4 vs. 18.7 degrees; C2/T1S ratio, 0.49 vs. 0.77 vs. 0.78, P <0.05). The receiver operating characteristic curve analysis demonstrated that the C2/T1S ratio had higher specificity and similar sensitivity as a predictor of postoperative SAS than C2S (specificity: 0.90 vs. 0.87; sensitivity: 0.73 vs. 0.73). The estimated cutoff values of the C2S and C2/T1S ratio were 14 degrees and 0.58, respectively.

CONCLUSIONS

The preoperative C2/T1S ratio was closely associated with postoperative SAS. Patients with a C2/T1S ratio <0.58 were at a high risk of SAS after atlantoaxial fusion.

LEVEL OF EVIDENCE

Level 4.

Dynamics of atlantoaxial rotation related to age and sex: a cross-sectional study of 308 subjects

BACKGROUND CONTEXT

Physiological ranges and dynamic changes of atlantoaxial rotation (ROTC1/2), total cervical spine rotation (ROTCs) and the percentage of ROTC1/2 from ROTCs (ROTCperc) for different age groups have not yet been investigated in a sufficiently sized cohort. Furthermore, it is not clear whether demographic variables such a sex, smoking status or diabetes affect ROTC1/2, ROTCs and ROTCperc.

PURPOSE

Obtain physiological ranges of ROTC1/2, ROTCs and ROTCperc for different age groups and determine their age-based dynamics. Investigate whether ROTC1/2, ROTCs and ROTCperc are affected by sex, smoking status or diabetes.

DESIGN

Observational cross-sectional study.

PATIENT SAMPLE

Patients undergoing elective CT examinations of the head and neck region between August 2020 and January 2022.

OUTCOME MEASURES

Ranges of motion of ROTC1/2, ROTCs and ROTCperc in degrees.

METHODS

A total of 308 subjects underwent dynamic rotational CT examinations of the upper cervical spine. Patients were divided into three age categories A1 (27-49 years), A2 (50-69 years) and A3 (≥70 years). Category A3 was further divided into B1 (70-79 years) and B2 (≥80 years). Values of ROTC1/2, ROTCs and ROTCperc were compared between all age groups, males and females, smokers and nonsmokers, diabetics a nondiabetics. Dynamics of ROTC1/2, ROTCs related to age and sex were visualized using scatterplot and trendline models.

RESULTS

ROTC1/2 significantly decreased from group A1 (64.4°) to B2 (46.7°) as did ROTCs from A1 (131.2°) to B2 (97.6°). No significant differences of ROTperc were found between groups A1-B2 with values oscillating between 49% and 51%. Smoking and diabetes did not significantly affect ROTC1/2, ROTCs and ROTCperc, females had significantly higher ROTCs than males. Males and females demonstrated a different dynamic of ROTC1/2 and ROTCs demonstrated by out scatterplot and trendline models.

CONCLUSIONS

Both ROTC1/2 and ROTCs significantly decrease with age, whereas ROTCperc remains stable. Females demonstrated higher ROTCs and their decrease of ROTC1/2 and ROTCs occurred in higher age groups compared to males. The functional repercussions atlantoaxial fusion are variable based on patient age and sex and should be taken into account prior to surgery.

Evolution of Patient-Reported Outcome Measures, 1, 2, and 5 years after Surgery for Subaxial Cervical Spine Fractures, A Nation-Wide Registry Study

BACKGROUND CONTEXT

A longer duration of patient follow-up arguably provides more reliable data on the long-term effects of a treatment. However, the collection of long-term follow-up data is resource demanding and often complicated by missing data and patients being lost to follow-up. In surgical fixation for cervical spine fractures, data are lacking on the evolution of patient reported outcome measures (PROMs) beyond 1-year of follow-up. We hypothesized that the PROMs would remain stable beyond the 1-year postoperative follow-up mark, regardless of the surgical approach.

PURPOSE

To assess the trends in the evolution of patient-reported outcome measures (PROMs) at 1, 2-, and 5-years following surgery in patients with traumatic cervical spine injuries.

STUDY DESIGN

Nation-wide observational study on prospectively collected data.

PATIENT SAMPLE

Individuals treated for subaxial cervical spine fractures with anterior, posterior, or combined anteroposterior approaches, between 2006 and 2016 were identified in the Swedish Spine Registry (Swespine).

OUTCOME MEASURES

PROMs consisting of EQ-5D-3L_index and the Neck Disability Index (NDI) were considered.

METHODS

PROMs data were available for 292 patients at 1 and 2 years postoperatively. Five-years PROMs data were available for 142 of these patients. A simultaneous within-group (longitudinal) and between group (approach-dependent) analysis was performed using mixed ANOVA. The predictive ability of 1-year PROMs was subsequently assessed using linear regression.

RESULTS

Mixed ANOVA revealed that PROMs remained stable from 1- to 2-years as well as from 2- to 5-years postoperatively and were not affected by the surgical approach (p<0.05). A strong correlation was found between 1-year and both 2- and 5-years PROMs (R>0.7; p<0.001). Linear regression confirmed the accuracy of 1-year PROMs in predicting both 2- and 5-years PROMs (p<0.001).

CONCLUSION

PROMs remained stable beyond 1-year of follow-up in patients treated with anterior, posterior, or combined anteroposterior surgeries for subaxial cervical spine fractures. The 1-year PROMs were strong predictors of PROMs measured at 2, and 5 years. The 1-year PROMs were sufficient to assess the outcomes of subaxial cervical fixation irrespective of the surgical approach.

Assessment of atlantoaxial rotation: how accurate is clinical measurement? a comparative study of cervical range of motion using MRI and standard orthopedic techniques

PURPOSE

Measurement of neck rotation is currently reliant on radiologic imaging. Given the radiation exposure for CT imaging and the additional inconvenience for the patients, an alternative assessment is needed. Goniometers are comfortably to use and easy to access, also for private consulting. The aim of this study was the assessment of whether a handheld goniometer can be used for accurately measuring the rotation of C1-C2.

METHODS

Clinical measurement of rotation was taken in flexed position of the neck. As comparison functional MRI was used. The measured rotation of C1-C2 was compared to identify the accuracy of the goniometer, in comparison to functional MRI scan.

RESULTS

Analysis of accuracy using a goniometer and dynamic MRI to assess C1-2 axial rotation showed significant differences for absolute values, but not regarding the percentage of rotation compared to total neck rotation.

CONCLUSION

The goniometer is exact to impartially determine the percentage contribution of C1-2 rotation to total neck rotation.

Analysis of time-space variations during dynamic cervical spine motion in cervical spondylosis myelopathy patients

BACKGROUND CONTEXT

Decreased cervical range of motion (ROM) is a common symptom of myelopathy patients. Many previous studies have relied on a variety of experimental approaches for quantifying static cervical range of motion. However, the change rules of time-space variation during dynamic cervical spine motion remains unknown.

PURPOSE

To develop and validate the effectiveness of a novel wearable robot-based sensor system, Analysis of Dynamic Cervical spine Motion (ADCM), in evaluating the dynamic cervical spine motion dysfunction of patients with cervical spondylotic myelopathy (CSM).

STUDY DESIGN/SETTING

A cross-sectional study.

PATIENT SAMPLE

One hundred forty consecutive healthy individuals (70 men and 70 women) and 120 CSM patients (60 men and 60 women) were enrolled in the present study.

OUTCOME MEASURES

The cervical motion process parameters, including the flexion and extension ROM, the flexion and extension time, and the Japanese Orthopedic Association scores (JOA) for cervical spine were measured.

METHODS

Two hundred and sixty consecutive participants were asked to wear ADCM system and then fully flex and extend their neck rapidly and evenly at tolerable maximum speed. The cervical motion process was recorded and converted into waveforms. Relevant waveform parameters were measured and analyzed. The number of complete flexion-extension motions in 10 seconds has been defined as 10s F-E cycles. The Japanese Orthopedics Association (JOA) scores of CSM patients were marked.

RESULTS

CSM patients had a lower number of 10s F-E cycles than healthy subjects. There were significant differences in flexion and extension time and ROM between two groups. The waveforms of myelopathy patients were wider and lower than those in healthy individuals. The average ratio value (defined as F) of wave height to wave width (a+b/c+d) could quantitatively reflect such differences of waveforms. The average F value was correlated with the JOA scores of the cervical motion function (r=0.7538), and F value declined as JOA scores decreased. According to receiver operating characteristic curve analysis, the optimal threshold value of the normal average ratio was more than 34.7.

CONCLUSIONS

ADCM appears to be an objective and quantitative severity assessment tool for confirmed CSM patients by evaluating dynamic cervical spine motion dysfunction.

Normal Range of Movement During Rotation Stress Testing for the Alar Ligaments: An Observational Study

OBJECTIVE

The purpose of this study was to determine the normal range of rotation occurring during rotation stress testing for alar ligament integrity and to ascertain whether rotation range on testing is affected by an individual's age.

METHOD

In this observational study, 88 people aged 18 to 86 years old with no current neck problems or known risk factors for craniocervical instability underwent rotation stress testing for the alar ligaments. The test was performed in each direction in neutral, flexion, and extension, with the participant both sitting and supine. Rotation range was recorded using an electromagnetic movement tracking system. Range was assessed overall and then compared by 10-year age groups using analysis of variance. Reliability of measurements was assessed by intraclass correlation coefficient_(2,1) and standard error of measurement.

RESULTS

Mean angles of upper cervical rotation ranged between 10.91° (standard deviation 3.38°) to 16.12° (standard deviation 5.13°). Overall measured rotation ranged from 1.37° to 33.22°. Participants in older age groups generally displayed reduced rotation; however, the reduction was less than 4°. Reliability of rotation measurements was good to excellent, with the intraclass correlation coefficient ranging from 0.80 to 0.99.

CONCLUSIONS

Normal range of rotation measured during stress testing for the alar ligament varied widely but did not exceed 33^o. All values measured in this study fell below recommendations for ligament integrity. Age-related change was not clinically significant in the interpretation of this test in this asymptomatic population.

Spontaneous Osseous Fusion after Remodeling Therapy for Chronic Atlantoaxial Rotatory Fixation and Recovery Mechanism of Rotatory Range of Motion of the Cervical Spine

We aimed to investigate the risk factors of spontaneous osseous fusion (SOF) of the atlantoaxial joint after closed reduction under general anesthesia followed by halo fixation (remodeling therapy) for chronic atlantoaxial rotatory fixation, and to elucidate the recovery mechanism of the rotatory range of motion (ROM) after halo removal. Twelve patients who underwent remodeling therapy were retrospectively reviewed. Five patients with SOF were categorized as the fusion group and seven patients without SOF as the non-fusion group. Three dimensional CT was used to detect direct osseous contact (DOC) of facet joints before and during halo fixation, while dynamic CT at neutral and maximally rotated head positions was performed to measure rotatory ROM after halo removal. The duration from onset to initial visit was significantly longer (3.2 vs. 5.7 months, p = 0.04), incidence of DOC during halo fixation was higher (0/7 [0%] vs. 4/5 [80%], p = 0.004), and segmental rotatory ROM of Occiput/C1 (Oc/C1) at final follow-up was larger (9.8 vs. 20.1 degrees, p = 0.003) in the fusion group. Long duration from the onset to the initial visit might induce irreversible damage to the articular surface of the affected facet, which was confirmed as DOC during halo fixation and resulted in SOF. Long duration from the onset to the initial visit and DOC during halo fixation could be used to suggest the risk for SOF. Nonetheless, rotatory ROM of Oc/C1 increased to compensate for SOF.

Test - re-test reliability and concurrent validity of cervical active range of motion in young asymptomatic adults using a new inertial measurement unit device

OBJECTIVES

Cervical range of motion (CROM) is one of the first things evaluated in cervical disorders. DyCare-Lynx is an inertial measurement unit device that was recently designed to measure CROM. Therefore, the objectives of the present study were to test the reliability and validity of the DyCare-Lynx device for active CROM.

MATERIALS AND METHODS

This study included 36 healthy individuals for the reliability study and 31 individuals for the validity study. Test-retest reliability was examined in three different days, by the same examiner with a 4 ± 1-day interval between them in all cervical movements in random order. For validity, the CROM was tested with the Zebris Motion Analysis system and DyCare-Lynx simultaneously.

RESULTS

The interclass correlation coefficient (ICC) of the DyCare-Lynx ranged from 0.54 to 0.90. The standard error of measurement (SEM) ranged from 2.12°-7.65°. The smallest detectable change (SDD) ranged from 11.25% to 29.75%. The Pearson's r correlation of DyCare-Lynx with Zebris ranged from 0.655 to 0.957.

CONCLUSION

DyCare-Lynx showed moderate to excellent reliability and moderate-to-high validity. Moreover, SEM was low with acceptable SDD values for all movements. Overall, it can be suggested that DyCare-Lynx is a reliable and valid tool to evaluate active CROM.

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.

Upper cervical range of rotation during the flexion-rotation test is age dependent: an observational study

Background:

The flexion-rotation test (FRT) is widely used to detect movement dysfunction in the spinal segment C1/C2, especially in patients with cervicogenic headache. The current published literature indicates that range recorded during the FRT is not age dependent. This is questionable, considering the well documented relationship between aging and degeneration in the cervical spine and loss of cervical movement in older people. The present study therefore aims to examine the influence of age on FRT mobility, and to provide normative values for different age groups. An additional aim is to examine the influence of age on the ratio between lower and upper cervical rotation mobility.

Methods:

For this cross-sectional, observational study, healthy subjects aged from 18 to 90 years were recruited. The upper cervical range of rotation during the FRT was measured using a digital goniometer. Personal data including age, weight, height, and lifestyle factors were also assessed.

Results:

A total of 230 (124 male) healthy, asymptomatic subjects, aged between 18 and 87 years were included. Regression analysis showed that 27.91% (p < 0.0001) of the variance in FRT mobility can be explained by age alone, while 41.28% (p < 0.0001) of the variance in FRT mobility can be explained by age and total cervical range of motion (ROM). Normative values for different age decades were calculated using regression analysis. No significant influence of age on the ratio between ROM of lower and upper cervical rotation was found. There was no relevant impact of personal (gender, height, and weight) and lifestyle (smartphone and PC use) factors on ROM during the FRT.

Conclusion:

Upper cervical rotation mobility determined by the FRT correlates strongly with age; hence, the results of the FRT have to be interpreted taking into account the individual age of the tested subject. The ratio between lower and upper cervical rotation mobility is maintained in all age groups.

Normative values of cervical range of motion for both children and adults: A systematic review

STUDY DESIGN

Systematic review.

OBJECTIVE

To synthesize studies reporting normative values of active cervical range of motion (ROM) in healthy children and adults.

SUMMARY OF BACKGROUND DATA

Evaluating active cervical ROM is part of routine assessment of patients with neck pain. Interpretation of outcomes necessitates having normative data per age category. Currently available normative values differ across studies, perhaps due to (the measurement properties of) the devices used.

METHODS

A systematic review according to PRISMA guidelines was conducted. Electronic searches included EMBASE, MEDLINE, Web of Science, Cochrane, CINAHL and Google Scholar databases from inception to August 2018. Included studies had to involve healthy subjects in which active cervical ROM was assessed or when determining normative values was the aim of the study. Methodological quality of the included studies was assessed using an adapted version of the QUADAS. A mean value was re-calculated for the total group in case data were presented per gender per age-category only. When possible, data were pooled.

RESULTS

From 2151 unique hits, 217 articles were selected for full text assessment, after which 162 articles were excluded. Data were extracted from 55 articles using 16 different measurement devices. Twenty-five studies were rated as being of "low risk of bias". Only data from studies evaluating the CROM device and Zebris could be pooled.

CONCLUSIONS

This systematic review revealed that although a large number of studies assessed normative data for active cervical ROM, the methodological quality of most studies was low and the heterogeneity between studies was high. Only the normative data for active cervical ROM using the CROM device seems to be useful. Overall, reference values for measuring active cervical ROM is unclear for most measurement devices. Normative values of cervical range of motion for both children and adults: a systematic review.

Recurrent Cervical Spinal Epidural Hematoma: Case Report and Literature Review

Spinal epidural hematoma (SEDH) is an uncommon pathology. Here, we report a case of SEDH with recurrences, along with a literature review of relevant cases to identify characteristics of SEDH recurrence. A 13-year-old girl experienced sudden-onset of back pain and bilateral leg weakness. She was diagnosed with a cervical idiopathic epidural hematoma, and the symptoms subsided with conservative management. Four months after the event, she again experienced back pain due to recurrence of the cervical epidural hematoma, but she was observed because no neurological deficits could be detected. Fifteen months after the initial SEDH, she experienced severe back pain and tetra-paresis due to recurrence. The SEDH was located in the left ventral and dorsal aspect at the C6–T1 level, with severe spinal cord compression. The hematoma was removed through left hemilaminectomy. Bleeding was noted from the epidural venous plexus along the left C6 spinal root, which had coagulated. After hematoma resection, her symptoms gradually improved, and she was discharged 3 weeks after surgery without any neurological deficits. No hematoma recurrence has since been experienced. Recurrent SEDH is relatively rare, with only 11 cases previously reported. Recurrent hematoma cases are more common in young, female patients, while SEDH, in general, is more common in males in their late forties. The recurrence interval is shorter in non-surgical cases than those requiring surgery. Knowledge of these characteristics may be useful in the future management of SEDH.

Which is the best-suited landmark to assess the thoracic orientation?

Several skin surface-based techniques exist to non-invasively determine the spinal kinematics. However, the accuracy of these techniques is limited by soft-tissue artefacts. Furthermore, structures like the thorax are frequently assumed to be rigid but display considerable mobility within itself. This study aimed to quantify the accuracy at different thoracic landmarks for measuring mobility in healthy individuals during different activities to provide a recommendation for the best suited measurement location. The locations of 29 landmarks were continuously captured on 19 individuals (age: 25-59 years) during sitting, standing, walking, jumping, intra-thoracic motions, and different breathing depths using reflective markers. Marker triplets were used at every landmark to calculate their orientations by first backtracking the rigid-body motion (RBM) of the thorax in general, and subsequently calculating the RBM of each rigid marker triplet. Of the latter, the maximum axis angle for each exercise was statistically evaluated. Landmarks at the middle of the clavicles displayed the largest overall errors (approximately 90° during worst case scenario). However, the variability of errors among the investigated exercises was large. Landmarks at the cranial sternal region (particularly at the "Louis angle") and at the T3 spinous process showed the smallest errors for all subjects and tasks (e.g., <5° and <11°, respectively, during normal breathing). When only one sensor is to be used, it is recommended to use the cranial sternal region to assess the thoracic orientation. Study results highly sensitive to thoracic orientation should be considered with care or performed using more appropriate methods.

Age Is a Greater Influence on Small Saccades Than Target Size in Normal Subjects on the Horizontal Video Head Impulse Test

Objective: This study sought to investigate whether the size of the target used in the horizontal vHIT has an effect on the saccade profile of healthy subjects, and to expand upon previous work linking age to the existence of small vHIT saccades.

Methods: Forty eight participants were recruited between 18 and 77 years of age, with no history of vestibular, oculomotor or neurological conditions and a visual acuity of at least 0.3 LogMAR. Participants underwent four consecutive horizontal vHIT trials using the standard target size and three smaller targets. VOR gain and metrics for saccadic incidence, peak eye velocity and latency were then extracted from results.

Results: Target size was a statistically significant influence on saccade metrics. As target size increased, saccadic incidence decreased while peak eye velocity and latency increased. However, a potential order effect was also discovered, and once this was corrected for the remaining effect of target size was small and is likely clinically insignificant. The effect of age was much stronger than target size; increasing age was strongly positively correlated with saccadic incidence and showed a medium size correlation with peak velocity, though not with saccadic latency.

Conclusion: While this study suggests that target size may have a statistically significant impact on the vHIT saccade profile of normal subjects, age has a greater influence on the incidence and size of small vHIT saccades.

Cervical Spine Assessment Using Passive and Active Mobilization Recorded Through an Optical Motion Capture

OBJECTIVE

The purpose of this study was to develop and measure a protocol for evaluation of cervical range of motion (ROM), based on passive mobilization (PM) combined with active mobilization (AM) and recorded through an optical motion capture system.

METHODS

Passive and active mobilization were applied to 24 asymptomatic participants. Cervical ROM was recorded in 3 anatomic planes (transversal, frontal, and sagittal) using a precision optical system and a set of rigid bodies placed on the sacrum, spinous processes of the C7-T1 vertebrae, and the head. Three captures were made for each participant, distributed over 2 days. The characteristics of the PM, the interaction with the AM, and the coherence patterns between tests were analyzed. Reliability was studied for these procedures.

RESULTS

The reliability results of the PM were high in all analyzed indices; only flexion showed low values. Reliability of AM was greater than PM for flexion, extension, and lateralization because of the similarity to rotation. No statistically significant differences were found comparing PM and AM techniques.

CONCLUSION

The authors present a cervical ROM assessment based on combined PM and AM protocols at different sessions. This model demonstrated high reliability, individually and combined, and no differences were detected between PM and AM ROMs. Because the evaluator, instrumentation, and the patient are factors that could influence outcomes, the authors suggest that they be combined in protocols. These protocols could be used to evaluate the functional and structural capacity of patients and inform clinical outcomes.

Cervical flexion and extension includes anti-directional cervical joint motion in healthy adults

BACKGROUND CONTEXT

Anti-directional cervical joint motion has previously been demonstrated. However, quantitative studies of anti-directional and pro-directional cervical flexion and extension motions have not been published.

PURPOSE

This study aimed for a quantitative assessment of directional and anti-directional cervical joint motion in healthy subjects.

STUDY DESIGN

An observational study was carried out.

PATIENTS SAMPLE

Eighteen healthy subjects comprised the study sample.

OUTCOME MEASURES

Anti-directional and pro-directional cervical flexion and extension motion from each cervical joint in degrees were the outcome measures.

METHODS

Fluoroscopy videos of cervical flexion and extension motions (from neutral to end-range) were acquired from 18 healthy subjects. The videos were divided into 10% epochs of C0/C7 range of motion (ROM). The pro-directional and anti-directional motions in each 10% epoch were extracted, and the ratios of anti-directional motions with respect to the pro-directional motions (0%=no anti-directional movement) were calculated for joints and 10% epochs.

RESULTS

The flexion and extension ROM for C0/C7 were 51.9°±9.3° and 57.2°±12.2°. The anti-directional motions of flexion and extension ROM constituted 42.8%±9.7% and 41.2%±8.2% of the respective pro-directional movements. For flexion, the first three joints (C0/C1, C1/C2, C2/C3) demonstrated larger ratios compared with the last three joints (C4/C5, C5/C6, C6/C7) (p<.03). For extension, C1/C2 and C2/C3 ratios were larger compared with C0/C1, C4/C5, and C5/C6 (p<.03). Comparisons between flexion and extension motions showed larger C0/C1 ratio but smaller C5/C6 and C6/C7 ratios in extension (p<.05).

CONCLUSIONS

This is the first report of quantified anti-directional cervical flexion and extension motion. The anti-directional motion is approximately 40% of the pro-directional motion. The results document that large proportions of anti-directional cervical flexion and extension motions were normal.

Assessment of cervical range of motion in patients after axis fracture

BACKGROUND

Surgical treatment of odontoid fractures with posterior C1/C2 fusion always leads to severe limitations in mobility of the cervical spine and head.

PURPOSE

To assess the mobility of the cervical spine in patients treated with various surgical methods after an axis body fracture.

MATERIAL AND METHODS

A group of 61 subjects receiving surgical treatment in a group of 214 subjects treated for odontoid fractures at one ward of neurosurgery at a regional hospital. Studies also included odontoid peg and Hangman fractures. The range of motion of the head was compared to standards by the International Standard Orthopedic Measurements (ISOM) and to head mobility in a control group of 80 healthy subjects without any pathologies or complaints associated with the cervical spine. Ranges of motion were measured with the CROM goniometre with regard to flexion, extension, right and left lateral flexion and right and left rotation. The functional status was evaluated with Neck Disability Index (NDI) standard questionnaires indicated for patients with cervical spine pain.

RESULTS

Except for flexion and extension, patients after odontoid fractures had a statistically significantly smaller range of motion of the cervical spine in all planes compared to the control group and ISOM standards.

CONCLUSIONS

Odontoid fractures lead to limitations in mobility of the cervical spine even after treatment with methods that in theory should preserve the C1/C2 mobility.

To What Degree Does Active Cervical Range of Motion Differ Between Patients With Neck Pain, Patients With Whiplash, and Those Without Neck Pain? A Systematic Review and Meta-Analysis

OBJECTIVES

To quantify differences in active cervical range of motion (aCROM) between patients with neck pain and those without neck pain, in patients with whiplash-associated disorders (WADs) and nontraumatic neck pain, and in patients with acute complaints versus those with chronic complaints.

DATA SOURCES

Seven bibliographic databases were searched from inception to April 2015. In addition, a manual search was performed.

STUDY SELECTION

Full articles on a numerical comparison of aCROM in patients with neck pain and asymptomatic control persons of similar ages were included. Two reviewers independently selected studies and assessed risk of bias.

DATA EXTRACTION

Two reviewers extracted the data. Pooled mean differences of aCROM were calculated using a random-effects model.

DATA SYNTHESIS

The search yielded 6261 hits; 27 articles (2366 participants, 13 low risk of bias) met the inclusion criteria. The neck pain group showed less aCROM in all movement directions compared with persons without neck pain. Mean differences ranged from -7.04° (95% CI, -9.70° to -4.38°) for right lateral bending (11 studies) to -89.59° (95% CI, -131.67° to -47.51°) for total aCROM (4 studies). Patients with WADs had less aCROM than patients with nontraumatic neck pain. No conclusive differences in aCROM were found between patients with acute and patients with chronic complaints.

CONCLUSIONS

Patients with neck pain have a significantly decreased aCROM compared with persons without neck pain, and patients with WADs have less aCROM than those with nontraumatic neck pain.

On the relevance of surrogate parameter deduction in biomedical research: mediated regression analysis for variance explanation of cervical range of motion

PURPOSE

Research on cervical range of motion (ROM) often includes age and body mass index (BMI) as potential variables to explain inter-individual variances. The BMI may not be a predictor of ROM but an age-affected surrogate parameter: the described effect of BMI on ROM is, thus, suspected being partially or completely mediated by age.

METHODS

Healthy and adult volunteers (n = 139, 65 female, age 19-75 years, BMI 24.2 ± 3.8 kg m^-2) performed five repetitive maximal cervical movements in the sagittal plane to assess maximal ROM (primary outcome). After the examination of underlying assumptions, data were analysed by mediation regression analyses using a SPSS-macro provided by Hayes. ROM represented the outcome variable, independent variable was BMI and mediator variable was age. Total as well as direct and indirect effects were calculated: (1) for all subjects included and (2) for subject with a BMI <35 kg m^-2.

RESULTS

Analysis including all subjects revealed both a direct (-1.1, s _e .46, p < .05, 95 %CI -2; -1.7) and an existing indirect effect (mediated by age, -2.4, s _e .33, p < .05, 95 %CI -3.1; -1.8) of BMI on ROM. Analysis without obese 2 subjects showed no direct effect of BMI (effect -1, s _e .54, p > .05, 95 %CI -2.1; +.1) but a systematic indirect effect, mediated by age, on ROM (effect -2.4, s _e .33, p < .001, 95 %CI -3.1; -1.8).

CONCLUSIONS

After the withdrawal of the surrogate parameter BMI, age explains 53 % of maximal ROM. No impact of BMI on ROM was detected after excluding highly obese participants. Our results illustrate the relevance of including each supposable predictor in causal mediation models development.

The Compensatory Relationship of Upper and Subaxial Cervical Motion in the Presence of Cervical Spondylosis

STUDY DESIGN

This study was an in vivo kinematic magnetic resonance imaging analysis of cervical spinal motion in human subjects.

OBJECTIVE

The objective of the study was to identify associations between disk degeneration in the subaxial cervical spine and upper cervical spinal motion in patients with general age-related cervical spondylosis.

SUMMARY OF BACKGROUND DATA

The kinematic relationship between the occipital-atlantoaxial complex and subaxial cervical spine in patients with cervical spondylosis and decreased cervical motion is not well understood.

METHODS

A total of 446 symptomatic patients who had neck pain with and without neurogenic symptoms were included in this study. Kinematic magnetic resonance imaging was performed with dynamic motion of the cervical spine in upright, weight-bearing neutral, flexion, and extension positions. Intervertebral disk degeneration for each segment from C2-3 to C7-T1 and sagittal angular motion between flexion and extension for each segment from Oc-C1 to C7-T1 was evaluated. Depending on the amount of sagittal subaxial angular motion, the patients were classified into 3 groups by sagittal angular motion using cutoff points based on tertile (<36-degree group: 149 cases; 36-47-degree group: 148 cases; and >47-degree group: 149 cases).

RESULTS

A significant correlation was found between subaxial angular motion and intervertebral disk degeneration, indicating that the subaxial motion decreases according to the degree of disk degeneration. Mean angular motion of the occipital-atlantoaxial complex, especially of Oc-C1, was significantly higher in the <36-degree and 36-47-degree group than in the >47-degree group, whereas no significant difference was found at C1-C2.

CONCLUSIONS

Our study demonstrates that decreased subaxial cervical spinal motion is associated with intervertebral disk degeneration in a symptomatic population. This decrease in mobility at the subaxial cervical spine is compensated for by an increase in angular mobility of the upper cervical spine at the occipital-atlantoaxial complex, especially at Oc-C1.

A comparison of neck bending and flexion measurement methods for assessment of ergonomic risk

Head movements of workers were measured in the sagittal plane in order to establish a precise and accurate assessment method to be used in real work situations. Measurements were performed using two inclinometers connected to an embedded recording system. Two quantitative analysis methods were tested, i.e., measurement of bending with an inclinometer attached to the head, and measurement of flexion/extension by using an additional inclinometer located at C7/T1. The results were also compared with a video observation method (qualitative). The results showed that bending measurements were significantly different from those of flexion/extension for angles between 0° and 20°, and angles >45°. There were also significant differences between workers for flexion >45°, reflecting individual variability. Additionally, several limitations of observational methods were revealed by this study.

The envelope of motion of the cervical spine and its influence on the maximum torque generating capability of the neck muscles

The posture of the head and neck is critical for predicting and assessing the risk of injury during high accelerations, such as those arising during motor accidents or in collision sports. Current knowledge suggests that the head's range-of-motion (ROM) and the torque-generating capability of neck muscles are both dependent and affected by head posture. A deeper understanding of the relationship between head posture, ROM and maximum torque-generating capability of neck muscles may help assess the risk of injury and develop means to reduce such risks. The aim of this study was to use a previously-validated device, known as Neck Flexibility Tester, to quantify the effects of head's posture on the available ROM and torque-generating capability of neck muscles. Ten young asymptomatic volunteers were enrolled in the study. The tri-axial orientation of the subjects' head was controlled via the Neck Flexibility Tester device. The head ROM was measured for each flexed, extended, axially rotated, and laterally bent head's orientation and compared to that in unconstrained neutral posture. Similarly, the torque applied about the three anatomical axes during Isometric Maximum Voluntary Contraction (IMVC) of the neck muscles was measured in six head's postures and compared to that in fully-constrained neutral posture. The further from neutral the neck posture was the larger the decrease in ROM and IMVC. Head extension and combined two-plane rotations postures, such as extension with lateral bending, produced the largest decreases in ROM and IMVC, thus suggesting that these postures pose the highest potential risk for injury.

Age-related changes in cervical sagittal range of motion and alignment

Study Design Retrospective cohort study. Objective To compare sagittal cervical range of motion (ROM) and alignment in young versus middle-aged adults. Methods One hundred four asymptomatic adults were selected randomly out of 791 subjects who underwent lateral cervical radiographs in neutral, flexion, and extension positions. They were divided into two groups: young (age 20 to 29, 52 people) and middle-aged adults (age 50 to 59, 52 people). We determined the ROMs of upper cervical (occipital-C2 angle), midcervical (C2-C7 angle), and cervicothoracic spine (cervicosternal angle). We compared the alignment differences of the two groups by calculating the distances between C2 and C7 plumb lines, and C2 central-offset distance. Results In neutral position, there was no significant difference between young and middle-aged adults. However, in flexion, C2-C7 angle, distance between C2-C7 plumb lines, and C2 central-offset distance decreased with age. In extension, C2-C7 angle and C2 central-offset distance decreased with age. During flexion and extension, midcervical ROM and the range of C2 central-offset distance decreased in the middle-aged group. However, there was no difference between the two age groups in the ROM of the upper cervical and the cervicothoracic regions during flexion and extension. Conclusion We found that, despite of the presence of age-related cervical alignment changes, the only difference between the two groups was in the sagittal ROM of the midcervical spine during flexion and extension. Only the ROM of the midcervical spine appears to change significantly, consistent with findings that these levels are most likely to develop both symptomatic and asymptomatic degenerative changes.

Influence of movement speed on cervical range of motion

PURPOSE

Cervical range of motion (RoM) has been the subject of many studies. However, only very few of these studies have considered the influence of movement execution speed on the cervical kinematics. The aim of this study is to evaluate the influence of movement speed on cervical RoM.

METHOD

Cervical RoM was recorded using an optoelectronic system; 32 healthy subjects performed movements in two modes: the best possible and as fast as possible.

OUTCOME MEASURES

The primary movements (flexion-extension, lateral bending, axial rotation) and coupled movements were studied. Paired Student's tests were performed to compare the two modes of movement.

RESULTS

The results showed that cervical RoM differed significantly between movement speeds. Amplitudes were higher for each movement (p < 0.001 for flexion-extension, p < 0.001 for lateral flexion, p = 0.008 for axial rotations) when movements were performed as quickly as possible. The range of movements carried out the best possible reached only 95% of those during movements carried out as fast as possible. Concerning coupled movements, an increase in rotational movements coupled to lateral flexion during fast movements was observed.

CONCLUSION

The range of motion reported in the literature corresponds to movement carried out in a mode resembling the best possible of our study. Movements made as quickly as possible can display larger motion ranges.

Sagittal range of motion after extensive cervical fusion

BACKGROUND CONTEXT

Complicated cervical spine revision and deformity correction surgeries are becoming increasingly common. These challenging operations often necessitate fusion of the entire cervical spine. Patients frequently express concern over the likely loss of range of motion (ROM) of the neck postoperatively. However, we are aware of no study that specifically examines the sagittal cervical ROM after extensive cervical fusion.

PURPOSE

To characterize sagittal ROM after extensive cervical fusion.

STUDY DESIGN

Retrospective case series.

PATIENT SAMPLE

Thirty patients were included.

OUTCOME MEASURES

Radiographs at final follow-up were measured for cervical ROM by the occipitocervical and cervicosternal angles with the neck in full flexion and extension.

METHODS

The surgical and medical records at one tertiary referral academic institution were used to identify adults who had undergone extensive cervical fusion between 1996 and 2008. An "extensive cervical fusion" entailed an upper instrumented vertebra proximal to C3 and lower instrumented vertebra distal to C7. Radiographs at final follow-up were measured for cervical ROM by the occipitocervical and cervicosternal angles with the neck in full flexion and extension.

RESULTS

The average age at surgery was 58.3±10.0 years. The surgical levels were occiput-T1 (one patient), occiput-T4 (one patient), occiput-T6 (one patient), C1-T1 (one patient), C1-T2 (one patient), C2-T1 (nine patients), C2-T2 (eight patients), C2-T3 (six patients), and C2-T4 (two patients). Twenty-seven of the procedures were revisions. The other surgical indications were chin-on-chest deformity (one patient), cervical scoliosis (one patient), and multilevel cervical myelopathy (one patient). The mean follow-up period was 34.5±30.9 months (range, 6-154 months). The mean cervical ROM values by the occipitocervical and cervicosternal angles were 29.5±11.0° and 7.5±5.0°, respectively. The mean total cervical ROM value was 34.1±14.7°.

CONCLUSIONS

A substantial degree of sagittal ROM can be maintained after extensive surgical fusion of the cervical spine.

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.

Cervical coupling motion characteristics in healthy people using a wireless inertial measurement unit

Objective. The objectives were to show the feasibility of a wireless microelectromechanical system inertial measurement unit (MEMS-IMU) to assess the time-domain characteristics of cervical motion that are clinically useful to evaluate cervical spine movement. Methods. Cervical spine movements were measured in 18 subjects with wireless IMUs. All rotation data are presented in the Euler angle system. Amount of coupling motions was evaluated by calculating the average angle ratio and the maximum angle ratio of the coupling motion to the primary motion. Reliability is presented with intraclass correlation coefficients (ICC). Results. Entire time-domain characteristics of cervical motion were measured with developed MEMS-IMU system. Cervical range of motion (CROM) and coupling motion range were measured with high ICCs. The acquired data and calculated parameters had similar tendency with the previous studies. Conclusions. We evaluated cervical motion with economic system using a wireless IMU of high reliability. We could directly measure the three-dimensional cervical motion in degrees in realtime. The characteristics measured by this system may provide a diagnostic basis for structural or functional dysfunction of cervical spine. This system is also useful to demonstrate the effectiveness of any intervention such as conventional medical treatment, and Korean medical treatment, exercise therapy.

Objective evaluation of cervical spine mobility after surgery during free-living activity

BACKGROUND

Evaluation of cervical spine mobility after surgery is mainly based on the measurement of the range of motion during imposed movements. It can thus be questionable if this assessment represents the mobility experienced during daily life. The goal of this study was to propose a new evaluation tool based on the monitoring of cervical spine movement during daily activities.

METHODS

The detection of cervical movement and the determination of primary motion component (lateral bending, axial rotation or flexion-extension), using two inertial sensors, were first validated in laboratory settings. Fifteen patients who underwent a cervical arthrodesis and nine healthy control subjects were monitored during their daily activity for half a day. The frequency of cervical movement was quantified according to posture, i.e. static and walking periods. The amplitude and velocity of cervical movement were evaluated using the median and cumulative distribution function.

FINDINGS

The movement detection and classification showed an excellent performance (sensitivity and specificity>94%). For the daily monitoring, the patients presented a movement frequency similar to controls, whereas the amplitude and velocity in patients were lower than in controls (P<0.05). The differences between patients and controls were larger for the velocity parameters (effect sizes>0.37 and >0.54 for static and walking periods respectively) than for the amplitude parameters.

INTERPRETATION

Body-worn inertial sensors enable the quantitative evaluation of global cervical movement. The movement amplitude and velocity during free-living conditions can be used as objective parameters to evaluate the cervical spine mobility after treatment.

Clinical and statistical correlation of various lumbar pathological conditions

Current clinical evaluations often rely on static anatomic imaging modalities for diagnosis of mechanical low back pain, which provide anatomic snapshots and a surrogate analysis of a functional disease. Three dimensional in vivo motion is available with the use of digital fluoroscopy, which was used to capture kinematic data of the lumbar spine in order to identify coefficients of motion that may assist the physician in differentiating patient pathology. Forty patients distributed among 4 classes of lumbar degeneration, from healthy to degenerative, underwent CT, MRI, and digital x-ray fluoroscopy. Each patient underwent diagnosis by a neurosurgeon. Fluoroscopy was taken as the patient performed lateral bending (LB), axial rotation (AR) and flexion-extension (FE). Patient specific models were registered with the fluoroscopy images to obtain in vivo kinematic data. Motion coefficients, C(LB), C(AR), C(FE), were calculated as the ratio of in-plane motion to total out-of-plane motion. Range of motion (ROM) was calculated about the axis of motion for each exercise. Inter- and Intra- group statistics were examined for each coefficient and a flexible Bayesian classifier was used to differentiate patients with degeneration. The motion coefficients C(LB) and C(FE) were significantly different (p<0.05) in 4 of 6 group comparisons. In plane motion, ROM(LB), was significantly different in only 1 of 6 group comparisons. The classifier achieved 95% sensitivity and specificity using (C(FE), C(LB), ROM(LB)) as input features, and 40% specificity and 80% sensitivity using ROM variables. The new coefficients were better correlated with patient pathology than ROM measures. The coefficients suggest a relationship between pathology and measured motion which has not been reported previously.

A 3D motion analysis study comparing the effectiveness of cervical spine orthoses at restricting spinal motion through physiological ranges

OBJECTIVE

To compare the effectiveness of the Aspen, Aspen Vista, Philadelphia, Miami-J and Miami-J Advanced collars at restricting cervical spine movement in the sagittal, coronal and axial planes.

METHODS

Nineteen healthy volunteers (12 female, 7 male) were recruited to the study. Collars were fitted by an approved physiotherapist. Eight ProReflex (Qualisys, Sweden) infrared cameras were used to track the movement of retro-reflective marker clusters placed in predetermined positions on the head and trunk. 3D kinematic data were collected during forward flexion, extension, lateral bending and axial rotation from uncollared to collared subjects. The physiological range of motion in the three planes was analysed using the Qualisys Track Manager System.

RESULTS

The Aspen and Philadelphia were significantly more effective at restricting flexion/extension than the Vista (p < 0.001), Miami-J (p < 0.001 and p < 0.01) and Miami-J Advanced (p < 0.01 and p < 0.05). The Aspen was significantly more effective at restricting rotation than the Vista (p < 0.001) and the Miami-J (p < 0.05). The Vista was significantly the least effective collar at restricting lateral bending (p < 0.001).

CONCLUSION

Our motion analysis study found the Aspen collar to be superior to the other collars when measuring restriction of movement of the cervical spine in all planes, particularly the sagittal and transverse planes, while the Aspen Vista was the least effective collar.

Test-retest reliability of 3D ultrasound measurements of the thoracic spine

OBJECTIVE

To explore the reliability of the Zebris CMS 20 ultrasound analysis system with pointer application for measuring end-range flexion, end-range extension, and neutral kyphosis angle of the thoracic spine.

SETTING

The study was performed within the School of Physiotherapy in cooperation with the Orthopedic Department at a University Hospital.

PARTICIPANTS

The thoracic spines of 28 healthy subjects were measured.

METHODS

Measurements for neutral kyphosis angle, end-range flexion, and end-range extension were taken once at each time point. The bone landmarks were palpated by one examiner and marked with a pointer containing 2 transmitters using a frequency of 40 kHz. A third transmitter was fixed to the pelvis, and 3 microphones were used as receiver. The real angle was calculated by the software. Bland-Altman plots with 95% limits of agreement, intraclass correlations (ICC), standard deviations of mean measurements, and standard error of measurements were used for statistical analyses. The test-retest reliability in this study was measured within a 24-hour interval.

MAIN OUTCOME MEASUREMENTS

Statistical parameters were used to judge reliability.

RESULTS

The mean kyphosis angle was 44.8° with a standard deviation of 17.3° at the first measurement and a mean of 45.8° with a standard deviation of 16.2° the following day. The ICC was high at 0.95 for the neutral kyphosis angle, and the Bland-Altman 95% limits of agreement were within clinical acceptable margins. The ICC was 0.71 for end-range flexion and 0.34 for end-range extension, whereas the Bland-Altman 95% limits of agreement were wider than with the static measurement of kyphosis. Compared with static measurements, the analysis of motion with 3-dimensional ultrasound showed an increased standard deviation for test-retest measurements.

CONCLUSIONS

The test-retest reliability of ultrasound measuring of the neutral kyphosis angle of the thoracic spine was demonstrated within 24 hours. Bland-Altman 95% limits of agreement and the standard deviation of differences did not appear to be clinically acceptable for measuring flexion and extension.

Do inertial sensors represent a viable method to reliably measure cervical spine range of motion?

A rise in neck pain cases has initiated an exponential interest in the assessment and treatment of cervical spine range of motion (CROM). Experimental limitations, however, have been reported as therapists strive to collect continuous, dynamic data to aid prognosis. This technical report seeks to explore the viability of using inertial sensors to reliably assess CROM. In recognition of the need for secure skin-sensor attachment, four combinations of sensor pairings were established and investigated based upon four clinically identifiable surface landmarks. Twelve participants were recruited and asked to perform three specific movement cycles in each plane (i.e. flexion-extension; rotation; lateral bending). The reliability of the peak CROM, and the movement pattern, recorded in each of the three movement cycles was statistically analysed using the intra-class correlation coefficient (ICC) and coefficient of multiple correlations (CMC). It was determined that the most reliable positions of the orientation sensors, with one adhered to the forehead and the other representing T4, enables data to be recorded with a reliability that is comparable to other CROM measuring techniques. Subsequently, it is concluded that inertial sensors represent a viable method to assess CROM.

Immediate effects of inhibitive distraction on active range of cervical flexion in patients with neck pain: a pilot study

The purpose of this pilot study was to examine the immediate effects of a manual therapy technique called Inhibitive Distraction (ID) on active range of motion (AROM) for cervical flexion in patients with neck pain with or without concomitant headache. A secondary objective of this study was to see whether patient subgroups could be identified who might benefit more from ID by studying variables such as age, pain intensity, presence of headache, or pre-intervention AROM. We also looked at patients' ability to identify pre- to post-intervention changes in their ability to actively move through a range of motion. Forty subjects (mean age 34.7 years; range 16-48 years) referred to a physical therapy clinic due to discomfort in the neck region were randomly assigned to an experimental and a control group. We used the CROM goniometer to measure pre- and post-intervention cervical flexion AROM in the sagittal plane within a single treatment session. The between-group difference in AROM increase was not statistically significant at P<0.05 with a mean post-intervention increase in ROM of 2.4 degrees (SD 6.2 degrees ) for the experimental group and 1.2 degrees (SD 5.8 degrees ) for the placebo group. We were also unable to identify potential subgroups more likely to respond to ID, although a trend emerged for greater improvement in chronic patients with headaches, lower pain levels, and less pre-intervention AROM. In the experimental group and in both groups combined, subjects noting increased AROM indeed had a significantly greater increase in AROM than those subjects not noting improvement. In conclusion, this study did not confirm immediate effects of ID on cervical flexion AROM but did provide indications for potential subgroups likely to benefit from this technique. Recommendations are provided with regard to future research and clinical use of the technique studied.

A review of direct neck measurement in occupational settings

No guidelines are available to orient researchers on the availability and applications of equipment and sensors for recording precise neck movements in occupational settings. In this study reports on direct measurements of neck movements in the workplace were reviewed. Using relevant keywords two independent reviewers searched for eligible studies in the following databases: Cinahal, Cochrane, Embase, Lilacs, PubMed, MEDLINE, PEDro, Scopus and Web of Science. After applying the inclusion criteria, 13 articles on direct neck measurements in occupational settings were retrieved from among 33,666 initial titles. These studies were then methodologically evaluated according to their design characteristics, exposure and outcome assessment, and statistical analysis. The results showed that in most of the studies the three axes of neck movement (flexion-extension, lateral flexion and rotation) were not simultaneously recorded. Deficiencies in available equipment explain this flaw, demonstrating that sensors and systems need to be improved so that a true understanding of real occupational exposure can be achieved. Further studies are also needed to assess neck movement in those who perform heavy-duty work, such as nurses and electricians, since no report about such jobs was identified.

Co-occurrence of outlet impingement syndrome of the shoulder and restricted range of motion in the thoracic spine--a prospective study with ultrasound-based motion analysis

Background

Shoulder complaints, and especially the outlet-impingement syndrome, are a common condition. Among other things, poor posture has been discussed as a cause. A correlation between impingement syndrome and restricted mobility of the thoracic spine (T) has been described earlier, but there has been no motion analysis of the thoracic spine to show these correlations. In the present prospective study, we intended to find out whether there is a significant difference in the thoracic sagittal range of motion (ROM) between patients with a shoulder outlet impingement syndrome and a group of patients who had no shoulder pathology. Secondly, we wanted to clarify whether Ott's sign correlates with ultrasound topometric measurements.

Methods

Two sex- and age-matched groups (2 × n = 39) underwent a clinical and an ultrasound topometric examination. The postures examined were sitting up straight, sitting in maximal flexion and sitting in maximal extension. The disabilities of the arm, shoulder and hand (DASH) score (obtained by means of a self-assessment questionnaire) and the Constant score were calculated. Lengthening and shortening of the dorsal projections of the spine in functional positions was measured by tape with Ott's sign.

Results

On examination of the thoracic kyphosis in the erect seated posture there were no significant differences between the two groups (p = 0.66). With ultrasound topometric measurement it was possible to show a significantly restricted segmental mobility of the thoracic spine in the study group compared with the control group (p = 0.01). An in-depth look at the mobility of the subsegments T1-4, T5-8 and T9-12 revealed that differences between the groups in the mobility in the lower two sections of the thoracic spine were significant (T5-8: p = 0.03; T9-12: p = 0.02). The study group had an average Constant score of 35.1 points and the control group, 85.5 (p < 0.001). On the DASH score the patient group reached 34.2 points and the control group, 1.4 (p < 0.001). The results of Ott's sign differed significantly between the two collectives (p = 0.0018), but showed a weak correlation with the ultrasound topometric measurements (study group flexion/extension: r = 0.36/0.43, control group flexion/extension: r = 0.29/0.26).

Conclusion

The mobility of the thoracic spine should receive more attention in the diagnosis and therapy of patients with shoulder outlet impingement syndrome.

In vivo intersegmental motion of the cervical spine using an inverse kinematics procedure

BACKGROUND

The main functions of the cervical spine are the stabilization and the orientation of the head. Pathologies are complex and difficult to diagnose. The first sign of the dysfunction is an abnormal intervertebral motion. It is the purpose of this feasibility study to determine the intersegmental motions and loading conditions of the cervical spine in vivo with standard clinical investigation methods.

METHODS

We propose a new approach which merges full flexion-extension X-ray images, and continuous motion of the whole cervical spine obtained with a tracking motion system. These data were used as input for a subject-specific rigid body model of the cervical spine computed with the software MSC.Adams. This model simulates the cervical spine extension/flexion, the intervertebral motions are deduced using an inverse kinematics procedure.

FINDINGS

Subject-specific rigid body models were computed from data of two subjects. The intersegmental motion and loading conditions were calculated. We found that the loading amplitudes depended on the intervertebral level, and that subject specific patterns were highlighted. We noticed an unsymmetrical behavior in flexion and extension. Furthermore intervertebral rotations were correlated with the global motion of the cervical spine.

INTERPRETATION

A subject-specific rigid body model merged data from classical flexion-extension radiographs and noninvasive external motion capture. Our approach is based on inverse kinematics allowing the estimation of the intervertebral motion and mechanical behavior of the cervical spine in vivo, which gives valuable information concerning biomechanics of the cervical spine in vivo for cervical spine clinical investigation.

Cervicogenic headache in the general population: the Akershus study of chronic headache

OBJECTIVE

The objective was to study the prevalence of cervicogenic headache (CEH) in the general population.

METHODS

An age- and gender-stratified random sample of 30,000 persons aged 30-44 years received a mailed questionnaire. Those with self-reported chronic headache were interviewed by neurological residents. The criteria of the Cervicogenic Headache International Study Group and the International Classification of Headache Disorders, second edition, were applied.

RESULTS

The questionnaire response rate was 71% and the participation rate of the interview was 74%. The prevalence of CEH was 0.17% in the general population, with a female preponderance. Fifty per cent had co-occurrence of medication overuse and 42% had co-occurrence of migraine. The pericranial muscle tenderness score was significantly higher on the pain than non-pain side (p < .005). The cervical range of motion was significantly reduced compared to healthy controls (p < .005). The mean duration of CEH was eight years. Based on patients' self-reports, greater occipital nerve (GON) blockage and cryotherapy was reported effective in 90% of those who had this procedure, while other treatment alternatives were reported less effective.

Impaired depth perception and restricted pitch head movement increase obstacle contacts when dual-tasking in older people

BACKGROUND

Trips are the largest contributor to falls in older people, yet little is known about the underlying physiological mechanisms for safe obstacle negotiation. The aims of the study were to determine (i) the effect of a secondary visual task on obstacle contacts when older people negotiated an obstacle course and (ii) physiological factors associated with obstacle contacts.

METHODS

Thirty community-living adults aged 65 years and older walked along a 14.5-m walkway containing 21 obstacles with and without a secondary task. The secondary task required participants to call out a series of letters presented in front of them at head height and the suit of a playing card framed on the sidewall. Obstacle contacts, secondary task errors, eye peak-to-peak pitch amplitude and head peak-to-peak pitch amplitude (PA-H), and head angle in pitch were measured. Participants also completed assessments of sensorimotor function and balance.

RESULTS

Compared with the obstacle-only trials, participants performed the dual-task trials more slowly (p < .001), contacted more obstacles (p = .032), showed greater PA-H (p < .001), and an extended head position (p < .001). Most participants also made secondary task errors. Regression analysis revealed that depth perception was the only significant determinant of obstacle contacts (explaining 20.6% of the variance) in the obstacle-only task and that depth perception and PA-H were independent and significant determinants of obstacle contacts (explaining 42.3% of the variance) in the dual task.

CONCLUSION

The findings demonstrate the importance of depth perception and head movement for safe negotiation of obstacles in older people and suggest that depth perception in particular should form part of fall risk assessments.

Assessment of two measurement techniques of cervical spine and C1-C2 rotation in the outcome research of axis fractures: a morphometrical analysis using dynamic computed tomography scanning

STUDY DESIGN

In vivo study on cervical spine motion.

OBJECTIVE

To estimate the accuracy of clinical measurements, using a handheld goniometer for the assessment of total cervical neck rotation in outcome research of patients with C2 fractures and particularly odontoid fractures. Investigation on whether functional computed tomography (CT)-scanning is decisive in the investigation of functional outcome after C2 fractures.

SUMMARY OF BACKGROUND DATA

Pertinent literature exists concerning indications, techniques, complications of treatment, and risk factors for nonunion in C2 fractures; however, there are scarce data regarding the functional outcome in C2 fractures. Only a few studies assess functional outcome in terms of clinical outcome vehicles and clinical investigation of axial neck rotation, using a handheld goniometer. Measurements of axial neck rotation using a handheld goniometer are assumed not sufficient to compare the results of treatment strategies for C2-fractures or elucidate the ability for posttreatment rotation of C1-C2.

METHODS

The authors selected a homogenous group of 35 patients treated for C2 fractures using nonsurgical and surgical techniques. 69% of patients had odontoid fractures. Mean age of patients was 52 years. Patients were subjected to clinical assessment of axial cervical range of motion for rotation, using a handheld goniometer. Patients were also subjected to functional CT-scanning and measurements of total neck and atlantoaxial rotation were performed according to an established protocol.

RESULTS

With clinical measurements mean range of motion for left and right axial neck rotation was both 56 degrees. According to the functional CT scans, the mean left-sided and right-sided axial neck rotation was 48.6 degrees and 52.0 degrees. The mean for left- and right-sided atlantoaxial rotation was 20.2 degrees and 20.6 degrees. Total axial atlantoaxial rotation on CT scans was 40.3 degrees and total axial neck rotation was 103.3 degrees. In comparison to age and gender matched normal individuals total cervical neck rotation was reduced to a mean of 69.5%. The differences between total axial neck rotation assessed using a handheld goniometer and with functional CT-scanning were strongly significant (P < 0.0001). In addition, there was no statistically significant correlation between the clinically assessed total neck rotation to either the left or the right side and the ipsilateral percentage atlantoaxial rotation of total head neck rotation.

CONCLUSION

The current study demonstrated that for the comparison of functional outcome after different therapies of C2 fractures clinical measurements do not serve for reliable data on total neck rotation and particularly atlantoaxial rotation and the percentage of C1-C2 rotation of total neck rotation. The use of dynamic CT-scans in the analysis of functional outcome after C2 fractures is strongly recommended.

Three-dimensional analysis of the cervical spine kinematics: effect of age and gender in healthy subjects

STUDY DESIGN.: A three-dimensional (3D) analysis of the cervical spine kinematics in vivo about a large asymptomatic database in order to evaluate the impact of age and gender on the neck's performances. OBJECTIVE.: To investigate the effect of age and gender on kinematical parameters of the cervical spine, specifically quantitative parameters concerning coupled movements and proprioception, using the infra-red POLARIS measurement system. SUMMARY OF BACKGROUND DATA.: Cervical spine kinematics has been investigated in vivo by numerous authors using various devices. However, few is known about the influence of gender and age on the 3D cervical biomechanics, specifically regarding coupled movements and proprioceptive abilities. METHODS.: A total of 140 asymptomatic volunteers (70 men and 70 women) aged 20 to 93 years old were enrolled. The noninvasive infrared system Polaris was used to quantify the 3D range of motion (ROM) of cervical spine and to evaluate proprioceptive abilities. For validating the protocol in terms of reproducibility, 12 volunteers were tested 3 times by 2 independent operators. RESULTS.: The standard error of measurement for the maximal ROM in the 3 space planes was 5%. Gender had no significant influence on the 3D cervical ROM, except for the "70-79 years old" group. Age had a significant influence on all main movements showing 0.55 degrees to 0.79 degrees magnitude decrease per decade. Age and gender had no significant influence on coupled movements. "Head-to-Target" proprioception was significantly affected by the age only in the horizontal plane. CONCLUSION.: A data base for cervical ROM, pattern of motion, and proprioceptive capability was established in population of 140 healthy subjects of various age and gender. Significant age-related decrease in ROM and proprioceptive abilities were observed in this study. Coupled movements did not vary with gender or age; however, their role in the cervical performance increased with age since main movements were limited.

Active head and cervical range of motion: effect of age in healthy females

STUDY DESIGN

A study on active cervical range of motion (RoM) in healthy females of different ages.

OBJECTIVE

Perform a three-dimensional quantitative analysis of active head-cervical RoM in healthy females to assess the relationship with age.

SUMMARY OF BACKGROUND DATA

Age-related variations in active cervical RoM are still partially unknown: some investigations demonstrated that age has no effect whatsoever on the primary movements, whereas other studies found an inverse proportionality between age and cervical RoM.

METHODS

Three groups of females were compared: 22 aged 15 to 18 years (adolescents), 25 aged 20 to 30 years (young adults), and 16 aged 35 to 45 years (mid-aged women). Active flexion and extension, lateral bending and axial rotation were recorded via an optoelectronic system. After the mathematical exclusion of thoracic movements, cervical RoM was referred to head local reference system and calculated using the tilt/twist method. Data were compared using analysis of variance.

RESULTS

Flexion and extension were larger in the adolescents (137 degrees ) than in the young adults (128 degrees ) and mid-aged women (127 degrees ). Lateral bending had similar ranges in the 3 groups: 103 degrees for adolescents, 101 degrees for young adults, and 100 degrees for mid-aged women. Axial rotation had similar ranges in the adolescents and in the mid-aged women (143 degrees ) and a slightly larger range in the young adults (151 degrees ). Primary movements were always associated with out-of-plane components.

CONCLUSION

In healthy females, between 15 and 45 years old, cervical RoMs in the principal planes decrease (except for rotation), but these variations are not statistically significant (P > 0.05).

C2-fractures: part II. A morphometrical analysis of computerized atlantoaxial motion, anatomical alignment and related clinical outcomes

Knowledge on the outcome of C2-fractures is founded on heterogenous samples with cross-sectional outcome assessment focusing on union rates, complications and technical concerns related to surgical treatment. Reproducible clinical and functional outcome assessments are scant. Validated generic and disease specific outcome measures were rarely applied. Therefore, the aim of the current study is to investigate the radiographic, functional and clinical outcome of a patient sample with C2-fractures. Out of a consecutive series of 121 patients with C2 fractures, 44 met strict inclusion criteria and 35 patients with C2-fractures treated either nonsurgically or surgically with motion-preserving techniques were surveyed. Outcome analysis included validated measures (SF-36, NPDI, CSOQ), and a functional CT-scanning protocol for the evaluation of C1-2 rotation and alignment. Mean follow-up was 64 months and mean age of patients was 52 years. Classification of C2-fractures at injury was performed using a detailed morphological description: 24 patients had odontoid fractures type II or III, 18 patients had fracture patterns involving the vertebral body and 11 included a dislocated or a burst lateral mass fracture. Thirty-one percent of patients were treated with a halo, 34% with a Philadelphia collar and 34% had anterior odontoid screw fixation. At follow-up mean atlantoaxial rotation in left and right head position was 20.2 degrees and 20.6 degrees, respectively. According to the classification system of posttreatment C2-alignment established by our group in part I of the C2-fracture study project, mean malunion score was 2.8 points. In 49% of patients the fractures healed in anatomical shape or with mild malalignment. In 51% fractures healed with moderate or severe malalignment. Self-rated outcome was excellent or good in 65% of patients and moderate or poor in 35%. The raw data of varying nuances allow for comparison in future benchmark studies and metaanalysis. Detailed investigation of C2-fracture morphology, posttreatment C2-alignment and atlantoaxial rotation allowed a unique outcome analysis that focused on the identification of risk factors for poor outcome and the interdependencies of outcome variables that should be addressed in studies on C2-fractures. We recognized that reduced rotation of C1-2 per se was not a concern for the patients. However, patients with worse clinical outcomes had reduced total neck rotation and rotation C1-2. In turn, C2-fractures, especially fractures affecting the lateral mass that healed with atlantoaxial deformity and malunion, had higher incidence of atlantoaxial degeneration and osteoarthritis. Patients with increased severity of C2-malunion and new onset atlantoaxial arthritis had worse clinical outcomes and significantly reduced rotation C1-2. The current study offers detailed insight into the radiographical, functional and clinical outcome of C2-fractures. It significantly adds to the understanding of C2-fractures.

The assessment of the cervical spine. Part 1: Range of motion and proprioception

Neck pain and headache of cervical origin are complaints affecting an increasing number of the general population. Mechanical factors such as sustained neck postures or movements and long-term "abnormal" physiologic loads on the neck are believed to affect the cervical structures and compromise neck function. A comprehensive assessment of neck function requires evaluation of its physical parameters such as range of motion, proprioception, strength and endurance/fatigue. The complicated structure of the cervical spine however, makes it difficult for any clinician to obtain reliable and valid results. The aim of the first part of this systematic critical review is to identify the factors influencing the assessment of range of motion and proprioception of the cervical spine.