From: Work. 2012 Jan 1;41(0):2535-8

The aim was to analyze the relationship between periods with uninterrupted neck muscle activity for ≥4 min and neck and shoulder pain. The trapezius muscle activity was recorded bilaterally on 40 young workers and students during a full shift. Neck and shoulder pain, mechanical work load and decision control were reported at the same time as the muscle activity recording and 6 months later. A dose-response relationship was found between uninterrupted muscle activity and neck and shoulder pain, with a ten-fold higher risk for the group with more than half, compared to less than a third, of the shift with uninterrupted muscle activity. Self-reported mechanical work load showed a small but protective effect related to pain. Gender and decision control did not emerge as important risk factors in this model. In conclusion, this study indicates that work or other exposures that contains long periods with uninterrupted neck muscle activity of 4 min duration or longer should be minimized to reduce risk of neck and shoulder pain.

Long periods with uninterrupted muscle activity related to neck and shoulder pain

From: Work. 2012 Jan 1;41(0):2591-5

This study aimed to evaluate the posture, muscle activities, and self reported discomforts of neck pain notebook computer users on three monitor tilt conditions: 100°, 115°, and 130°. Six subjects were recruited in this study to completed typing tasks. Results showed subjects have a trend to show the forward head posture in the condition that monitor was set at 100°, and the significant less neck and shoulder discomfort were noted in the condition that monitor was set at 130°. These result suggested neck pain notebook user to set their monitor tilt angle at 130°.

Man Ther. 2012 Feb 4. [Epub ahead of print]

There is considerable evidence that neck pain is associated with alterations in spatial and temporal behaviors of the neck muscles and changes in muscle properties. Changes have been identified in various neck and axio-scapular muscles and the neck flexors have received particular attention. There is some functional specificity between superficial and deep flexors. Superficial muscles, sternocleidomastoid and anterior scalenes are major contributors to flexion torque while deep neck flexor muscles (longus capitis and colli) have an important role in supporting the normal neck curve and segments in posture and movement.

Of clinical and functional relevance, reduced activation of the deep neck flexor muscles has been identified in association with increased activation of the superficial flexor muscles in studies using the cranio cervical flexion test in patients with a variety of neck disorders. The evidence of reduced deep neck flexor activity comes from laboratory studies using a direct measure of electromyographic (EMG) amplitudes. A number of clinical studies have limited measurement to sternocleidomastoid activity using surface EMG electrodes and have indirectly inferred reduced deep neck flexor function on the evidence of an inverse relationship between sternocleidomastoid, anterior scalenes and deep neck flexor muscle activity from laboratory measures of neck pain patients.

Training the deep neck flexor muscles is regarded as an important component of neck rehabilitation programs because of the functional importance of the deep neck flexor and the evidence suggesting that the altered pattern of activation between the deep and superficial flexors (1) does not correct automatically with pain relief and (2) persists without specific training. Many factors influence the magnitude of neck pain. It is uncertain whether changes in muscle function are a cause or effect of pain, but a relationship has been shown between neck pain intensity and activity in the deep (lesser) and superficial (greater) neck flexor muscles. Concomitantly, the degree of pain reduction in patients with chronic neck pain has a relationship with the change in deep neck flexor activity following training. Clinical trials also support the effectiveness of training the deep neck flexor muscles and restoring their normal temporal relationship with the superficial flexors as a component of a multimodal program for the rehabilitation of neck pain disorders.

Appropriate training methods are required to address the observed impairment in neck flexor muscle behavior in the clinical setting. Cervical flexor strengthening exercises such as a head lift regime, while improving strength, do not successfully address the altered pattern of activation between the deep and superficial neck flexor muscles but a motor relearning approach using low load exercises to target the deep neck flexors can do so. A common form of deep neck flexor muscle training involves the patient learning the cranio cervical flexion action and training the endurance capacity of the deep neck flexor in the supine position. Training in this way effectively redresses the altered behavior in the flexor synergy identified in the cranio cervical flexion test by increasing the measurable activity in the deep neck flexors and reducing the activity of sternocleidomastoid and anterior scalene muscles. From a clinical viewpoint, training in supine alone limits the number of repetitions that a patient can practice in a day. Repetition is an important feature in the motor learning process. Training in supine also is not functional and there is mixed evidence for the transfer of improvement in cervical flexor muscle performance to function with such training alone.

Facilitating an upright posture activates the longus capitis/colli group. Thus a postural correction exercise which can be performed easily during the working day is advocated within a training program. It is unknown whether training the deep neck flexor with a postural exercise is effective and can change the aberrant pattern of neck flexor muscle activity demonstrated in the cranio cervical flexion test. The purpose of this initial study was to investigate the effect of a postural exercise in a controlled trial of a 2-week intervention in the first instance. It was hypothesized that the postural exercise alone was sufficient to improve deep neck flexor muscle performance, indicated by a measureable decrease in sternocleidomastoid activity over progressive stages of the cranio cervical flexion test.

The exercise intervention consisted of a 2-week program in this preliminary study as a change in muscle behavior can be expected from a motor learning program in this period. The intervention began immediately after the baseline assessment for subjects allocated to the exercise group. The postural exercise was performed in sitting and required the subject to assume firstly, an upright posture in a neutral lumbo-pelvic position. They were then taught to gently lift the base of the skull from the top of the neck as if to lengthen the cervical spine. This neck lengthening manoeuvre strongly activated the longus colli. A neutral scapular position was taught if the scapulae were judged clinically for example, to be in a position of downward rotation or protraction. Subjects received training until it was assessed that they could perform the postural exercise properly. They were asked to perform the exercise, holding the position for 10s ideally every 15–20 min throughout their waking day, akin to a work break and exercise routine for the two week duration of the trial. Subjects were provided with an exercise diary to record the number of times the exercise was performed each day. Subjects returned twice in the two week period before the follow up assessment to ensure correct performance of the exercise and for motivation and compliance purposes.

Training with a functional postural exercise improved performance in the cranio cervical flexion test, measured in this study as a decrease in sternocleidomastoid activity. No change was observed in the control group. The pre to post-intervention analysis within the exercise group revealed decreased sternocleidomastoid EMG amplitudes at the first and third stages of the test with non-significant lower amplitudes in the other stages. The exercise involved assuming an upright neutral postural position with the addition of a neck lengthening manoeuvre. Both elements have been shown to activate the deep neck flexor. It can only be inferred from this study that the decrease in sternocleidomastoid activity in the cranio cervical flexion test was accompanied by an improvement in the activation of the deep neck flexor. Nevertheless this relationship was shown training the deep neck flexor in supine where reduced sternocleidomastoid activity in the cranio cervical flexion test was associated with an increase in deep neck flexor activity. Thus the authors hypothesis that the postural exercise can improve deep neck flexor muscle performance can be provisionally supported. However it is premature to comment on whether this exercise alone would be would be sufficient to address the altered behaviour of the neck flexor synergy in neck pain patients. Importantly, the results provide a justification for a larger study with direct measures of both sternocleidomastoid and deep neck flexor muscles using more invasive direct measures of deep neck flexor muscle activity.

Training the deep neck flexor in supine and achieved an increase in deep neck flexor and a decrease in sternocleidomastoid EMG amplitude across all cranio cervical flexion test stages, with the exception of the lowest level (22 mmHg). This could imply that training the deep neck flexor in supine is more effective. However it may merely reflect the longer training period (6-weeks) as opposed to the 2-week period in the present study. The 2-week training period was chosen for this preliminary study as a change in muscle behaviour could be expected in this time but future trials of the two methods would necessarily test equivalent periods of training. Alternately the results could be a product of the relatively small sample size of the current study. Nevertheless, the present study demonstrating a decrease in activation of the sternocleidomastoid post-intervention suggests, albeit indirectly, that a functional method of training the deep neck flexor in an upright position does lead to improvements in deep neck flexor activation. From a clinical viewpoint, a greater benefit may be achieved by combining both formal and functional methods of training in the management of patients with neck pain disorders. Future research is warranted to explore longer periods of training with the postural exercise alone against formal training in the supine position as well as the possible combination of these training methods in a management regime for patients with neck pain disorders.

The functional, postural exercise to improve cervical muscle performance is a suitable option to cater for the increasing number of people working in office environments or other sedentary occupations. Evidence of altered working postures such as increased forward head posture, implying poor function of the deep neck flexor, has been shown in those with neck pain. Improvements in the maintenance of neck posture during sustained sitting postures have been achieved with training the deep neck flexor in the supine position. A practical, time efficient exercise performed easily throughout the day, such as the postural exercise evaluated in this study, may prove an essential aspect for effective training of the deep neck flexor in those sedentary workers with neck pain. Judging by the compliance rate recorded in this study, the exercise is convenient to perform. On average, the exercise was performed 15 times per day, equating to approximately once per waking hour, or twice per productive day-time hour.

It appears important that patients are taught the postural exercise with precision as undertaken in this currently study. Deep neck flexor muscles were activated when subjects were merely instructed to sit in a good posture. However higher levels of activity were recorded in the deep neck flexor (and lumbar multifidus) when subjects were facilitated into an upright neutral lumbo-pelvic and spinal posture. This highlights the need for care in teaching and training a postural exercise in the rehabilitation of neck pain patients. Incorporating a specific neck lengthening manoeuvre in the postural exercise is likely to enhance the deep neck flexor contraction.

Two weeks of training with the postural exercise alone did not change pain and disability measures, which is not surprising. Only one exercise intervention was used, focusing on a single muscle group, which is inadequate and unrealistic given the potential extent of changes in cervical and axio-scapular muscle function in neck pain disorders. There is ample evidence from systematic reviews that clearly indicates that multimodal management is superior to any single modality in reducing neck pain and disability.

This study determined that training with a postural exercise consisting of assumption of a neutral lumbo-pelvic and spinal posture with an added neck lengthening manoevre led to an improved pattern of cervical flexor muscle activity in the cranio cervical flexion test. The improvement manifested as a reduced level of sternocleidomastoid activity, infering an increase in deep neck flexor activation post-training. While further research is necessary to explore the benefits of this exercise, these observations suggest the worth of including such an exercise in the rehabilitation of patients with neck pain disorders.

From: Scand J Public Health. 2012 Feb 3. [Epub ahead of print]

To study whether having ever had local low back pain, sciatica, neck pain, or some combination of low back pain and neck pain, predicts sickness absence among municipal employees. The study sample (n=6911, 80% women, response rate 67%) included employees of the City of Helsinki who reached the age of 40, 45, 50, 55, or 60 years between 2000-02. Survey data on pain, working conditions, and health behaviours were linked to register data on sickness absence for three subsequent years. Sickness absence was categorised as self-certified (lasting for 1-3 days) and medically certified (lasting for 4 days or more) and the number of spells during the follow up was analysed using Poisson regression analysis.

In women, medically certified sickness absence was predicted by sciatica, neck pain and the combination of sciatica and neck pain, allowing for working conditions, body mass index, and smoking. Local low back pain did not predict medically certified sickness absence. Self-certified sickness absence was modestly predicted by all pain categories and by neck pain alone and with local low back pain or sciatica in men.

Medically certified sickness absence was predicted by sciatica and neck pain, but not by local low back pain. The association was accentuated in those with both sciatica and neck pain. Pain combinations may have a stronger effect on work ability than pain in one location.

From: BMC Musculoskelet Disord. 2012 Jan 31;13(1):10. [Epub ahead of print]

Cervical or neck pain is a general term used to designate any musculoskeletal disorder in the cervical region. Various pathologies encompass that generic definition and are most commonly related to degenerative changes or inflammation of cervical structures such as intervertebral discs, articular facets joints or nerve roots. Neck pain is a very common, disabling and costly condition. According to a review by the Neck Pain Task Force pertaining the prevalence of neck pain in industrialised countries, annual prevalence is situated within 30 to 50% in adult populations. In accordance with these results, in Canada, a bi-annual prevalence of 54% has been reported.

Cervical radiculopathy forms an important subgroup of neck disorders and, although less prevalent than general neck pain, it has been shown to lead to more severe pain and disability. Cervical radiculopathy primarily results from an inflammation of a cervical nerve root induced by a lesion reducing the intervertebral foramen. This reduction is primarily induced by a herniated disc or a degenerative lesion of zygapophysial joints. Typical symptoms of cervical radiculopathy include pain in the cervical or periscapular region and in the upper limb, as well as neurological signs such as paresthesia, numbness, weakness and loss of reflexes in the affected nerve root distribution.

The diagnosis of cervical radiculopathy is commonly made through patient history and physical examination. A a positive response to the following four clinical tests results in a high predictive value for a diagnosis of cervical radiculopathy: 1 – cervical distraction test, 2 – upper limb tension test, 3 – Spurling test, and 4 – ipsilateral cervical rotation reduced by more than 60 degrees. If all four of these tests are positive, the positive likelihood ratio (LR+) of having a cervical radiculopathy is 30. If three out of these four tests are positive, the LR+ decreases to 6. A LR+ superior to 10 is considered large, and between 5 and 10 moderate; thus, it increases the possibility that the impairment in question is present. Hence, by combining these clinical tests, the possibility of obtaining a good clinical diagnostic accuracy in patients presenting signs and symptoms compatible with cervical radiculopathy is high.

While the clinical diagnostic process of cervical radiculopathy is relatively well documented, studies evaluating the effectiveness of rehabilitation interventions remain sparse. Published in 2010, a systematic review by Miller et al., pertaining to the effects of manual therapy and exercises on the treatment of neck pain, concluded that there is little evidence supporting the efficacy of these modalities in the treatment of cervical radiculopathies. Of the 17 randomised clinical trials (RCT) included in this systematic review, only three included subjects who presented radicular signs. Furthermore, in these three RCTs, subjects with or without radicular signs were combined for the statistical analysis used to evaluate the effects of the intervention. The authors of the systematic review concluded that, for neck pain, a combination of cervicothoracic mobilisations and exercises is the most effective rehabilitation approach to reduce pain and disability. No specific recommendation was, however, brought forth for cervical radiculopathies. Three RCTs published in 2009, but not included in the systematic review by Miller et al., also evaluated the effects of rehabilitation approaches for the treatment of cervical radiculopathy.

Kuijper etal. randomised 205 patients suffering from cervical radiculopathy within 3 groups: a cervical collar approach, an active physiotherapy approach, and a wait and see approach. The active physiotherapy approach involved mobilisations and stabilisation exercises; whereas the cervical collar approach included the use of a semi-hard cervical collar worn at all times for three weeks, then gradually weaned for three additional weeks. Three and six weeks into the intervention, a diminution of arm and neck pain was observed in the cervical collar and active physiotherapy groups. Functional improvement was also observed in both experimental groups at three weeks, but was only noted in the cervical collar group at six weeks. While this study’s conclusions seem to favour the cervical collar approach, it remains a controversial treatment option. According to the Quebec Task Force, cervical collar should be avoided due to its passive and decondition properties, and because it has been shown to hinder neck pain recuperation following motor vehicle accidents. These initial recommendations regarding the potential drawbacks of cervical collar use have recently been generalised to encompass all types of neck pain. Finally, two other studies have evaluated the effect of intermittent traction on patients suffering from cervical radiculopathy. They have, however, obtained contradictory results: one demonstrated that the addition of neck traction to a conventional intervention does not increase treatment efficacy, whereas the other claimed that traction supplementing a conventional intervention improves cervical and radicular pain, in comparison to a conventional intervention.

Numerous other approaches are commonly utilised in clinical settings, but a formal demonstration of their efficacy remains to be shown. Clinical approaches for cervical radiculopathies commonly include interventions targeting the opening of intervertebral foramen. It is well recognised that cervical movements causing the opening of intervertebral foramen, such as flexion, rotation and lateral flexion contralateral to the nerve root, increase the volume of the foramen, and consequently might decompress a swollen nerve root. Inversely, movements of extension, rotation and lateral flexion ipsilateral to the nerve root close the intervertebral foramen around the root. Thus, for acute and sub-acute radiculopathies, intervention programs should include treatment modalities that allow the opening of the intervertebral foramen. On the other hand, movements and positions that lead to intervertebral foramen closure should be avoided. However, no studies have evaluated the effects of a treatment approach that specifically take into consideration these biomechanical principles.

Due to the important incapacities related to cervical radiculopathy, and to the few studies pertaining to the efficacy of rehabilitation in this population, the authors believe in the importance of better understanding the potential of cervical mobilisations and exercises that lead to the opening of the intervertebral foramen. The primary objective of this RCT is to compare, in terms of pain and disability, a rehabilitation program targeting the opening of intervertebral foramen to a conventional rehabilitation program, in patients presenting acute or subacute cervical radiculopathy. Based on biomechanical principles, the hypothesis is that the rehabilitation program targeting the opening of intervertebral foramen will be significantly more effective in reducing pain and disability than the conventional rehabilitation program, mainly at the 4-week evaluation. In considering the passage of time, the differences between the two interventions should be less important at 8-week.

This double-blind randomised clinical trial will allow the comparison, in terms of pain and disability, of patients presenting a cervical radiculopathy which will have been randomly assigned to one of the two intervention groups: the first group (n = 18) will receive a 4-week rehabilitation program targeting the opening of intervertebral foramen, the second group (n = 18) will receive a 4-week conventional rehabilitation program. Participants will be evaluated on three separate occasions: at baseline (week 0), at the end of the 4-week program (week 4), and four weeks following the end of the program (week 8).

Rehabilitation program targeting the opening of intervertebral foramen: The same program as for the conventional rehabilitation program will be applied, with two exceptions:

• Of the four mobilisation techniques, there will be two mandatory techniques targeting the opening of the intervertebral foramen on the same side and at the same level as the radiculopathy: global contralateral rotation mobilisation and ipsilateral lateral glide in a flexion position (10 repetitions * 30 seconds for each technique). The physiotherapist, according to the biomechanical evaluation results, will choose the two other mobilisation techniques including rotations, lateral glides, postero-anterior glides, infero-medial glides or supero-anterior glides mobilisations.

• The third exercise of the home program will be an opening technique: contralateral rotation exercise (contralateral to the affected segment; 10 repetitions * 3 seconds, 10 times /day). Therefore, the number of mobilisation techniques and home exercises will be the same for the two intervention groups.

Based on the important incapacities related to cervical radiculopathy, control trials are urgently needed to define ideal intervention approaches in rehabilitation for this population. Recent systematic reviews have highlighted the lack of such trials, and thus, the need to establish the effectiveness of rehabilitation approaches. The rational for the need to determine the effectiveness of a rehabilitation program targeting the opening of intervertebral foramen of the affected segment was presented. This RCT will be the first study that directly compares a rehabilitation program targeting the opening of intervertebral foramen to a conventional rehabilitation program for patients with cervical radiculopathy. The results of this study may help to establish best clinical practice guidelines for this patient population.

For participant recruitment, please visit Effect of Mobilizations and Exercises Targeting the Opening of Intervertebral Foramens Following Cervical Radiculopathy

From: J Electromyogr Kinesiol. 2012 Jan 28. [Epub ahead of print]

The objectives of this article are to (1) describe spinal manipulation use by time, place, and person, and (2) identify predictors of the use of spinal manipulation. We conducted a systematic review of the English-language literature published from January 1, 1980 through June 30, 2011. Of 822 citations identified, 213 were deemed potentially relevant; 75 were included after further consideration. Twenty-one additional articles were identified from reference lists. The literature is heavily weighted toward North America, Europe, and Australia and thus largely precludes inferences about spinal manipulation use in other parts of the world.

In the regions covered by the literature, chiropractors, osteopaths, and physical therapists are most likely to deliver spinal manipulation, often in conjunction with other conservative therapies. Back and neck pain are the most frequent indications for receiving spinal manipulation; non-musculoskeletal conditions comprise a very small percentage of indications. Although spinal manipulation is more commonly used in adults than children, evidence suggests that spinal manipulation may be more likely used for non-musculoskeletal ailments in children than in adults. Patient satisfaction with spinal manipulation is very high.

From: Arthritis Rheum. 2012 Jan 27. doi: 10.1002/art.33462. [Epub ahead of print]

This study addressed the association of overweight and obesity to the presence, extent, and severity of lumbar disc degeneration on MRI in adults. A population-based cross-sectional study of 2,599 Southern Chinese volunteers. Radiographic and clinical assessment, including weight and height, was conducted. Sagittal T2-weighted MRIs of the lumbar spine were obtained. The presence, extent, and severity of disc degeneration as well as additional radiographic and clinical findings were assessed. Asian-modified BMI (kg/m2) categories were utilized.

There were 1,040 males and 1,559 females (mean age= 41.9 years). Disc degeneration was noted in 1,890 (72.7%) subjects. BMI was significantly higher in subjects with disc degeneration compared to subjects without degeneration. A significant increase in the number of degenerated levels, global severity of disc degeneration, and end stage disc degeneration with disc space narrowing was noted with elevated BMI, in particular in overweight and obese individuals. In the adjusted multivariate logistic regression model, there was a positive linear trend between BMI categories and the overall presence of disc degeneration for overweight and obese. End stage disc degeneration with disc space narrowing was significantly more pronounced in obese individuals.

In one of the largest studies to systematically assess lumbar disc degeneration on MRI, our study noted a significant association between the presence, increased extent, and global severity of disc degeneration in overweight and obese adults.

From: BMC Musculoskelet Disord. 2012 Jan 24;13(1):7.

Nearly 4 million people in Australia suffer from back pain at any one time, with total treatment costs exceeding $1 billion a year. In the US, the figure is an astonishing US$32 billion a year. Back complaints are the seventh most common condition in patients consulting general practitioners in Australia, and the most common musculoskeletal condition. It is also the most common health problem for which an imaging test is ordered by a general practitioner.

A potential solution to managing the problem of low back pain is the identification and control of modifiable risk factors. This approach is appealing and seemingly logical and there are notable examples where such an approach has provided major improvements in public health. For back pain this approach has not yet been fruitful: Cochrane reviews of workplace interventions, insoles and lumbar supports have failed to support these traditional back pain prevention approaches. Prevention strategies have to date been largely based on controlling long-term exposure to risk factors, for example, modifying seats to control vibration in truck drivers. However it is likely that the full potential of prevention will not be reached unless we also consider commonly occurring, modifiable risk factors that happen just before the onset of back pain. In this regard the authors see this proposed research as complementary to, rather than in conflict with, research evaluating long term risk factors.

The existence of short term risk factors or ‘triggers’ is consistent with the time course of back pain. It is well established that most people will experience low back pain in their lifetime, that pain is typically recurrent and that episodes are usually of sudden onset. For example research conducted by this group demonstrated that in an inception cohort of 969 subjects, 82% reported that their onset of low back pain was sudden. This pattern of low back pain suggests that rather than solely looking at long term exposure to risk factors it would be instructive to also look closely at events occurring immediately prior to the episode to identify modifiable triggers to the episode. This information is routinely sought by health practitioners when a patient with low back pain seeks care. The treating clinician commonly asks the patient what activity they were performing just prior to the onset of pain, in essence, “was the episode triggered by something unusual that happened just before?” The scientific method best suited to answer this question is the case-crossover design.

The authors will use the case-crossover design to provide the first accurate estimates of the transient increase in risk of low back pain associated with transient exposure to various triggers. It is possible that they will identify several factors that are not modifiable but this information will be extremely important to our understanding and explanation of the causes of low back pain.

From: J Pain. 2012 Jan 24. [Epub ahead of print]

A controlled experimental study was performed to examine the efficacy of the endogenous pain inhibitory systems and whether this (mal)functioning is associated with symptom increases following exercise in patients with chronic whiplash associated disorders. In addition, 2 types of exercise were compared. Twenty-two women with chronic whiplash associated disorders and 22 healthy controls performed a submaximal and a self-paced, physiologically limited exercise test on a cycle ergometer with cardiorespiratory monitoring on 2 separate occasions. Pain pressure thresholds, health status, and activity levels were assessed in response to the 2 exercise bouts.

In chronic whiplash associated disorders, pain pressure thresholds decreased following submaximal exercise, whereas they increased in healthy subjects. The same effect was established in response to the self-paced, physiologically limited exercise, with exception of the pain pressure thresholds at the calf which increased. A worsening of the chronic whiplash associated disorders symptom complex was reported post-exercise. Fewer symptoms were reported in response to the self-paced, physiologically limited exercise.

These observations suggest abnormal central pain processing during exercise in patients with chronic whiplash associated disorders. Submaximal exercise triggers post-exertional malaise, while a self-paced and physiologically limited exercise will trigger less severe symptoms, and therefore seems more appropriate for chronic whiplash associated disorders patients.

The results from this exercise study suggest impaired endogenous pain inhibition during exercise in people with chronic whiplash associated disorders. This finding highlights the fact that one should be cautious when evaluating and recommending exercise in people with chronic whiplash associated disorders, and that the use of more individual, targeted exercise therapies is recommended.

From: Eur Spine J. 2012 Jan 24. [Epub ahead of print]

Chronic radicular symptoms have been documented in whiplash patients, potentially caused by cervical neural tissue compression during an automobile rear crash. The goals of this study were to determine neural space narrowing of the lower cervical spine during simulated rear crashes with whiplash protection system and active head restraint and to compare these data to those obtained with no head restraint. We extrapolated our results to determine the potential for cord, ganglion, and nerve root compression.

The model, consisting of a human neck specimen within a BioRID II crash dummy, was subjected to simulated rear crashes in a whiplash protection system seat (n = 6, peak 12.0 g and ΔV 11.4 kph) or active head restraint seat and subsequently with no head restraint (n = 6, peak 11.0 g and ΔV 10.2 kph with AHR; peak 11.5 g and ΔV 10.7 kph with no head restraint). Cervical canal and foraminal narrowing were computed and average peak values statistically compared (P < 0.05) between whiplash protection system, active head restraint, and no head restraint.

Average peak canal and foramen narrowing could not be statistically differentiated between whiplash protection system, active head restraint, or no head restraint. Peak narrowing with whiplash protection system or active head restraint was 2.7 mm for canal diameter and 1.6 mm, 2.7 mm, and 5.9 mm(2) for foraminal width, height and area, respectively.

While lower cervical spine cord compression during a rear crash is unlikely in those with normal canal diameters, these results demonstrated foraminal kinematics sufficient to compress spinal ganglia and nerve roots. Future anti-whiplash systems designed to reduce cervical neural space narrowing may lead to reduced radicular symptoms in whiplash patients.

A simple and proven method of improving head restraints for whiplash protection that is user friendly and effective - proven in crash test results and highly recommended by heath care professionals is the add on headrest