Can interventional MRI provide an insight into the mechanics of a posterior-anterior mobilisation?

Neural responses of posterior to anterior movement on lumbar vertebrae: a functional magnetic resonance imaging study

OBJECTIVE

The purpose of this study was to develop and test a clinically relevant method to mechanically stimulate lumbar functional spinal units while recording brain activity by means of functional magnetic resonance imaging (MRI).

METHODS

Subjects were investigated in the prone position with their face lying on a modified stabilization pillow. To minimize head motion, the pillow was fixed to the MRI headrest, and supporting straps were attached around the shoulders. An experienced manual therapist applied controlled, nonpainful pressure stimuli to 10 healthy subjects at 3 different lumbar vertebrae (L1, L3, and L5). Pressure applied to the thumb was used as a control. The stimulation consisted of posterior to anterior (PA) pressure movement. The therapist followed a randomized stimulation protocol projected onto a screen in the MRI room. Blood oxygenation level-dependent responses were analyzed in relation to the lumbar and the thumb stimulations. The study was conducted by the Chiropractic Department, Faculty of Medicine, University of Zürich, Switzerland.

RESULTS

No participant reported any discomfort due to the prone-lying position or use of the pillow. Importantly, PA-induced pressure produced only minimal head movements. Stimulation of the lumbar spinous processes revealed bilateral neural responses in medial parts of the postcentral gyrus (S1). Additional activity was observed in the secondary somatosensory cortex (S2), posterior parts of the insular cortex, different parts of the cingulate cortex, and the cerebellum. Thumb stimulations revealed activation only in lateral parts of the contralateral S1.

CONCLUSION

The current study demonstrates the feasibility of the application of PA pressure on lumbar spinous processes in an MRI environment. This approach may serve as a promising tool for further investigations regarding neuroplastic changes in chronic low back pain subjects.

Relative effectiveness and adverse effects of cervical manipulation, mobilisation and the activator instrument in patients with sub-acute non-specific neck pain: results from a stopped randomised trial

BACKGROUND

Neck pain of a mechanical nature is a common complaint seen by practitioners of manual medicine, who use a multitude of methods to treat the condition. It is not known, however, if any of these methods are superior in treatment effectiveness. This trial was stopped due to poor recruitment. The purposes of this report are (1) to describe the trial protocol, (2) to report on the data obtained from subjects who completed the study, (3) to discuss the problems we encountered in conducting this study.

METHODS

A pragmatic randomised clinical trial was undertaken. Patients who met eligibility criteria were randomised into three groups. One group was treated using specific segmental high velocity low amplitude manipulation (diversified), another by specific segmental mobilisation, and a third group by the Activator instrument. All three groups were also treated for any myofascial distortions and given appropriate exercises and advice. Participants were treated six times over a three-week period or until they reported being pain free. The primary outcome measure for the study was Patient Global Impression of Change (PGIC); secondary outcome measures included the Short-Form Health Survey (SF-36v2), the neck Bournemouth Questionnaire, and the numerical rating scale for pain intensity. Participants also kept a diary of any pain medication taken and noted any perceived adverse effects of treatment. Outcomes were measured at four points: end of treatment, and 3, 6, and 12 months thereafter.

RESULTS

Between January 2007 and March 2008, 123 patients were assessed for eligibility, of these 47 were considered eligible, of which 16 were allocated to manipulation, 16 to the Activator instrument and 15 to the mobilisation group. Comparison between the groups on the PGIC adjusted for baseline covariants did not show a significant difference for any of the endpoints. Within group analyses for change from baseline to the 12-month follow up for secondary outcomes were significant for all groups on the Bournemouth Questionnaire and for pain, while the mobilisation group had a significant improvement on the PCS and MCS subscales of the SF-36v2. Finally, there were no moderate, severe, or long-lasting adverse effects reported by any participant in any group.

CONCLUSIONS

Although the small sample size must be taken into consideration, it appears that all three methods of treating mechanical neck pain had a long-term benefit for subacute neck pain, without moderate or serious adverse events associated with any of the treatment methods. There were difficulties in recruiting subjects to this trial. This pragmatic trial should be repeated with a larger sample size.

Is it reasonable to use an individual patient's progress after treatment as a guide to ongoing clinical reasoning?

Systematic assessment of a patient's progress after an intervention is frequently used to inform decision making in ongoing conservative management of patients with musculoskeletal symptoms. Although reassessment of impairments immediately after treatment is commonplace in clinical practice, relatively little research has considered whether this method is reasonable. The history of, rationale behind, and evidence for the use of patient responses to inform clinical reasoning are explored in this commentary. Although the evidence is not conclusive, an argument is presented suggesting it is more reasonable to use a patient's response to treatment to inform ongoing clinical reasoning than to follow predetermined protocols. A methodical approach that considers change in parameters such as patient impairments is likely to be a useful guide for decision making during ongoing patient management but only when the change being reassessed can be directly linked to functional goals. Changes in active range of movement or centralization of pain appear to be better indicators of treatment effectiveness than changes in either pain intensity or assessment of joint position. There is limited evidence to support the use of changes in segmental stiffness to guide ongoing management. Although reassessment of some impairments has been found to be useful, the author suggests that care is required in the selection of reassessments used to guide ongoing management. The usefulness of any reassessment is considered to rely on how well a change in the selected impairment predicts that individual patient's ability to achieve their goals.

Measuring the posteroanterior stiffness of the cervical spine

An essential part of improving manual therapy treatment for cervical spine disorders is the identification of the mechanical effects of manual techniques. The aims of this research were to develop a reliable and safe instrument for measuring cervical spine stiffness, and to document stiffness in a group of asymptomatic individuals. A device for measuring cervical spine stiffness was designed and tested. The stiffness of the cervical spine of 67 asymptomatic individuals was measured at C2 and C7 on one or more occasions. Stiffness was defined as the slope of the linear region of the force-displacement curve (coefficient K). For C2, the linear region of the force-displacement curve was from 7 to 40 N, and for C7, 20-70 N. The mean stiffness (coefficient K) on the first measurement occasion at C2 was 4.58 N/mm (95% CI 4.30-4.85), and at C7 was 7.03 N/mm (95% CI 6.50-7.57). ICC(2,1) for repeated measurements was 0.84 (95% CI 0.74-0.90). Stiffness measurements in the cervical spine were generally lower than those previously reported for the lumbar spine. Age was positively associated with C2 stiffness (p=0.01). Males were stiffer at C7 than females (p<0.001). This research provides a basis for future studies investigating the effects of manual techniques on cervical spine stiffness, potentially leading to improved outcomes for patients treated by manual therapy.

Relation between changes in posteroanterior stiffness and active range of movement of the cervical spine following manual therapy treatment

STUDY DESIGN

Repeated measures study of active and passive movements in patients with neck pain.

OBJECTIVES

To determine if, following manual therapy: (1) changes occur in active range of movement (AROM) and stiffness of posteroanterior (PA) movements, (2) such changes are dependent on the location treated, and (3) there is a relation between changes in PA stiffness and AROM.

SUMMARY OF BACKGROUND DATA

PA movements are frequently used to assess patients with neck pain but little is known about how these movements are related to patient symptoms.

METHODS

One location deemed symptomatic and hypomobile and 1 asymptomatic location were selected in 20 patients with neck pain for more than 2 weeks. PA stiffness at each location and AROM were measured before and after each of 4 manual therapy interventions: PA movements to each location, a general treatment, and a control intervention.

RESULTS

The general intervention had a greater increase in each axis of AROM than the other interventions (F = 2.814 to 7.929, DF = 3) but there were no differences in PA stiffness across interventions (F = 0.945, DF = 3). Differences in PA stiffness was divided into regions by applied force. After treatment to the symptomatic location, regions of stiffness at forces above 8 N demonstrated significant correlations with total AROM (R = -0.466 to -0.628).

CONCLUSION

After manual therapy, increased AROM is related to decreased PA stiffness in patients with neck pain, but only for the treated location and only when that location had been identified previously as symptomatic and hypomobile.

Intertester reliability and validity of motion assessments during lumbar spine accessory motion testing

BACKGROUND AND PURPOSE

Posterior-anterior (PA) assessment of the lumbar spine correlates with radiographic signs of instability and can guide treatment choices, yet studies of the validity of lumbar PA assessments have not been conducted in vivo. The purposes of this study were to determine the intertester reliability of the PA examination in assessing intersegmental lumbar spine motion and to evaluate the validity of this procedure in vivo with dynamic magnetic resonance imaging (MRI).

SUBJECTS

Twenty-nine subjects with central lumbar pain participated in this study.

METHODS

Two physical therapists independently identified each subject's most and least mobile lumbar segments using the PA procedure. Midsagittal lumbar images were obtained simultaneously during one examiner's assessment. Lumbar segmental mobility was quantified from magnetic resonance images as the change in the intervertebral angle between the resting position and the end range of the PA force application. For each vertebral level tested, maximal sagittal-plane segmental motion was determined.

RESULTS

The intertester reliability for identifying the least mobile segment was good (agreement=82.8%, kappa=.71, 95% confidence interval [CI]=.48 to .94), but it was poor for identifying the most mobile segment (kappa=.29, 95% CI=-.13 to .71), despite good agreement (79.3%). The level of agreement between the PA assessments and intervertebral motion measured by MRI was poor (kappa=.04, 95% CI=-.16 to .24, and kappa=.00, 95% CI=-.09 to .08, for the least and most mobile segments, respectively).

DISCUSSION AND CONCLUSION

Despite good intertester reliability for identifying the least mobile segment, PA assessments of lumbar segmental mobility did not agree with sagittal-plane motion measured by dynamic MRI. This finding calls into question the validity of the PA procedure for assessing intervertebral lumbar spine motion.

Manual Forces Applied During Posterior-to-Anterior Spinal Mobilization: A Review of the Evidence

OBJECTIVE

The objective of this review was to evaluate the evidence for the consistency of force application by manual therapists when carrying out posterior-to-anterior (PA) mobilization techniques, including the factors that influence the application and measurement of mobilization forces.

METHODS

Studies were identified by searching 6 electronic databases up to April 2005, screening the reference lists of retrieved articles, and contacting experts by e-mail. Relevant articles were defined as those that described the measurement of forces applied during spinal mobilization or discussed the reliability of measurement of manual forces.

RESULTS

Twenty studies described the quantitative measurement of applied force during a PA mobilization technique, with most focusing on the lumbar spine. When defined by magnitude, frequency, amplitude, and displacement, PA mobilization forces are extremely variable among clinicians applying the same manual technique. Variability may be attributed to differences in techniques, measurement or reporting procedures, or variations between therapists or between patients.

CONCLUSIONS

The inconsistency in manual force application during PA spinal mobilization in existing studies suggests that further studies are needed to improve the clinical standardization of manual force application. Future research on mobilization should include forces applied to the cervical and thoracic spines in addition to the lumbar spine while thoroughly describing force parameters and measurement methods to facilitate comparison between studies.

Comparative effectiveness of manipulation, mobilisation and the activator instrument in treatment of non-specific neck pain: a systematic review

Background

Neck pain is a common problem and different forms of manual therapy are used in its treatment. The purpose of this systematic review was to critically appraise the literature that directly compared manipulation, mobilisation and the Activator instrument for non-specific neck pain.

Methods

Electronic databases (MEDLINE, MANTIS and CINAHL) were searched from their inception to October 2005 for all English language randomised clinical trials that directly compared manipulation, mobilisation and the Activator instrument. Inclusion and exclusion criteria were applied to select the studies and these studies were then evaluated using validated criteria.

Results

Five such studies were identified. The methodological quality was mostly poor. Findings from the studies were mixed and no one therapy was shown to be more effective than the others.

Conclusion

Further high quality research has to be done before a recommendation can be made as to the most effective manual method for non-specific neck pain.

An objective spinal motion imaging assessment (OSMIA): reliability, accuracy and exposure data

BACKGROUND

Minimally-invasive measurement of continuous inter-vertebral motion in clinical settings is difficult to achieve. This paper describes the reliability, validity and radiation exposure levels in a new Objective Spinal Motion Imaging Assessment system (OSMIA) based on low-dose fluoroscopy and image processing.

METHODS

Fluoroscopic sequences in coronal and sagittal planes were obtained from 2 calibration models using dry lumbar vertebrae, plus the lumbar spines of 30 asymptomatic volunteers. Calibration model 1 (mobile) was screened upright, in 7 inter-vertebral positions. The volunteers and calibration model 2 (fixed) were screened on a motorized table comprising 2 horizontal sections, one of which moved through 80 degrees. Model 2 was screened during motion 5 times and the L2-S1 levels of the volunteers twice. Images were digitised at 5fps. Inter-vertebral motion from model 1 was compared to its pre-settings to investigate accuracy. For volunteers and model 2, the first digitised image in each sequence was marked with templates. Vertebrae were tracked throughout the motion using automated frame-to-frame registration. For each frame, vertebral angles were subtracted giving inter-vertebral motion graphs. Volunteer data were acquired twice on the same day and analysed by two blinded observers. The root-mean-square (RMS) differences between paired data were used as the measure of reliability.

RESULTS

RMS difference between reference and computed inter-vertebral angles in model 1 was 0.32 degrees for side-bending and 0.52 degrees for flexion-extension. For model 2, X-ray positioning contributed more to the variance of range measurement than did automated registration. For volunteer image sequences, RMS inter-observer variation in intervertebral motion range in the coronal plane was 1.86 degrees and intra-subject biological variation was between 2.75 degrees and 2.91 degrees. RMS inter-observer variation in the sagittal plane was 1.94 degrees. Radiation dosages in each view were below the levels recommended for a plain film.

CONCLUSION

OSMIA can measure inter-vertebral angular motion patterns in routine clinical settings if modern image intensifier systems are used. It requires skillful radiography to achieve optimal positioning and dose limitation. Reliability in individual subjects can be judged from the variance of their averaged inter-vertebral angles and by observing automated image registration.

Spinal manipulation and spinal mobilization influence different axial sensory beds

Manipulation and mobilization are two forms of manual therapy commonly employed in the management of musculoskeletal disorders. Spinal manipulation and mobilization are often distinguished from one another by reference to certain biomechanical parameters such as peak force, duration and magnitude of translation. However, as of yet, there is relatively little research which distinguishes between them in terms of neurological mechanisms or clinical effectiveness. Theories concerning the mechanisms underlying the therapeutic effects of manipulation and mobilization commonly make reference to mechanical events such as the release of entrapped tissue or the disruption of intra-articular adhesions. Relatively less attention is given to neural effects. In this paper, we hypothesize that, at least in part, spinal manipulation preferentially influences a sensory bed which, in terms of anatomical location and function, is different from the sensory bed influenced by spinal mobilization techniques. More specifically, we hypothesize that manipulation may particularly stimulate receptors within deep intervertebral muscles, while mobilization techniques most likely affect more superficial axial muscles. In part, our rationale for this hypothesis is based on differences in mechanical advantage of the respective manual procedures on multi-segmental versus short intervertebral muscles.

Dynamic response of the cervical spine to posteroanterior mobilisation

BACKGROUND

Posteroanterior mobilisation is a manual therapy technique that is commonly used in the examination and treatment of neck pain, but little is known about its biomechanical effect. The purpose of this study was to determine the intervertebral movements of the cervical spine produced by posteroanterior mobilisation.

METHODS

The cervical spines of nineteen healthy subjects were scanned using an open interventional magnetic resonance imaging scanner. Posteroanterior mobilisation forces were applied to the fifth cervical vertebra whilst they were in the prone position. Sagittal images of the spine were obtained before and during mobilisation.

FINDINGS

It was shown that posteroanterior mobilisation of the cervical spine generally produced extension of the upper motion segments and flexion of the lower segments. The middle segments were inconsistent in the direction of rotation. The cervical lordosis was found to increase with repeated PA loading cycles.

INTERPRETATION

The magnitude of intervertebral movement produced by mobilisation is small. Forces applied at one spinous process produced not only movements at the target vertebra but also movements of the entire cervical spine resulting in an increase in lordosis. Mobilisation should be interpreted as three-point bending of the entire cervical spine, rather than simple gliding of one vertebra upon another.