Correlates of myoelectric asymmetry detected in low back pain patients using hand-held post-style surface electromyography.

OBJECTIVE: Paraspinal surface electromyographic (SEMG) scanning, utilizing post-style hand-held electrodes, was conducted to determine the usefulness of the technique as an assessment for myoelectric indicators of low back pain (LBP). A secondary objective was to correlate myoelectric abnormalities with other known outcome measures of the manipulable lesion. DESIGN: Blinded SEMG assessments with the patients standing upright, fully flexed and extended at the trunk, and measures of pressure pain thresholds (PPT) were made after four tests administered by another examiner. SETTING: The research was conducted on patients in a private chiropractic practice. PATIENTS: A convenience sample of 10 of the practitioner's most acute LBP patients without neurological deficit were asked to participate and none refused. Six patients without recent LBP volunteered as controls. MAIN OUTCOME MEASURES: Preset myoelectric indicators included: thoracolumbar asymmetry (T-L/A: first seen in an earlier pilot study), loss of flexion/relaxation (F/R) at L3, contralateral responsivity (increased myoelectric activity opposite the side of leg pain) and right/left asymmetry (R-L/A) at L3. RESULTS: Significant differences between groups were seen in T-L/A (p = .04) and R-L/A [data averaged from three postures (p = .04)], and robust group differences were seen in F/R (p = .011 right; p = .026 left). Contralateral responsivity was not significant. Loss of F/R was the only indicator that correlated with diminished PPT (r = .52 right; r = .46 left) and with Oswestry disability (r = .42), and that negatively correlated, as expected, with straight leg raising (r = -.50 right; r = -.74 left). CONCLUSIONS: Results support use of the technique to detect muscle dysfunction related to LBP. Further research of SEMG correlations with measures of the manipulable lesion is warranted.

Line drawing analyses of static cervical X ray used in chiropractic.

OBJECTIVE: This review article identifies the chiropractic techniques used to assess the structure of the cervical spine as seen on the static cervical radiograph. DATA SOURCES: On-line search of MEDLINE, key words, radiograph and X ray in combination with cervical spine (vertebrae); the Chiropractic Research Archives Collection (CRAC); indexes published in the Journal of Chiropractic Research; conference proceedings from Annual Biomechanics Conference of the Spine, FCER sponsored conferences and Annual Upper Cervical Spine Conference; references identified from bibliographies of pertinent articles; a telephone poll of radiography/technique instructors at chiropractic colleges. STUDY SELECTION: Techniques that quantitatively assess relative alignment of skeletal structures or distortion of the spinal column. DATA EXTRACTION: Techniques were grouped according to the structures analyzed and the views used. DATA SYNTHESIS: Variables and artifacts that limit the reliability or validity of static cervical X ray line drawing analysis were identified and the techniques assessed for their reported reliability and validity. CONCLUSIONS: Reliability studies exist showing that inter- and intraexaminer reliability are sufficient to measure lateral and rotational displacements of C1 to within +/- 1 degree. This amount of error allows objective analysis of upper cervical X rays to detect changes in the angular positional relationships of radiographic images on the order of those already seen clinically. Methods of cervical analysis that use relative angular measures of skeletal positioning are best able to control the effects of radiographic distortion. The accuracy of the analysis methods has not been ascertained to establish the extent to which angular measurement of vertebral relationships actually reflect three-dimensional movement. It is not known how much of the changes that are seen in pre/post-radiograph sets are due to positioning changes of the patient between radiographic procedure, and how much are due to actual changes of skeletal relationships brought about by adjustment.

A critique of applications of the Euler equation to the human spine.

The Euler buckling theory has been presented as evidence that spinal curves increase the spine's axial load carrying capacity. The Euler theory is however, derived for an initially straight beam or column and as such cannot be applied to initially curved structures, such as the human spine.