Lumbar Spine and Pelvic Posture Between Standing and Sitting: The Lumbar Lordosis Measure
Diana De Carvalho, DC, MSc, David Soave, MSc
Objective: Sitting has been identified as a cause of mechanical low back pain. The purpose of this study was to use plain-film X-rays to measure lumbar spine and pelvic posture differences between standing and sitting.
Methods: Eight male subjects were radiographed standing and sitting in an automobile seat. Measures of lumbar lordosis, intervertebral disk angles, lumbosacral angle, lumbosacral lordosis, and sacral tilt were completed. One-way analysis of variance (∝ = .05) was conducted on the variables stated above. A Bland-Altman analysis was conducted to assess agreement and repeatability of the lumbar lordosis angle using two raters.
Results: Lumbar lordosis values in standing (average, 63° ± 15°) and sacral inclination (average, 43° ± 10°) decreased by 43° and 44°, respectively, in sitting. Intervertebral joint angles in sitting underwent substantial flexion (L1/L2—5° [±3°], L2/L3—7° [±3°], L3/L4—8° [±3°], L4/L5—13° [±3°], and L5/S1—4° [±10°]). Measures of lumbar lordosis; intervertebral disk angles between L2/L3, L3/L4, and L4/L5; lumbosacral lordosis, lumbosacral angle and sacral tilt were significantly decreased between standing and sitting (P < .001). Intervertebral disk angle between L5/S1 was not significantly different. Analysis using the Bland-Altman technique found good agreement and stable repeatability of measures with no statistical significant differences between or within raters (R1, P = .8474; R2, P = .4402; and R-R2, P = .8691).
Conclusion: The significant differences in lumbar and pelvic measures from standing to sitting further emphasize the range of motion experienced at vertebral levels in sitting. Based on the results of this study, interventions to return motion segments to a less flexed posture should be investigated because they may play a role in preventing injury and low back pain.
Microstructural Damage in Arterial Tissue Exposed to Repeated Tensile Strains
Neal Austin, BSc, Lisa DiFrancesco, MD, Walter Herzog, PhD
Objectives: Vertebral artery (VA) damage has been anecdotally linked to high-speed, low-amplitude spinal manipulative treatments (SMTs) of the neck. Apart from a single study quantifying the maximum stresses and strains imposed on the VA during cervical SMT, there are no data on the mechanics of the VA for this treatment modality, and there is no information on the possible long-term effects of repeat exposure to cervical SMT. The purpose of this study was to quantify microstructural damage in arterial tissue exposed to repeat strain loading of a magnitude similar to the maximum strains measured in the VA during high-speed, low-amplitude cervical SMT.
Methods: Twenty-four test specimens from cadaveric rabbit ascending aorta were divided into two control groups (n = 12) and two experimental groups (n = 6 each). Specimens were exposed to 1,000 strain cycles of 0.06 and 0.30 of their in situ length. A pathologist, blinded to the experimental groups, assessed microstructural changes in the arteries using quantitative histology. Pearson X2 analysis (∝ = .05) was used to assess differences in tissue microstructure between groups.
Results: Control and 0.06 strain tissues were statistically the same (P = .406), whereas the 0.30 strain group showed microstructural damage beyond that seen in the control group (P = .024).
Conclusions: We conclude that cadaveric rabbit arterial tissue similar in size and mechanical properties of that of the human VA can withstand repeat strains of magnitudes and rates similar to those measured in the cadaveric VA during cervical SMT without incurring microstructural damage beyond control levels.
Immediate Effects of Hamstring Stretching on Pressure Pain Sensitivity and Active Mouth Opening
Cristina Bretischwerdt, DO, et al.
Objective: This study analyzed the immediate effect of hamstring muscle stretching on pressure pain sensitivity over the masseter and the upper trapezius muscles and maximum active mouth opening in healthy subjects.
Methods: One hundred twenty volunteers, 70 males and 50 females, between the ages of 22 and 47, were randomly divided into three groups: group 1 (control group), which did not receive any intervention; group 2, where a unilateral hamstring muscle stretching was applied; and group 3, where a bilateral stretching was applied. Pressure pain thresholds (PPTs) were bilaterally assessed over the masseter and upper trapezius muscles pre- and 5 minutes posttreatment by an assessor blinded to group assignment. Maximum mouth opening was also assessed pre- and 5 minutes posttreatment. Mixed-model analyses of variance (ANOVAs) were used to examine the effects of the intervention. The primary analysis was the group x time interaction.
Results: The ANOVA revealed significant group x time interaction for changes in PPTs over the upper trapezius (F = 4.5; P = .01) and masseter (F = 6.3; P = .002) muscles. Pre-post effect sizes were moderate (0.5 > d > 0.7) for both stretching groups and negative (d < -0.2) for the control group. A significant group x time interaction (F = 8.15; P < .001) for maximum mouth opening was also found; both experimental groups showed greater improvement when compared to the control group (P < .001). Pre-post effect sizes were large (d > 0.7) for both stretching groups and negative (d < -0.2) for the control group.
Conclusions: The application of a stretching of the hamstring musculature produced an immediate increase in PPTs over both masseter and upper trapezius muscles in healthy subjects.
Effects of a Manual Medicine Treatment on Nitric Oxide Release in Healthy Adults
James Kiernan, MS, DC
Objective: The objective of this study was to measure if a manual treatment would alter the levels of exhaled nitric oxide in healthy adults.
Methods: A study was performed using 23 healthy adults (ages 18-30 years). Nitric oxide (NO) was measured amperometrically before and after a manual treatment. The treatment used was a cranial-thoracic trapezius stretch.
Results: In healthy adults, manual manipulation was associated with changes in NO levels in exhaled breath. The level of NO increased from 13.3 ± 2.09 (SD) to 15.0 ± 2.95 (SD) ppb (P = .001, based upon the paired t tests of the subjects). The median level of NO before manual manipulation was 13.0 ppb (ranging from 8 to 17 ppb); after manual manipulation, it was 16.0 ppb (ranging from 6 to 18 ppb).
Conclusion: The cranial-thoracic trapezius stretch was associated with an increase in exhaled NO, compared to baseline levels for the subjects in this study.
JMPT abstracts appear in DC with permission from the journal. Due to space restrictions, we cannot always print all abstracts from a given issue. Visit www.journals.elsevierhealth.com/periodicals/ymmt for access to the complete January 2010 issue of JMPT.