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BackgroundAlthough the connective tissues forming the fascial planes of the back have been hypothesized to play a role in the pathogenesis of chronic low back pain (LBP), there have been no previous studies quantitatively evaluating connective tissue structure in this condition. The goal of this study was to perform an ultrasound-based comparison of perimuscular connective tissue structure in the lumbar region in a group of human subjects with chronic or recurrent LBP for more than 12 months, compared with a group of subjects without LBP.MethodsIn each of 107 human subjects (60 with LBP and 47 without LBP), parasagittal ultrasound images were acquired bilaterally centered on a point 2 cm lateral to the midpoint of the L2-3 interspinous ligament. The outcome measures based on these images were subcutaneous and perimuscular connective tissue thickness and echogenicity measured by ultrasound.ResultsThere were no significant differences in age, sex, body mass index (BMI) or activity levels between LBP and No-LBP groups. Perimuscular thickness and echogenicity were not correlated with age but were positively correlated with BMI. The LBP group had ~25% greater perimuscular thickness and echogenicity compared with the No-LBP group (ANCOVA adjusted for BMI, p < 0.01 and p < 0.001 respectively).ConclusionThis is the first report of abnormal connective tissue structure in the lumbar region in a group of subjects with chronic or recurrent LBP. This finding was not attributable to differences in age, sex, BMI or activity level between groups. Possible causes include genetic factors, abnormal movement patterns and chronic inflammation.

This study surface anatomy of the articular facets for the entire human vertebral cbJumn based on a study of 276 vertebrae. M eerie and standard errors trf the msansfor 11 n ea r, a n gu la r, a n d area dimensions of the su perio r e nd inferior flrticular faeels wflna measured for fill vortcbrae from CZ to 1.6, Facet Orients!l*n$ wena descrfhedas angieiwlLli respect (otfie sagittal and transverse planes and also a card angles. The piano angles aresimilar tea the angles seen on traditional radiograph re vl aws-rodlograp h s and comp u:ed torn og ra ph io scans. The card angles, a new concept, are better at helping vlsuafiwthe facets. Exclu ding th B superior Cl facet, the mi niriL rn an d max.1 m um d irnen sfons were fou nd fo r the facets from C3tp L3: width = 9.6-16.3 mm; height = 10.2-18,4; surface area =72.3-211.9 mm 2 ; interface! width = 20.fl-M.fl; intcrfacot height -12.2-33.0 mm; transverse planeangle = 41.0-W.fl; sagltiel plane angle -67.4-154.8; X-card angle = 4i.0-B6.D;and V^ard angle = 5.B-6B.1. The quantitative anatomy of the fscats may improve the undarsiandinQ of the spinal anatomy, halp Fmprovetha clinical diagnosis and trestir.-rv, n-ri provide the nacossary data for constructing more nealietic mathHrnatical mode Is of the spine, [Kay wa-ds; spfne, vertebres, anstamy, vprtehral articular facets, zygapaptiyseal joints]The shapes and sizes of human vertebrae are often artist's drawings based on visual inspection of cadavers, 15 ' 16 with no quantitative geometric information provided. The quantification of vertebral articular facets into a geometric database has several applications. The orientation of the articular facets was hypothesized to be a cause of rotational coupling in the lumbar spine. 9 The role of the articular facets in intervertebral joint kinematics has been studied fre-

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Acupuncture needle manipulation gives rise to "needle grasp," a biomechanical phenomenon characterized by an increase in the force necessary to pull the needle out of the tissue (pullout force). This study investigates the hypothesis that winding of connective tissue, rather than muscle contraction, is the mechanism responsible for needle grasp. We performed 1) measurements of pullout force in humans with and without needle penetration of muscle; 2) measurements of pullout force in anesthetized rats, with and without needle rotation, followed by measurements of connective tissue volume surrounding the needle; 3) imaging of rat abdominal wall explants, with and without needle rotation, using ultrasound scanning acoustic microscopy. We found 1) no evidence that increased penetration of muscle results in greater pullout force than increased penetration of subcutaneous tissue; 2) that both pullout force and subcutaneous tissue volume were increased by needle rotation; 3) that increased periodic architectural order was present in subcutaneous tissue with rotation, compared with no rotation. These data support connective tissue winding as the mechanism responsible for the increase in pullout force induced by needle rotation. Winding may allow needle movements to deliver a mechanical signal into the tissue and may be key to acupuncture's therapeutic mechanism.