| Objective: ( 1 ) To study the effect of Lumbar Rotatory Manipulations(LRM) on the variations of intradiscal pressure, the movements of disc communicating with nerve roots and the changes of stress within lumbar facet joints. (2) To describe the anatomical and histological characteristics of the lumbar joint capsules and the Lumbar foraminal ligaments(LFL), and discuss the effect of LRM on the fibers of capsules and LFL. Methods: (1) Seven fresh cadaveric lumbar spines were subjected by three kinds of LRM, such as rotation manipulation, sitting-rotation manipulation and traction-rotation manipulation, while the variations of intradiscal pressure of L34,L45, and L5S1 were measured by pressure sensor, the movements of L34, L45 disc communicating with L4, L5 nerve roots were observed by biomedical extensometer, and the changes of stress on lumbar facet joints of L34, L45 and L5S1 were measured by sensitive film. (2) Macroscopic investigations were performed on LFL and facet joint capsules, which dissected from five embalmed cadavers; With microscopic studies, facet joint capsules and LFL, obtained from two fresh cadavers, were stained by the resorzinoroseine-VG method. Results: (1) The pressure of lumbar nucleus increased during experimental rotation manipulation and sitting-rotation manipulation, and reduced or slightly increased during traction-rotation manipulation. The increase of the pressures was the most obvious at the segment of L5S1 during sitting-rotation manipulation (P<0.001); The ranges of displacement between L45 disc and L5 nerve roots during the three kinds of manipulations were respectively (1. 34±0. 74)mm, (1. 30± 1. 05)mm, (1. 13±0. 92)mm; The changes of stress on lumbar facet joints in these simulating manipulations were no significant difference. (2) The Ligaments had been found in all lumbar objects. More ligaments laid in the upper lumbar region The vertical diameter of the lumbar foramen the nerve root passing pore and the nerve root is ( 17.09 ± 2. 92) mm, (11. 19 ± 3. 06)mm,(4. 37 ± 1. 08) mm respectively. Ligaments are consist of denseconnective tissues. (3) In the superior part of the facet joint capsules, the fibers direction is different from it in the inferior part of the joint. The outer layer of capsules is composed of parallel bundles of collagenous fibers, and in the middle layer bundles of elastic fibers lie in the roots of capsules. Conclusions: (1) LRM can not make the protruded nucleus pulposus replace in, but the moderate direction of LRM can change the position of the protruded nucleus puplosus and release the compression of nerve roots which were suffered by protruded nucleus puplosus, and that might be the biomechanic mechanism of LRM in treating for lumbar disc herniation. The stress of lumbar facet was lower than the limitation of lumbar facet fracture during LRM, so the manipulations are safe within certain rotation angle, and traction-rotation manipulation is the safest in the three kinds of LRM. (2) LFL are probably normal components of the intervertebral foramen, and the segmental blood vessels and nerve roots are protected by LFL. With the development of spinal segmental degeneration and the narrowing of foramen, the ligaments could become a source of entrapments to the passage of spinal nerves, segmental blood vessels. (3) Anatomical and histologic features of the lumbar facet joint capsule are complicated. The complex of morphologic factors can affect the biomechanics of the lumbar facet joints. Rotatory Manipulations in crude way may result in the capsule injury, and this may be the reason, in some cases, that low back pain become severe after LRM. |
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