PDF | On Jan 1, , G. Plaugher and others published Clinical anatomy and biomechanics of the spine. Request PDF on ResearchGate | Clinical Biomechanics of the Spine | Combining orthopedic surgery with biomechanical engineering, this reference and. A clear understanding of biomechanical principles is essential in the treatment of orthopedic and spinal disorders. Charnley designed a smaller.
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You can finely include the soft file Clinical Biomechanics Of The Spine By Augustus A. White,. Manohar M. Panjabi PhD DTech to the gizmo or every computer. clinical biomechanics of spine - dokument [*.pdf] Clinical Biomechanics geSpine Second Edition ~,.B. LIPPINCarr COMPA Y Clinical. Spondylolopsis of lumbar L4 vertebra. Person was neurologically intact. Radiograph from White & Panjabi Clinical Biomechanics of the Spine. The cervical.
In clinical terms it is most significant that it also provides flexible armor to the spinal cord and cauda equina. Owning in part to its unique, dual roles of support and protection and to the number of pain and other neurological problems arising in the spine, it has received widespread attention from scientists as well as clinicians.
In addition to the obvious concern of physicians and surgeons in disorders of the spine, the allied professions also seek a better understanding of the nature of pain-related and otherwise disabling abnormalities.
Others with a professional interest in the spine include those seeking a more basic understanding of its structure and function, both normal and abnormal, and of its tolerance to adverse environments and its susceptibility to damage. This process is experimental and the keywords may be updated as the learning algorithm improves. This is a preview of subscription content, log in to check access.
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Preview Unable to display preview. Download preview PDF. References 1. Spine Google Scholar 4. Advances in Bioengineering. Part 1: Theory.
Clin Biomech 7: 19—26 Google Scholar Part 2: Experiment. Clin Biomech 7: 27—32 Google Scholar Connect Tissue Res 8: — Google Scholar Clin Orthop — Google Scholar Holm S, Nachemson AL Variations in the nutrition of the canine intervertebral disc induced by motion. As the biomechanical properties of the spine change, there is also an alteration in the stress-strain relationship as well as translation of the instantaneous axis of rotation IAR from its usual position [ 1 ].
This complex process of degeneration moves across stages including dysfunction, instability, and stabilization [ 2 ] and may ultimately produce low back pain and other clinical symptoms. Biomechanics affords a means of characterizing and assessing the status of the spine both precisely and quantitatively. Benefits of an improved understanding of biomechanics of normal and degenerative spinal conditions are the ability to counsel patients, treat pathological processes, and determine the effect of both medical and surgical treatment on spinal mechanics and, potentially, clinical outcomes.
Understanding the biomechanical consequences of degeneration is imperative for the treatment of spinal disorders, regardless of etiology. In this review, we discuss key concepts of spinal anatomy and degenerative processes of the spine. Anatomy Thirty-three vertebrae comprise the spinal column: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal bones.
Functionally, the spinal column transmits loads, permits limited motion, and protects the spinal cord. The range of normal spinal alignment is dependent upon the region of the spine. In the coronal plane, the normal spine has a neutral curvature.
In the sagittal plane, the cervical and lumbar segments are lordotic whereas the thoracic and sacral regions are kyphotic. Regional kyphosis or lordosis are evolutionary responses to an upright stance in the bipedal human and serve to balance the occiput over the pelvis in an energy efficient manner [ 3 , 4 ].
White III Augustus A., Panjabi Manohar M. (eds.) Clinical Biomechanics of the Spine
However, vertebral bodies within a spinal segment do not evenly distribute alignment. Similarly, L4—5 and L5—S1 provide about two-thirds of lumbar lordosis [ 6 ]. Sagittal alignment can be measured by dropping a plumb line from the C7 vertebral body to the lumbosacral junction and, when within normal limits, permits balanced posture, minimal energy expenditure, and appropriate tension of perispinal ligaments [ 7 ].
The intimate relationships between global balance and both clinical outcomes [ 8 , 9 ] and biomechanics [ 10 ] have been reported. As sagittal imbalance increases, defined as a plumb line that fails to fall between the sacrum and femoral heads, the pelvis undergoes retroversion in relation to the feet. The change in pelvic positioning maintains a fixed gravity line-heel offset, which preserves a center of force near the feet and permits standing balance [ 10 ].
The functional spinal unit FSU or spinal motion segment is the smallest segment that represents the characteristics of the entire spinal column. It consists of two vertebrae, the intervertebral disc, zygaphophyseal facet joints, and supporting ligaments ligamentum flavum, supraspinous, interspinous, anterior longitudinal, and posterior longitudinal.
The disc and paired facet joints at each level therefore form a three-joint complex between which loads are transmitted [ 11 ]. The intervertebral disc functions to transmit loads between adjacent vertebrae and permit motion.
Biomechanics of Degenerative Spinal Disorders
As such, it carries and distributes forces to which the trunk is subjected [ 12 ]. Each motion segment has an IAR, which is a dynamic point about which the FSU rotates and is dependent upon spinal alignment and forces acting on the spine.
There are 12 potential movements about the IAR due to rotation around the three axes x, y, and z that pass through the center of rotation. The IAR is not constant; for example, during flexion-extension at C0-C1 the IAR passes through the center of the mastoid processes whereas during lateral bending the IAR is located 2 cm above the dens [ 13 ].
The IAR in the lumbar spine is similarly dependent upon position. The IAR is located in the anterior disc in flexion, lateral aspect of the disc with contralateral side-bending, and in the posterior annulus during axial rotation [ 14 , 15 ]. Surgical intervention, trauma, and degenerative processes affect the position of the IAR. Soft tissues about the spine also play a tremendous role in flexibility and mobility.
Below the subaxial spine, there are seven ligaments that play a paramount role in maintaining physiologic motion.
Ligaments, composed of elastin and collagen [ 16 ], and joint capsules restrict motion to within normal limits. The ligaments have variable strengths, but weaker ligaments such as the interspinous and supraspinous contribute greatly to spinal stability by providing resistance to flexion via a long moment arm from the spinous process to the IAR [ 17 ]. The ligamentum flavum, in contrast, is a pair of broad ligaments that provides compression at the disc space by maintaining resting tension as it courses along the ventral laminae [ 18 ].
Spinal motion is also influenced by intervertebral discs and the synovial facet joints, which consist of sliding cartilaginous surfaces. Increases in postural load-bearing coupled with decreasing elastin and increasing collagen concentration in facet capsules with aging prohibits viscoelastic materials from returning to their elastic zone.
The result is stretching of soft tissues, increasing motion between interfaces, and adaptations of bony architecture to provide mechanical support. Disc Degeneration Degenerative disc disease begins early in life and precedes the development of facet joint changes.
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A histologic study of age-related changes in the human lumbar disc revealed reduced end plate blood supply that resulted in the breakdown of the nucleus pulposus by the second decade of life [ 19 ]. The significance of this can be understood by considering the function and response of the healthy disc during normal movements.
During normal motion, the disc deforms predictably: the annulus bulges on the side of compression and is under tension on the opposite side. Under compression, load transmission between two vertebrae is via the intervertebral disc, which is composed of type II collagen.
Resultant pressures within the pulposus are transferred to the annulus. Horst and Brinckmann [ 20 ] performed a cadaveric study of axial stress distribution by implanting pressure transducers within thoracic and lumbar intervertebral discs.
Their results showed that stress distribution is dependent upon the status of the disc and differs between thoracic and lumbar spinal segments. Healthy lumbar discs distributed stress evenly across the endplates in compression and eccentric loading increasing end-plate inclination. The same uniform stress distribution occurred in degenerative discs under axial compression.Includes bibliographical references. Osteophytes develop as the annulus is distorted and pulls from its bony attachments.
Benefits of an improved understanding of biomechanics of normal and degenerative spinal conditions are the ability to counsel patients, treat pathological processes, and determine the effect of both medical and surgical treatment on spinal mechanics and, potentially, clinical outcomes.
A histologic study of age-related changes in the human lumbar disc revealed reduced end plate blood supply that resulted in the breakdown of the nucleus pulposus by the second decade of life [ 19 ]. Current concept review. The IAR is not constant; for example, during flexion-extension at C0-C1 the IAR passes through the center of the mastoid processes whereas during lateral bending the IAR is located 2 cm above the dens [ 13 ].
Jan 31, - Implantable sensors have a high impact on several clinical applications, including fracture fixation, spine fixation, and joint arthroplasty.