Spine stability: The six blind men and the elephant

Reeves, N. Peter; Narendra, Kumpati S.; Cholewicki, Jacek

doi:10.1016/j.clinbiomech.2006.11.011

Cited by 220 publications

(47 citation statements)

References 56 publications

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“…Although most clinicians agree on the clinical definition of spinal instability, there is still ambiguity in using the term "spinal stability" because its quantitative assessment remains challenging and subjective in the clinical setting [93,95]. Currently, clinicians consider the spine as a three-column system in their assessment of spinal instability with the first column containing the anterior longitudinal ligament and the anterior half of the body and discs, the middle column contains the posterior half of the vertebral body and disc, and the posterior column contains the interspinous ligaments, spinous processes, pedicles, and the facets [93] (Fig.…”

Section: Synovium Menisci and Capsular Ligamentmentioning

confidence: 99%

Spinal Facet Joint Biomechanics and Mechanotransduction in Normal, Injury and Degenerative Conditions

Jaumard¹,

Welch²,

Winkelstein³

2011

J. Biomech. Eng.

276

225

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The facet joint is a crucial anatomic region of the spine owing to its biomechanical role in facilitating articulation of the vertebrae of the spinal column. It is a diarthrodial joint with opposing articular cartilage surfaces that provide a low friction environment and a ligamentous capsule that encloses the joint space. Together with the disc, the bilateral facet joints transfer loads and guide and constrain motions in the spine due to their geometry and mechanical function. Although a great deal of research has focused on defining the biomechanics of the spine and the form and function of the disc, the facet joint has only recently become the focus of experimental, computational and clinical studies. This mechanical behavior ensures the normal health and function of the spine during physiologic loading but can also lead to its dysfunction when the tissues of the facet joint are altered either by injury, degeneration or as a result of surgical modification of the spine. The anatomical, biomechanical and physiological characteristics of the facet joints in the cervical and lumbar spines have become the focus of increased attention recently with the advent of surgical procedures of the spine, such as disc repair and replacement, which may impact facet responses. Accordingly, this review summarizes the relevant anatomy and biomechanics of the facet joint and the individual tissues that comprise it. In order to better understand the physiological implications of tissue loading in all conditions, a review of mechanotransduction pathways in the cartilage, ligament and bone is also presented ranging from the tissue-level scale to cellular modifications. With this context, experimental studies are summarized as they relate to the most common modifications that alter the biomechanics and health of the spine-injury and degeneration. In addition, many computational and finite element models have been developed that enable more-detailed and specific investigations of the facet joint and its tissues than are provided by experimental approaches and also that expand their utility for the field of biomechanics. These are also reviewed to provide a more complete summary of the current knowledge of facet joint mechanics. Overall, the goal of this review is to present a comprehensive review of the breadth and depth of knowledge regarding the mechanical and adaptive responses of the facet joint and its tissues across a variety of relevant size scales.

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Section: Synovium Menisci and Capsular Ligamentmentioning

confidence: 99%

Spinal Facet Joint Biomechanics and Mechanotransduction in Normal, Injury and Degenerative Conditions

Jaumard¹,

Welch²,

Winkelstein³

2011

J. Biomech. Eng.

276

225

View full text Add to dashboard Cite

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“…Denis13 later suggested instability could not be determined by the compromise of the posterior ligament complex alone and proposed that the rupture of the posterior longitudinal ligament and the annulus fibrosus also implies instability. The classification of the injury and assessment of the stability are critical if appropriate treatment is to be administered, however this is not trivial because the concept of spinal stability is ambiguous and often difficult to define 45. In addition, the injuries sustained following spinal trauma can vary significantly in severity35 often causing a wide variety of symptoms and fracture patterns.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Approach Investigating Burst Fracture Augmentation Using PMMA and Calcium Phosphate Cements

et al. 2014

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The aim of the study was to use a computational and experimental approach to evaluate, compare and predict the ability of calcium phosphate (CaP) and poly (methyl methacrylate) (PMMA) augmentation cements to restore mechanical stability to traumatically fractured vertebrae, following a vertebroplasty procedure. Traumatic fractures (n = 17) were generated in a series of porcine vertebrae using a drop-weight method. The fractured vertebrae were imaged using μCT and tested under axial compression. Twelve of the fractured vertebrae were randomly selected to undergo a vertebroplasty procedure using either a PMMA (n = 6) or a CaP cement variation (n = 6). The specimens were imaged using μCT and re-tested. Finite element models of the fractured and augmented vertebrae were generated from the μCT data and used to compare the effect of fracture void fill with augmented specimen stiffness. Significant increases (p < 0.05) in failure load were found for both of the augmented specimen groups compared to the fractured group. The experimental and computational results indicated that neither the CaP cement nor PMMA cement could completely restore the vertebral mechanical behavior to the intact level. The effectiveness of the procedure appeared to be more influenced by the volume of fracture filled rather than by the mechanical properties of the cement itself.

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“…The extension of the Reeves et al (2007) ball-on-curved-surface example discussed in our companion paper (Jin and Mirka, 2015) also could be employed to explain the difference between two stooping techniques in Agonist, Antagonist and Lower Extremity muscle activation patterns. For an example, the stable pelvis in the restricted posture may not need to have significant recruitment of the passive mechanism by the activation of Antagonist and Lower Extremity after the fatigue protocols; a significant recruitment of…”

mentioning

confidence: 97%

A systems-level perspective of the biomechanics of the trunk flexion-extension movement: Part II – Fatigued low back conditions

Jin

Mirka

2015

International Journal of Industrial Ergonomics

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Our companion paper demonstrated the importance of a systems-level perspective on spine biomechanics by showing the effects of lower extremity constraints during simple, trunk flexion-extension motions. This paper explores the impact of trunk muscle fatigue and stress-relaxation of lumbar passive tissues on this systems-level response. Twelve participants performed experimental protocols to achieve lumbar passive tissue stressrelaxation fatigue and lumbar muscle fatigue. Participants performed full range of sagittal-plane trunk flexion-extension under unconstrained stoop movement and pelvic/lower extremity constrained stoop movement. They performed these motions both before and after the fatigue protocols and trunk kinematics and muscle activities in trunk and lower extremity muscles were monitored. Under the condition of passive tissue fatigue, low back muscles and lower extremity muscles revealed significantly increased activation level (21% and 22%, respectively) in the free stoop condition but under the restricted stoop condition, there was no significant effect of the protocol. Under the lumbar muscle fatigue condition, a significant antagonistic and lower extremity activation effect (34% increase in abdominal muscles, 16% increase in lower extremity muscles) was observed in the free stooping condition while these variables were not affected by the protocol under the restricted stooping condition.Relevance to Industry: Fatigue of the lumbar musculature and passive tissues is prevalent in jobs requiring full trunk flexion postures. Developing accurate biomechanical models of spinal stress in these full stooping postures can help in the development of appropriate interventions to reduce the prevalence of back injuries in these jobs. Highlights Effects of abnormal low back conditions on lifting biomechanics were tested. Low back passive tissue fatigue increases lower extremity muscle activity. Low back muscle fatigue increases lower extremity muscle activity. Interactions between trunk and lower extremity exist under abnormal low back condition.

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Spine stability: The six blind men and the elephant

Cited by 220 publications

References 56 publications

Spinal Facet Joint Biomechanics and Mechanotransduction in Normal, Injury and Degenerative Conditions

Spinal Facet Joint Biomechanics and Mechanotransduction in Normal, Injury and Degenerative Conditions

Experimental and Computational Approach Investigating Burst Fracture Augmentation Using PMMA and Calcium Phosphate Cements

A systems-level perspective of the biomechanics of the trunk flexion-extension movement: Part II – Fatigued low back conditions

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