Morphometric measurements can improve prediction of progressive vertebral deformity following vertebral damage.

Purpose: A damaged vertebral body can exhibit accelerated 'creep' under constant load, leading to progressive vertebral deformity. However, the risk of this happening is not easy to predict in clinical practice. The present cadaveric study aimed to identify morphometric measurements in a damaged vertebral body that can predict a susceptibility to accelerated creep.

A predictive model for creep deformation following vertebral compression fractures.

Many vertebral compression fractures continue to collapse over time, resulting in spinal deformity and chronic back pain. Currently, there is no adequate screening strategy to identify patients at risk of progressive vertebral collapse. This study developed a mathematical model to describe the quantitative relationship between initial bone damage and progressive ("creep") deformation in human vertebrae.

Associations Between Intervertebral Disc Degeneration Grading Schemes and Measures of Disc Function.

Disc degeneration is a major cause of spinal dysfunction and pain, but grading schemes concentrate on tissue changes rather than altered function. The aim of this study was to compare disc degeneration grading systems with each other, and with biomechanical measures of disc function. Sixty-six motion segments (T8-9 to L5-S1) were dissected from cadavers aged 48-98 years.

Nerves and blood vessels in degenerated intervertebral discs are confined to physically disrupted tissue.

Nerves and blood vessels are found in the peripheral annulus and endplates of healthy adult intervertebral discs. Degenerative changes can allow these vessels to grow inwards and become associated with discogenic pain, but it is not yet clear how far, and why, they grow in. Previously we have shown that physical disruption of the disc matrix, which is a defining feature of disc degeneration, creates free surfaces which lose proteoglycans and water, and so become physically and chemically conducive to cell migration.

Development and validation of a subject-specific finite element model of the functional spinal unit to predict vertebral strength.

Finite element models of an isolated vertebral body cannot accurately predict compressive strength of the spinal column because, in life, compressive load is variably distributed across the vertebral body and neural arch. The purpose of this study was to develop and validate a patient-specific finite element model of a functional spinal unit, and then use the model to predict vertebral strength from medical images. A total of 16 cadaveric functional spinal units were scanned and then tested mechanically in bending and compression to generate a vertebral wedge fracture.

How are adjacent spinal levels affected by vertebral fracture and by vertebroplasty? A biomechanical study on cadaveric spines.

Background Context: Spinal injuries and surgery may have important effects on neighboring spinal levels, but previous investigations of adjacent-level biomechanics have produced conflicting results. We use "stress profilometry" and noncontact strain measurements to investigate thoroughly this long-standing problem.

Purpose: This study aimed to determine how vertebral fracture and vertebroplasty affect compressive load-sharing and vertebral deformations at adjacent spinal levels.

Defects of the vertebral end plate: implications for disc degeneration depend on size.

Background Context: Bony vertebral end plates must be porous to allow metabolite transport into the disc, and yet strong to resist high intradiscal pressure (IDP). End plate defects may therefore have nutritional and mechanical consequences for the disc, depending on their size and type. We hypothesize that broad, diffuse defects are more closely associated with disc decompression and degeneration than are focal Schmorl's node-type defects.

Annulus Fibrosus Can Strip Hyaline Cartilage End Plate from Subchondral Bone: A Study of the Intervertebral Disk in Tension.

Study Design Biomechanical study on cadaveric spines. Objective Spinal bending causes the annulus to pull vertically (axially) on the end plate, but failure mechanisms in response to this type of loading are poorly understood. Therefore, the objective of this study was to identify the weak point of the intervertebral disk in tension.

Porosity and Thickness of the Vertebral Endplate Depend on Local Mechanical Loading.

Study Design: Mechanical and microcomputed tomography (micro-CT) study of cadaver spines.

Objective: To compare porosity and thickness of vertebral endplates with (1) compressive stresses measured in adjacent intervertebral discs and (2) grade of disc degeneration.

Summary Of Background Data: Endplate porosity is important for disc metabolite transport, and yet porosity increases with age and disc degeneration.

Pathogenesis of Vertebral Anterior Wedge Deformity: A 2-Stage Process?

Study Design: Biomechanical and radiographical study on cadaveric spines.

Objective: To explain the pathogenesis of vertebral "anterior wedge" deformity, which causes senile kyphosis.

Summary Of Background Data: This deformity arises with minimal trauma and is difficult to reproduce in cadaveric spines.

Sensorimotor function of the cervical spine in healthy volunteers.

Background: Sensorimotor mechanisms are important for controlling head motion. However, relatively little is known about sensorimotor function in the cervical spine. This study investigated how age, gender and variations in the test conditions affect measures of position sense, movement sense and reflex activation in cervical muscles.

Is kyphoplasty better than vertebroplasty at restoring form and function after severe vertebral wedge fractures?

Background Context: The vertebral augmentation procedures, vertebroplasty and kyphoplasty, can relieve pain and facilitate mobilization of patients with osteoporotic vertebral fractures. Kyphoplasty also aims to restore vertebral body height before cement injection and so may be advantageous for more severe fractures.

Purpose: The purpose of this study was to compare the ability of vertebroplasty and kyphoplasty to restore vertebral height, shape, and mechanical function after severe vertebral wedge fractures.

Significance of cartilage endplate within herniated disc tissue.

Purpose: Disc herniations sometimes contain hyaline cartilage fragments, but their origins and significance are uncertain.

Methods: Herniations were removed surgically from 21 patients (aged 35-74 years) whose main symptom was sciatica (10 patients) or back pain (11 patients). Frozen sections, 5 µm thick, were examined histologically, and antibodies were used to label the matrix-degrading enzyme MMP 1, pro-inflammatory mediator TNFα, and cell proliferation marker Ki-67.

Quality of life and neck pain in nurses.

Objectives: To investigate the association between neck pain and psychological stress in nurses.

Material And Methods: Nurses from the Avon Orthopaedic Centre completed 2 questionnaires: the Short Form-36 (SF-36) and 1 exploring neck pain and associated psychological stress.

Results: Thirty four nurses entered the study (68% response).

ISSLS Prize winner: Mechanical influences in progressive intervertebral disc degeneration.

Study Design: Mechanical study on cadaver motion segments.

Objective: To determine whether high gradients of compressive stress within the intervertebral disc are associated with progressive disc degeneration.

Summary Of Background Data: Mechanical loading can initiate disc degeneration but may be unimportant in disease progression, because degenerative changes cause the disc to be increasingly "stress-shielded" by the neural arch.

Why do some intervertebral discs degenerate, when others (in the same spine) do not?

This review suggests why some discs degenerate rather than age normally. Intervertebral discs are avascular pads of fibrocartilage that allow movement between vertebral bodies. Human discs have a low cell density and a limited ability to adapt to mechanical demands.

Intervertebral disc decompression following endplate damage: implications for disc degeneration depend on spinal level and age.

Study Design: Mechanical and morphological studies on cadaveric spines.

Objective: To explain how spinal level and age influence disc degeneration arising from endplate fracture.

Summary Of Background Data: Disc degeneration can be initiated by damage to a vertebral body endplate, but it is unclear why endplate lesions, and patterns of disc degeneration, vary so much with spinal level and age.

Intervertebral disc degeneration: evidence for two distinct phenotypes.

We review the evidence that there are two types of disc degeneration. 'Endplate-driven' disc degeneration involves endplate defects and inwards collapse of the annulus, has a high heritability, mostly affects discs in the upper lumbar and thoracic spine, often starts to develop before age 30 years, usually leads to moderate back pain, and is associated with compressive injuries such as a fall on the buttocks. 'Annulus-driven' disc degeneration involves a radial fissure and/or a disc prolapse, has a low heritability, mostly affects discs in the lower lumbar spine, develops progressively after age 30 years, usually leads to severe back pain and sciatica, and is associated with repetitive bending and lifting.

Rational redesign of glucose oxidase for improved catalytic function and stability.

Glucose oxidase (GOx) is an enzymatic workhorse used in the food and wine industries to combat microbial contamination, to produce wines with lowered alcohol content, as the recognition element in amperometric glucose sensors, and as an anodic catalyst in biofuel cells. It is naturally produced by several species of fungi, and genetic variants are known to differ considerably in both stability and activity. Two of the more widely studied glucose oxidases come from the species Aspergillus niger (A.

Annulus fissures are mechanically and chemically conducive to the ingrowth of nerves and blood vessels.

Study Design: Mechanical and biochemical analyses of cadaveric and surgically removed discs.

Objective: To test the hypothesis that fissures in the annulus of degenerated human discs are mechanically and chemically conducive to the ingrowth of nerves and blood vessels.

Summary Of Background Data: Discogenic back pain is closely associated with fissures in the annulus fibrosus, and with the ingrowth of nerves and blood vessels.

Vertebral deformity arising from an accelerated "creep" mechanism.

Introduction: Vertebral deformities often occur in patients who recall no trauma, and display no evident fracture on radiographs. We hypothesise that vertebral deformity can occur by a gradual creep mechanism which is accelerated following minor damage. "Creep" is continuous deformation under constant load.

Biomechanics of vertebral compression fractures and clinical application.

Local biomechanical factors in the etiology of vertebral compression fractures are reviewed. The vertebral body is particularly vulnerable to compression fracture when its bone mineral density (BMD) falls with age. However, the risk of fracture, and the type of fracture produced, does not depend simply on BMD.