The biomechanics of metaphyseal cone augmentation in revision knee replacement.

The demand for revision knee replacement (RKR) has increased dramatically with rising patient life expectancy and younger recipients for primary TKR. However, significant challenges to RKR arise from osseous defects, reduced bone quality, potential bone volume loss from implant removal and the need to achieve implant stability. This study utilizes the outcomes of an ongoing RKR clinical trial using porous metaphyseal cones 3D-printed of titanium, to investigate 1) bone mineral density (BMD) changes in three fixation zones (epiphysis, metaphysis, and diaphysis) over a year and 2) the biomechanical effects of the cones at 6 months post-surgery.

Multiphoton imaging and Raman spectroscopy of the bovine vertebral endplate.

The interface between the intervertebral disc and the vertebral body is important to the discs' biomechanics and physiology, and is widely implicated in its pathology. This study aimed to explore biochemically and structurally the bony endplate, cartilage endplate and intervertebral disc, below the nucleus and below the annulus in healthy bovine tails. Multiphoton imaging and spontaneous Raman spectroscopy were employed.

The feasibility of using citizens to segment anatomy from medical images: Accuracy and motivation.

The development of automatic methods for segmenting anatomy from medical images is an important goal for many medical and healthcare research areas. Datasets that can be used to train and test computer algorithms, however, are often small due to the difficulties in obtaining experts to segment enough examples. Citizen science provides a potential solution to this problem but the feasibility of using the public to identify and segment anatomy in a medical image has not been investigated.

In Vivo Assessment of Thoracic Vertebral Shape From MRI Data Using a Shape Model.

Study Design: Feasibility study on characterizing thoracic vertebral shape from magnetic resonance images using a shape model.

Objectives: Assess the reliability of characterizing thoracic vertebral shape from magnetic resonance images and estimate the normal variation in vertebral shape using a shape model.

Summary Of Background Data: The characterization of thoracic vertebra shape is important for understanding the initiation and progression of deformity and in developing surgical methods.

Increased radiation dose and projected radiation-related lifetime cancer risk in patients with obesity due to projection radiography.

Purpose: Primarily to evaluate the radiation dose delivered to patients with obesity in projection radiography and its relationship to the patient's size. A secondary purpose is to estimate the subsequent projected radiation-related lifetime cancer risk to patients with obesity compared to normal-weight patients.

Method And Material: Data from 1964 patients from a bariatric clinic in the UK were reviewed with the relevant permission.

Variation in lifting kinematics related to individual intrinsic lumbar curvature: an investigation in healthy adults.

Objective: Lifting postures are frequently implicated in back pain. We previously related responses to a static load with intrinsic spine shape, and here we investigate the role of lumbar spine shape in lifting kinematics.

Methods: Thirty healthy adults (18-65 years) performed , and lifts with a weighted box (6-15 kg, self-selected) while being recorded by Vicon motion capture.

Markers of oxidative stress, skeletal muscle mass and function, and their responses to resistance exercise training in older adults.

Background: Oxidative stress (OS) negatively affects skeletal muscle homeostasis in experimental models of ageing. However, little is known about the associations between circulating OS markers and parameters of muscle mass and function, and their responses to exercise training, in humans.

Methods: Maximal voluntary contraction (MVC, primary outcome) and isokinetic torque of the knee extensors at 30° s (MIT), muscle cross-sectional area (MCSA) and quality (MQ, secondary outcomes), and plasma concentrations of malondialdehyde (MDA, pro-OS), homocysteine (HCY, pro-OS), taurine (TAU, anti-OS), and protein sulphydryl groups (PSH, anti-OS) were measured in 27 healthy older males and 23 females at baseline and after an 18-week resistance exercise program, with or without a nutritional intervention (fish oil vs.

Estimation of in vivo inter-vertebral loading during motion using fluoroscopic and magnetic resonance image informed finite element models.

Finite element (FE) models driven by medical image data can be used to estimate subject-specific spinal biomechanics. This study aimed to combine magnetic resonance (MR) imaging and quantitative fluoroscopy (QF) in subject-specific FE models of upright standing, flexion and extension. Supine MR images of the lumbar spine were acquired from healthy participants using a 0.

A model-based approach for estimation of changes in lumbar segmental kinematics associated with alterations in trunk muscle forces.

The kinematics information from imaging, if combined with optimization-based biomechanical models, may provide a unique platform for personalized assessment of trunk muscle forces (TMFs). Such a method, however, is feasible only if differences in lumbar spine kinematics due to differences in TMFs can be captured by the current imaging techniques. A finite element model of the spine within an optimization procedure was used to estimate segmental kinematics of lumbar spine associated with five different sets of TMFs.

The effects of needle damage on annulus fibrosus micromechanics.

Unlabelled: Needle puncture of the intervertebral disc can initiate a mechanical and biochemical cascade leading to disc degeneration. Puncture's mechanical effects have been shown near the puncture site, mechanical effects should be observed far, relative to needle size, from the puncture site, given the disc-wide damage induced by the stab. The aim of this work was to quantify these far-field effects, and to observe the local structural damage provoked by the needle.

Age-related changes in the effects of strength training on lower leg muscles in healthy individuals measured using MRI.

Background: We previously measured the rate of regaining muscle strength during rehabilitation of lower leg muscles in patients following lower leg casting. Our primary aim in this study was to measure the rate of gain of strength in healthy individuals undergoing a similar training regime. Our secondary aim was to test the ability of MRI to provide a biomarker for muscle function.

Muscle function and size in the lumbar spine before and after a four week exercise intervention.

Background: Exercise of the spinal muscles is recommended for a variety of rehabilitative reasons but it is not always clear whether interventions are effective in improving the performance of the muscles or whether their benefit is elicited via other mechanisms.

Objective: To explore the effects of an exercise intervention on the size and exercise performance of the lumbar spine extensor muscles.

Methods: Eleven healthy participants undertook a four week programme of exercise.

Bovine and degenerated human annulus fibrosus: a microstructural and micromechanical comparison.

The complex structure of the annulus fibrosus is strongly related to its mechanical properties. Recent work showed that it is possible to observe the relative movement of fibre bundles in loaded cow tail annulus; the aim of this work was to describe and quantify annulus fibrosus micromechanics in degenerated human disc, and compare it with cow tail annulus, an animal model often used in the literature. Second harmonic generation was used to image the collagen matrix in twenty strips of annulus fibrosus harvested from intervertebral disc of seven patients undergoing surgery.

Sex differences in the effect of fish-oil supplementation on the adaptive response to resistance exercise training in older people: a randomized controlled trial.

Background: Resistance exercise increases muscle mass and function in older adults, but responses are attenuated compared with younger people. Data suggest that long-chain n-3 polyunsaturated fatty acids (PUFAs) may enhance adaptations to resistance exercise in older women. To our knowledge, this possibility has not been investigated in men.

Sex differences in the response to resistance exercise training in older people.

Resistance exercise training is known to be effective in increasing muscle mass in older people. Acute measurement of protein metabolism data has indicated that the magnitude of response may differ between sexes. We compared adaptive responses in muscle mass and function to 18 weeks resistance exercise training in a cohort of older (>65 years) men and women.

Lamellar and fibre bundle mechanics of the annulus fibrosus in bovine intervertebral disc.

Unlabelled: The intervertebral disc is a multicomposite structure, with an outer fibrous ring, the annulus fibrosus, retaining a gel-like core, the nucleus pulposus. The disc presents complex mechanical behaviour, and it is of high importance for spine biomechanics. Advances in multiscale modelling and disc repair raised a need for new quantitative data on the finest details of annulus fibrosus mechanics.

Image driven subject-specific finite element models of spinal biomechanics.

Finite element (FE) modelling is an established technique for investigating spinal biomechanics. Using image data to produce FE models with subject-specific geometry and displacement boundary conditions may help extend their use to the assessment spinal loading in individuals. Lumbar spine magnetic resonance images from nine participants in the supine, standing and sitting postures were obtained and 2D poroelastic FE models of the lumbar spine were created from the supine data.

Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging.

Purpose: Magnetically controlled growth rods (MCGRs) are a new technology for the management of early-onset pediatric deformity enabling guided spinal growth by controlling the curvature. These rods contain a rare earth magnet and are contraindicated for MRI. We have investigated the behavior MCGRs to determine whether MRI adversely affects rod properties and to determine the extent of image distortion.

The lumbar spine has an intrinsic shape specific to each individual that remains a characteristic throughout flexion and extension.

Purpose: We have previously shown that the lumbar spine has an intrinsic shape specific to the individual and characteristic of sitting, standing and supine postures. The purpose of this study was to test the hypothesis that this intrinsic shape is detectable throughout a range of postures from extension to full flexion in healthy adults.

Methods: Sagittal images of the lumbar spine were taken using a positional MRI with participants (n = 30) adopting six postures: seated extension, neutral standing, standing with 30, 45 and 60° and full flexion.

The relationship between sagittal curvature and extensor muscle volume in the lumbar spine.

A previous modelling study predicted that the forces applied by the extensor muscles to stabilise the lumbar spine would be greater in spines that have a larger sagittal curvature (lordosis). Because the force-generating capacity of a muscle is related to its size, it was hypothesised that the size of the extensor muscles in a subject would be related to the size of their lumbar lordosis. Magnetic resonance imaging (MRI) data were obtained, together with age, height, body mass and back pain status, from 42 female subjects.

The accuracy of active shape modelling and end-plate measurements for characterising the shape of the lumbar spine in the sagittal plane.

The 2D shape of the lumbar spine in the sagittal plane can be determined from lordosis angles measured between the corresponding end-plates of the vertebral bodies or by using an active shape model (ASM) of the vertebral body outline. The ASM was previously shown to be a more efficient and reliable method, but its accuracy has not been assessed. The aim of this study was to determine the accuracy of an ASM for characterising lumbar spine shape and compare this to conventional measurements.

A longitudinal MRI study of muscle atrophy during lower leg immobilization following ankle fracture.

Purpose: To investigate MRI biomarkers of muscle atrophy during cast immobilization of the lower leg.

Materials And Methods: Eighteen patients (8 male, 10 female), who had one lower leg immobilized in a cast, underwent 3.0 Tesla (T) MR imaging 5, 8, 15, 29, and 43 days after casting.

The intrinsic shape of the human lumbar spine in the supine, standing and sitting postures: characterization using an active shape model.

The shape of the lumbar spine in the sagittal plane varies between individuals and as a result of postural changes but it is not known how the shape in different postures is related. Sagittal images of the lumbar spines of 24 male volunteers were acquired using a positional magnetic resonance scanner. The subjects were imaged lying supine, standing and sitting.