Rebecca Barr - Academia.edu (original) (raw)
Papers by Rebecca Barr
Osteoarthritis and Cartilage
Osteoarthritis and Cartilage
Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JA... more Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JAMESTOWN RD, LONDON NW1 7BY, ENGLAND LONDON Suppl. 2
Osteoarthritis and Cartilage
Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JA... more Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JAMESTOWN RD, LONDON NW1 7BY, ENGLAND LONDON Suppl. 2
Osteoarthritis and Cartilage
The Journals of Gerontology Series A Biological Sciences and Medical Sciences
Falls among elderly people is a major issue in public health, causing debilitating outcomes inclu... more Falls among elderly people is a major issue in public health, causing debilitating outcomes including fracture. The identification of genetic risk factors for falling may provide a strategy for effectively targeting falls prevention programs. We investigated whether a common functional variant of skeletal muscle α-actinin-3 (ACTN3 p. R577X) previously associated with impairments in muscle strength, power, and physical functioning represents a risk factor for falls. Case-control analysis was conducted using two large cohorts of Caucasian postmenopausal women--the North of Scotland Osteoporosis Study (n = 1,245) and the Aberdeen Prospective Osteoporosis Screening Study (n = 2,918)--for whom self-reported falls status and DNA samples were available. Cross-sectional analysis of fallers versus nonfallers at baseline and follow-up was performed. In addition, individuals who reported having fallen at more than one timepoint (recurrent fallers) were compared with those who reported not fall...
Osteoarthritis and Cartilage
Osteoarthritis and Cartilage
Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JA... more Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JAMESTOWN RD, LONDON NW1 7BY, ENGLAND LONDON Suppl. 2
Journal of Clinical Densitometry, 2014
Advances in image quality from modern dual-energy X-ray absorptiometry (DXA) scanners now allow n... more Advances in image quality from modern dual-energy X-ray absorptiometry (DXA) scanners now allow near radiograph-like quality images at a low radiation dose. This opens potential new applications for the use of DXA scanners to study other musculoskeletal conditions, such as osteoarthritis, which is often investigated by visual assessment of radiographs. Together, osteoporosis and osteoarthritis are the 2 most common musculoskeletal conditions, both of which primarily affect older people. The aim of this study was to determine whether Kellgren-Lawrence grading of DXA images can be used to grade hip osteoarthritis as effectively as radiographs. People who had attended for recent pelvic radiographs underwent DXA of hips (50 hips from 25 people) using a GE Healthcare iDXA scanner. Three observers assigned Kellgren-Lawrence grades to each image, and grading was repeated at least 1 week apart. Intraobserver and interobserver reliability for radiographs and DXA images were calculated using quadratic-weighted kappa (QWK). People were recalled 12 months later, and the tests were repeated with both the radiograph and DXA scans taken within 2 weeks of each other. Hip DXA intraobserver reproducibility achieved a QWK range of 0.88-0.95 and interobserver reproducibility of 0.85-0.88, similar to QWK from hip radiographs. Intraobserver reliability between subject-matched radiograph and iDXA images revealed QWK ranging between 0.80 and 0.88. Reproducibility of hip osteoarthritis grading using DXA was comparable with that of radiographs in this study and similar to repeatability scores previously published in literature. Given the lower radiation dose and the opportunity to simultaneously investigate osteoporosis, DXA presents an attractive imaging option for osteoarthritis.
Purpose and Background: Low birthweight is related to decreased lumbar spine vertebral canal size... more Purpose and Background: Low birthweight is related to decreased lumbar spine vertebral canal size and bone mineral content later in life, suggesting that antenatal factors affect spine development. The purpose of this study was to explore associations between antenatal factors and lumbar spine morphology in childhood. Methods: Antenatal data and supine MR images of the lumbar spine were available for 161 children. Shape modelling, using principle components analysis, was performed on mid-sagittal images to quantify different modes of variation in lumbar spine shape. Previously collected measures of spine canal dimensions were analysed. Results: Almost 75 % of all of the variation in lumbar spine shape was explained by just three modes. Modes 1 and 3 described the total amount and the distribution of curvature along the spine, respectively. Mode 2 (M2) captured variation in vertebral shape and size; increasing mode scores represented flatter vertebral bodies with increasing anterior-...
Background and Aim: Low back pain is highly prevalent, particularly in manual occupations. We pre... more Background and Aim: Low back pain is highly prevalent, particularly in manual occupations. We previously showed that the lumbar spine has an intrinsic shape, identifiable in lying, sitting and standing postures, that affects the spine’s response to load. Its effects on motion are unknown. Here we investigate whether intrinsic spinal shape is detectable throughout a greater range of postures and its effect on how healthy adults lift a weighted box. Methods: The lumbar spine was imaged using a positional MRI with participants (n=30) in 6 postures ranging from extension to full flexion. Active shape modelling was used to identify and quantify ‘modes’ of variation in lumbar spine shape. 3D motion capture analysed participants’ motion while lifting a box (6-15 kg, self-selected). Results: Two modes accounted for 89.5% of variation in spinal shape, describing the overall curvature (mode 1) and distribution of curvature (mode 2). Within the first 9 modes, scores were significantly correlat...
Background and Aim: Spinal stability is associated with low back pain and affects the spines abil... more Background and Aim: Spinal stability is associated with low back pain and affects the spines ability to support loads. Stability can be achieved if the applied force follows the curvature of the spine, passing close to the vertebral centroids. Previously we showed that calculated muscle forces required for stability in an idealised model increased with increasing and more evenly distributed lumbar curvatures. The purpose of this study was to calculate the muscle forces required for stability in standing in a group of healthy adults. Methods: Positional MRI was used to acquire sagittal images of the lumbar spine in a standing posture in 30 healthy adults. Sacral inclination was measured and active shape modelling used to characterise lumbar spine shape. A two-dimensional model of the lumbar spine was constructed using vertebral centroid positions and a simplified representation of the lumbar extensor muscles. The muscle forces required at each level to produce a follower load were ca...
Osteoporosis International, 2010
Randomised control trial of osteoporosis screening in 4,800 women aged 45-54 years was carried ou... more Randomised control trial of osteoporosis screening in 4,800 women aged 45-54 years was carried out. Screened group observed an increase of 7.9% in hormone replacement therapy (HRT) use (p < 0.001), 15% in other osteoporosis treatments (p < 0.001) and a 25.9% reduction in fracture risk compared with control. Screening for osteoporosis significantly increases treatment use and reduces fracture incidence. Population screening programmes can identify menopausal women with low bone mineral density (BMD) and elevated risk of future fracture but require to be proven effective by a randomised control trial. A total of 4,800 women, 45-54 years, were randomised in equal numbers to screening or no screening (control) groups. Following screening, those in the lowest quartile of BMD were advised to consider HRT. Nine years later, the effect of screening on the uptake of treatment and the incidence of fractures were assessed by postal questionnaire. Categorical differences were assessed using chi(2) test. Cox regression was used to assess hazard ratio (HR). Of the screened and the control groups, 52.4% vs 44.5%, respectively, reported taking HRT (p < 0.001). In addition, 36.6% of the screened vs 21.6% of the control groups reported the use of vitamin D, calcium, alendronate, etidronate or raloxifene (p < 0.001). In a per protocol analysis of verified incident fractures, a 25.9% reduction in risk of fractures (of any site) in the screened group was observed (HR = 0.741, 95% CI = 0.551-0.998 adjusted age, weight and height). Screening for osteoporosis as assessed by low bone density significantly increases the use of HRT and other treatments for osteoporosis and reduces fracture incidence.
Osteoarthritis and Cartilage, 2012
Abnormalities in the shape of the hip joint are thought to be important factors in the developmen... more Abnormalities in the shape of the hip joint are thought to be important factors in the development of osteoarthritis (OA) of the hip. Quantifying these changes in shape may help us to understand their role in the progression of the disease. Active Shape Modelling (ASM) of the hip enables sensitive quantification of changes in hip morphology. In this study ASM was used to examine the relationship of hip shape and the risk of end-stage OA in a group of women who have undergone total hip arthroplasty (THA).
European Spine Journal, 2014
We have previously shown that the lumbar spine has an intrinsic shape specific to the individual ... more 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. 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. Active shape modelling (ASM) was used to identify and quantify 'modes' of variation in the shape of the lumbar spine. ASM showed that 89.5% of the variation in the shape of the spine could be explained by the first two modes; describing the overall curvature and the distribution of curvature of the spine. Mode scores were significantly correlated between all six postures (modes 1-9, r = 0.4-0.97, P < 0.05), showing that an element of intrinsic shape was maintained when changing postures. The spine was most even in seated extension (P < 0.001) and most uneven between 35 and 45° flexion (P < 0.05). This study shows that an individual's intrinsic lumbar spine shape is quantifiable and detectable throughout lumbar flexion and extension. These findings will enable the role of lumbar curvature in injury and low back pain to be assessed in the clinic and in the working and recreational environments.
Bone, 2013
Purpose. There is a continuing need to improve the prediction of hip fractures to identify those ... more Purpose. There is a continuing need to improve the prediction of hip fractures to identify those at highest risk, enabling cost-effective use of preventative therapies.
Rheumatology, 2012
Objective. Previously, active shape modelling (ASM) of the proximal femur was shown to identify t... more Objective. Previously, active shape modelling (ASM) of the proximal femur was shown to identify those individuals at highest risk of developing radiographic OA. Here we determine whether ASM predicts the need for total hip replacement (THR) independent of KellgrenLawrence grade (KLG) and other known risk factors.
Osteoarthritis and Cartilage
Osteoarthritis and Cartilage
Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JA... more Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JAMESTOWN RD, LONDON NW1 7BY, ENGLAND LONDON Suppl. 2
Osteoarthritis and Cartilage
Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JA... more Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JAMESTOWN RD, LONDON NW1 7BY, ENGLAND LONDON Suppl. 2
Osteoarthritis and Cartilage
The Journals of Gerontology Series A Biological Sciences and Medical Sciences
Falls among elderly people is a major issue in public health, causing debilitating outcomes inclu... more Falls among elderly people is a major issue in public health, causing debilitating outcomes including fracture. The identification of genetic risk factors for falling may provide a strategy for effectively targeting falls prevention programs. We investigated whether a common functional variant of skeletal muscle α-actinin-3 (ACTN3 p. R577X) previously associated with impairments in muscle strength, power, and physical functioning represents a risk factor for falls. Case-control analysis was conducted using two large cohorts of Caucasian postmenopausal women--the North of Scotland Osteoporosis Study (n = 1,245) and the Aberdeen Prospective Osteoporosis Screening Study (n = 2,918)--for whom self-reported falls status and DNA samples were available. Cross-sectional analysis of fallers versus nonfallers at baseline and follow-up was performed. In addition, individuals who reported having fallen at more than one timepoint (recurrent fallers) were compared with those who reported not fall...
Osteoarthritis and Cartilage
Osteoarthritis and Cartilage
Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JA... more Times Cited: 0 Meeting Abstract English Cited References Count: 0 670UN W B SAUNDERS CO LTD 32 JAMESTOWN RD, LONDON NW1 7BY, ENGLAND LONDON Suppl. 2
Journal of Clinical Densitometry, 2014
Advances in image quality from modern dual-energy X-ray absorptiometry (DXA) scanners now allow n... more Advances in image quality from modern dual-energy X-ray absorptiometry (DXA) scanners now allow near radiograph-like quality images at a low radiation dose. This opens potential new applications for the use of DXA scanners to study other musculoskeletal conditions, such as osteoarthritis, which is often investigated by visual assessment of radiographs. Together, osteoporosis and osteoarthritis are the 2 most common musculoskeletal conditions, both of which primarily affect older people. The aim of this study was to determine whether Kellgren-Lawrence grading of DXA images can be used to grade hip osteoarthritis as effectively as radiographs. People who had attended for recent pelvic radiographs underwent DXA of hips (50 hips from 25 people) using a GE Healthcare iDXA scanner. Three observers assigned Kellgren-Lawrence grades to each image, and grading was repeated at least 1 week apart. Intraobserver and interobserver reliability for radiographs and DXA images were calculated using quadratic-weighted kappa (QWK). People were recalled 12 months later, and the tests were repeated with both the radiograph and DXA scans taken within 2 weeks of each other. Hip DXA intraobserver reproducibility achieved a QWK range of 0.88-0.95 and interobserver reproducibility of 0.85-0.88, similar to QWK from hip radiographs. Intraobserver reliability between subject-matched radiograph and iDXA images revealed QWK ranging between 0.80 and 0.88. Reproducibility of hip osteoarthritis grading using DXA was comparable with that of radiographs in this study and similar to repeatability scores previously published in literature. Given the lower radiation dose and the opportunity to simultaneously investigate osteoporosis, DXA presents an attractive imaging option for osteoarthritis.
Purpose and Background: Low birthweight is related to decreased lumbar spine vertebral canal size... more Purpose and Background: Low birthweight is related to decreased lumbar spine vertebral canal size and bone mineral content later in life, suggesting that antenatal factors affect spine development. The purpose of this study was to explore associations between antenatal factors and lumbar spine morphology in childhood. Methods: Antenatal data and supine MR images of the lumbar spine were available for 161 children. Shape modelling, using principle components analysis, was performed on mid-sagittal images to quantify different modes of variation in lumbar spine shape. Previously collected measures of spine canal dimensions were analysed. Results: Almost 75 % of all of the variation in lumbar spine shape was explained by just three modes. Modes 1 and 3 described the total amount and the distribution of curvature along the spine, respectively. Mode 2 (M2) captured variation in vertebral shape and size; increasing mode scores represented flatter vertebral bodies with increasing anterior-...
Background and Aim: Low back pain is highly prevalent, particularly in manual occupations. We pre... more Background and Aim: Low back pain is highly prevalent, particularly in manual occupations. We previously showed that the lumbar spine has an intrinsic shape, identifiable in lying, sitting and standing postures, that affects the spine’s response to load. Its effects on motion are unknown. Here we investigate whether intrinsic spinal shape is detectable throughout a greater range of postures and its effect on how healthy adults lift a weighted box. Methods: The lumbar spine was imaged using a positional MRI with participants (n=30) in 6 postures ranging from extension to full flexion. Active shape modelling was used to identify and quantify ‘modes’ of variation in lumbar spine shape. 3D motion capture analysed participants’ motion while lifting a box (6-15 kg, self-selected). Results: Two modes accounted for 89.5% of variation in spinal shape, describing the overall curvature (mode 1) and distribution of curvature (mode 2). Within the first 9 modes, scores were significantly correlat...
Background and Aim: Spinal stability is associated with low back pain and affects the spines abil... more Background and Aim: Spinal stability is associated with low back pain and affects the spines ability to support loads. Stability can be achieved if the applied force follows the curvature of the spine, passing close to the vertebral centroids. Previously we showed that calculated muscle forces required for stability in an idealised model increased with increasing and more evenly distributed lumbar curvatures. The purpose of this study was to calculate the muscle forces required for stability in standing in a group of healthy adults. Methods: Positional MRI was used to acquire sagittal images of the lumbar spine in a standing posture in 30 healthy adults. Sacral inclination was measured and active shape modelling used to characterise lumbar spine shape. A two-dimensional model of the lumbar spine was constructed using vertebral centroid positions and a simplified representation of the lumbar extensor muscles. The muscle forces required at each level to produce a follower load were ca...
Osteoporosis International, 2010
Randomised control trial of osteoporosis screening in 4,800 women aged 45-54 years was carried ou... more Randomised control trial of osteoporosis screening in 4,800 women aged 45-54 years was carried out. Screened group observed an increase of 7.9% in hormone replacement therapy (HRT) use (p < 0.001), 15% in other osteoporosis treatments (p < 0.001) and a 25.9% reduction in fracture risk compared with control. Screening for osteoporosis significantly increases treatment use and reduces fracture incidence. Population screening programmes can identify menopausal women with low bone mineral density (BMD) and elevated risk of future fracture but require to be proven effective by a randomised control trial. A total of 4,800 women, 45-54 years, were randomised in equal numbers to screening or no screening (control) groups. Following screening, those in the lowest quartile of BMD were advised to consider HRT. Nine years later, the effect of screening on the uptake of treatment and the incidence of fractures were assessed by postal questionnaire. Categorical differences were assessed using chi(2) test. Cox regression was used to assess hazard ratio (HR). Of the screened and the control groups, 52.4% vs 44.5%, respectively, reported taking HRT (p < 0.001). In addition, 36.6% of the screened vs 21.6% of the control groups reported the use of vitamin D, calcium, alendronate, etidronate or raloxifene (p < 0.001). In a per protocol analysis of verified incident fractures, a 25.9% reduction in risk of fractures (of any site) in the screened group was observed (HR = 0.741, 95% CI = 0.551-0.998 adjusted age, weight and height). Screening for osteoporosis as assessed by low bone density significantly increases the use of HRT and other treatments for osteoporosis and reduces fracture incidence.
Osteoarthritis and Cartilage, 2012
Abnormalities in the shape of the hip joint are thought to be important factors in the developmen... more Abnormalities in the shape of the hip joint are thought to be important factors in the development of osteoarthritis (OA) of the hip. Quantifying these changes in shape may help us to understand their role in the progression of the disease. Active Shape Modelling (ASM) of the hip enables sensitive quantification of changes in hip morphology. In this study ASM was used to examine the relationship of hip shape and the risk of end-stage OA in a group of women who have undergone total hip arthroplasty (THA).
European Spine Journal, 2014
We have previously shown that the lumbar spine has an intrinsic shape specific to the individual ... more 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. 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. Active shape modelling (ASM) was used to identify and quantify 'modes' of variation in the shape of the lumbar spine. ASM showed that 89.5% of the variation in the shape of the spine could be explained by the first two modes; describing the overall curvature and the distribution of curvature of the spine. Mode scores were significantly correlated between all six postures (modes 1-9, r = 0.4-0.97, P < 0.05), showing that an element of intrinsic shape was maintained when changing postures. The spine was most even in seated extension (P < 0.001) and most uneven between 35 and 45° flexion (P < 0.05). This study shows that an individual's intrinsic lumbar spine shape is quantifiable and detectable throughout lumbar flexion and extension. These findings will enable the role of lumbar curvature in injury and low back pain to be assessed in the clinic and in the working and recreational environments.
Bone, 2013
Purpose. There is a continuing need to improve the prediction of hip fractures to identify those ... more Purpose. There is a continuing need to improve the prediction of hip fractures to identify those at highest risk, enabling cost-effective use of preventative therapies.
Rheumatology, 2012
Objective. Previously, active shape modelling (ASM) of the proximal femur was shown to identify t... more Objective. Previously, active shape modelling (ASM) of the proximal femur was shown to identify those individuals at highest risk of developing radiographic OA. Here we determine whether ASM predicts the need for total hip replacement (THR) independent of KellgrenLawrence grade (KLG) and other known risk factors.