Emma M Clark

Association between bone mass and fractures in children: a prospective cohort study

This is the first prospective cohort study of the association between bone mass and fracture risk in childhood. A total of 6213 children 9.9 years of age were followed for 24 months. Results showed an 89% increased risk of fracture per SD decrease in size‐adjusted BMC.

Association Between Bone Density and Fractures in Children: A Systematic Review and Meta-analysis

OBJECTIVE. The objective of this article was to systematically review all published studies that investigated the association between bone density and fractures in children. DESIGN. Potentially relevant articles were identified by searching electronic databases. Duplicates were removed, abstracts were inspected, and relevant articles were obtained. Studies were included in the systematic review if participants were <16.0 years old, were healthy, had extractable data on bone mass, and had fractures as the outcome. RESULTS. Ten case-control studies were identified. No prospective studies were found. There was no evidence of heterogeneity between studies or of funnel-plot asymmetry. Eight of the studies were included in the meta-analysis, because they presented results as means and standard deviations of bone density in cases and controls. The pooled standardized mean difference for bone mass in children with and without fractures, from a fixed-effects model, was −0.32 (95% confidence interval: −0.43 to −0.21). CONCLUSIONS. Evidence for an association between bone density and fractures in children is limited. The results from this meta-analysis suggest that there is an association between low bone density and fractures in children. Although there was no evidence of heterogeneity or publication bias, this meta-analysis is based on case-control studies that are prone to bias. Large, well-conducted prospective cohort studies are required to confirm the association between bone density and fractures in children.

90-day mortality after 409,096 total hip replacements for osteoarthritis, from the National Joint Registry for England and Wales: a retrospective analysis.

BACKGROUND Death within 90 days after total hip replacement is rare but might be avoidable dependent on patient and treatment factors. We assessed whether a secular decrease in death caused by hip replacement has occurred in England and Wales and whether modifiable perioperative factors exist that could reduce deaths. METHODS We took data about hip replacements done in England and Wales between April, 2003, and December, 2011, from the National Joint Registry for England and Wales. Patient identifiers were used to link these data to the national mortality database and the Hospital Episode Statistics database to obtain details of death, sociodemographics, and comorbidity. We assessed mortality within 90 days of operation by Kaplan-Meier analysis and assessed the role of patient and treatment factors by Cox proportional hazards model. FINDINGS 409,096 primary hip replacements were done to treat osteoarthritis. 1743 patients died within 90 days of surgery during 8 years, with a substantial secular decrease in mortality, from 0·56% in 2003 to 0·29% in 2011, even after adjustment for age, sex, and comorbidity. Several modifiable clinical factors were associated with decreased mortality according to an adjusted model: posterior surgical approach (hazard ratio [HR] 0·82, 95% CI 0·73-0·92; p=0·001), mechanical thromboprophylaxis (0·85, 0·74-0·99; p=0·036), chemical thromboprophylaxis with heparin with or without aspirin (0·79, 0·66-0·93; p=0·005), and spinal versus general anaesthetic (0·85, 0·74-0·97; p=0·019). Type of prosthesis was unrelated to mortality. Being overweight was associated with lower mortality (0·76, 0·62-0·92; p=0·006). INTERPRETATION Postoperative mortality after hip joint replacement has fallen substantially. Widespread adoption of four simple clinical management strategies (posterior surgical approach, mechanical and chemical prophylaxis, and spinal anaesthesia) could, if causally related, reduce mortality further. FUNDING National Joint Registry for England and Wales.

Vigorous Physical Activity Increases Fracture Risk in Children Irrespective of Bone Mass : A Prospective Study of the Independent Risk Factors for Fractures in Healthy Children

Low bone mass is a determinant of fractures in healthy children. Small studies provide limited evidence on the association between ethnicity, birth weight, family size, socioeconomic status, dietary calcium intake, or physical activity and fracture incidence. No studies have investigated whether these determinants of fracture risk act through affecting bone mass or through other mechanisms. The aim of this study was to use a population‐based birth cohort to confirm which variables are determinants of fracture risk and to further study which of these risk factors act independently of bone mass. Children from the Avon Longitudinal Study of Parents and Children have been followed up from birth to 11 yr of age. Maternal self‐reported data have been collected contemporaneously on early life factors, diet, puberty, and physical activity. These were linked to reported fractures between 9 and 11 yr of age. Multivariable logistic regression techniques were used to assess whether these potential determinants were independent of, or worked through, estimated volumetric BMD or estimated bone size relative to body size measured by total body DXA scan at 9.9 yr of age. A total of 2692 children had full data. One hundred ninety‐three (7.2%) reported at least one fracture over the 2‐yr follow‐up period. Children who reported daily or more episodes of vigorous physical activity had double the fracture risk compared with those children who reported less than four episodes per week (OR, 2.06; 95% CI, 1.21–1.76). No other independent determinants of fracture risk in healthy children were found. In conclusion, reported vigorous physical activity is an independent risk factor for childhood fracture risk. However, the interrelationship between physical activity, bone mass, and childhood fracture risk suggests that the higher bone mass associated with increased physical activity does not compensate for the risk caused by increased exposure to injuries.

45-day mortality after 467,779 knee replacements for osteoarthritis from the National Joint Registry for England and Wales: an observational study.

BACKGROUND Understanding the risk factors for early death after knee replacement could help to reduce the risk of mortality after this procedure. We assessed secular trends in death within 45 days of knee replacement for osteoarthritis in England and Wales, with the aim of investigating whether any change that we recorded could be explained by alterations in modifiable perioperative factors. METHODS We took data for knee replacements done for osteoarthritis in England and Wales between April 1, 2003, and Dec 31, 2011, from the National Joint Registry for England and Wales. Patient identifiers were used to link these data to the national mortality database and the Hospital Episode Statistics database to obtain details of death, sociodemographics, and comorbidity. We assessed mortality within 45 days by Kaplan-Meier analysis and assessed the role of patient and treatment factors by Cox proportional hazards models. FINDINGS 467,779 primary knee replacements were done to treat osteoarthritis during 9 years. 1183 patients died within 45 days of surgery, with a substantial secular decrease in mortality from 0·37% in 2003 to 0·20% in 2011, even after adjustment for age, sex, and comorbidity. The use of unicompartmental knee replacement was associated with substantially lower mortality than was total knee replacement (hazard ratio [HR] 0·32, 95% CI 0·19–0·54, p<0·0005). Several comorbidities were associated with increased mortality: myocardial infarction (HR 3·46, 95% CI 2·81–4·14, p<0·0005), cerebrovascular disease (3·35, 2·7–4·14, p<0·0005), moderate/severe liver disease (7·2, 3·93–13·21, p<0·0005), and renal disease (2·18, 1·76–2·69, p<0·0005). Modifiable perioperative risk factors, including surgical approach and thromboprophylaxis were not associated with mortality. INTERPRETATION Postoperative mortality after knee replacement has fallen substantially between 2003 and 2011. Efforts to further reduce mortality should concentrate more on older patients, those who are male and those with specific comorbidities, such as myocardial infarction, cerebrovascular disease, liver disease, and renal disease. FUNDING National Joint Registry for England and Wales.

Bone Fragility Contributes to the Risk of Fracture in Children, Even After Moderate and Severe Trauma

We prospectively examined whether the relationship between skeletal fragility and fracture risk in children 9.9 ± 0.3 (SD) yr is affected by trauma level. Bone size relative to body size and humeral vBMD showed similar inverse relationships with fracture risk, irrespective of whether fractures followed slight or moderate/severe trauma.

Obesity is a risk factor for musculoskeletal pain in adolescents: findings from a population-based cohort.

Summary Obesity is associated with the occurrence and severity of several musculoskeletal pain phenotypes, including knee pain and chronic regional pain in adolescents. Abstract Obesity is a risk factor for fibromyalgia in adults, but whether a similar relationship exists in children is uncertain. This study examined whether obesity is associated with reporting of musculoskeletal pain, including chronic regional pain (CRP) and chronic widespread pain (CWP), in adolescents, in a population‐based setting. A pain questionnaire was administered to offspring of the Avon Longitudinal Study of Parents and Children at age 17, asking about site, duration, and pain intensity, from which participants with different types of musculoskeletal pain were identified. Relationships between obesity and pain were examined by calculating odds ratios stratified by gender and adjusted for socioeconomic status as reflected by level of maternal education. A total of 3376 participants (1424 boys) with complete data were identified, mean age 17.8; 44.7% of participants reported any pain within the last month lasting 1 day or longer; 16.3% reported lower back pain, 9.6% shoulder pain, 9.4% upper back pain, 8.9% neck pain, 8.7% knee pain, 6.8% ankle/foot pain, 4.7% CRP, and 4.3% CWP; 7.0% of participants were obese. Obesity was associated with increased odds of any pain (odds ratio [OR] 1.33, P = .04), CRP (OR 2.04, P = .005), and knee pain (OR 1.87, P = .001), but not CWP (OR 1.10, P = .5). Compared with non obese participants, those with any pain, knee pain, and CRP reported more severe average pain (P < .01). Obese adolescents were more likely to report musculoskeletal pain, including knee pain and CRP. Moreover, obese adolescents with knee pain and CRP had relatively high pain scores, suggesting a more severe phenotype with worse prognosis.

Epidemiology of Generalized Joint Laxity (Hypermobility) in Fourteen-Year-Old Children From the UK: A Population-Based Evaluation

Objective Although diagnostic criteria for generalized ligamentous laxity (hypermobility) in children are widely used, their validity may be limited, due to the lack of robust descriptive epidemiologic data on this condition. The present study was undertaken to describe the point prevalence and pattern of hypermobility in 14-year-old children from a population-based cohort. Methods We performed a cross-sectional analysis using the Avon Longitudinal Study of Parents and Children, a large population-based birth cohort. Hypermobility among children in the cohort (mean age 13.8 years) was measured using the Beighton scoring system. Objective measures of physical activity were ascertained by accelerometry. Data on other variables, including puberty and socioeconomic status, were collected. Simple prevalence rates were calculated. Chi-square tests and logistic regression analyses were used to assess associations of specific variables with hypermobility. Results Among the 6,022 children evaluated, the prevalence of hypermobility (defined as a Beighton score of ≥4 [i.e., ≥4 joints affected]) in girls and boys age 13.8 years was 27.5% and 10.6%, respectively. Forty-five percent of girls and 29% of boys had hypermobile fingers. There was a suggestion of a positive association between hypermobility in girls and variables including physical activity, body mass index, and maternal education. No associations were seen in boys. Conclusion We have shown that the prevalence of hypermobility in UK children is high, possibly suggesting that the Beighton score cutoff of ≥4 is too low or that this scoring is not appropriate for use in subjects whose musculoskeletal system is still developing. These results provide a platform to evaluate the relationships between the Beighton criteria and key clinical features (including pain), thereby testing the clinical validity of this scoring system in the pediatric population.

Joint Hypermobility Is a Risk Factor for Musculoskeletal Pain During Adolescence: Findings of a Prospective Cohort Study

OBJECTIVE To determine whether joint hypermobility (JH) in childhood is a risk factor for the subsequent development of musculoskeletal pain. METHODS JH was determined according to the Beighton score at age 13.8 years in children from the Avon Longitudinal Study of Parents and Children (ALSPAC), using a cutoff of ≥6 for the presence of hypermobility. Musculoskeletal pain was evaluated by questionnaire at age 17.8 years. Logistic regression analysis was performed in 2,901 participants (1,267 boys and 1,634 girls) who had complete data. RESULTS A total of 4.6% of participants had JH at age 13.8 years. Moderately troublesome musculoskeletal pain at age 17.8 years was reported most commonly in the lower back (16.1%), shoulder (9.5%), upper back (8.9%), knee (8.8%), neck (8.6%), and ankle/foot (6.8%). JH was associated with an increased risk of at least moderately troublesome musculoskeletal pain at the shoulder (odds ratio [OR] 1.68 [95% confidence interval (95% CI) 1.04, 2.72]), knee (OR 1.83 [95% CI 1.10, 3.02]), and ankle/foot (OR 1.82 [95% CI 1.05, 3.16]) (adjusted for sex, maternal education, and body mass index). An equivalent relationship was not observed at other sites, including the spine, elbows, hands, and hips. In analyses examining interactions with obesity, associations between JH and knee pain showed higher ORs in obese participants (OR 11.01) as compared with nonobese participants (OR 1.57) (P=0.037 for the interaction of hypermobility and obesity). CONCLUSION JH represents a risk factor for musculoskeletal pain during adolescence, comprising a specific distribution, namely, the shoulder, knee, and ankle/foot. These relationships were strongest in the presence of obesity, which is consistent with a causal pathway whereby JH leads to pain at sites exposed to the greatest mechanical forces.

Social position affects bone mass in childhood through opposing actions on height and weight.

We studied relationships between social position of the mother in pregnancy and bone mass of the child at age 9.9 years. The tendency for social position to increase bone area and bone mass through a positive influence on height was opposed by a negative effect of social position on weight and fat mass.