Maternal smoking during pregnancy, other prenatal and perinatal factors, and the risk of Legg-Calvé-Perthes disease

Epidemiology, natural evolution, pathogenesis, clinical spectrum, and management of Legg-Calvé-Perthes

Background

Legg-Calvé-Perthes disease is a self-limiting disorder that develops in children following interruption of the blood supply to the capital femoral epiphysis. This review outlines the current knowledge on the epidemiology, natural evolution, clinical spectrum, and management of the disease.

Methods

The literature pertaining to these aspects of the disease were studied and summarized in this review.

Results

Epidemiological studies suggest that environmental factors contribute to the causation of the disease. Incidence rates monitored over time indicate that the incidence of Legg-Calvé-Perthes disease is declining. The natural evolution followed on sequential plain radiographs enables division of the disease into Stages Ia, Ib, IIa, IIb, IIIa, IIIb, and IV. Reversible deformation of the capital occurs in Stages Ia-IIa simply on standing while irreversible deformation may occur in Stages IIb and IIIa. Treatment of Legg-Calvé-Perthes disease in Stages Ia-IIa aims to prevent the femoral head from getting deformed by containment and avoidance of weight-bearing. In Stages IIb and IIIa, treatment aims to remedy the effects of early irreversible deformation of the femoral head. In Stage IIIb and IV, treatment is directed to correcting the altered shape of the femoral head. The impression that these treatment methods are helpful is based on poor quality evidence.

Conclusion

There is an urgent need to undertake Level I studies to establish the efficacy of currently treatment.

Level of evidence

level V.

Legg-Calve-Perthes' disease: an opportunity to prevent blindness?

Legg-Calve-Perthes' disease (LCP) is defined as avascular necrosis of the femoral head in a child and may present to a variety of disciplines from general practice to orthopaedics, paediatrics, rheumatology and more. The Stickler syndromes are a group of disorders of type II, IX and XI collagen associated with hip dysplasia, retinal detachment, deafness and cleft palate. The pathogenesis of LCP disease remains an enigma but there have been a small number of cases reporting variants in the gene encoding the α1 chain of type II collagen (COL2A1). Variants in COL2A1 are known to cause type 1 Stickler syndrome (MIM 108300, 609508), which is a connective tissue disorder with a very high risk of childhood blindness, and it is also associated with dysplastic development of the femoral head. It is unclear whether COL2A1 variants make a definitive contribution to both disorders, or whether the two are indistinguishable using current clinical diagnostic techniques. In this paper, we compare the two conditions and present a case series of 19 patients with genetically confirmed type 1 Stickler syndrome presenting with a historic diagnosis of LCP. In contrast to isolated LCP, children with type 1 Stickler syndrome have a very high risk of blindness from giant retinal tear detachment, but this is now largely preventable if a timely diagnosis is made. This paper highlights the potential for avoidable blindness in children presenting to clinicians with features suggestive of LCP disease but with underlying Stickler syndrome and proposes a simple scoring system to assist clinicians.

Radiologic Outcomes of Bilateral and Unilateral Perthes Disease: A Comparative Cohort Study

INTRODUCTION

This study was undertaken to compare the radiologic outcomes of bilateral and unilateral Perthes disease and also to evaluate the outcome of synchronous and metachronous bilateral Perthes disease.

METHODS

Of 353 children with Perthes disease followed up from presentation to healing during the last 10 years, 37 had bilateral involvement (11 synchronous and 26 metachronous onset). The radiologic outcomes of each hip of children with bilateral disease were compared with outcomes of 148 children with unilateral disease who were matched for age, sex, and treatment. Children with unilateral or bilateral diseases were treated with a proximal femoral varus derotation osteotomy if they fulfilled the criteria for surgery. The primary outcome measure was the shape of the femoral head at healing assessed by the Sphericity Deviation Score (SDS).

RESULTS

The children with bilateral disease were younger than those with unilateral disease (6.2 vs. 7.03 y; P<0.001), and they had a longer duration of the disease. All other characteristics of bilateral and unilateral cases were similar. The SDS values of unilateral and bilateral disease were comparable, as were the SDS of synchronous and metachronous bilateral disease. The effect of early surgery on the evolution of the disease in bilateral cases was similar to that reported in unilateral disease. The age of onset of the disease alone influenced the SDS in bilateral cases.

CONCLUSION

The age at onset of the bilateral disease is lower, the duration of the disease longer than that of unilateral disease, but the disease outcome is similar.

Can large doses of glucocorticoids lead to Perthes? a case report and review of the literature

Background

Perthes disease (Legg-Calvé-Perthes, LCP) is a self-limited and non-systemic disease occurring in the femoral heads of children, which is mainly manifested as an ischemic necrosis of the femoral head epiphysis, leading to subchondral ossification injury of the femoral head.

Case presentation

Here we report a case of 11-year-old child with long-term use of high-dose glucocorticoids. With MRI examination finding the epiphyseal necrosis of right humeral head, femur and tibia, and X-ray examination finding bilateral femoral head necrosis, the child was diagnosed as Perthes disease based on his clinical and imaging data.

Conclusions

Long-term and high-dose glucocorticoids may be one of the causes of Perthes disease.

Influence of passive smoking on the onset of Legg-Calvè-Perthes disease: a systematic review and meta-analysis

The relationship between passive smoking and the onset of Legg-Calvè-Perthes disease is still controversial. Therefore, we conducted the study to systematically evaluate and analyze the relationship. A comprehensive search was conducted. Meta-analysis was performed with RevMan 5.3 software, with the odds ratio as the effect size. Eight English articles with a total of 1379 Legg-Calvè-Perthes disease patients were eventually included. Passive smoking type of family members smoking in indoor (odds ratio = 2.53), paternal smoking (odds ratio = 2.76), maternal smoking (odds ratio = 2.02), maternal smoking during pregnancy (odds ratio = 1.68), using stove indoor (odds ratio = 2.56) are statistically significant (P < 0.05). For the family members smoking indoor, region may be a confounding factor (European group I = 92%, odds ratio = 2.51; USA group I = 5%, odds ratio = 3.26; and Asian group I = 0%, odds ratio = 2.25). In addition, the type of maternal smoking (odds ratio = 0.80, for 1-10 per day; odds ratio = 2.73, for 10-20 per day; odds ratio = 2.78, for >20 per day) and the type of maternal smoking during pregnancy (odds ratio = 1.36, for 1-9 per day; odds ratio = 2.02, for ≥10 per day) may show a dose-effect relationship. Passive smoking is a risk factor for the onset of Legg-Calvè-Perthes disease, but the specific types of passive smoking (haze, etc.), dose, dose-effect relationship, regional confounding, pathological mechanisms, etc. also require clinicians and researchers to continue exploring.

Risk factors during pregnancy and delivery for the development of Perthes' disease, a nationwide Swedish study of 2.1 million individuals

Background

To ascertain or disprove a correlation between suboptimal birth characteristics, breech position at delivery and development of Perthes’ disease.

Methods

Study material was collected from nationwide registers regarding diagnoses, birth statistics and delivery data. As study population were included children with a diagnosis code for Perthes’ disease who were alive and living in Sweden at age 13. Children with missing birth statistics were excluded. All children with no Perthes’ disease diagnosis were used as control group. Both single and multiple logistical regression analyses were used to calculate OR for the included characteristics.

Results

Children in breech position had a higher risk for developing Perthes’ disease. Children with Perthes’ disease had also a higher probability of having been born pre-term, very pre-term or post-term. Lower than normal birth weight and a lower Apgar-score were also associated with Perthes’ disease.

Conclusions

There is a correlation between breech birth and development of Perthes’ disease. There is also correlation to suboptimal birth characteristics. Despite our findings this should not be used for screening of Perthes’ disease as the percentage of children who actually develop it is very low. Also, as of yet there is no possibility to diagnose Perthes’ disease before the presence of skeletal changes. Our findings could be important in finding the cause of Perthes’ disease and therefore developing better diagnostics, treatment and prevention.

Aetiology of Legg-Calvé-Perthes disease: A systematic review

BACKGROUND

Legg-Calvé-Perthes disease (LCPD) is a clinical condition affecting the femoral head of children during their growth. Its prevalence is set to be between 0.4/100000 to 29.0/100000 children less than 15 years of age with a peak of incidence in children aged from 4 years to 8 years. LCPD aetiology has been widely studied, but it is still poorly understood.

AIM

To analyse the available literature to document the up-to-date evidence on LCPD aetiology.

METHODS

A systematic review of the literature was performed regarding LCPD aetiology, using the following inclusion criteria: studies of any level of evidence, reporting clinical or preclinical results and dealing with the aetiology or pathogenesis of LCPD. Two reviewers searched the PubMed and Science Direct databases from their date of inception to the 20th of May 2018 in accordance with the Preferred Reporting Items for Systemic Reviews and Meta-Analyses guidelines. To achieve the maximum sensitivity of the search strategy, we combined the terms: ‘‘Perthes disease OR LCPD OR children avascular femoral head necrosis” with “pathology OR aetiology OR biomechanics OR genetics” as either key words or MeSH terms.

RESULTS

We include 64 articles in this review. The available evidence on LCPD aetiology is still debated. Several hypotheses have been researched, but none of them was found decisive. While emerging evidence showed the role of environmental risk factors and evidence from twin studies did not support a major role for genetic factors, a congenital or acquired predisposition cannot be excluded in disease pathogenesis. One of the most supported theories involved mechanical induced ischemia that evolved into avascular necrosis of the femoral head in sensible patients.

CONCLUSION

The literature available on the aetiology of LCPD presents major limitations in terms of great heterogeneity and a lack of high-profile studies. Although a lot of studies focused on the genetic, biomechanical and radiological background of the disease, there is a lack of consensus on one or multiple major actors of the etiopathogenesis. More studies are needed to understand the complex and multifactorial genesis of the avascular necrosis characterizing the disease.

What are the Demographics and Epidemiology of Legg-Calvé-Perthes Disease in a Large Southern California Integrated Health System?

BACKGROUND

Although many authors have reported the incidence of Legg-Calvé-Perthes disease (LCPD), there have been few incidence studies in the United States on large, self-contained populations such as those within an integrated health system. Understanding the epidemiology and demographics of LCPD in this setting may help clinicians identify patients at the greatest risk and aid in diagnosis and subsequent treatment.

QUESTIONS/PURPOSES

In this study we sought (1) to determine the incidence and demographics of LCPD in a large cohort of children and adolescents in a Southern California integrated healthcare system, and (2) to identify any demographic or clinical factors (such as age, sex, race/ethnicity, or BMI) that are independently associated with LCPD.

METHODS

A retrospective chart analysis was done on patients diagnosed with LCPD within our integrated healthcare system in patients aged 2 to 12 years over a 3-year period between 2010-2012. There were nearly 800,000 children in this cohort. Patient demographics were recorded; the incidence of LCPD was determined for the entire group and by sex, age, and race/ethnicity. Odds ratios for an association with LCPD based on age, sex, BMI and race/ethnicity were determined using logistic regression models.

RESULTS

The LCPD incidence per 100,000 for all children was 2.84, with the highest incidence in 2- to 5-year-old children (3.05; 95% CI, 1.51-4.59) and the lowest in 9- to 12-year-old children (1.06; 95% CI, 0.21-1.91). Incidence varied markedly among ethnicities, with the highest incidence in whites (5.69; 95% CI, 3.13-8.24) and the lowest in Asians (0.78; 95% CI, 0.00-2.32). Data analysis revealed a 3.13-times increased odds ratio (OR) of LCPD in 2- to 5-year-old patients versus 9- to 12-year-olds (p = 0.011), and boys had a 12.44 times greater OR of LCPD than girls (p < 0.001). Data analysis showed an increased OR for LCPD (3.41; 95% CI, 1.28-9.09) in patients with extreme obesity (BMI-for-age ≥ 1.2 × 95th percentile or a BMI ≥ 35 kg/m) compared with patients with a normal BMI.

CONCLUSIONS

Our study of a large integrated healthcare system in Southern California revealed an increased association of male sex and young age (2 to 5 years old) with LCPD. The overall incidence was lower overall than previously reported, although the incidence seen in white patients was similar to that in prior studies. The finding that patients with extreme obesity may have an increased association with LCPD merits further study. These findings may increase providers' awareness of the risk of the disease in younger patients and in extremely obese patients, and it also merits further future investigation as to whether there is a cause or effect relationship between extreme obesity and LCPD.

LEVEL OF EVIDENCE

Level IV, prognostic study.

The Pathogenesis and Treatment of Legg-Calvé-Perthes Disease

Legg-Calvé-Perthes disease is a childhood hip condition in which the blood supply to the capital femoral epiphysis is interrupted, causing osteonecrosis and chondronecrosis that lead to progressive deformity of the femoral head and secondary degenerative osteoarthritis in later life. The etiology of Legg-Calvé-Perthes disease remains unclear, with both biological and mechanical factors playing important roles in the pathogenesis of the condition. The treatment of Legg-Calvé-Perthes disease remains controversial but is dependent on several salient factors, including the age at clinical onset, the extent of epiphyseal involvement, the stage of the disease, and the degree of femoral head deformity. The literature supports operative containment treatment in the early stage of disease. Such treatment has led to improved femoral head sphericity with better patient outcomes in multicenter prospective cohort studies. The number of hips that need to be treated operatively in order to achieve a modest treatment effect remains high. Multicenter prospective cohort studies have shown that 6 to 7 patients need to be managed to create 1 spherical femoral head that would not have otherwise occurred.

A case control study to determine the association between Perthes' disease and the recalled use of tobacco during pregnancy, and biological markers of current tobacco smoke exposure

AIMS

It is well established that there is a strong association between Perthes' disease and worsening socioeconomic deprivation. It has been suggested that the primary determinant driving this association is exposure to tobacco smoke. This study aimed to examine this hypothesis.

PATIENTS AND METHODS

A hospital case-control study (n = 149/146) examined the association between tobacco smoke exposure and Perthes' disease, adjusting for area-level socioeconomic deprivation. Tobacco smoke exposure was assessed by parental questionnaire of smoking habits during pregnancy, and by quantitative assay of current exposure using the urinary cotinine-creatinine ratio, which is a widely used and validated measure of tobacco smoke exposure.

RESULTS

The odds of Perthes' disease significantly increased with reported in utero exposure after adjustment for socioeconomic deprivation (maternal smoking odds ratio (OR) 2.06, 95% confidence interval (CI) 1.17 to 3.63; paternal smoking OR 2.09, 95% CI 1.26 to 3.46). The cotinine-creatinine ratio was significantly greater in cases, OR 1.63 (95% CI 1.09 to 2.43), suggesting a greater 'dose' of current tobacco exposure.

CONCLUSION

An association exists between tobacco smoke exposure and Perthes' disease but we remain unable to disentangle the association with socioeconomic deprivation. Cite this article: Bone Joint J 2017;99-B:1102-8.

The Declining Incidence of Legg-Calve-Perthes' Disease in Northern Ireland: An Epidemiological Study

BACKGROUND

Legg-Calve-Perthes' disease (LCPD) is an idiopathic disease of the femoral head affecting the pediatric population. The causative factors remains poorly understood and it is associated with significant hip pathology in adult life. Research has demonstrated wide geographical variation in the incidence rates of LCPD with a relatively high incidence occurring in Northern Ireland (NI) shown in a previous study of incidence from the same unit. The number of new diagnoses of LCPD seems to be declining over time. This study aimed to track changes in the incidence of LCPD within the 0- to 14-year-old population over a 15-year period in NI.

METHODS

An established database was utilized to collate information of any individual between the ages of 0 to 14 years with a diagnosis of LCPD. The data were compared with electronic radiologic records to confirm the diagnosis. Postal code data were used to the determine location of residence and used as a proxy measure of deprivation.

RESULTS

The results of this epidemiological study have demonstrated a 61% decrease in the incidence of LCPD over a 15-year period within the pediatric population of NI. Comparison between 2 cohorts reveals no distinguishable change in distribution of age or sex. The relationship between geographical proxy measures of deprivation in NI and LCPD remains evident.

CONCLUSIONS

The number of new cases of LCPD is decreasing over time. The epidemiological data are unchanged between 2 cohorts over a 15-year period, and this therefore supports a change within the patients' environment relating to this decline. This change could relate to a number of factors including smoking rates, breastfeeding, lead use, and vaccination implementation.

LEVEL OF EVIDENCE

Level IV-retrospective cohort study.

Skeletal immaturity, rostral sparing, and disparate hip morphologies as biomechanical causes for Legg-Calvé-Perthes' disease

Legg-Calvé-Perthes' (Perthes') disease is a developmental disease of the hip joint that may result in numerous short and long term problems. The etiology of the disease remains largely unknown, but the mechanism is believed to be vascular and/or biomechanical in nature. There are several anatomical characteristics that tend to be prevalent in children with Perthes' disease, namely: skeletal immaturity, reduced height, and rostral sparing. We present an overview of the literature, summarizing the current understanding of the pathogenesis, particularly related to how the formation of the vasculature to the femoral epiphysis places children aged 5-8 at a higher risk for Perthes' disease, how skeletal immaturity and rostral sparing could increase the probability of developing Perthes' disease, and how animal models have aided our understanding of the disease. In doing so, we also explore why Perthes' disease is correlated to latitude, with populations at higher latitudes having higher incidence rates than populations closer to the Equator. Finally, we present five hypotheses detailing how Perthes' disease could have a biomechanical cause. Clin. Anat. 29:759-772, 2016. © 2016 Wiley Periodicals, Inc.

Linking databases on perinatal health: a review of the literature and current practices in Europe

Background: International comparisons of perinatal health indicators are complicated by the heterogeneity of data sources on pregnancy, maternal and neonatal outcomes. Record linkage can extend the range of data items available and thus can improve the validity and quality of routine data. We sought to assess the extent to which data are linked routinely for perinatal health research and reporting. Methods: We conducted a systematic review of the literature by searching PubMed for perinatal health studies from 2001 to 2011 based on linkage of routine data (data collected continuously at various time intervals). We also surveyed European health monitoring professionals about use of linkage for national perinatal health surveillance. Results: 516 studies fit our inclusion criteria. Denmark, Finland, Norway and Sweden, the US and the UK contributed 76% of the publications; a further 29 countries contributed at least one publication. Most studies linked vital statistics, hospital records, medical birth registries and cohort data. Other sources were specific registers for: cancer (70), congenital anomalies (56), ART (19), census (19), health professionals (37), insurance (22) prescription (31), and level of education (18). Eighteen of 29 countries (62%) reported linking data for routine perinatal health monitoring. Conclusion: Research using linkage is concentrated in a few countries and is not widely practiced in Europe. Broader adoption of data linkage could yield substantial gains for perinatal health research and surveillance.

Epigenetics in Legg-Calvé-Perthes disease: A study of global DNA methylation

OBJECTIVE

To examine the global methylation status of DNA in blood cells of children with Legg-Calvé-Perthes disease (LCPD), since the aetiopathogenesis of LCPD remains unclear, and many factors closely associated with DNA methylation may be linked to the occurrence of LCPD.

METHODS

Children with LCPD and age-, sex- and body mass index-matched controls were evaluated. Methylation levels of the long interspersed nuclear element 1 (LINE-1), a biomarker of global DNA methylation, were quantified by methylation-specific polymerase chain reaction.

RESULTS

Of 82 children with LCPD (68 male/14 female) and 120 matched controls (98 male/22 female), methylation of the LINE-1 promoter was significantly lower in patients with LCPD compared with controls. Subgroup analyses showed that methylation of the LINE-1 promoter was significantly lower in male patients with LCPD compared with male controls. No significant between-group differences were observed in female participants.

CONCLUSIONS

Reduced global DNA methylation may be associated with increased risk of LCPD in male children. Further research is required to understand whether detection of global DNA methylation may provide a basis for clinical diagnosis and early intervention of LCPD.

Perthes disease: evaluation and management

Perthes disease refers to self-limiting idiopathic avascular necrosis of capital femoral epiphysis in a child. There is no consensus for the optimum treatment of Perthes disease even 100 years after the first description. The prime aim of the treatment is to maintain the sphericity of the femoral head and the congruency of the femur-acetabulum relationship to prevent secondary degenerative arthritis. Early diagnosis and management can help the collapse of femoral head, progressive femoral head deformity, and impingement.

Female patients with late-onset legg-calvé-perthes disease are frequently gymnasts: is there a mechanical etiology for this subset of patients?

BACKGROUND

The cause of Legg-Calvé-Perthes disease (LCPD) is unknown. We have observed a relatively high prevalence of female gymnasts presenting with LCPD. The purpose of this study was to determine: (1) the percentage of LCPD patients exposed to high-level gymnastics training, (2) the demographics of this subset of patients, and (3) their clinical outcomes.

METHODS

Several adolescent female gymnasts presented to our clinic with recent-onset LCPD. We reviewed our cases to discern the prevalence and treatment of the disorder in this patient cohort. From 1999 to 2010, 572 patients were evaluated for a diagnosis of LCPD at our tertiary referral center. Clinical records were retrospectively reviewed. Of those, 13 patients had a history of gymnastics participation with 8 patients (all females) having competitive participation.

RESULTS

For females aged 10 years and older presenting with LCPD, 7 of 9 patients (78%) were involved in high-level competitive gymnastics. These patients had disease onset between 10 and 12 years of age (mean, 11 y). Competitive gymnasts represented 6.6% (8 of 120) of females with LCPD and 1.4% (8 of 572) of all patients evaluated with LCPD during the study period. Only 1 of 111 females below 10 years with LCPD participated in competitive gymnastics (χ, P<0.0001).Patients underwent a variety of treatments. Two patients underwent nonoperative treatment, and the remainder underwent surgical management. All 7 gymnasts had a Stulberg IV result. In the nongymnast group of females 10 years and older, there were 1 Stulberg III result and 1 Stulberg IV result.

CONCLUSIONS

At our center, competitive gymnasts comprise >75% of the female patients over the age of 10 who presented with late-onset LCPD. Results in general were poor. Further studies are needed to explore the association between the physical demands of advanced gymnastic training and the development of LCPD in this subset of patients.

LEVEL OF EVIDENCE

IV, case series.

Comorbidities in Perthes' disease: a case control study using the General Practice Research database

Perthes' disease is an osteonecrosis of the juvenile hip, the aetiology of which is unknown. A number of comorbid associations have been suggested that may offer insights into aetiology, yet the strength and validity of these are unclear. This study explored such associations through a case control study using the United Kingdom General Practice Research database. Associations investigated were those previously suggested within the literature. A total of 619 cases of Perthes' disease were included, as were 2544 controls. The risk of Perthes' disease was significantly increased with the presence of congenital anomalies of the genitourinary and inguinal region, such as hypospadias (odds ratio (OR) 4.04 (95% confidence interval (CI) 1.41 to 11.58)), undescended testis (OR 1.83 (95% CI 1.12 to 3.00)) and inguinal herniae (OR 1.79 (95% CI 1.02 to 3.16)). Attention deficit hyperactivity disorder was not associated with Perthes' disease (OR 1.01 (95% CI 0.48 to 2.12)), although a generalised behavioural disorder was (OR 1.55 (95% CI 1.10 to 2.17)). Asthma significantly increased the risk of Perthes' disease (OR 1.44 (95% CI 1.17 to 1.76)), which remained after adjusting for oral/parenteral steroid use. Perthes' disease has a significant association with congenital genitourinary and inguinal anomalies, suggesting that intra-uterine factors may be critical to causation. Other comorbid associations may offer insight to support or refute theories of pathogenesis.

Cesarean section and development of the immune system in the offspring

This review examines the relation between the mode of delivery and development of the immune system in the offspring. Recent epidemiological studies provide evidence that elective cesarean section (CS) is associated with aberrant short-term immune responses in the newborn infant, and a greater risk of developing immune diseases such as asthma, allergies, type 1 diabetes, and celiac disease. However, it is still unknown whether CS causes a long-term effect on the immune system of the offspring that contributes to compromised immune health. With the dramatic increase in the rate of CS today, a greater emphasis should be placed on the discussion among both professionals and childbearing women on potential consequences of CS on the health of the offspring.

Environmental tobacco and wood smoke increase the risk of Legg-Calvé-Perthes disease

BACKGROUND

The etiology of Legg-Calvé-Perthes disease (LCPD) remains unknown. A few studies have suggested passive smoke inhalation may be a risk factor, although the association is not confirmed and a causal relationship has not been established.

QUESTIONS/PURPOSES

We therefore undertook this study to confirm an association between environmental tobacco smoke, firewood smoke, and socioeconomic status and the risk of LCPD.

METHODS

We prospectively recruited 128 children with LCPD and 384 children attending the hospital for other orthopaedic complaints. The control subjects were frequency-matched with the cases by age and gender. Conditional logistic regression was used to assess the association between the exposures and risk of LCPD.

RESULTS

The main risk factors for LCPD were indoor use of a wood stove (adjusted odds ratio [OR], 2.56) and having a family member who smoked indoors (adjusted OR, 2.07). Children from the middle socioeconomic group appeared to be at a greater risk of developing LCPD (adjusted OR, 3.60).

CONCLUSIONS

This study provides further evidence that environmental tobacco smoke is associated with an increased risk of LCPD. Exposure to wood smoke also appears to be a risk factor. However, it remains unclear why there are profound differences in the incidence of the disease between regions when the prevalence of smoking is comparable and why bilateral involvement and familial disease are infrequent.

Legg-Calvé-Perthes disease in the UK: geographic and temporal trends in incidence reflecting differences in degree of deprivation in childhood

OBJECTIVE

Little is known about Legg-Calvé-Perthes disease, a common childhood precursor to osteoarthritis of the hip. This study was undertaken to analyze the incidence of Legg-Calvé-Perthes disease in the UK, with respect to geographic and temporal trends over a 19-year period.

METHODS

The General Practice Research database was analyzed to identify incident cases between 1990 and 2008 in children ages 0-14 years. Incidence rates were calculated by year and by region (National Health Service Strategic Health Authority regions in England, and Scotland, Wales, and Northern Ireland), and the association with regional markers of deprivation examined.

RESULTS

Over the 19-year period there was a dramatic decline in Legg-Calvé-Perthes disease incidence, with annual rates among children 0-14 years old declining from 12.2 per 100,000 to 5.7 per 100,000 (P < 0.001). There was also marked geographic variation, with incidence rates in Scotland more than twice those in London (10.39 [95% confidence interval 8.05-13.2] versus 4.6 [95% confidence interval 3.4-6.1] per 100,000 0-14-year-olds). A more rapid decline in incidence was apparent in the Northern regions compared to Southern regions. The quintile with the highest degree of deprivation had the highest disease incidence (rate ratio 1.49 [95% confidence interval 1.10-2.04]) and, with the exception of London, regional incidence showed a strong linear relationship with regional deprivation score (P < 0.01).

CONCLUSION

The incidence of Legg-Calvé-Perthes disease in the UK has a strong North-South divide, with a greater disease incidence within the Northern regions of the UK. There was a marked decline in incidence over the study period, which was more marked in Northern areas. The declining incidence, along with the geographic variation, suggests that a major etiologic determinant in Legg-Calvé-Perthes disease is environmental and closely linked to childhood deprivation.

Abnormalities of vascular structure and function in children with Perthes disease

BACKGROUND AND OBJECTIVES

Perthes disease is a childhood precipitant to osteoarthritis of the hip, for which the etiology and mechanism are unknown. There is mounting evidence to suggest a vascular insult is responsible for disease, and it is suggested that this may have long-term implications for the vascular health of affected individuals. This study sought to use ultrasound measures to investigate vascular structure and function in children affected by Perthes disease.

METHODS

This case control study encompassed 149 cases and 146 controls, frequency matched for age and gender. Endothelial function was measured by using the technique of flow-mediated dilation of the brachial artery, and alterations in arterial flow were recorded in response to an ischemic stimulus.

RESULTS

There was a significant structural alteration in the vasculature among individuals with Perthes disease (resting brachial artery diameter (cases 2.97 mm versus controls 3.11 mm; P = .01), which remained even after adjusting for height. In addition, there was a notable reduction in blood velocity (cases 33.84 cm/s versus controls 37.83 cm/s; P = .01) and blood flow (cases 149.82 mL/min versus controls 184.67 mL/min; P = .001), which was independent of baseline arterial size. There was no evidence to suggest that flow-mediated dilation of the brachial artery was impaired among affected individuals (P = .71).

CONCLUSIONS

Children with Perthes disease exhibit small artery caliber and reduced function, which is independent of body composition. These data imply that that Perthes disease may reflect a wider vascular phenomenon that could have long-term implications for the vascular health of affected individuals.

Pathophysiology and new strategies for the treatment of Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease is a juvenile form of idiopathic osteonecrosis of the femoral head that can lead to permanent femoral head deformity and premature osteoarthritis. According to two recent multicenter, prospective cohort studies, current nonoperative and operative treatments have modest success rates of producing a good outcome with a spherical femoral head in older children with Legg-Calvé-Perthes disease. Experimental studies have revealed that the immature femoral head is mechanically weakened following ischemic necrosis. Increased bone resorption and delayed new bone formation, in combination with continued mechanical loading of the hip, contribute to the pathogenesis of the femoral head deformity. Biological treatment strategies to improve the healing process by decreasing bone resorption and stimulating bone formation appear promising in nonhuman preclinical studies.

The epidemiology and demographics of legg-calvé-perthes' disease

The etiology of Legg-Calvé-Perthes' disease (LCPD) is unknown. There are many insights however from epidemiologic/demographic information. A systematic medical literature review regarding LCPD was performed. The incidence ranges from 0.4/100,000 to 29.0/100,000 children <15 years of age. There is significant variability in incidence within racial groups and is frequently higher in lower socioeconomic classes. The typical age at presentation ranges from 4 to 8 years (average 6.5 years), except for children from the Indian subcontinent (average 9.5 years). There is a mild familial component. The children demonstrate impaired growth in height, skeletal age, and birth weight. This impaired growth coincides with an age appropriate reduced somatomedin A activity and decreased levels of IGF. LCPD can be associated with abnormalities in the coagulation cascade, including an increase in factor V Leiden mutation, low levels of protein C and/or S, and decreased antithrombin activity. There is decreased turnover in type I collagen and synthesis of type III collagen, as well as reduced levels of urinary glycosaminoglycans in the active phases of the disorder. Subtle abnormalities in the opposite hip and other minor/major congenital defects are reported. Children with LCPD are active and score abnormally in certain standardized psychological tests.

The epidemiology and etiology of Perthes disease

The incidence of Perthes disease varies markedly both between countries and within countries down to a local level. The disease is more common in white than in Asian or black African children. The disease is associated with deprivation; with a steep disease gradient across social class groups. This epidemiology alongside the lack of concordance in twins suggests a strong environmental etiology, with little evidence to suggest a genetic predisposition. Children are frequently short, with a growth pattern described as "rostral-sparing". A propensity to associated congenital anomalies suggests an intrauterine cause.

Ischial spine sign reveals acetabular retroversion in Legg-Calvé-Perthes disease

BACKGROUND

Acetabular retroversion has been identified in mature patients with sequelae of Legg-Calvé-Perthes (LCP) disease. Whether this is a contributing etiologic factor that leads to the disease process or result of the head deformity is not known. The prominence of the ischial spine (PRIS) sign, which reflects retroversion, can be observed before ossification of the anterior and posterior walls in a skeletally immature patient and could help determine whether the retroverted acetabulum is present before or after head involvement in patients with LCP disease.

QUESTIONS/PURPOSE

We therefore determined (1) the prevalence of the PRIS sign in patients with LCP disease compared with healthy control subjects, (2) whether the PRIS sign is seen at the time of head involvement in patients with LCP disease, and (3) the prevalence of bilaterality of the PRIS sign in patients with LCP disease and control subjects.

PATIENTS AND METHODS

Of 295 patients with LCP disease, 47 (49 hips) met our inclusion criteria. Of these, 39 (41 hips) had open triradiate cartilage and comprised the study group. Twenty-five pediatric patients with polytrauma (50 hips) with standardized radiographs comprised the control group.

RESULTS

A positive PRIS sign was noted in 37 of the 41 skeletally immature hips compared with only 16 of the 50 control hips. We observed a positive PRIS sign early in the LCP disease process with eight of nine patients in the fragmentation phase having a positive PRIS sign. The PRIS sign was seen bilaterally in 25 of 39 patients with unilateral LCP disease and in only five of 25 control patients.

CONCLUSIONS

Acetabular retroversion, as evidenced by a positive PRIS, was present in nine of 10 children with LCP disease. It is uncertain if retroversion is a cause or a sequela of the disease, but it was seen early in the disease process at the time of head involvement in the majority of patients.

LEVEL OF EVIDENCE

Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Legg-Calve-Perthes disease and risks for cardiovascular diseases and blood diseases

OBJECTIVE

We hypothesized that patients with Legg-Calvé-Perthes disease (LCPD) might have higher risks of cardiovascular and blood diseases.

METHODS

A total of 3141 patients, 2 to 15 years of age, with LCPD diagnosed between 1965 and 2005 were identified with the Swedish Inpatient Register. A total of 15 595 individuals without LCPD were selected randomly from among the Swedish general population, with matching according to year of birth, age, gender, and region of residence. Cox proportional-hazard regression analyses, with adjustment for socioeconomic index, were used to estimate relative risks. The patients also were compared with their same-gender siblings.

RESULTS

Patients with LCPD had a hazard ratio (HR) of 1.70 (95% confidence interval [CI]: 1.39-2.09) for cardiovascular diseases, compared with individuals without LCPD. The point estimate was slightly higher among subjects >30 years of age at the follow-up (HR: 2.10 [95% CI: 1.52-2.91]). There were statistically significantly higher risks for blood diseases, including anemias and coagulation defects (HR: 1.41 [95% CI: 1.07-1.86]), which were more pronounced among subjects >30 years of age at the follow-up (HR: 2.70 [95% CI: 1.50-4.84]). Patients also had statistically significantly higher risks of hypertensive disease (HR: 2.97 [95% CI: 1.87-4.72]) and nutritional anemia (HR: 2.92 [95% CI: 1.58-5.40]). Analyses using siblings as the comparison group showed consistent results for cardiovascular diseases.

CONCLUSION

The results are consistent with the hypothesis that an insufficient blood supply to the femoral head, attributable to vascular pathologic conditions, is involved in the pathogenesis of LCPD.

From the American Academy of Pediatrics: Technical report--Secondhand and prenatal tobacco smoke exposure

Secondhand tobacco smoke (SHS) exposure of children and their families causes significant morbidity and mortality. In their personal and professional roles, pediatricians have many opportunities to advocate for elimination of SHS exposure of children, to counsel tobacco users to quit, and to counsel children never to start. This report discusses the harms of tobacco use and SHS exposure, the extent and costs of tobacco use and SHS exposure, and the evidence that supports counseling and other clinical interventions in the cycle of tobacco use. Recommendations for future research, policy, and clinical practice change are discussed. To improve understanding and provide support for these activities, the harms of SHS exposure are discussed, effective ways to eliminate or reduce SHS exposure are presented, and policies that support a smoke-free environment are outlined.