Bone disease in pediatric rheumatologic disorders

Aqua-Plyometric Exercises-Induced Changes in Muscle Strength, Bone Mineral Properties, and Physical Fitness in Patients With Juvenile Idiopathic Arthritis: A 12-Week, Randomized Controlled Trial

PURPOSE

To determine whether a 12-week, lower body-targeted aqua-plyometric (AquaPlyo) exercise program could improve muscle strength, bone mineral properties, and physical fitness in patients with juvenile idiopathic arthritis.

METHODS

A randomized controlled trial was adopted and included 48 patients with polyarticular juvenile idiopathic arthritis (age: 12-18 y). Patients were assigned to undergo either AquaPlyo exercises (AquaPlyo group, n = 24) or standard exercises (control group, n = 24). The outcome measures were assessed pretreatment and posttreatment and included concentric quadriceps peak torque, bone mineral properties (areal bone mineral density [BMD], volumetric BMD, bone mineral content, and BMD Z score), and physical fitness.

RESULTS

A significant posttreatment increase in the concentric quadriceps peak torque was detected in the AquaPlyo group compared with the control group (either at an angular velocity of 90°/s [right side: P = .016, left side: P = .025] or 180°/s [right side: P = .007, left side: P = .029]). Besides, a considerably greater improvement in the areal BMD (P = .0006), volumetric BMD (P = .027), bone mineral content (P = .002), and BMD Z score (P = .0004) was observed in the AquaPlyo group. Moreover, a remarkably greater rise in the physical fitness (P < .001) was revealed in the AquaPlyo group.

CONCLUSION

AquaPlyo training can efficiently enhance muscle strength, improve bone mineral properties, and boost physical fitness in patients with juvenile idiopathic arthritis.

Assessing the risks of children with preoperative comorbidities undergoing comminuted fracture surgery

Introduction

Comminuted fractures are characterized by bones broken in at least two places, destabilizing the bone and requiring surgery. Children whose bones are still developing and maturing tend to have a higher risk of sustaining comminuted fractures as the result of trauma. Trauma is a major cause of death in children and constitutes a major issue in orthopedics because of the unique properties of children's bones compared to adult bones and the associated complications.

Methods

This retrospective, cross-sectional study aimed to refine the association between comorbid disease and comminuted fractures in pediatric subjects using a large, national database. All data were extracted from the National Inpatient Sample (NIS) database from 2005 to 2018. Logistic regression analysis was used to evaluate associations between comorbidities and comminuted fracture surgery and between various comorbidities and LOS or unfavorable discharge.

Results

A total of 2,356,483 patients diagnosed with comminuted fractures were selected initially, of whom 101,032 patients aged younger than 18 years who underwent surgery for comminuted fractures were included. Study results suggest that patients with any comorbidities undergoing orthopedic surgery for comminuted fracture appear to have longer LOS and a higher proportion of discharge to long-term care facilities.

Discussion

Almost all comorbidities were significantly associated with poor in-hospital outcomes and longer LOS. The analysis of comminuted fractures in children may provide useful information to help first responders and medical personnel evaluate and manage comminuted fractures appropriately.

Broad application prospects of bone turnover markers in pediatrics

BACKGROUND

Bone turnover markers (BTMs) have been studied for application in clinical medicine. However, BTMs in children are challenging, and few studies explore these BTMs in children. The application of BTMs is complicated mainly due to pre-analytical factors, variable reference intervals of age- and sex-related BTMs for adolescents and children in different regions and laboratories. Therefore, laboratory testing of BTMs is critical for understanding pediatric bone development and metabolism, which provides additional information about bone development and diseases.

METHODS

Literature search was conducted using the MeSH term "child" combined with the terms that bone turnover markers such as "osteocalcin," "Procollagen type I N-terminal propeptide," "procollagen type I C-terminal propeptide," "osteocalcin," "N-terminal cross-linked telopeptide," and "C-terminal cross-linked telopeptide," Several databases including Web of Science, Google Scholar, and PubMed were searched to obtain the relevant studies.

RESULTS

BTMs represent the combined effects of skeletal development, growth, and remodeling in children, which can be used in clinical pediatrics to assist in the diagnosis and prognosis of bone metabolic disorders.

CONCLUSION

BTMs are clearly helpful for diagnosis and monitoring of bone growth and development as well as bone metabolic disorders.

Bone health in idiopathic inflammatory myopathies

OBJECTIVE

To review the extant literature relating to bone health in the idiopathic inflammatory myopathies (IIM) including both adult and juvenile patients.

METHODS

A PubMed search® identified relevant studies from 1966 to 2020 in accordance with PRISMA guidelines. Two independent reviewers screened and extracted the abstracts/full manuscripts, and a third author was consulted in the case of disagreement.

RESULTS

We identified 37 articles (3 review articles, 2 RCTs, 9 cross-sectional, 16 cohort and 7 case-control studies). The prevalence of osteopenia (n = 7) ranges from 7 to 75% and osteoporosis (n = 7) between 13% to 27%. The prevalence of vertebral fractures ranged from 11 to 75%. Systemic inflammation likely contributes to reduced bone mineral density (BMD) in children with IIM but data is currently lacking in adult patients. Association between with impaired BMD and Vitamin D or calcium intake and physical activity has not been demonstrated in IIM. There is no clear consensus regarding the impact of age, menopause or BMI on bone health. Gender, smoking status, disease activity and inflammatory markers are not obvious independent predictors of low BMD. Several studies have demonstrated that glucocorticoids are associated with an increased risk of low BMD. There are no specific guidelines relating to the management of bone health in adult and juvenile patients with IIM.

CONCLUSION

Both adult and juvenile patients with IIM are at high risk of impaired bone health and fracture. The mechanisms behind this are likely multifactorial including systemic inflammation, glucocorticoid treatment, reduced mobility and impaired calcium/vitamin D homeostasis. There are a lack of guidelines and studies relating to the screening, prevention and treatment of impaired bone health in adult and juvenile patients with IIM. Future research is required to understand the complexity of bone health in IIM including to develop much needed disease-specific management recommendations.

No radiographic wrist damage after treatment to target in recent-onset juvenile idiopathic arthritis

BACKGROUND

To evaluate radiographic progression of patients with new-onset juvenile idiopathic arthritis (JIA) in response to an early, tightly-controlled, treatment-to-target.

METHODS

Patients with JIA participating in the BeSt-for-Kids-study, randomized to 3 treatment strategy arms, were eligible if at least 1 conventional wrist-radiograph was available. Bone damage as reflected by carpal length was assessed using the Poznanski-score. The BoneXpert-method was used to determine the Bone Age (BA, > 5 years) and bone mineral density (BMD) of the wrist. These scores were evaluated over time and compared between the treatment arms and mean JADAS10-score using linear mixed models corrected for age and symptom duration.

RESULTS

In 60 patients, 252 radiographs were analysed. Baseline age and symptom duration were different between the arms. No difference in comparison to the healthy reference population was found at baseline for the Poznanski-score (IQR varying from - 0,82; 0.68), nor for BA (varying from - 0.88 to 0.74). Baseline BMD was statistically significantly lower in arm 3 (initial treatment with etanercept and methotrexate) (- 1.48; - 0.68) compared to arm 1 (- 0.84; - 0.04) and arm 2 (- 0.93; 0.15). After treatment to target inactive disease, the Poznanski-scores and the BA remained clinically unchanged, while the BMD in arm 3 improved (p < 0.05 vs arm 1).

CONCLUSIONS

Recent-onset JIA patients, treated-to-target aimed at inactive disease, showed no signs of radiographic wrist damage (Poznanski-score, BA or BMD) either at baseline or at follow-up, irrespective of treatment arm. A lower BMD at baseline in arm 3, initially treated with methotrexate and etanercept, improved significantly after treatment.

TRIAL REGISTRATION

NTR, NL1504 (NTR1574). Registered 01-06-2009.

[Fractures and bone mineral density in childhood]

BACKGROUND

In juvenile idiopathic arthritis and related chronic inflammatory diseases, proinflammatory cytokines inhibit bone formation and stimulate bone resorption. Anti-inflammatory drugs, such as glucocorticoids and nonsteroidal antirheumatic drugs (NSARD) have as a side effect the potential to inhibit growth and maintenance of bone. These issues are of particular importance for the growing skeleton in childhood and adolescence.

OBJECTIVE

This article presents a narrative overview about the dimension of the problem, a critical evaluation of diagnostic procedures and a discussion of available countermeasures.

METHODS

A systematic literature search was carried out and the available evidence was evaluated based on the authors' knowledge and clinical experience as experts in the field.

RESULTS AND CONCLUSION

In recent years solid data have been accumulated with respect to the interpretation of bone mineral density (BMD) measurements in children and adolescents. Based on these data from the literature and given that the radiation exposure is also very low, it is now possible to clinically apply BMD measurements in this population using dual energy X‑ray absorption (DXA) technology for risk evaluation and diagnosis, taking the respective phase of development and body length into consideration. Dynamic measurements over time appear to be especially valuable in the context of individual clinical data. Hence, BMD measurements can be helpful in monitoring bone health, especially in juvenile idiopathic arthritis and other related inflammatory diseases. Apart from the specific indications for extended diagnostics and bone targeted pharmacological treatment, this method can also contribute to the management of preventive measures, such as sufficient calcium and vitamin D intake and targeted exercise interventions. Even in times of extremely effective antirheumatic drugs, children with chronic inflammatory diseases still bear a risk for bone health.

Feasibility and safety of a 6-month exercise program to increase bone and muscle strength in children with juvenile idiopathic arthritis

BACKGROUND

Arthritis in childhood can be associated with muscle weakness around affected joints, low bone mass and low bone strength. Exercise is recognized as an important part of management of children with juvenile idiopathic arthritis (JIA) but the exercise prescription to best promote bone and muscle health is unknown. We therefore aimed to: 1. assess feasibility and safety of a 6-month home- and group-based exercise program for children with JIA; 2. estimate the effect of program participation on bone mass and strength, muscle function and clinical outcomes and 3. determine if any positive changes in bone and muscle outcomes are maintained 6 months later.

METHODS

We recruited 24 children with JIA who were part of the Linking Exercise, Physical Activity and Pathophysiology in Childhood Arthritis (LEAP) study to participate in a 6-month home-based exercise program involving jumping and handgrip exercises, resistance training and one group exercise session per month. We assessed lumbar spine bone mass (dual energy X-ray absorptiometry), distal tibia and radius bone microarchitecture and strength (high-resolution peripheral quantitative computed tomography), muscle function (jumping mechanography, dynamometry) and clinical outcomes (joint assessment, function, health-related quality of life) at baseline, 6- and 12-months. Adherence was assessed using weekly activity logs.

RESULTS

Thirteen children completed the 6-month intervention. Participants reported 9 adverse events and post-exercise pain was rare (0.4%). Fatigue improved, but there were no other sustained improvements in muscle, bone or clinical outcomes. Adherence to the exercise program was low (47%) and decreased over time.

CONCLUSION

Children with JIA safely participated in a home-based exercise program designed to enhance muscle and bone strength. Fatigue improved, which may in turn facilitate physical activity participation. Prescribed exercise posed adherence challenges and efforts are needed to address facilitators and barriers to participation in and adherence to exercise programs among children with JIA.

TRIAL REGISTRATION

Data of the children with JIA are from the LEAP study (Canadian Institutes of Health Research (CIHR; GRANT# 107535 ). http://www.leapjia.com/.

A randomized double-blind placebo-controlled trial of vitamin D supplementation in juvenile-onset systemic lupus erythematosus: positive effect on trabecular microarchitecture using HR-pQCT

In this randomized double-blind placebo-controlled 24-week trial, cholecalciferol supplementation at 50,000 IU/week effectively improved bone microarchitecture parameters in juvenile-onset systemic lupus erythematosus (JoSLE) patients, as assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) at tibia site. An increase in the trabecular number and a decrease in the trabecular separation were observed, suggesting that vitamin D supplementation may be recommended for JoSLE patients with its deficiency.

INTRODUCTION

Vitamin D has an important effect on bone but there are no trials that directly address the boosting of serum levels of 25-hydroxyvitamin D (25OHD) in bone microarchitecture in JoSLE patients. The aim of this study was to evaluate the effect of vitamin D supplementation on bone microarchitecture parameters using HR-pQCT in JoSLE patients.

METHODS

This study was a randomized double-blind placebo-controlled 24-week trial. Forty female JoSLE patients were randomized (1:1) to receive oral cholecalciferol at 50,000 IU/week (JoSLE-VitD) or placebo (JoSLE-PL). The medications remained stable throughout the study. Serum levels of 25OHD were measured using a radioimmunoassay. The bone microarchitecture and volumetric bone density were analyzed using HR-pQCT at tibia site.

RESULTS

At baseline, the groups were similar with respect to their age, body mass index, organ involvement, glucocorticoid dose, immunosuppressant use, serum 25OHD levels, and HR-pQCT parameters. After 24 weeks, higher 25OHD levels were observed in the JoSLE-VitD group compared to the JoSLE-PL group [31.3 (8.6) vs. 16.5 (5.8) ng/mL, p < 0.001]. An increase in the trabecular number [∆Tb.N 0.16 (0.24) vs. 0.03 (0.19) 1/mm, p = 0.024] and a decrease in the trabecular separation [∆ThSp -0.045 (0.067) vs. 0.001 (0.009) mm, p = 0.017] were found in the JoSLE-VitD group compared to the JoSLE-PL group at tibia site. No differences were observed in other structural parameters [trabecular (Tb.Th) or cortical thickness (Ct.Th)], volumetric bone mineral densities, cortical porosity, and biomechanical parameters (p > 0.05).

CONCLUSION

This study suggests that cholecalciferol supplementation for 24 weeks effectively improved the bone microarchitecture parameters, mainly the trabecular number, in JoSLE patients.

TRIAL REGISTRATION

NCT01892748.

Bone impairment assessed by HR-pQCT in juvenile-onset systemic lupus erythematosus

High-resolution peripheral quantitative computed tomography (HR-pQCT) analysis of female juvenile-onset systemic lupus erythematosus (JoSLE) patients revealed trabecular/cortical bone damage and reduced bone strength primarily at the distal radius compared to healthy controls. We demonstrated for the first time that JoSLE patients with vertebral fracture (VF) present trabecular impairment at the distal radius.

INTRODUCTION

This study investigated the volumetric bone mineral density (vBMD), microarchitecture, and biomechanical features at the distal radius and tibia using HR-pQCT and laboratory bone markers in JoSLE patients compared to controls to determine whether this method discriminates JoSLE patients with or without VF.

METHODS

We compared 56 female JoSLE patients to age- and Tanner-matched healthy controls. HR-pQCT was performed at the distal radius and tibia. Serum levels of the amino-terminal pro-peptide of type I collagen, the C-terminal telopeptide of type I collagen, intact parathormone, sclerostin, and 25-hydroxyvitamin D (25OHD) were evaluated. VFs were analyzed using VFA-dual-energy X-ray absorptiometry (DXA) (Genant's method).

RESULTS

Reduced density and strength parameters and microarchitecture alterations of cortical and trabecular bones were observed in JoSLE patients compared to controls, primarily at the distal radius (p < 0.05). Patients with VF exhibited a significant decrease in trabecular bone parameters solely at the distal radius (Total.BMD, p = 0.034; Trabecular.BMD [Tb.BMD], p = 0.034; bone volume (BV)/trabecular volume (TV), p = 0.034; apparent modulus, p = 0.039) and higher scores for disease damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR-DI), p = 0.002). Bone metabolism markers were similar in all groups. Logistic regression analysis of parameters that were significant in univariate analysis revealed that Tb.BMD (OR 0.98, 95 % CI 0.95-0.99, p = 0.039) and SLICC/ACR-DI (OR 7.37, 95 % CI 1.75-30.97, p = 0.006) were independent risk factors for VF.

CONCLUSION

In conclusion, this study is the first demonstration of bone microstructure and strength deficits in JoSLE patients, particularly at the distal radius. Our results demonstrated that VF was associated with trabecular radius alteration and emphasized the potential detrimental effect of disease damage on this condition.

Pubertal induction in hypogonadism: Current approaches including use of gonadotrophins

Primary disorders of the gonad or those secondary to abnormalities of the hypothalamic pituitary axis result in hypogonadism. The range of health problems of childhood and adolescence that affect this axis has increased, as most children now survive chronic illness, but many have persisting deficits in gonadal function as a result of their underlying condition or its treatment. An integrated approach to hormone replacement is needed to optimize adult hormonal and bone health, and to offer opportunities for fertility induction and preservation that were not considered possible in the past. Timing of presentation ranges from birth, with disorders of sexual development, through adolescent pubertal failure, to adult fertility problems. This review addresses diagnosis and management of hypogonadism and focuses on new management strategies to address current concerns with fertility preservation. These include Turner syndrome, and fertility presevation prior to childhood cancer treatment. New strategies for male hormone replacement therapy that may impinge upon future fertility are emphasized.

An experimental therapy to improve skeletal growth and prevent bone loss in a mouse model overexpressing IL-6

Premature osteoporosis and stunted growth are common complications of childhood chronic inflammatory disease. Presently, no treatment regimens are available for these defects in juvenile diseases. We identified the sequential Fc-OPG/hPTH treatment as an experimental therapy that improves the skeletal growth and prevents the bone loss in a mouse model overexpressing IL-6.

INTRODUCTION

Premature osteoporosis and stunted growth are common complications of childhood chronic inflammatory diseases and have a significant impact on patients' quality of life. Presently, no treatment regimens are available for these defects in juvenile diseases. To test a new therapeutic approach, we used growing mice overexpressing the pro-inflammatory cytokine IL-6 (TG), which show a generalized bone loss and stunted growth.

METHODS

Since TG mice present increased bone resorption and impaired bone formation, we tested a combined therapy with the antiresorptive modified osteoprotegerin, Fc-OPG, and the anabolic PTH. We injected TG mice with Fc-OPG once at the 4th day of life and with hPTH(1-34) everyday from the 16th to the 30th day of age.

RESULTS

A complete prevention of growth and bone defects was observed in treated mice due to normalization of osteoclast and osteoblast parameters. Re-establishment of normal bone turnover was confirmed by RT-PCR analysis and by in vitro experiments that revealed the full rescue of osteoclast and osteoblast functions. The phenotypic recovery of TG mice was due to the sequential treatment, because TG mice treated with Fc-OPG or hPTH alone showed an increase of body weight, tibia length, and bone volume to intermediate levels between those observed in vehicle-treated WT and TG mice.

CONCLUSIONS

Our results identified the sequential Fc-OPG/hPTH treatment as an experimental therapy that improves the skeletal growth and prevents the bone loss in IL-6 overexpressing mice, thus providing the proof of principle for a therapeutic approach to correct these defects in juvenile inflammatory diseases.

Proline/arginine-rich end leucine-rich repeat protein N-terminus is a novel osteoclast antagonist that counteracts bone loss

(hbd) PRELP is a peptide corresponding to the N-terminal heparin binding domain of the matrix protein proline/arginine-rich end leucine-rich repeat protein (PRELP). (hbd) PRELP inhibits osteoclastogenesis entering pre-fusion osteoclasts through a chondroitin sulfate- and annexin 2-dependent mechanism and reducing the nuclear factor-κB transcription factor activity. In this work, we hypothesized that (hbd) PRELP could have a pharmacological relevance, counteracting bone loss in a variety of in vivo models of bone diseases induced by exacerbated osteoclast activity. In healthy mice, we demonstrated that the peptide targeted the bone and increased trabecular bone mass over basal level. In mice treated with retinoic acid to induce an acute increase of osteoclast formation, the peptide consistently antagonized osteoclastogenesis and prevented the increase of the serum levels of the osteoclast-specific marker tartrate-resistant acid phosphatase. In ovariectomized mice, in which osteoclast activity was chronically enhanced by estrogen deficiency, (hbd) PRELP counteracted exacerbated osteoclast activity and bone loss. In mice carrying osteolytic bone metastases, in which osteoclastogenesis and bone resorption were enhanced by tumor cell-derived factors, (hbd) PRELP reduced the incidence of osteolytic lesions, both preventively and curatively, with mechanisms involving impaired tumor cell homing to bone and tumor growth in the bone microenvironment. Interestingly, in tumor-bearing mice, (hbd) PRELP also inhibited breast tumor growth in orthotopic sites and development of metastatic disease in visceral organs, reducing cachexia and improving survival especially when administered preventively. (hbd) PRELP was retained in the tumor tissue and appeared to affect tumor growth by interacting with the microenvironment rather than by directly affecting the tumor cells. Because safety studies and high-dose treatments revealed no adverse effects, (hbd) PRELP could be employed as a novel biological agent to combat experimentally induced bone loss and breast cancer metastases, with a potential translational impact.

Physical activity, physical fitness, and exercise therapy in children with juvenile idiopathic arthritis

Arthritis in childhood can be associated with low levels of physical activity and poor physical fitness. Children with arthritis may have decreased aerobic and anaerobic fitness, muscle weakness, low bone mass, and low bone strength. Suboptimal physical activity and exercise capacity may contribute to further deconditioning and disability, placing children with arthritis at risk for poor health outcomes. Recent studies suggest that exercise therapy is safe and does not worsen arthritis. Exercise therapy may improve function, quality of life, and physical fitness. However, little is known about the exercise prescription that is most effective to improve clinical outcomes in children with arthritis. This article reviews the current literature on physical activity, physical fitness, and exercise therapy in children with juvenile idiopathic arthritis.

Drosophila growth and development: keeping things in proportion

Comment on: Colombani J, et al. Science 2012; 336:582-5.

The thoracic and lumbar spine in severe juvenile idiopathic arthritis: magnetic resonance imaging analysis in 50 children

OBJECTIVE

To determine the prevalence of vertebral fractures as a complication of juvenile idiopathic arthritis (JIA).

STUDY DESIGN

This cross-sectional study evaluated the prevalence and characteristics of spinal abnormalities in 50 children (aged 7.0-18.7 years) with treatment-resistant JIA by magnetic resonance imaging. Vertebral deformities, endplate irregularities, intervertebral disc involvement, spinal canal, neural foramina, and back muscles were analyzed and correlated with clinical characteristics and bone mineral density.

RESULTS

Magnetic resonance imaging revealed various abnormalities in 31 patients (62%). Vertebral compression was seen in 28%, disc degeneration in 46%, protrusions in 14%, prolapses in 4%, endplate changes in 26%, and anterior vertebral corner lesions in 16%. Two patients (4%) had mild spinal canal narrowing without medullar involvement; none had neural root compression. Six patients (12%) had mild back muscle atrophy. No correlation was observed between spinal fractures or other vertebral changes and disease activity or duration, pain or bone mineral density; patients with spinal fractures tended to have a higher recent glucocorticoid exposure (P=.086).

CONCLUSION

Children with severe JIA have a high prevalence of compression fractures and other vertebral, endplate, and disc abnormalities in the thoracic and lumbar spine.

Body composition abnormalities in long-term survivors of pediatric hematopoietic stem cell transplantation

OBJECTIVE

To quantify lean mass (LM) and fat mass (FM) in survivors of childhood allogeneic hematopoietic stem-cell transplantation (alloHSCT) compared with healthy reference participants and identify risk factors for body composition abnormalities.

STUDY DESIGN

Whole body LM and FM were measured with dual energy x-ray absorptiometry in 54 survivors (ages 5-25 years) and 894 healthy reference participants in a cross-sectional study. Multivariate regression models were used to compare sex- and race-specific Z-scores for LM for height (LM-Ht) and FM for height (FM-Ht) in survivors and reference participants and to identify correlates of LM-Ht and FM-Ht Z-scores in alloHSCT.

RESULTS

Height Z-scores were significantly lower in alloHSCT survivors (P < .001) compared with reference participants; body mass index Z-scores did not differ (P = .13). Survivors had significantly lower mean LM-Ht Z-scores (-0.72; 95% CI, -1.02--0.42; P < .001) and greater FM-Ht Z-scores (1.10; 95% CI, 0.84-1.39; P < .001) compared with reference participants. LM-Ht Z-score deficits in alloHSCT survivors were larger (-1.26; 95% CI, -1.53--0.99; P < .001) after adjustment for FM-Ht Z-scores. Endocrinopathies and alloHSCT characteristics were not associated with LM-Ht or FM-Ht Z-scores.

CONCLUSION

Survivors of childhood alloHSCT have significant LM deficits and FM excess. Future studies should identify the mechanism and consequences of these abnormalities.

Prevalence of vertebral compression fractures and associated factors in children and adolescents with severe juvenile idiopathic arthritis

OBJECTIVE

Vertebral fractures occur in patients with juvenile idiopathic arthritis (JIA), but data on their frequency and causes are scarce. Our cross-sectional study evaluated prevalence of compression fractures and associated factors in a high-risk pediatric population with severe JIA.

METHODS

Children and adolescents with a history of treatment-resistant polyarticular-course JIA for ≥ 5 years or systemic arthritis for ≥ 3 years were recruited. Clinical examination, dietary recall, laboratory measurements, bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry, and spinal radiography were performed.

RESULTS

Our study included 50 patients (41 girls), of whom 6 (12%) had systemic arthritis, with a median age of 14.8 years (range 7.0-18.7 yrs) and median disease duration of 10.2 years (range 3.9-16.8 years). Ninety-four percent had used systemic glucocorticoids (GC); the median total duration of GC treatment was 7.1 years (range 0-15.5 yrs). The median weight-adjusted cumulative GC dose for the preceding 3 years was 72 mg/kg (range 0-911 mg/kg). The median bone age-corrected lumbar spine and whole-body areal BMD Z-scores were -0.8 and -1.0, respectively. Twenty-two percent had vertebral fractures, mostly thoracic. Compression fractures were associated with high disease activity, high body mass index (BMI), and high recent cumulative GC dose, but not with disease duration or BMD. Thirty percent had sustained at least 1 peripheral low energy fracture. Twenty-six percent were deemed to have significantly compromised bone health.

CONCLUSION

Severe JIA is associated with a significant risk of vertebral compression fractures. Associated factors include high disease activity, high BMI, and high recent GC exposure. Further studies are needed to establish optimal prevention and treatment guidelines.

[Bone density measurements on growing skeletons and the clinical consequences]

The measurement of bone mineral density (BMD) was established to judge the fracture risk in an individual. The most commonly used densitometric technique DXA is a two-dimensional method and reports BMD (bone mass/projection area), which increases during growth. Bone mineral density (in g/cm(3)), however, is almost stable and does not change with age or height. To analyze the data special pediatric references including data on age, sex and ethnicity are necessary as well as correction for height. Bone forms a unit with muscle. Bone responds to mechanical loading with increase in bone size and therefore adapts to the biomechanical needs. Therefore, interpretation of bone development data requires data on muscle development.The indication for bone mineral density measurement and result reporting should be made by and together with a pediatric specialist. The diagnosis of osteoporosis should not be made based solely on densitometric measurements. History of low trauma fracture is an important aspect for the definition. Besides DXA there exist further methods with advantages and disadvantages.

[Analysis of risk factors for low bone mineral density in patients with inflammatory bowel disease]

BACKGROUND/AIMS

Several clinical risk factors for low bone mineral density (BMD) in the patients with inflammatory bowel disease (IBD) have been suggested. However, its prevalence and pathophysiology in Korean population have not been fully studied. The aim of this study was to investigate the prevalence and risk factors for low BMD in Korean IBD patient.

METHODS

BMD of the lumbar spine and femur was evaluated using dual-energy X-ray absorptiometry in 30 patients with IBD. Biochemical parameters of bone metabolism, such as serum calcium, phosphorus, osteocalcin, and deoxypyridinoline were measured. The associations between low BMD and clinical parameters such as disease duration, disease activity, drug history, body mass index (BMI), and others were evaluated retrospectively using medical records.

RESULTS

Low BMD at the lumbar spine or femur was observed in 63.3% of the patients, and there was no significant difference between the patients with Crohns disease and ulcerative colitis. Clinical and biochemical parameters were irrelevant to BMD. In the patients without glucocorticoid treatment prior to BMD measurement, already 50.0% of patients had low BMD.

CONCLUSIONS

Low BMD is a common feature in Korean IBD patients, even those who do not use glucocorticoid. The multiple factors may be involved in the pathogenesis of low BMD. Therefore, BMD should be examined in all IBD patients, irrespective of glucocorticoid treatment.

Bone marrow microenvironment controls the in vivo differentiation of murine dendritic cells into osteoclasts

Finding that activated T cells control osteoclast (OCL) differentiation has revealed the importance of the interactions between immune and bone cells. Dendritic cells (DCs) are responsible for T-cell activation and share common precursors with OCLs. Here we show that DCs participate in bone resorption more directly than simply through T-cell activation. We show that, among the splenic DC subsets, the conventional DCs have the higher osteoclastogenic potential in vitro. We demonstrate that conventional DCs differentiate into functional OCLs in vivo when injected into osteopetrotic oc/oc mice defective in OCL resorptive function. Moreover, this differentiation involves the presence of activated CD4+ T cells controlling a high RANK-L expression by bone marrow stromal cells. Our results open new insights in the differentiation of OCLs and DCs and offer new basis for analyzing the relations between bone and immune systems.

Bone density, structure, and strength in juvenile idiopathic arthritis: importance of disease severity and muscle deficits

OBJECTIVE

To identify determinants of musculoskeletal deficits (muscle cross-sectional area [mCSA], trabecular volumetric bone mineral density [vBMD], and cortical bone strength [section modulus]) in patients with juvenile idiopathic arthritis (JIA) and to determine if cortical bone strength is appropriately adapted to muscle forces.

METHODS

Peripheral quantitative computed tomography (pQCT) of the tibia was performed in 101 patients with JIA (79% female; 24 with oligoarticular JIA, 40 with polyarticular JIA, 18 with systemic JIA, and 19 with spondylarthritis [SpA]) and 830 healthy control subjects; all were ages 5-22 years. Outcomes of pQCT were expressed as sex- and race-specific Z scores. Multivariable linear regression models assessed mCSA and bone status in JIA patients compared with controls and identified factors associated with musculoskeletal deficits in JIA.

RESULTS

The median duration of JIA was 40 months; 29% of the JIA patients had active arthritis, and 28% had received glucocorticoid therapy during the previous year. Compared with the controls, the mCSA and section modulus Z scores were significantly lower in patients with polyarticular JIA and those with SpA. Trabecular vBMD Z scores were significantly lower in patients with polyarticular JIA, those with systemic JIA, and those with SpA. Significant predictors of musculoskeletal deficits included active arthritis in the previous 6 months (mCSA), temporomandibular joint disease (mCSA and section modulus), functional disability (mCSA and vBMD), short stature (vBMD), infliximab exposure (vBMD), and JIA duration (section modulus). The section modulus was significantly reduced relative to mCSA in patients with JIA after adjustment for age and limb length.

CONCLUSION

Marked deficits in vBMD and bone strength occur in JIA in association with severe and longstanding disease. Contrary to the findings of previous studies, bone deficits were greater than expected relative to the mCSA, which illustrates the importance of adjusting for age and bone length.

Chronic pediatric inflammatory diseases: effects on bone

In children, chronic inflammatory diseases present a significant challenge to long-term skeletal health. These conditions are often associated with poor appetite and suboptimal overall nutrition, altered nutrient utilization, delayed puberty, inactivity, and reduced muscle mass, all of which can alter bone metabolism. In addition, bone cell activity is susceptible to the effects of the immune response that characterizes these diseases. Moreover, drugs used to treat these maladies, notably glucocorticoids, may have negative effects on bone formation and on linear growth in developing children. As a result, predicted peak bone mass may not be achieved, and fracture risk may be increased in the short term or in the future. Studies using primarily dual energy X-ray absorptiometry have documented that deficits in bone mass are common in these diseases. However, there are wide variations in the prevalence of low bone mass, largely due to differences in the characteristics of each study population. Recent studies provide insight into the pathogenesis of decreased bone mass in these conditions. In this paper we will provide an overview of the effects of chronic inflammatory conditions on bone mass in children. We will also present relevant data from adult patients, when pediatric data are scant or not available.

Musculoskeletal abnormalities of the tibia in juvenile rheumatoid arthritis

OBJECTIVE

To characterize local bone geometry, density, and strength, using peripheral quantitative computed tomography (pQCT), compared with general bone characteristics as measured using dual x-ray absorptiometry (DXA), and to assess their relationship to disease-related factors in children with juvenile rheumatoid arthritis (JRA).

METHODS

Forty-eight children ages 4-18 years with JRA (17 pauciarticular, 23 polyarticular, 8 systemic) were compared with age-matched healthy controls (n = 266). Measurements included cortical and trabecular bone geometry, density, and strength at the distal and midshaft tibia determined by pQCT, and whole-body, lumbar spine, and femoral neck measurements by DXA.

RESULTS

Methotrexate (MTX) was prescribed to 23 of 48 patients (47.9%) and glucocorticoids and MTX were prescribed to 15 of 48 patients (31.3%), with the greatest use in children with systemic JRA. All JRA patients had decreased tibia trabecular bone density, cortical bone size and strength, and muscle mass. Children with systemic JRA had lower femoral neck densities. Systemic JRA was associated with a shorter, less mineralized skeleton, while a narrower, less mineralized skeleton was observed in polyarticular JRA. The tibia diaphysis was narrower with decreased muscle mass, but normal, size-adjusted bone mineral in all subtypes indicated a localized effect of JRA on bone. Patients exposed to glucocorticoids and MTX or to glucocorticoids or MTX alone had greatly reduced trabecular density, cortical bone geometry properties, and bone mineral content, muscle mass, and bone strength.

CONCLUSION

Children with JRA have decreased skeletal size, muscle mass, trabecular bone density, cortical bone geometry, and strength. Not surprisingly, these bone abnormalities are more pronounced in children with greater disease severity.

Glucocorticoid-induced osteoporosis in children: impact of the underlying disease

Glucocorticoids inhibit osteoblasts through multiple mechanisms, which results in significant reductions in bone formation. The growing skeleton may be especially vulnerable to adverse glucocorticoid effects on bone formation, which could possibly compromise trabecular and cortical bone accretion. Although decreased bone mineral density has been described in various pediatric disorders that require glucocorticoids, and a population-based study reported increased fracture risk in children who require >4 courses of glucocorticoids, some of the detrimental bone effects attributed to glucocorticoids may be caused by the underlying inflammatory disease. For example, inflammatory cytokines that are elevated in chronic disease, such as tumor necrosis factor alpha, suppress bone formation and promote bone resorption through mechanisms similar to glucocorticoid-induced osteoporosis. Summarized in this review are changes in bone density and dimensions during growth, the effects of glucocorticoids and cytokines on bone cells, the potential confounding effects of the underlying inflammatory-disease process, and the challenges in interpreting dual-energy x-ray absorptiometry results in children with altered growth and development in the setting of glucocorticoid therapy. Two recent studies of children treated with chronic glucocorticoids highlight the differences in the effect of underlying disease, as well as the importance of associated alterations in growth and development.

Can exercise influence low bone mineral density in children with juvenile rheumatoid arthritis?

PURPOSE

Low bone mineral density (BMD) is a common secondary condition associated with juvenile idiopathic arthritis (JIA). The purpose of this review was evaluate the literature pertinent to designing an effective, safe weight-bearing exercise program to reduce the risk of low BMD in children with JIA.

SUMMARY OF KEY POINTS

Thirty-seven articles on the risk of low BMD and children with JIA, weight-bearing interventions to improve BMD in healthy children, or safety and efficacy of exercise interventions with children with JIA were critiqued on the basis of their design. Three highly rated studies confirmed the multifactorial nature of low BMD in children with JIA, two highly rated studies support the efficacy of weight-bearing interventions for increasing BMD in children who are healthy, and one moderately rated study demonstrated the safety of low impact exercise by children with JIA.

STATEMENT OF CONCLUSIONS AND RECOMMENDATIONS FOR CLINICAL PRACTICE

Weight-bearing activities should be included in exercise programs for individuals with JIA, although more research is needed to determine the amount, duration, and frequency of weight-bearing activity needed to reduce the risk for low BMD.

Impaired skeletal development in interleukin-6-transgenic mice: a model for the impact of chronic inflammation on the growing skeletal system

OBJECTIVE

To identify the mediator responsible for the impact of chronic inflammation on skeletal development in children (bone loss, defective peak bone mass accrual, stunted growth), we evaluated the effects of chronic interleukin-6 (IL-6) overexpression on the skeletons of growing prepubertal mice.

METHODS

We studied IL-6-transgenic mice that had high circulating IL-6 levels since birth. Trabecular and cortical bone structure were analyzed by microcomputed tomography. Epiphyseal ossification, growth plates, and calvariae were studied by histology/histomorphometry. Osteoclastogenesis, osteoblast function/differentiation, and the effects of IL-6 on bone cells were studied in vitro. Osteoblast gene expression was evaluated by reverse transcriptase-polymerase chain reaction. The mineral apposition rate was evaluated dynamically in cortical bone by in vivo double fluorescence labeling.

RESULTS

In prepubertal IL-6-transgenic mice, we observed osteopenia, with severe alterations in cortical and trabecular bone microarchitecture, as well as uncoupling of bone formation from resorption, with decreased osteoblast and increased osteoclast number and activity. Increased osteoclastogenesis and reduced osteoblast activity, secondary to decreased precursor proliferation and osteoblast function, were present. IL-6-transgenic mice also showed impaired development of growth plates and epiphyseal ossification centers. Intramembranous and endochondral ossification and the mineral apposition rate were markedly affected, showing the presence of defective ossification.

CONCLUSION

Chronic overexpression of IL-6 alone induces a skeletal phenotype closely resembling growth and skeletal abnormalities observed in children with chronic inflammatory diseases, pointing to IL-6 as a pivotal mediator of the impact of chronic inflammation on postnatal skeletal development. We hypothesize that IL-6-modifying drugs may reduce skeletal defects and prevent the growth retardation associated with these diseases.

Childhood onset arthritis is associated with an increased risk of fracture: a population based study using the General Practice Research Database

BACKGROUND

Childhood onset arthritis is associated with low bone mass and strength.

OBJECTIVE

To determine whether childhood onset arthritis is associated with greater fracture risk.

METHODS

In a retrospective cohort study all subjects with onset of arthritis between 1 and 19 years of age in the United Kingdom General Practice Research Database were identified. As controls, all sex and age matched subjects from a practice that included a subject with arthritis were included. Incidence rate ratios (IRRs) for first fracture were generated using Mantel-Haenszel methods and Poisson regression.

RESULTS

1939 subjects with arthritis (51% female) and 207 072 controls (53% female) were identified. The median age at arthritis diagnosis was 10.9 years. A total of 129 (6.7%) first fractures were noted in subjects with arthritis compared with 6910 (3.3%) in controls over a median follow up of 3.90 and 3.95 years in the subjects with arthritis and controls, respectively. The IRR (95% confidence interval) for first fracture among subjects with arthritis, compared with controls, according to the age at the start of follow up were 1.49 (0.91 to 2.31) for age <10 years, 3.13 (2.21 to 4.33) at 10-15 years, 1.75 (1.18 to 2.51) at 15-20 years, 1.40 (0.91 to 2.08) at 20-45 years, and 3.97 (2.23 to 6.59) at >45 years.

CONCLUSIONS

Childhood onset arthritis is associated with a clinically significant increased risk of fracture in children, adolescents and, possibly, adults. Studies are urgently needed to characterise the determinants of structural bone abnormalities in childhood arthritis and devise prevention and treatment strategies.

A randomized clinical trial of dietary calcium to improve bone accretion in children with juvenile rheumatoid arthritis

OBJECTIVE

To examine a behavioral intervention (BI) to increase calcium intake in children with juvenile rheumatoid arthritis (JRA) on calcium intake and bone mass 6 and 12 months after treatment.

STUDY DESIGN

A randomized trial compared a 6-session BI to a 3-session enhanced standard of care (ESC) with 49 children ages 4 to 10 years with JRA. Calcium intake was assessed via 3-day diet diaries. Total body bone mineral content (BMC), arms and legs BMC, and lumbar spine bone mineral density were assessed by dual energy x-ray absorptiometry.

RESULTS

BI maintained an average calcium intake of 1500 mg/d at 6- and 12-month follow-up. This was greater than their baseline level of 972 mg/d, but not greater than the intake of 1300 mg/day maintained by ESC (P=.09). The BI had a 4% and 2.9% greater gain in total body bone mineral content than ESC at 6 and 12 months, respectively (P=.005), and a 7.1% and 5.3% greater gain in arms and legs BMC at 6 and 12 months than ESC (P=.0007).

CONCLUSIONS

BI is effective in increasing calcium intake and BMC in children with JRA over a 12-month period.

Outcome in juvenile onset systemic lupus erythematosus

PURPOSE OF REVIEW

Over the past 2 decades, there has been a marked improvement in survival among patients with juvenile-onset systemic lupus erythematosus. As a result of the increased life expectancy, children and adolescents with systemic lupus erythematosus are now faced with considerable morbidity resulting from sequelae of disease activity, side effects of medications, and comorbid conditions. This morbidity affects physical and psychosocial well-being. Therefore, the need is increasing for monitoring the development of irreversible organ damage and the effect of the disease and its treatment on daily life. This review summarizes the recent advances in the investigation on survival, accumulated damage, and health-related quality of life in patients with juvenile-onset systemic lupus erythematosus.

RECENT FINDINGS

The 5-year survival rate of patients with juvenile-onset systemic lupus erythematosus approaches 100%, and the 10-year survival rate is close to 90%. The development of cumulative organ damage has been observed in 50-60% of patients. Children and adolescents with systemic lupus erythematosus have been found to have poorer health-related quality of life, particularly in the physical domain, and lower socioeconomic achievements than their healthy peers.

SUMMARY

The prolongation of the life span of patients with juvenile-onset systemic lupus erythematosus has been accompanied by a substantial risk of damage accumulation and has not been paralleled by an improvement in health-related quality of life. This problem highlights the need of measuring cumulative organ damage and health-related quality of life in the long-term follow-up of patients with juvenile-onset systemic lupus erythematosus and of designing new treatments and treatment strategies that are aimed not only at improving control of disease activity but also at minimizing the development of nonreversible damage.

Current advances in bone health of disabled children

PURPOSE OF REVIEW

Bone health is now recognized to contribute to overall lifetime management of children, adolescents, and adults with disabling conditions including physical and intellectual disability and with many chronic disease processes. Such disorders have multiple components, with aspects of care covering a wide number of specialist practices. This review will highlight advances in understanding the nature of bone mass accumulation through childhood and adolescence, the impingement of a spectrum of chronic and disabling diseases and their treatments on bone, and will address current approaches to interpretation of bone mass in the growing skeleton and interventional strategies for improving outcomes for this group.

RECENT FINDINGS

Increased skeletal fragility in the disabled child is well recognized. Insights into the contributions of skeletal size and bone strength in males and females have altered interpretation of data, allowing a new focus on determinants of future bone health, particularly with regard to the contributions of growth and puberty. Strategies to address bone health including public and medical education concerning consumption of calcium, appropriate selection of vitamin D preparations, pubertal contribution to phases of growth and possible specialist use of newer drugs, such as bisphosphonates where indicated, are changing the outlook for this large group.

SUMMARY

Implications of these changed understandings provide a new focus on maximizing bone mass accumulation by the end of adolescence within the constraints of what is possible to achieve for an individual and for provision of an holistic approach to bone health.