Bone involvement in sickle cell disease

The many faces of sickle cell disease in children: complications in the appendicular skeleton

Sickle cell disease (SCD) is a hereditary red cell disorder with clinical manifestations secondary to sickling or crescent-shaped distortion of the red blood cells. Musculoskeletal complications of SCD are often the main causes for acute and chronic morbidities in children with manifestations including osteomyelitis, osteoporosis and osteonecrosis. This article aims to familiarise the paediatric radiologist with appendicular skeletal complications of SCD in the paediatric population and their imaging appearance.

BMP6 and VDR gene polymorphisms are associated with osteonecrosis in a sickle cell anaemia cohort

The occurrence and severity of osteonecrosis in sickle cell anaemia (SCA) vary due to risk factors, including genetic modifiers. Bone morphogenetic proteins (BMPs), particularly BMP6, and the vitamin D receptor (VDR) play key roles in cartilage and bone metabolism, making them potential contributors to orthopaedic outcomes in SCA. Here, we evaluated the association of polymorphisms in BMP6 (rs3812163, rs270393 and rs449853) and VDR (FokI rs2228570 and Cdx2 rs11568820) genes with osteonecrosis risk in a Brazilian SCA cohort. A total of 177 unrelated SCA patients were selected. The AA genotype of BMP6 rs3812163 was independently associated with a lower osteonecrosis risk (p = 0.015; odds ratio (OR): 0.38; 95% confidence interval (CI): 0.18-0.83) and with the long-term cumulative incidence of osteonecrosis (p = 0.029; hazard ratio: 0.56, 95% CI: 0.34-0.94). The VDR rs2228570 TT genotype was independently associated with a lower osteonecrosis risk (p = 0.039; OR: 0.14; 95% CI: 0.02-0.90). In summary, our results provide evidence that BMP6 rs3812163 and the VDR rs2228570 might be implicated in osteonecrosis pathophysiology in SCA and might help identify individuals at high risk.

Comparison of the effects of high dietary iron levels on bone microarchitecture responses in the mouse strains 129/Sv and C57BL/6J

Iron is an essential nutrient for all living organisms. Both iron deficiency and excess can be harmful. Bone, a highly metabolic active organ, is particularly sensitive to fluctuations in iron levels. In this study, we investigated the effects of dietary iron overload on bone homeostasis with a specific focus on two frequently utilized mouse strains: 129/Sv and C57BL/6J. Our findings revealed that after 6 weeks on an iron-rich diet, 129/Sv mice exhibited a decrease in trabecular and cortical bone density in both vertebral and femoral bones, which was linked to reduced bone turnover. In contrast, there was no evidence of bone changes associated with iron overload in age-matched C57BL/6J mice. Interestingly, 129/Sv mice exposed to an iron-rich diet during their prenatal development were protected from iron-induced bone loss, suggesting the presence of potential adaptive mechanisms. Overall, our study underscores the critical role of genetic background in modulating the effects of iron overload on bone health. This should be considered when studying effects of iron on bone.

A bone to pick-cellular and molecular mechanisms of bone pain in sickle cell disease

The bone is one of the most commonly affected organs in sickle cell disease (SCD). Repeated ischemia, oxidative stress and inflammation within the bone is largely responsible for promoting bone pain. As more individuals with SCD survive into adulthood, they are likely to experience a synergistic impact of both aging and SCD on their bone health. As bone health deteriorates, bone pain will likely exacerbate. Recent mechanistic and observational studies emphasize an intricate relationship between bone remodeling and the peripheral nervous system. Under pathological conditions, abnormal bone remodeling plays a key role in the propagation of bone pain. In this review, we first summarize mechanisms and burden of select bone complications in SCD. We then discuss processes that contribute to pathological bone pain that have been described in both SCD as well as non-sickle cell animal models. We emphasize the role of bone-nervous system interactions and pitfalls when designing new therapies especially for the sickle cell population. Lastly, we also discuss future basic and translational research in addressing questions about the complex role of stress erythropoiesis and inflammation in the development of SCD bone complications, which may lead to promising therapies and reduce morbidity in this vulnerable population.

Prevalence of bone complications in young patients with sickle cell disease presenting low bone mineral density

PURPOSE

Bone fragility in sickle cell disease (SCD) has been previously reported even in young patients, but the clinical consequences and specific management remain unclear. The objective of this study was to assess the prevalence of bone fragility in sickle cell patients and to evaluate the potential risk factors and associated complications.

METHODS

We conducted a single-center cross-sectional study. Bone mineral densitometry (BMD) at the lumbar spine and the hip, Vertebral Fracture Assessment (VFA) and biological measurements were performed in patients aged between 20 and 40 years.

RESULTS

One hundred and thirty-eight patients with sickle cell disease were included between June 2020 and December 2021. One hundred and one patients (73.2 %) were from Sub-Saharan Africa, 13 from North Africa (9.4 %), 11 from the Caribbean (7.9 %), 6 from the Indian Ocean. A Z-score < -2 was found in 43 patients (31.2 %) at the lumbar spine, in 4 patients (3 %) at the total hip, and in 5 patients (3.7 %) at the femoral neck. 59 patients (46.8 %) had vertebral deformities. Fragility fractures were recorded in 9 patients (10.8 %). Patients with low BMD had lower BMI (21.3 (19.0, 24.0) versus 24.0 (20.7, 26.1) Kg/m2, p = 0.003), lower osteonecrosis history (7 % versus 25.3 %, p = 0.011) and lower hemoglobin levels (9.0 (8.0, 10.0) versus 10.0 (9.0, 11.0) g/dL, p < 0.01). No association was found between history of fracture and low BMD.

CONCLUSION

Young patients with SCD commonly have low BMD at the lumbar spine, but the prevalence of fragility fracture was low. Low BMD - specifically at the spine - may not be tantamount to bone fragility.

Mouse models of sickle cell disease: Imperfect and yet very informative

The root cause of sickle cell disease (SCD) has been known for nearly a century, however, few therapies to treat the disease are available. Over several decades of work, with advances in gene editing technology and after several iterations of mice with differing genotype/phenotype relationships, researchers have developed humanized SCD mouse models. However, while a large body of preclinical studies has led to huge gains in basic science knowledge about SCD in mice, this knowledge has not led to the development of effective therapies to treat SCD-related complications in humans, thus leading to frustration with the paucity of translational progress in the SCD field. The use of mouse models to study human diseases is based on the genetic and phenotypic similarities between mouse and humans (face validity). The Berkeley and Townes SCD mice express only human globin chains and no mouse hemoglobin. With this genetic composition, these models present many phenotypic similarities, but also significant discrepancies that should be considered when interpreting preclinical studies results. Reviewing genetic and phenotypic similarities and discrepancies and examining studies that have translated to humans and those that have not, offer a better perspective of construct, face, and predictive validities of humanized SCD mouse models.

Imaging of pediatric skull lytic lesions: A review

Skull lesions in pediatric population are common findings on imaging and sometimes with heterogeneous manifestations, constituting a diagnostic challenge. Some lesions can be misinterpreted for their aggressiveness, as with larger lesions eroding cortical bone, containing soft tissue components, leading to excessive and, in some cases, invasive inappropriate etiological investigation. In this review, we present multiple several conditions that may present as skull lesions or pseudolesions, organized by groups (anatomic variants, congenital and development disorders, traumatic injuries, vascular issues, infectious conditions, and tumoral processes). Anatomic variants are common imaging findings that must be recognized by the neuroradiologist. Congenital malformations are rare conditions, such as aplasia cutis congenita and sinus pericranii, usually seen at earlier ages, the majority of which are benign findings. In case of trauma, cephalohematoma, growing skull fractures, and posttraumatic lytic lesions should be considered. Osteomyelitis tends to be locally aggressive and may mimic malignancy, in which cases, the clinical history can be the key to diagnosis. Vascular (sickle cell disease) and tumoral (aneurismal bone cyst, eosinophilic granuloma, metastases) lesions are relatively rare lesions but should be considered in the differential diagnosis, in the presence of certain imaging findings. The main difficulty is the differentiation between the benign and malignant nature; therefore, the main objective of this pictorial essay is to review the main skull lytic lesions found in pediatric age, describing the main findings in different imaging modalities (CT and MRI), allowing the neuroradiologist greater confidence in establishing the differential diagnosis, through a systematic and simple characterization of the lesions.

Racial and Ethnic Disparities in Metabolic Bone Disease

Racial and ethnic disparities exist in the prevalence and management of osteoporosis, metastatic cancer, and sickle cell disease. Despite being the most common metabolic bone disease, osteoporosis remains underscreened and undertreated among Black women. Skeletal-related events in metastatic cancer include bone pain, pathologic fractures, and spinal cord compression. Disparities in screening for and treating skeletal-related events disproportionately affect Black patients. Metabolic bone disease contributes significantly to morbidity in sickle cell disease; however, clinical guidelines for screening and treatment do not currently exist. Clinical care recommendations are provided to raise awareness, close health care gaps, and guide future research efforts.

Primary Anterior Thoracic Wall Abscess with Osteomyelitis by Salmonella paratyphi A : Case Report

Salmonella enterica serovar Typhi and Paratyphi have been imputed in the causation of enteric fever. Cardiovascular and extraintestinal Salmonella infections have been documented among immunocompromised individuals. Rarely these pathogens are ascribed in the causation of extraintestinal infections among immunocompetent hosts due to hematogenous seeding. We report a case of anterior chest wall abscess with osteomyelitis in an immunocompetent adult by Salmonella paratyphi A without any prior predisposing conditions or gastrointestinal symptoms. The patient underwent incision and drainage of the loculated pus and the involved costochondral junction was curetted. Medical management was guided by automated antibiotic susceptibility testing. Patient responded well to treatment and was discharged with no residual morbidities. Prompt diagnosis complements appurtenant treatment and thereby averts defunct consequential sequelae.

Defects in Bone and Bone Marrow in Inherited Anemias: the Chicken or the Egg

PURPOSE OF REVIEW

Recently, there has been an increasing number of studies on the crosstalk between the bone and the bone marrow and how it pertains to anemia. Here, we discuss four heritable clinical syndromes contrasting those in which anemia affects bone growth and development, with those in which abnormal bone development results in anemia, highlighting the multifaceted interactions between skeletal development and hematopoiesis.

RECENT FINDINGS

Anemia results from both inherited and acquired disorders caused by either impaired production or premature destruction of red blood cells or blood loss. The downstream effects on bone development and growth in patients with anemia often constitute an important part of their clinical condition. We will discuss the interdependence of abnormal bone development and growth and hematopoietic abnormalities, with a focus on the erythroid lineage. To illustrate those points, we selected four heritable anemias that arise from either defective hematopoiesis impacting the skeletal system (the hemoglobinopathies β-thalassemia and sickle cell disease) versus defective osteogenesis resulting in impaired hematopoiesis (osteopetrosis). Finally, we will discuss recent findings in Diamond Blackfan anemia, an intrinsic disorder of both the erythron and the bone. By focusing on four representative hereditary hematopoietic disorders, this complex relationship between bone and blood should lead to new areas of research in the field.

Invasive Bacterial Infections in Children With Sickle Cell Disease: 2014-2019

BACKGROUND

Children with sickle cell disease (SCD) are at a high risk of invasive bacterial infections (IBI). Universal penicillin prophylaxis and vaccination, especially against Streptococcus pneumoniae, have deeply changed its epidemiology. Analysis of IBI in children with SCD in a post-13-valent pneumococcal vaccine era is limited.

METHODS

Twenty-eight pediatric hospitals from 5 European countries retrospectively collected IBI episodes in SCD children aged 1 month to 18 years between 2014 and 2019. IBI was defined as a positive bacterial culture or polymerase chain reaction from a normally sterile fluid: blood, cerebrospinal, joint, or pleural fluid and deep surgical specimen.

RESULTS

We recorded 169 IBI episodes. Salmonella spp. was the main isolated bacteria (n = 44, 26%), followed by Streptococcus pneumonia (Sp; n = 31, 18%) and Staphylococcus aureus (n = 20, 12%). Salmonella prevailed in osteoarticular infections and in primary bacteremia (45% and 23% of episodes, respectively) and Sp in meningitis and acute chest syndrome (88% and 50%, respectively). All Sp IBI occurred in children ≤10 years old, including 35% in children 5 to 10 years old. Twenty-seven (17%) children had complications of infection and 3 died: 2 because of Sp, and 1 because of Salmonella. The main risk factors for a severe IBI were a previous IBI and pneumococcal infection (17 Sp/51 cases).

CONCLUSIONS

In a post-13-valent pneumococcal vaccine era, Salmonella was the leading cause of bacteremia in IBI in children with SCD in Europe. Sp came second, was isolated in children ≤10 years old, and was more likely to cause severe and fatal cases.

Bilateral Humeral Head Avascular Necrosis: A Rare Presentation in Sickle Cell Trait

Sickle cell disease (SCD) affects millions of people worldwide. It is an autosomal recessive hemoglobinopathy that occurs due to a point mutation in the sixth codon that replaces glutamic acid with valine in the beta-globin chain. Avascular necrosis (AVN), also known as osteonecrosis, is one of its complications. In this report, we present a case of a 25-year-old female with sickle cell trait without any comorbidities who presented to us with pain in both shoulder joints for three months and was diagnosed with AVN in bilateral shoulder joints. Appropriate treatment can dramatically reduce pain and improve the quality of life for these patients. This case drew our attention due to its rare presentation.

Femoral Head Core Decompression and Bone Marrow Concentrate Injection in Pediatric Sickle-cell Related Avascular Necrosis

BACKGROUND

Femoral head avascular necrosis affects 10% to 40% of patients with sickle cell disease (SCD). The purpose of this study was to evaluate the results of femoral head core decompression and bone marrow aspirate concentrate (CD-BMAC) injection in pediatric patients with SCD.

METHODS

Eligible patients were enrolled in this retrospective study of patients undergoing CD-BMAC. Patients with SCD who were younger than 18 at the time of surgery and had >1 year of follow-up were included in this analysis. Hips were staged based on the Ficat system by 2 raters. The visual analog score for pain, hip outcome score, modified Harris hip score, and the University of California, Los Angeles activity score were used as patient-reported outcome measures preoperatively, at 5 to 9 months postoperatively, and final follow-up. Treatment failure was defined as total hip arthroplasty or visual analog score >3 at the final follow-up.

RESULTS

Twenty-three hips in 17 patients were included, with a median age at the time of surgery of 15.8 years (interquartile range: 13.1 to 17.8 y). Patients were followed for 4.25 ± 1.7 years. Ten hips showed a 1-stage increase in the Ficat stage at the final follow-up, whereas 11 retained the same stage, and 1 hip had a 1-stage regression. All patient-reported outcome measures showed significant improvement from the preoperative visit to short-term follow-up, but the preoperative to final follow-up improvement was not significant. Six treatment failures were recorded, including 3 total hip arthroplasties and 3 painful hips at the final follow-up. In a multivariate logistic regression model, only skeletal maturity (odds ratio = 16.2, 95% CI: 1.44-183.0, P = 0.024) and femoral head collapse (odds ratio = 12.0, 95% CI: 1.1-130.5, P = 0.041) were significant predictors of treatment failure.

CONCLUSIONS

In the largest study on pediatric SCD patients undergoing CD-BMAC, we found that CD-BMAC injection offers significant improvement in pain and functional outcomes in the short term, with a very low risk for complications. Skeletal maturity and femoral head collapse were significant predictors of treatment failure. Patients with a collapsed femoral head experienced functional deterioration over time after initial improvement, whereas precollapse hips maintained their functional improvement up to the latest follow-up.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Inhibition of FGF23 is a therapeutic strategy to target hematopoietic stem cell niche defects in β-thalassemia

Clinical evidence highlights a relationship between the blood and the bone, but the underlying mechanism linking these two tissues is not fully elucidated. Here, we used β-thalassemia as a model of congenital anemia with bone and bone marrow (BM) niche defects. We demonstrate that fibroblast growth factor 23 (FGF23) is increased in patients and mice with β-thalassemia because erythropoietin induces FGF23 overproduction in bone and BM erythroid cells via ERK1/2 and STAT5 pathways. We show that in vivo inhibition of FGF23 signaling by carboxyl-terminal FGF23 peptide is a safe and efficacious therapeutic strategy to rescue bone mineralization and deposition in mice with β-thalassemia, normalizing the expression of niche factors and restoring hematopoietic stem cell (HSC) function. FGF23 may thus represent a molecular link connecting anemia, bone, and the HSC niche. This study provides a translational approach to targeting bone defects and rescuing HSC niche interactions, with potential clinical relevance for improving HSC transplantation and gene therapy for hematopoietic disorders.

Management of Older Adults with Sickle Cell Disease: Considerations for Current and Emerging Therapies

People with sickle cell disease (SCD) are living longer than ever before, with the median survival increasing from age 14 years in 1973, beyond age 40 years in the 1990s, and as high as 61 years in recent cohorts from academic centers. Improvements in survival have been attributed to initiatives, such as newborn screening, penicillin prophylaxis, vaccination against encapsulated organisms, better detection and treatment of splenic sequestration, and improved transfusion support. There are an estimated 100,000 people living with SCD in the United States and millions of people with SCD globally. Given that the number of older adults with SCD will likely continue to increase as survival improves, better evidence on how to manage this population is needed. When managing older adults with SCD (defined herein as age ≥ 40 years), healthcare providers should consider the potential pitfalls of extrapolating evidence from existing studies on current and emerging therapies that have typically been conducted with participants at mean ages far below 40 years. Older adults with SCD have historically had little to no representation in clinical trials; therefore, more guidance is needed on how to use current and emerging therapies in this population. This article summarizes the available evidence for managing older adults with SCD and discusses potential challenges to using approved and emerging drugs in this population.

Cemented Versus Uncemented Total Hip Arthroplasty in Sickle Cell Disease Patients: A Retrospective Study

Background and objective Sickle cell disease (SCD) can predispose patients to avascular necrosis (AVN) of the femoral head, resulting in severe disabling pain. Total hip arthroplasty (THA) is the leading treatment choice for end-stage arthritis caused by AVN. In this study, we aimed to compare complications associated with implant fixation with and without cement. Materials and methods We retrospectively analyzed 95 total hip implants in which 26 patients had staged bilateral THA. These surgeries were performed by four senior arthroplasty consultants between 2007 and 2018. Data were collected from the surgical logbook, physical files, and the electronic patient database (I-Seha, National Health Information System, Ministry of Health, Kingdom of Bahrain). Results The study included 95 hip implants in 69 patients. Forty-five (47%) were in males, and 50 (53%) were in females. Of these, 22 implants underwent revision (23%), two implants had periprosthetic infections (0.2%), two implants had periprosthetic fractures (0.2%), and 18 implants had implant loosening. We found that cemented THA was significantly associated with the development of implant loosening (p<0.001), small particle disease (p<0.001), and a higher revision rate (p<0.001). Conclusion We found that cemented THA in SCD patients led to a higher rate of aseptic implant loosening, mainly caused by osteolysis. Based on our findings, we recommend uncemented THA in SCD patients.

The sick(le) brain and spine: neuroimaging findings in paediatric patients with sickle cell disease

Sickle cell disease (SCD) is an autosomal recessive haemoglobinopathy, which manifests as multisystem ischaemia and infarction, as well as haemolytic anaemia. The morphological changes of red blood cells (RBCs) that promote ischaemia/infarction as the main multi-systemic manifestation, with associated vasculopathy, may also lead to haemorrhage and fat embolisation. Bone infarctions, whether of the skull or spine, are relatively common with subsequent increased infectious susceptibility. We present a broad spectrum of brain and spine imaging findings of SCD from a level III paediatric hospital in Lisbon, between 2010 and 2022. Our aim is to highlight brain and spine imaging findings from a serial review of multiple patients with SCD and respective neuroimaging characterisation.

Compound Heterogeneous Sickle Cell-B+ Thalassemia Incidentally Discovered Through Cytological Examination of a Fine-Needle Aspiration Specimen from an Aneurysmal Bone Cyst in a Young Child: A Case Report

Sickle cell beta-thalassemia (S/β) is a rare inherited variant of sickling disorders, usually occurring due to the inheritance of two abnormal genes, namely, the sickle cell gene, and the beta-thalassemia gene. There are two types of sickle cell β-thalassemia: (S/β+) and (S/β0), based on a decrease or complete absence of beta-globin synthesis, respectively. Skeletal complications, such as osteonecrosis, osteomyelitis, and septic arthritis, are well-known sequelae in sickle cell patients due to vaso-occlusive events. Nevertheless, the occurrence of aneurysmal bone cysts in patients with sickle cell hemoglobinopathy is an exceptional phenomenon. Herein, we report a case of a young boy who presented with nonspecific clinical symptoms over a few years. The patient was referred to our institution as a case of short stature with recurrent joint pain. A clinical workup was done and an aneurysmal bone cyst (ABC) of the left humerus was discovered radiologically with incidental detection of sickle cells through cytological evaluation of the cyst fluid. Further clinical investigation, including molecular and additional laboratory tests, confirmed the diagnosis of compound heterogeneous sickle cell-B+ thalassemia. Unfortunately, neither was the underlying pathology detected nor was the precise clinical diagnosis attained at the outside primary healthcare facility.

Hemoglobinopathy is Associated With Total Hip Arthroplasty Indication Even Beyond Sickle Cell Anemia

Background

The extent to which hemoglobinopathies other than sickle anemia (HbSS) are associated with hip osteonecrosis is unknown. Sickle cell trait (HbS), hemoglobin SC (HbSC), and sickle/β-thalassemia (HbSβTh) may also predispose to osteonecrosis of the femoral head (ONFH). We sought to compare the distributions of indications for a total hip arthroplasty (THA) in patients with and without specific hemoglobinopathies.

Methods

PearlDiver, an administrative claims database, was used to identify 384,401 patients aged 18 years or older undergoing a THA not for fracture from 2010 to 2020, with patients grouped by diagnosis code (HbSS N = 210, HbSC N = 196, HbSβTh N = 129, HbS N = 356). β-Thalassemia minor (N = 142) acted as a negative control, and patients without hemoglobinopathy as a comparison group (N = 383,368). The proportion of patients with ONFH was compared to patients without it by hemoglobinopathy groups using chi-squared tests before and after matching on age, sex, Elixhauser Comorbidity Index, and tobacco use.

Results

The proportion of patients with ONFH as the indication for THA was higher among those with HbSS (59%, P < .001), HbSC (80%, P < .001), HbSβTh (77%, P < .001), and HbS (19%, P < .001) but not with β-thalassemia minor (9%, P = .6) than the proportion of patients without hemoglobinopathy (8%). After matching, the proportion of patients with ONFH remained higher among those with HbSS (59% vs 21%, P < .001), HbSC (80% vs 34%, P < .001), HbSβTh (77% vs 26%, P < .001), and HbS (19% vs 12%, P < .001).

Conclusions

Hemoglobinopathies beyond sickle cell anemia were strongly associated with having osteonecrosis as the indication for THA. Further research is needed to confirm whether this modifies THA outcomes.

Sickle cell bone disease and response to intravenous bisphosphonates in children

Children with sickle cell disease (SCD) have the potential for extensive and early-onset bone morbidity. This study reports on the diversity of bone morbidity seen in children with SCD followed at three tertiary centers. IV bisphosphonates were effective for bone pain analgesia and did not trigger sickle cell complications.

INTRODUCTION

To evaluate bone morbidity and the response to intravenous (IV) bisphosphonate therapy in children with SCD.

METHODS

We conducted a retrospective review of patient records from 2003 to 2019 at three Canadian pediatric tertiary care centers. Radiographs, magnetic resonance images, and computed tomography scans were reviewed for the presence of avascular necrosis (AVN), bone infarcts, and myositis. IV bisphosphonates were offered for bone pain management. Bone mineral density was assessed by dual-energy X-ray absorptiometry (DXA).

RESULTS

Forty-six children (20 girls, 43%) had bone morbidity at a mean age of 11.8 years (SD 3.9) including AVN of the femoral (17/46, 37%) and humeral (8/46, 17%) heads, H-shaped vertebral body deformities due to endplate infarcts (35/46, 76%), and non-vertebral body skeletal infarcts (15/46, 32%). Five children (5/26, 19%) had myositis overlying areas of AVN or bone infarcts visualized on magnetic resonance imaging. Twenty-three children (8/23 girls) received IV bisphosphonate therapy. They all reported significant or complete resolution of bone pain. There were no reports of sickle cell hemolytic crises, pain crises, or stroke attributed to IV bisphosphonate therapy.

CONCLUSION

Children with SCD have the potential for extensive and early-onset bone morbidity. In this series, IV bisphosphonates were effective for bone pain analgesia and did not trigger sickle cell complications.

Management of Salter-Harris Type 1 Fracture Complicated with Osteomyelitis in a Sickle Cell Disease Patient: A Case Report and Review of Literature

Salter-Harris fractures may occur due to a single injury or repetitive stress fractures on the extremities. Type I to III fractures are managed medically, while types IV and V, which are rare, are treated surgically. In the pediatric population, Salter-Harris I fractures of the distal tibia are commonly seen, and management of such fractures are well established in the literature. Despite the availability of a wide range of treatment for such fractures, osteonecrosis or avascular necrosis of the proximal femur can subsequently develop. Avascular necrosis is cell death secondary to metabolic disturbances, trauma, adverse effects of certain medications, or sickle cell disease. Avascular necrosis commonly affects the talus, humerus, or tibia in addition to the femoral head. Radiographic images are essential for prompt diagnosis and to minimize negative health outcomes in these patients. However, Salter-Harris I fracture in sickle cell patients can be very challenging due to these patients' vulnerability to bone infections and sickle cell crisis. In this case report, our patient with a history of sickle cell disease and with a diagnosis of Salter-Harris I fracture was treated with surgical intervention as type V, which is discussed in this article, and responded well to treatment. Thus, this case suggests a new approach to managing Salter-Harris I fractures complicated with osteomyelitis in sickle cell patients.

Osteoporosis in children and young adults

Osteoporosis is a major public health problem with serious long-term complications. In children, the definition of osteoporosis is not only based on densitometric criteria but also takes into account vertebral and long bone fragility fractures. Several factors, such as long-term high-dose steroids, chronic inflammation, malnutrition, immobility, lack of sex steroids, and medication can reduce bone density and increase the risk for fragility fractures when left untreated. Also, genetic conditions can predispose to primary bone fragility disorders, with osteogenesis imperfecta being the most common. Furthermore, since the growing skeleton is at an increased rate of bone remodeling, the ability to heal long bone fractures and reshape vertebral fractures differentiates children from adults. The scope of this chapter is to review the risk factors of osteoporosis and fragility fractures and describe the commonest causes of primary and secondary osteoporosis and their management in children and young adults.

Molecular Mechanisms of Hepatic Dysfunction in Sickle Cell Disease: Lessons From The Townes Mouse Model

Sickle cell disease (SCD) is an autosomal-recessive-genetic disorder that affects ~100,000 Americans and millions of people worldwide. Erythrocyte sickling, vaso-occlusion, sterile inflammation and hemolysis are the major pathophysiological pathways leading to liver injury in SCD. Although hepatic dysfunction affects up to 10-40% of SCD patients, therapeutic approaches to prevent liver injury in SCD are not known, and the molecular mechanisms promoting progressive liver injury in SCD remain poorly understood. Animal models have been beneficial in bridging the gap between preclinical and translational research in SCD. Recent advances in methodology have allowed the development of several humanized mouse models to address various aspects of SCD related liver diseases. This review provides an overview of current knowledge of the molecular mechanisms and potential therapeutic options of SCD associated liver dysfunction using the Townes mouse model.

Transferrin receptor 1-mediated iron uptake regulates bone mass in mice via osteoclast mitochondria and cytoskeleton

Increased intracellular iron spurs mitochondrial biogenesis and respiration to satisfy high-energy demand during osteoclast differentiation and bone-resorbing activities. Transferrin receptor 1 (Tfr1) mediates cellular iron uptake through endocytosis of iron-loaded transferrin, and its expression increases during osteoclast differentiation. Nonetheless, the precise functions of Tfr1 and Tfr1-mediated iron uptake in osteoclast biology and skeletal homeostasis remain incompletely understood. To investigate the role of Tfr1 in osteoclast lineage cells in vivo and in vitro, we crossed Tfrc (encoding Tfr1)-floxed mice with Lyz2 (LysM)-Cre and Cathepsin K (Ctsk)-Cre mice to generate Tfrc conditional knockout mice in myeloid osteoclast precursors (Tfr1^ΔLysM) or differentiated osteoclasts (Tfr1^ΔCtsk), respectively. Skeletal phenotyping by µCT and histology unveiled a significant increase in trabecular bone mass with normal osteoclast number in long bones of 10-week-old young and 6-month-old adult female but not male Tfr1^ΔLysM mice. Although high trabecular bone volume in long bones was observed in both male and female Tfr1^ΔCtsk mice, this phenotype was more pronounced in female knockout mice. Consistent with this gender-dependent phenomena, estrogen deficiency induced by ovariectomy decreased trabecular bone mass in Tfr1^ΔLysM mice. Mechanistically, disruption of Tfr1 expression attenuated mitochondrial metabolism and cytoskeletal organization in mature osteoclasts in vitro by attenuating mitochondrial respiration and activation of the Src-Rac1-WAVE regulatory complex axis, respectively, leading to decreased bone resorption with little impact on osteoclast differentiation. These results indicate that Tfr1-mediated iron uptake is specifically required for osteoclast function and is indispensable for bone remodeling in a gender-dependent manner.

Fifteen-minute consultation: Recognition of sickle cell crises in the paediatric emergency department

Children with sickle cell disease can develop life-threatening and painful crises that require prompt assessment and efficient management by healthcare professionals in the emergency or acute care setting. Due to migration patterns and improved survival rates in high-prevalence countries, there is an increased tendency to encounter these patients across the UK. These factors warrant regular revisions in sickle cell crisis management, along with education for medical personnel and patients to improve clinical care and patient management. The focus of this article is on the initial assessment and management of acute paediatric sickle cell complications in the emergency setting. Specific case studies, including acute pain crises, trauma, splenic sequestration, aplastic crises, acute chest syndrome, infection, avascular necrosis, osteomyelitis and stroke, are discussed. Due to the current COVID-19 pandemic, we have also reviewed specific concerns around this patient group.

Targeting the Hematopoietic Stem Cell Niche in β-Thalassemia and Sickle Cell Disease

In the last decade, research on pathophysiology and therapeutic solutions for β-thalassemia (BThal) and sickle cell disease (SCD) has been mostly focused on the primary erythroid defect, thus neglecting the study of hematopoietic stem cells (HSCs) and bone marrow (BM) microenvironment. The quality and engraftment of HSCs depend on the BM microenvironment, influencing the outcome of HSC transplantation (HSCT) both in allogeneic and in autologous gene therapy settings. In BThal and SCD, the consequences of severe anemia alter erythropoiesis and cause chronic stress in different organs, including the BM. Here, we discuss the recent findings that highlighted multiple alterations of the BM niche in BThal and SCD. We point out the importance of improving our understanding of HSC biology, the status of the BM niche, and their functional crosstalk in these disorders towards the novel concept of combined therapies by not only targeting the genetic defect, but also key players of the HSC–niche interaction in order to improve the clinical outcomes of transplantation.

Six-point DIXON and Magnetic Resonance Spectroscopy Techniques in Quantifying Bone Marrow Fat in Sickle Cell Disease

RATIONALE AND OBJECTIVES

To compare bone marrow fat quantification using magnetic resonance spectroscopy (MRS) and six-point DIXON (6PD) techniques in patients with sickle cell disease (SCD) and healthy subjects.

MATERIALS AND METHODS

Prospective study, with 43 SCD patients (24 homozygous [SS], 19 double heterozygous [SC), and 41 healthy subjects paired by age, weight and sex with SCD patients. All participants underwent magnetic resonance imaging with 6PD and single voxel MRS in the L3 vertebral body. Pearson's correlation, ROC curve, and bland-altman analysis were performed, p-values ​​≤0.05 were considered statistically significant for all tests.

RESULTS

Significant linear correlation was found between fat fraction (FF) by 6PD and Total Lipids (TL) (r = 0.932; p < 0.001) and Saturated Lipids (SL) (r = 0.934; p < 0.001), in all subjects. Strong correlations were also identified considering subjects of the SS/SC subgroups. Despite high correlations, no significant difference was observed only between FF and SL in the SS subgroup (Bland-Altman analysis), indicating excellent agreement between the fat estimations in this specific situation. Significant differences were observed in all variables (FF, TL, SL) comparing the SCD and healthy subjects. The ROC curve between SCD and healthy subjects showed the following areas under the curve: FF(0.924) > TL(0.883) > SL(0.892).

CONCLUSIONS

The comparison between fat quantification by the 6PD with MRS demonstrated an excellent correlation in SCD patients, especially in the SS subgroup, which usually has a higher degree of hemolysis. The diagnostic performance of 6PD and MRS is similar, with advantages of shorter imaging processing time and larger studied area with the 6PD.

The spectrum and burden of in-patient paediatric musculoskeletal diseases in Northern Tanzania

BACKGROUND

Musculoskeletal diseases (MSD) are a major contributor to the global burden of disease and disability, and disproportionally affect low- and middle-income countries; however, there is a dearth of epidemiological data. Affected children often face increased morbidity, social isolation and economic hardship.

AIM

To assess the spectrum and burden of paediatric MSD in children aged 5-18 years admitted to a major referral hospital in Tanzania.

METHODS

This was a retrospective cohort study of children aged 5-18 years admitted to Kilimanjaro Christian Medical Centre (KCMC) whose initial diagnosis was recognised as a musculoskeletal condition by the International Classification of Diseases-10 between 1 January and 31 December 2017.

RESULTS

During 2017, 163 cases of confirmed paediatric MSD were admitted to KCMC, representing 21.2% of all admissions of children aged 5-18 years (n = 769). Bone disease was the most common diagnosis. They comprised 106 (65.0%) traumatic fractures, 31 (19.0%) osteo-articular infections, 9 (5.5%) malunions and 3 (1.8%) pathological fractures. Congenital defects and rheumatic disease were relatively uncommon, accounting for only 6 (3.7%) and 4 (2.5%) MSD admissions, respectively.

CONCLUSION

The majority of cases of MSD were related to fractures, followed by osteo-articular infections, while recognised cases of rheumatic disease were rare. The study, although small, identified the sizeable burden and spectrum of paediatric MSD admitted to a hospital in Tanzania over a 12-month period and highlights the need for larger studies to inform the optimal allocation of health resources.

ABBREVIATION

CI: confidence interval; HIC: high-income countries; HIV: human immunodeficiency virus; ICD-10: International Classification of Diseases 10; IQR: interquartile range; JIA: juvenile idiopathic arthritis; KCMC: Kilimanjaro Christian Medical Centre; LMIC: low- and middle-income countries; MSD: musculoskeletal diseases: NAI: non-accidental injury; NIHR: National Institute for Health Research; PAFLAR: Paediatric Society of the African League Against Rheumatism; RTA: road traffic accidents; SCD: sickle cell disease; SLE: systemic lupus erythematosus; SSA: sub-Saharan Africa.

Mineral bone disorders and kidney disease in hospitalized children with sickle cell anemia

BACKGROUND

Mineral bone disorders (MBD) are common in sickle cell anemia (SCA). Frequent vaso-occlusive crises (VOC) further impact MBD in children with SCA. We evaluated the prevalence of markers of SCA-related MBD (sMBD) in hospitalized children and assessed the relationship between sMBD and individual mineral abnormalities with kidney disease.

METHODS

We prospectively recruited 185 children with SCA hospitalized with a VOC. Serum measures of mineral bone metabolism (calcium, phosphate, parathyroid hormone, 25-hydroxy vitamin D, FGF23, osteopontin) were measured at enrollment. The primary outcome was markers of sMBD defined as a composite of hypocalcemia, hyperphosphatemia, hyperparathyroidism, or deficiency in 25-OH vitamin D. Secondary outcomes included individual abnormalities in mineral metabolism. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines were used to define SCA-associated acute kidney injury (AKI). AKI was further assessed using urine NGAL as a marker of tubular injury. Acute kidney disease (AKD) was defined as a composite of AKI, an eGFR < 90 ml/min per 1.73 m² using the Cystatin C GFR equation, or evidence of structural injury (positive biomarker test or albuminuria).

RESULTS

The mean age of children was 8.9 years and 41.6% were female. The prevalence of sMBD was 47.6%, with hypocalcemia the most frequent abnormality (29.9%, 55/184) followed by hyperphosphatemia (20.7%, 38/184), hyperparathyroidism (8.7%, 16/185), and vitamin D deficiency (5.4%, 10/185). There was no association between sMBD and sKDIGO-defined AKI using serial changes in creatinine or when incorporating biomarkers to define AKI. However, the presence of AKD was associated with a 2.01-fold increased odds of sMBD (95% CI 1.05 to 3.83) and was driven by a decrease in eGFR (OR, 2.90 95% CI: 1.59 to 5.29). When evaluating individual mineral abnormalities, hypocalcemia was associated with AKD and low eGFR while hyperparathyroidism was associated with low eGFR, AKI and structural injury. Vitamin D deficiency was associated with structural kidney injury. Vitamin D deficiency, hyperparathryoidism, and increases in FGF23 and osteopontin predicted mortality (p < 0.05 for all).

CONCLUSION

MBD is common among children with SCA hospitalized with VOC. Biomarkers of kidney injury and bone health may help risk stratify children at risk of sMBD. Routine evaluation of sMBD in children with SCA may improve long-term bone health.

Polimorfismos e necrose avascular em pacientes com doença falciforme – Uma revisão sistemática

Resumo Objetivo: Estabelecer, de modo sistemático, se existe associação entre polimorfismos e a necrose avascular em pacientes com doença falciforme. Fontes de dados: A revisão, conduzida segundo as diretrizes Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) e registrada no International Prospective Register of Systematic Reviews (PROSPERO), foi baseada na busca de estudos nas bases de dados PubMed, Scientific Electronic Library Online (SciELO), Literatura Latino-Americana e do Caribe em Ciências da Saúde (LILACS), Biblioteca Virtual em Saúde (BVS) e na literatura cinza (Google Scholar e Open Gray) até junho de 2020. A análise da qualidade dos artigos foi baseada nos critérios do Strengthening the Reporting of Observational Studies in Epidemiology (STROBE). Síntese dos dados: Dez artigos foram selecionados nas bases de dados e dois incluídos por meio da busca manual, totalizando 12 estudos elencados. As amostras resultaram em 2.362 pacientes incluídos. Com base na iniciativa STROBE, sete estudos atenderam total e/ou parcialmente mais de 70% dos itens essenciais e dois atingiram menos que 60% deles, com variação geral de 86,4–54,5%. Os resultados mostram que os polimorfismos nos genes da proteína morfogenética óssea 6 (BMP6), da Klotho (KL) e da Anexina A2 (ANXA2) podem ter associação com osteonecrose no contexto da doença falciforme. Seis artigos estudaram o polimorfismo no gene da enzima MTHFR, mas apenas um obteve associação positiva. Os polimorfismos associados ao receptor DARC, ao gene ITGA4, ao CD36 e aos genes de proteínas trombofílicas não demonstraram associação em nenhum dos estudos. Conclusões: Os polimorfismos nos genes BMP6, KL e ANXA2 estão possivelmente associados com a necrose avascular em indivíduos com doença falciforme. Entretanto, para a confirmação dessas alterações genéticas como fatores de risco, é necessário que mais estudos com maior poder estatístico e com maior rigor metodológico sejam realizados.

Polymorphisms and avascular necrosis in patients with sickle cell disease – A systematic review

Objective:

To systematically establish whether there is an association between polymorphisms and avascular necrosis in patients with sickle cell disease.

Data source:

The review, conducted according to PRISMA guidelines and registered with PROSPERO, was based on research of studies in PubMed, SciELO, LILACS, BVS databases and in the gray literature (Google Scholar and Open Gray) published until June 2020. The STROBE initiative was used to analyze the articles’ quality.

Data synthesis:

Ten articles were selected from the databases and two were included through manual search, totaling 12 studies. All samples gathered 2,362 patients. According to STROBE, seven studies fully and/or partially covered more than 70% of the essential items and two studies reached less than 60%, with an overall variation of 86.4–54.5%. The results indicate that polymorphisms in the genes of the bone morphogenetic protein 6 (BMP6), Klotho (KL) and Annexin A2 (ANXA2) may be associated with osteonecrosis in the context of sickle cell disease. Six articles addressed the polymorphism in the MTHFR enzyme gene, but only one found a positive association. Polymorphisms associated with the DARC receptor, the ITGA4 gene, CD36 and thrombophilia protein genes were not associated in any of the studies.

Conclusions:

The results indicate that the polymorphisms in BMP6, Klotho and ANXA2 genes may be associated with avascular necrosis in patients with sickle cell disease. However, in order to confirm these genetic changes as risk factors, further studies with greater statistical power and methodological rigor are needed.

Early oral switch to combined cefixime therapy for management of osteoarticular infections in pediatric sickle cell disease patients: A descriptive analysis

BACKGROUND

The treatment of osteoarticular infections in pediatric patients with sickle cell disease (SCD) is a challenging task for the practitioner. The aim of this study is to evaluate cefixime for the treatment of osteoarticular infections in pediatric SCD patients by retrospective design.

METHODS

This study was done in the pediatric hospital of King Saud Medical City, Riyadh, Saudi Arabia. The data was obtained from medical records of patients aged 1-16 years admitted between January 2019 to December 2020, diagnosed with SCD and received cefixime for the treatment of OI. A descriptive study for pediatric patients admitted between January 2019 to December 2020 diagnosed with sickle cell disease and diagnosed with osteoarticular infection. All patients were treated with cefixime. Medians and interquartile ranges (IQRs) were used for the descriptive analysis.

RESULTS

A total of 260 patients were screened, and 51 cases [osteomyelitis (OM), n = 43, and septic arthritis (SA), n = 8] met the inclusion criteria. The median age of OM patients was 7 years, with males making up 67.4% of the cohort. The median length of IV antibiotics and hospital stays were 10 days and 11 days, respectively. The median total duration of antibiotic use was 37 and 25 days for OM and SA, respectively. The treatment success rate was 88% in OM cases and 100% in SA patients. Readmission was noted in 39.5% of the OM patients, while only 25% of the SA patients were recorded for reinfection.

CONCLUSION

The study's findings revealed that Cefixime is a viable oral alternative for treating osteoarticular infection in pediatric SCD patients. Nonetheless, a prospective investigation is required to corroborate the findings of this study.

Iron Overload in Patients With Heavily Transfused Sickle Cell Disease-Correlation of Serum Ferritin With Cardiac T2* MRI (CMRTools), Liver T2* MRI, and R2-MRI (Ferriscan®)

The treatment of sickle cell disease (SCD) is mainly supportive, except for a minority, who receive bone marrow transplantation (BMT). Serum ferritin (SF) is routinely available but is notoriously unreliable as a tool for iron-overload assessment since it is an acute-phase reactant. Although blood transfusion is one of the most effective ways to deal with specific acute and chronic complications of SCD, this strategy is often associated with alloimmunization, iron overload, and hemolytic reactions. This study, thus, aims to evaluate iron overload in patients with SCD on chronic blood transfusions and specifically, correlate SF with the current standard of care of iron-overload assessment using MRI-based imaging techniques. Amongst a historic cohort of 58 chronically transfused patients with SCD, we were able to evaluate 44 patients who are currently alive and had multiple follow-up testing. Their mean age (±SD) was 35 (9) years and comprised of 68.2% of women. The studied iron-overload parameters included cardiac T2^* MRI, liver iron concentration (LIC) by Liver T2^* MRI, and serial SF levels. Additionally, in a smaller cohort, we also studied LIC by FerriScan^© R2-MRI. Chronic blood transfusions were necessary for severe vaso-occlusive crisis (VOC) (38.6%), severe symptomatic anemia (38.6%), past history of stroke (15.9%), and recurrent acute chest syndrome (6.9%). About 14 (24%) patients among the original cohort died following SCD-related complications. Among the patients currently receiving chelation, 26 (96%) are on Deferasirox (DFX) [Jadenu® (24) or Exjade® (2)], with good compliance and tolerance. However, one patient is still receiving IV deferoxamine (DFO), in view of the significantly high systemic iron burden. In this evaluable cohort of 44 patients, the mean SF (±SD) reduced marginally from 4,311 to 4,230 ng/ml, mean Liver T2^* MRI dropped from 12 to 10.3 mg/gm dry weight, while the mean cardiac T2^*MRI improved from 36.8 to 39.5 ms. There was a mild to moderate correlation between the baseline and final values of SF ng/ml, r = 0.33, p = 0.01; Cardiac T2^* MRI ms, r = 0.3, p = 0.02 and Liver T2^* MRI mg/kg dry weight, r = 0.6, p < 0.001. Overall, there was a positive correlation between SF and Liver T2^* MRI (Pearson's r = 0.78, p < 0.001). Cardiac T2^*MRI increased with the decreasing SF concentration, showing a negative correlation which was statistically significant (Pearson's r = -0.6, p < 0.001). Furthermore, there was an excellent correlation between SF ng/ml and LIC by FerriScan^© R2-MRI mg/g or mmol/kg (Spearmen's rho = -0.723, p < 0.008) in a small subset of patients (n = 14) who underwent the procedure. In conclusion, our study demonstrated a good correlation between serial SF and LIC by either Liver MRI T2^* or by FerriScan^© R2-MRI, even though SF is an acute-phase reactant. It also confirms the cardiac sparing effect in patients with SCD, even with the significant transfusion-related iron burden. About 14 (24%) patients of the original cohort died over the past 15 years, indicative of a negative impact of iron overload on disease morbidity and mortality.

Core Decompression and Bone Marrow Aspirate Concentrate in the Treatment of Femoral Head Avascular Necrosis in Pediatric Sickle Cell Disease: Can We Improve Natural History?

INTRODUCTION

Femoral head avascular necrosis (AVN) affects between 10% and 41% of children with sickle cell disease (SCD), resulting in the development of proximal femoral deformity and residual hip pain in the majority of patients without treatment. There have been multiple adult studies published on the outcomes of core decompression with and without the use of bone marrow aspirate concentrate (BMAC) injection both in idiopathic and SCD-related AVN with promising results, however, few studies have reported on outcomes in skeletally immature patients.

PURPOSE

This study sought to report on a single surgeon's outcomes for core decompression with BMAC injection in pediatric patients with AVN of the femoral head secondary to underlying SCD.

METHODS

A single-center, retrospective review was performed for pediatric patients undergoing core decompression with BMAC injection for femoral head AVN in patients with SCD with a minimum of 12-month follow-up. Demographic, radiographic, and clinical variable were collected. Patients were subdivided based upon presence of open femoral physes at the time of surgery. Successful treatment was defined as the ability to return to activities without limitations.

RESULTS

A total of 13 patients (average age 14.1±2.8 y, 84.6% male, 6 skeletally immature and 7 skeletally mature) with 18 affected extremities were identified. Open physes were present in 50% of operative extremities. Skeletally immature patient demonstrated reconstitution of the femoral head in 78% of cases and 89% demonstrated regression of at least 1 Steinberg grade and none had progression. Skeletally immature patients were significantly more likely to return to activities (100% vs. 55.6%, P=0.023) and achieve a final Tonnis grade <2 (89% vs. 44%, P=0.046).

CONCLUSION

Core decompression appears to alter the natural history of AVN in skeletally immature patients with SCD. Skeletal immaturity was a positive prognostic factor for the ability to return to activities without pain and achieve a lower Tonnis grade at final follow-up.

Sickle cell disease promotes sex-dependent pathological bone loss through enhanced cathepsin proteolytic activity

Age- and sex-dependent bone loss occurs in a Townes mouse model of SCD, with female mice more prone to trabecular bone loss.

Reduced cathepsin activity leads to increased thickness and density of cortical and trabecular bone in the Townes mouse model of SCD.

Sickle cell disease (SCD) is the most common hereditary blood disorder in the United States. SCD is frequently associated with osteonecrosis, osteoporosis, osteopenia, and other bone-related complications such as vaso-occlusive pain, ischemic damage, osteomyelitis, and bone marrow hyperplasia known as sickle bone disease (SBD). Previous SBD models have failed to distinguish the age- and sex-specific characteristics of bone morphometry. In this study, we use the Townes mouse model of SCD to assess the pathophysiological complications of SBD in both SCD and sickle cell trait. Changes in bone microarchitecture and bone development were assessed by using high-resolution quantitative micro–computed tomography and the three-dimensional reconstruction of femurs from male and female mice. Our results indicate that SCD causes bone loss and sex-dependent anatomical changes in bone. SCD female mice in particular are prone to trabecular bone loss, whereas cortical bone degradation occurs in both sexes. We also describe the impact of genetic knockdown of cathepsin K– and E-64–mediated cathepsin inhibition on SBD.

Testicular Volume in Children with Sickle Cell Anaemia in Uyo, a South-South Nigerian City

INTRODUCTION

Sickle cell anaemia (SCA) often presents in early childhood with repeated vaso-occlusive crisis that leads to ischaemia, infarction and fibrosis which may result in a reduction in expected testicular volume (TV) at puberty.

METHOD

This was a cross-sectional study of 95 children with SCA aged 1-18 years compared with 95 age-matched controls. Participants responded to an interviewer-administered questionnaire, with their anthropometric measurements taken, pubertal maturity assessed by Tanner staging and testicular ultrasonography done. Changes in TV across the ages were compared graphically and regression analyses were used to determine the factors independently associated with TV. A p-value of <0.05 was considered statistically significant.

RESULTS

In the prepubertal period, the haemoglobin SS (HbSS) participants had larger median ultrasound TV (MUSTV) compared to the haemoglobin AA (HbAA) controls (p = 0.001). This trend reversed in the pubertal period. On regression analysis, the frequency of testicular pain (p = 0.04), weight (p = 0.02) and pubic hair rating (p = 0.03) of the HbSS participants were significant predictors of increased TVs in the HbSS participants, irrespective of pubertal status.

CONCLUSION

The prepubertal MUSTV of the HbSS participants were higher than those of the HbAA controls, while the HbAA controls had higher MUSTV at puberty and beyond. The frequency of testicular pain episodes, pubic hair rating and weight were independent predictors of TV changes in the HbSS participants. Prevention of repeated vaso-occlusive crisis in the prepubertal period may help prevent the reduction in TV and possible hypogonadism. Lay summarySickle cell anaemia (SCA) causes repeated episodes of painful crisis and in boys, these may affect the way their testes grow. The study set out to document testicular sizes on a one-time basis in boys aged 1-18 years with SCA compared with controls of similar ages. The participants responded to structured questions assisted by the researchers and their body measurements were appropriately taken. Their level of sexual maturation was assessed according to the method by Tanner and the sizes of their testes were measured using an ultrasound machine. The research information was analysed and a statistical value less than 0.05 was taken to mean that there was a difference between the measured variables. The mid-testicular sizes of the SCA participants were noted to be higher than that of their controls during the prepubertal period while the non-SCA boys had higher sizes from puberty onwards. The frequency of testicular pain, weight and pubic hair stage of the SCA boys were important contributors to their increased testes sizes, irrespective of pubertal status. Efforts aimed at preventing painful crisis should start during early childhood to forestall future sexual challenges in adulthood.

A Rare and Successfully Managed Complication of Stem Cell Transplantation in an Adult Patient With Sickle Cell Disease: Bone Marrow Necrosis

Sickle cell disease is the most common genetic disorder in the Eastern Mediterranean region where our transplant center is located. Today, adult patients with sickle cell disease can also be successfully treated with allogeneic hematopoietic stem cell transplantation. Bone marrow necrosis is a rare and serious clinical condition. Herein, we present this complication for the first time in the literature, which developed in the course of allogeneic hematopoietic stem cell transplantation and was successfully managed with additional bone marrow support. The recognition, prevention, and management of this rare and potentially fatal complication, bone marrow necrosis, are vitally important, especially in regions with high prevalence of sickle cell disease.

Transcranial color-coded duplex sonography reliably identifies intracranial vasculopathy in adult patients with sickle cell disease

In order to prevent stroke, screening for disease-related intracranial vasculopathy using Doppler ultrasound is recommended in sickle-cell disease (SCD) children. How to screen such vasculopathy in adults remains largely unknown. The objective of this study was to assess whether transcranial color-coded duplex sonography (TCCD) is sensitive and specific enough to identify SCD adult patients with vasculopathy, compared with magnetic resonance angiography (MRA). Sickle cell disease adults followed in referral centers at high risk of vasculopathy were included in this study. Transcranial color-coded duplex sonography examination and 3-D time-of-flight MRA were performed on the same day. On MRA, vasculopathy was defined by the presence of at least one ≥50% arterial stenosis. On TCCD, vasculopathy was defined by a time-averaged mean of the maximum velocity (TAMx) stenotic/prestenotic ratio ≥ 3, an occlusion, or a Moyamoya pattern. Vasculopathy was also considered as present when TAMx ratio could not be calculated because of the presence of severe cervical lesions. Among 80 included patients, quality of MRA was insufficient in three patients. Among the 38 patients with vasculopathy on MRA, 37 had a vasculopathy according to TCCD criteria: TAMx ratio ≥ 3 or intracranial occlusion in 33 patients and cervical lesion in four patients. A Moyamoya pattern was identified with TCCD in all 17 patients with Moyamoya on MRA. Sensitivity and specificity of TCCD to identify patients with ≥50% vasculopathy on MRA were (n = 37/38) 97% and (n = 28/34) 82%, respectively. Positive and negative predictive values were (n = 37/43) 86% and (n = 28/29) 97%, respectively. Note, TCCD may be used to identify SCD adult patients with vasculopathy.

Osteoblast Dysfunction in Non-Hereditary Sclerosing Bone Diseases

A review of the available literature was performed in order to summarize the existing evidence between osteoblast dysfunction and clinical features in non-hereditary sclerosing bone diseases. It has been known that proliferation and migration of osteoblasts are concerted by soluble factors such as fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), transforming growth factor (TGF), bone morphogenetic protein (BMP) but also by signal transduction cascades such as Wnt signaling pathway. Protein kinases play also a leading role in triggering the activation of osteoblasts in this group of diseases. Post-zygotic changes in mitogen-activated protein kinase (MAPK) have been shown to be associated with sporadic cases of Melorheostosis. Serum levels of FGF and PDGF have been shown to be increased in myelofibrosis, although studies focusing on Sphingosine-1-phosphate receptor was shown to be strongly expressed in Paget disease of the bone, which may partially explain the osteoblastic hyperactivity during this condition. Pathophysiological mechanisms of osteoblasts in osteoblastic metastases have been studied much more thoroughly than in rare sclerosing syndromes: striking cellular mechanisms such as osteomimicry or complex intercellular signaling alterations have been described. Further research is needed to describe pathological mechanisms by which rare sclerosing non hereditary diseases lead to osteoblast dysfunction.

Qualitative and quantitative magnetic resonance imaging evaluation of bone tissue vaso-occlusive events in patients with sickle cell disease

OBJECTIVE

To evaluate the association between bone changes due to vaso-occlusive events in sickle cell disease (SCD) revealed by conventional MRI sequences and the fat fraction obtained using a 6-point DIXON technique (FFdix), in an attempt to use quantitative data as a biomarker for bone complications.

METHODS

Cross-sectional study, with 48 SCD patients, 26-homozygous (HbSS), and 22-compound heterozygous (HbSC). Forty-eight healthy individuals paired by age, weight, and sex with SCD patients. All participants underwent lumbar spine and pelvis MRI. Conventional sequences: bone complications related to vaso-occlusive events-femoral head avascular necrosis, bone infarctions, "H"-shaped vertebrae, bone marrow necrosis. Six-point DIXON technique: quantitative evaluation of the bone marrow at pre-established sites (lumbar vertebrae, sacrum, iliacs, femoral heads, greater femoral trochanters, femoral necks). Pearson's correlation, ROC curve, and binary logistic regression analysis were performed.

RESULTS

The most frequent findings in the SCD group included femoral head avascular necrosis (75%), bone infarctions (58.3%), "H"-shaped vertebrae (58.3%), and typical imaging findings of bone marrow necrosis (8.3%). Cortical bone thickness in the proximal femoral diaphysis in patients with SCD was moderately negatively correlated with FFdix in lumbar vertebrae, iliacs, femoral necks, and first sacral vertebrae. The ROC curves and odds ratios demonstrated excellent performance of FFdix in all the evaluated anatomical sites and identified patients having bone complications.

CONCLUSIONS

FFdix could serve as a potential biomarker in SCD because of its association with bone complications secondary to vaso-occlusive events in patients with SCD, especially in femoral heads, femoral necks, and iliacs.

Shaping the bone through iron and iron-related proteins

Well-controlled iron levels are indispensable for health. Iron deficiency is the most common cause of anemia, whereas iron overload, either hereditary or secondary due to disorders of ineffective erythropoiesis, causes widespread organ failure. Bone is particularly sensitive to fluctuations in systemic iron levels as both iron deficiency and overload are associated with low bone mineral density and fragility. Recent studies have shown that not only iron itself, but also iron-regulatory proteins that are mutated in hereditary hemochromatosis can control bone mass. This review will summarize the current knowledge on the effects of iron on bone homeostasis and bone cell activities, and on the role of proteins that regulate iron homeostasis, i.e. hemochromatosis proteins and proteins of the bone morphogenetic protein pathway, on bone remodeling. As disorders of iron homeostasis are closely linked to bone fragility, deeper insights into common regulatory mechanisms may provide new opportunities to concurrently treat disorders affecting iron homeostasis and bone.

Plasmodium falciparum goes bananas for sex

The sexual blood stages of the human malaria parasite Plasmodium falciparum undergo a remarkable transformation from a roughly spherical shape to an elongated crescent or "falciform" morphology from which the species gets its name. In this review, the molecular events that drive this spectacular shape change are discussed and some questions that remain regarding the mechanistic underpinnings are posed. We speculate on the role of the shape changes in promoting sequestration and release of the developing gametocyte, thereby facilitating parasite survival in the host and underpinning transmission to the mosquito vector.

Bone Marrow Multipotent Mesenchymal Stromal Cells as Autologous Therapy for Osteonecrosis: Effects of Age and Underlying Causes

Bone marrow (BM) is a reliable source of multipotent mesenchymal stromal cells (MSCs), which have been successfully used for treating osteonecrosis. Considering the functional advantages of BM-MSCs as bone and cartilage reparatory cells and supporting angiogenesis, several donor-related factors are also essential to consider when autologous BM-MSCs are used for such regenerative therapies. Aging is one of several factors contributing to the donor-related variability and found to be associated with a reduction of BM-MSC numbers. However, even within the same age group, other factors affecting MSC quantity and function remain incompletely understood. For patients with osteonecrosis, several underlying factors have been linked to the decrease of the proliferation of BM-MSCs as well as the impairment of their differentiation, migration, angiogenesis-support and immunoregulatory functions. This review discusses the quality and quantity of BM-MSCs in relation to the etiological conditions of osteonecrosis such as sickle cell disease, Gaucher disease, alcohol, corticosteroids, Systemic Lupus Erythematosus, diabetes, chronic renal disease and chemotherapy. A clear understanding of the regenerative potential of BM-MSCs is essential to optimize the cellular therapy of osteonecrosis and other bone damage conditions.

Salmonella Osteomyelitis in Adults: A Systematic Review

The aim of this systematic review was to characterize the clinical features of adults with Salmonella osteomyelitis and summarize diagnosis and treatment methods to provide guidance for clinicians. This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) guidelines. We conducted a literature search in the PubMed, EMBASE, and Cochrane Library databases. Article screening and data extraction were performed by two reviewers individually. All the included studies were independently evaluated by two reviewers using the Methodological Index for Non‐Randomized Studies (MINORS) criteria. A total of 67 articles published between 1970 and 2019 were selected, which include 69 patients with an average age of 47.5 years (range, 18–79).The majority of cases (47.76%) occurred in immunocompetent adults without common risk factors. Aspiration and biopsy cultures were all positive in Salmonella osteomyelitis patients who underwent aspiration or biopsy. All infections were monomicrobial, and a total of 12 different serotypes were identified. The three most commonly reported Salmonella serotypes were Salmonella typhi (19 cases), Salmonella typhimurium (12 cases), and Salmonella enteritidis (11 cases). Only 12 of the 67 cases in our data (17.91%) had diarrhea symptoms, and 44 of the 67 cases (65.67%) had fever symptoms. Fifty‐nine of the 67 cases (88.06%) had local inflammatory manifestations, such as erythema, swelling, and tenderness in the affected area. The commonly reported involved sites were the vertebrae, femur, and tibia. Antibiotic therapy alone was utilized in 30 cases, and 24 patients (80.00%) were eventually cured. In total, 75.68% of patients achieved satisfactory results after treatment with surgery and antibiotics. Third‐generation cephalosporins were most commonly utilized, and antibiotic treatment was administered for an average of 11.3 weeks (95% CI, 8.31–14.37 weeks). Salmonella osteomyelitis should be considered in patients without any common risk factors. Aspiration or biopsy can facilitate the identification of pathogens to guide antibiotic choice. Empirical therapy with a third‐generation cephalosporin is recommended until the susceptibility of the strain is determined.

Evaluation of the expression of red blood cell CD36, interleukin-6 and interleukin-8 in sickle cell anemia pediatric patients

Sickle cell anemia (SCA) is a complex multisystem disease characterized by acute and chronic inflammation, with alterations in inflammatory cytokines and adhesion molecules. This case-control study was carried out to assess the levels of CD36, immature reticulocytes, interleukin (IL)-6 and IL8 in SCA patients (in crisis and the steady state) and healthy controls. It included 90 children who were 2-18 years old; 60 with SCA and 30 healthy controls. Complete blood count, total reticulocyte count, reticulocyte subpopulations, immature reticulocyte fraction (IRF), percentage of CD36-positive red blood cells (RBCs), IL-6 and IL-8 levels were evaluated. The total white blood cell (WBC) and neutrophil counts, CD36-positive RBCs percentage, IRF, IL-6 and IL-8 levels were significantly higher in crises than in the steady state (P < 0.05). We also found that patients with SCA had significantly higher reticulocyte, WBC and neutrophil counts, fetal hemoglobin, CD36-positive RBCs percentage, IRF, and IL-6 and IL-8 levels than healthy children (P < 0.05). A significant positive linear correlation was reported between IL-6 and neutrophils during crises (Spearman correlation coefficient = 0.397, P = 0.03). These findings suggest that the levels of adhesion molecules and inflammatory markers and IRF, as evidenced by CD36-positive RBCs, IL-6 and IL-8, are elevated in SCA patients, both during steady state and crises, although these elevations are more marked during crises. Further knowledge about these cytokines and adhesion molecules will help in understanding the pathogenesis and improve therapy of SCA.

Spontaneous osteonecrosis of the jaw in a β-Thalassemia intermedia patient

The resultant anemia in hemoglobinopathies like thalassemia can lead to expansion of the bone marrow cavities due to compensatory hyperplasia. This article reports a case of spontaneous osteonecrosis of the left maxillary alveolus in a patient with β-Thalassemia intermedia. The area affected presented as areas of osteosclerosis on the radiographic examination and sequestrectomy of the left maxillary alveolus was performed after consultation with his hematologist. The exact pathogenesis for the osteonecrosis is unclear. One possible postulation for the cause of osteonecrosis in our case could be that the alveolar bone suffered ischemic infarction secondary to occlusion of the microvasculature within the expanded cancellous bone.