Sickle cell disease and silent avascular necrosis of the hip

Is cost of surgery and hospital length of stay increased for sickle cell disease patients undergoing total joint replacement surgeries? Systematic review and multivariate meta-analysis

Background

Sickle cell disease (SCD) patients undergo major joint replacement surgeries with significant improvement in quality of life. Previous literature have tried to explore differences in hospital charges and length of stay between patients with and without SCD. The aim of this meta-analysis is to find out if both outcomes are increased for patients with SCD patients compared to those without SCD.

Methods

Literature search was conducted and studies that compared hospital charges and length of stay between patients with and without sickle cell disease following major arthroplasties were retrieved. A multivariate meta-analysis was conducted using Random-Effect model with the Restricted Maximum Likelihood (REML) using the Metafor Package in R and Rstudio.

Results

Four observational studies were found eligible for the study. The estimated average mean difference based on the random effect model for hospital charges was 7548.50 (95 % CI: 3779.65 to 11317.65) and for length of stay was 2.28 (95 % CI: 1.32 to 3.24) while the prediction interval for the true mean difference for both outcomes were -1810.56 to 16907.56 and -0.01 to 4.57 respectively.

Conclusion

This present study showed that hospital charges and length of stay are increased for patients with SCD compared to patients without.

A Molecular Troika of Angiogenesis, Coagulopathy and Endothelial Dysfunction in the Pathology of Avascular Necrosis of Femoral Head: A Comprehensive Review

Avascular necrosis of the femoral head (ANFH) is a painful disorder characterized by the cessation of blood supply to the femoral head, leading to its death and subsequent joint collapse. Influenced by several risk factors, including corticosteroid use, excessive alcohol intake, hypercholesterolemia, smoking and some inflammatory disorders, along with cancer, its clinical consequences are thrombus formation due to underlying inflammation and endothelial dysfunction, which collaborates with coagulopathy and impaired angiogenesis. Nonetheless, angiogenesis resolves the obstructed free flow of the blood by providing alternative routes. Clinical manifestations of early stage of ANFH mimic cysts or lesions in subchondral bone, vasculitis and transient osteoporosis of the hip, rendering it difficult to diagnose, complex to understand and complicated to cure. To date, the treatment methods for ANFH are controversial as no foolproof curative strategy is available, and these depend upon different severity levels of the ANFH. From an in-depth understanding of the pathological determinants of ANFH, it is clear that impaired angiogenesis, coagulopathy and endothelial dysfunction contribute significantly. The present review has set two aims, firstly to examine the role and relevance of this molecular triad (impaired angiogenesis, coagulopathy and endothelial dysfunction) in ANFH pathology and secondly to propose some putative therapeutic strategies, delineating the fact that, for the better management of ANFH, a combined strategy to curtail this molecular triangle must be composed rather than focusing on individual contributions.

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.

Occult ischemic bone lesions in children with sickle cell disease: A study of prevalence

INTRODUCTION

Avascular necrosis (AVN) is a severe complication of sickle cell disease (SCD) and involves principally the femoral head. Few data exist about the prevalence of lesions in other segments.

METHODS

In this cross-sectional study, 42 children (20 males and 22 females) underwent a magnetic resonance imaging (MRI) of the spine, upper arms, and femurs. The primary outcome was to define the prevalence and locations of bone infarcts.

RESULTS

Forty-two patients completed the study; the total median age was 11.9 years (interquartile range = 9.5-13.9). Eleven patients (26.2%) were positive for altered bone findings for a total of 32 lesions. Most of the lesions were in the humerus 17 (53.1%), 11 (34.4%) in the femurs, and 4 (12.5%) in the vertebrae. The median number of vaso-occlusive crises (VOCs) was two and four for patients without and with bone lesions, respectively (p = .01). The annual rate of VOC is the best marker for the positive MRI (odds ratio = 82.6; p = .03), and it is correlated with the number of sites involved (p = .02).

CONCLUSIONS

Our study highlights that the prevalence of skeletal lesions could be underestimated, and it provides the basis for clinical reasoning and tailored therapy in SCD children.

Normal Bone Marrow and Non-neoplastic Systemic Hematopoietic Disorders in the Adult

This article provides an overview of the imaging appearances of normal adult bone marrow with an emphasis on magnetic resonance imaging. We also review the cellular processes and imaging features of normal developmental yellow-to-red marrow conversion and compensatory physiologic or pathologic red marrow reconversion. Key imaging features that differentiate between normal adult marrow, normal variants, non-neoplastic hematopoietic disorders, and malignant marrow disease are discussed, as well as posttreatment changes.

Clinical and laboratory characterization of adult sickle cell anemia patients in Kinshasa

BACKGROUND

Sickle cell anemia (SCA) is a monogenic hemoglobinopathy associated with severe acute and chronic complications, with the highest incidence worldwide in Sub-Saharan Africa. The wide variability in clinical manifestations suggest that a uniform response to hydroxurea may not be attained. In view of a potential treatment with hydroxyurea (HU), we assessed the variability of clinical and hematological manifestations in a cohort of adults with SCA in Kinshasa, capital of the DR Congo in Central Africa.

METHODS

A cross-sectional study was conducted in a hospital dedicated to SCA management in Kinshasa. Clinical history of patients was recorded, a complete physical examination performed. The diagnosis was confirmed by means of DNA analysis. A full blood count and hemolysis markers were measured. The severity of the disease was evaluated by means of a previously reported score.

RESULTS

The study group consisted of 166 genetically confirmed SCA patients. The SCA severity was mild in 28.9%, moderate in 64.5% and severe in 6.6%. The disease severity score increased with patient's age (p ≤ 0.001). The severity was higher in males compared to females (p = 0.012). In males, the severity score was correlated with the presence of priapism (p = 0.045), a manifestation not previously incorporated in the severity score. The severity score was inversely correlated with the fetal hemoglobin (HbF) rate (p = 0.005). Malnutrition (BMI <18.5 kg/m2) was present in 47% of patients and was related to the male sex, hip disease (aOR 3.11; p = 0.019) and severe phenotype (aOR 3.53; p = 0.012). Leg ulcers were more frequent in males than in females (p = 0.001; OR 24.3) and were correlated with the number of days of hospitalization (p = 0.029). Hip disease was related to the increasing age (p = 0.008).

CONCLUSION

In this selected, hospital-based populations of adults with SCA, severe disease was rare, which may be due to survival bias. However, two thirds had moderate severity of the disease, mostly with a low HbF, and they may benefit from HU treatment. In the Central-African setting the separation between vaso-occlusive and hyperhemolytic sub-phenotypes was not applicable.

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.

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.

Bone infarct transformation into undifferentiated pleomorphic sarcoma in sickle cell disease: A case report

•

Sickle cell disease pathophysiology.

•

Natural progression of a pre-existing bone infarct.

•

Malignant transformation of a pre-existing bone infarct.

•

A rare case describing malignant transformation of a pre-existing bone infarct in a known sickle cell anemia patient into malignancy in specific undifferentiated pleomorphic sarcoma.

Introduction

Avascular necrosis of the bone is a very common finding in sickle cell disease (SCD). The malignant transformation of a pre-existing bone infarct is extremely rare, only few cases has been reported related to different etiologies one of which is SCD.

Presentation of case

40 years old male, known to have SCD, he presented as a case of avascular necrosis of the left proximal femur. Upon further investigations the lesion has transformed into undifferentiated pleomorphic sarcoma also known as Malignant Fibrous Histiocytoma (MFH).

Discussion

The exact mechanism of the malignant transformation of bone infarcts is not fully understood and yet to be investigated. Few cases were reported in literature of similar malignant transformation of a pre-exciting bone infarct and only one was linked to SCD.

Conclusion

In reporting this case we hope that further cases worldwide will be reported. A high index of suspicion should be present when encountering bone infarct lesion with an unusual course.

Total Hip Arthroplasty in Patients With Sickle Cell Disease: A Comprehensive Systematic Review

BACKGROUND

Total hip arthroplasty (THA) is a common treatment for end-stage osteonecrosis of the hip in patients with sickle cell disease (SCD). This patient population presents unique challenges in the perioperative period. This systematic review aims to investigate the existing literature on the outcomes, complications, and survivorship of primary THA in SCD patients.

METHODS

A systematic search using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed of PubMed, MEDLINE, EMBASE, and Cochrane databases for clinical studies on THA in SCD patients. Studies on primary THA in SCD patients with a mean follow-up greater than 90 days were included.

RESULTS

Sixteen studies containing 5193 SCD patients met criteria for inclusion. The Coleman Quality of Evidence score ranged from poor to moderate. SCD patients had a significant increase in Harris Hip Scores and Merle d'Aubigne Scores after undergoing THA. Compared to non-SCD patients, SCD patients had increased hospital length-of-stay, 30-day and 90-day readmission rates, and rates of medical complications, including pain crises, acute chest syndrome, cardiac complications, sepsis, and mortality. SCD patients also had increased rates of surgical complications, including wound complications, infection, periprosthetic fracture, and aseptic loosening. Overall, THA revision rates were higher in SCD patients relative to those with primary osteoarthritis.

CONCLUSION

THA remains an effective treatment modality for osteonecrosis of the hip in SCD patients. However, these patients are at increased risk of medical and surgical complications. Surgeons should be aware of the unique challenges in this patient population when counseling and managing these patients in the perioperative period.

Spectrum of common and uncommon causes of knee joint hyaline cartilage degeneration and their key imaging features

Hyaline cartilage lining the surfaces of diarthrodial joints is an important construct for transmission of load and to reduce friction between the bones. Normal wear and tear accounts for about 3-5 percent knee cartilage loss ever year in otherwise healthy people after the age of 30 years. Several conditions and diseases lead to premature cartilage degeneration. Standardized description of cartilage loss, detailed evaluation of the joint health and determining the underlying etiology of cartilage loss are important for effective reporting, multidisciplinary communications and patient management. In this article, the authors discuss normal and abnormal imaging appearances of the hyaline cartilage of knee with focus on using controlled terminology and MRI classifications. The reader will benefit and learn key MR imaging features of a spectrum of common and uncommon conditions and diseases affecting the knee cartilage, such as trauma, secondary injury associated with meniscus and ligament injury related instability, arthritis, ischemia, idiopathic, and hereditary conditions including Matrix metalloproteinase-2 (MMP-2) mutations and mucopolysaccharidosis type IX disease with illustrative case examples.

Sickle cell disease: Clinical presentation and management of a global health challenge

Sickle cell disease is an autosomal recessive, multisystem disorder, characterised by chronic haemolytic anaemia, painful episodes of vaso-occlusion, progressive organ failure and a reduced life expectancy. Sickle cell disease is the most common monogenetic disease, with millions affected worldwide. In well-resourced countries, comprehensive care programs have increased life expectancy of sickle cell disease patients, with almost all infants surviving into adulthood. Therapeutic options for sickle cell disease patients are however, still scarce. Predictors of sickle cell disease severity and a better understanding of pathophysiology and (epi)genetic modifiers are warranted and could lead to more precise management and treatment. This review provides an extensive summary of the pathophysiology and management of sickle cell disease and encompasses the characteristics, complications and current and future treatment options of the disease.

Risk of avascular necrosis of the femoral head in children with sickle cell disease on hydroxyurea: MRI evaluation

BACKGROUND

There are conflicting reports on the role of hydroxyurea (HU) in the pathogenesis of avascular necrosis of the femoral head (AVNFH) in patients with sickle cell disease (SCD).

PROCEDURE

The present study is a prospective cohort study of Kuwaiti children with SCD who were treated with HU. They had magnetic resonance imaging of the hips before starting HU and at regular intervals during a follow-up period, ranging from 1 to 15 years.

RESULTS

There were 40 patients (18 SS, 19 Sβ0-thalassemia, and three SD genotypes), aged 6-20 years. Pre-HU, 11 (27.5%) had varying grades of AVNFH, while post HU, the prevalence was 32.5%. Two patients developed new lesions during the study, while five (45.5%) that had lesions pre-HU remained static, another five (45.5%) progressed, and one (9%) improved radiologically. The older patients who had been on HU the longest were more likely to deteriorate. The only hematological parameter that was consistently associated with AVNFH was the reticulocyte count.

CONCLUSIONS

The frequency and rate of progression of AVNFH in this study is much less than that previously reported for our patients not treated with HU. There is no evidence that HU therapy is a risk factor for AVNFH. It may, in fact, prevent new lesions and deter the progression of existing AVNFH.

Orthopaedic Manifestations of Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive disorder that results in hemolytic anemia related to abnormal hemoglobin and erythrocyte levels. SCD is characterized by vascular occlusive episodes, visceral sequestration, and aplastic or hemolytic crises. These crises most commonly occur in bone. The orthopaedic manifestations of SCD comprise much of the morbidity associated with this disorder. Osteonecrosis and osteomyelitis are among the most disabling and serious musculoskeletal complications in patients with SCD. Effective management of the bone and joint sequelae requires an accurate diagnosis, an understanding of the pathophysiology of the disease, and knowledge of available medical and surgical treatment alternatives. The major orthopaedic manifestations of SCD are osteonecrosis, osteomyelitis, septic arthritis, and bone infarction. Patients with SCD require close monitoring in the perioperative period because of the risk for vasoocclusive crisis.

Symptomatic Avascular Necrosis: An Understudied Risk Factor for Acute Care Utilization by Patients with SCD

OBJECTIVES

Sickle cell disease (SCD) is associated with high healthcare utilization rates and poor outcomes in a subset of patients, although the underlying factors that predict this phenotype are poorly understood. Prior studies suggest that comorbid avascular necrosis (AVN) contributes to high healthcare utilization. We sought to clarify whether AVN independently predicts acute care utilization in adults with SCD and to identify characteristics of those with AVN that predict higher utilization.

METHODS

We reviewed the medical records of 87 patients with SCD with symptomatic AVN and compared acute care utilization and clinical characteristics with 87 sex- and age-matched patients with SCD without symptomatic AVN. Patients with ≥2 years of follow-up were included. Outcomes were compared using bivariate analysis and multivariate regression.

RESULTS

Our study included 1381 follow-up years, with a median of 7 years per patient. The AVN cohort had greater median rates of urgent care visits (3.2/year vs 1.3/year; P = 0.0155), admissions (1.3/year vs 0.4/year; P = 0.0002), and admission days (5.1 days/year vs 1.8 days/year; P = 0.0007). History of high utilization (odds ratio [OR] 4.28; P = 0.001), acute chest syndrome (OR 3.12; P = 0.005), pneumonia (OR 3.20; P = 0.023), hydroxyurea therapy (OR 2.23; P = 0.0136), and long-term transfusion (OR 2.33; P = 0.014) were associated with AVN. In a median regression model, AVN, acute chest syndrome, and pneumonia were independently associated with greater urgent care visits and admissions.

CONCLUSIONS

Symptomatic AVN was found to be an independent risk factor for acute care utilization in patients with SCD. Because this is a potentially modifiable factor, further studies are urgently needed to determine whether AVN prevention/early treatment interventions will alter utilization and improve outcomes for patients with SCD.

Hemoglobin to Hematocrit Ratio: The Strongest Predictor of Femoral Head Osteonecrosis in Children With Sickle Cell Disease

BACKGROUND

Femoral head osteonecrosis (ON) secondary to sickle cell disease (SCD) often progresses to femoral head collapse, requiring total hip arthroplasty. However, this treatment has a limited durability and patients with SCD have higher rates of complications, requiring multiple revision operations. Identifying risk factors linked to ON in SCD can facilitate earlier precollapse diagnosis and surgical treatment aimed at preservation of the native hip joint.

METHODS

Fifty-nine children treated at our institution between January 2001 and April 2012 with SCD and ON, as diagnosed by magnetic resonance imaging or radiographic imaging, were compared with age-matched and sickle cell phenotype-matched (SS, SC, Sβ, Sβ) controls with no evidence of ON. Two sided t-tests assuming unequal variances determined statistically risk factors and threshold values were assigned to calculate odds ratios.

RESULTS

Systolic blood pressure (P=1.2×10, OR=3.68), diastolic blood pressure (P=0.0084, OR=1.41), weight in the SCD-SS population (P=0.04, OR=1.85), and hemoglobin (Hb) in the SCD-SS population (P=0.036, OR=2.56) were elevated in cases. Curiously, dividing the Hb by the hematocrit to serve as a clinical proxy for the mean corpuscular Hb concentration (MCHC) produced an excellent predictor of ON (P=2.06×10, OR=5.17), which was especially pronounced in the SCD-SS subpopulation (P=2.28×10, OR=8.65). Among children with SCD, the overall prevalence of ON was 9% (59/658) and the phenotype with the highest prevalence of ON was Sβ thalassemia with an ON prevalence of 11.1%. There was no observed correlation between ON and height, body mass index, cholesterol, mean corpuscular volume, hematocrit, or glucocorticoid use.

CONCLUSIONS

These data support a novel clinical marker, the MCHC proxy, as the strongest predictor of ON in children with SCD. High-risk children should receive hip magnetic resonance imaging to diagnose early ON and facilitate interventions focused on hip preservation, forestalling, or possibly preventing, the need for total hip arthroplasty.

Microarchitectural and mechanical characterization of the sickle bone

Individuals with sickle cell disease often experience acute and chronic bone pain due to occlusive events within the tissue vasculature that result in ischemia, necrosis, and organ degeneration. Macroscopically, sickle bone is identified in clinical radiographs by its reduced mineral density, widening of the marrow cavity, and thinning of the cortical bone due to the elevated erythroid hyperplasia accompanying the disease. However, the microstructural architecture of sickle bone and its role in mechanical functionality is largely unknown. This study utilized micro-CT and biomechanical testing to determine the relationship between the bone morphology, tissue mineral density, and trabecular and cortical microarchitecture of 10- and 21-week-old femurs from transgenic sickle male mice and littermates with sickle trait, as well as a wild-type control. While bone tissue mineral density did not vary among the genotypes at either age, variation in bone microstructure were observed. At 10 weeks, healthy and trait mice exhibited similar morphology within the cortical and trabecular bone, while sickle mice exhibited highly connected trabeculae. Within older femurs, sickle and trait specimens displayed significantly fewer trabeculae, and the remaining trabeculae had a more deteriorated geometry based on the structure model index. Thinning of the cortical region in sickle femurs contributed to the displayed flexibility with a significantly lower elastic modulus than the controls at both 10- and 21-weeks old. Wild-type and trait femurs generally demonstrated similar mechanical properties; however, trait femurs had a significantly higher modulus than sickle and wild-type control at 21-weeks. Overall, these data indicate that the progressive damage to the microvasculature caused by sickle cell disease, results in deleterious structural changes in the bone tissue׳s microarchitecture and mechanics.

Short term results of cementless total hip arthroplasty in sicklers

BACKGROUND

Sickle cell (SC) disease leading to endarteritis induces skeletal changes in the form of osteitis, sclerosis of femoral canal and osteonecrosis of the femoral head. All these make total hip arthroplasty (THA) difficult and prolonged. There is increased risk of infection, SC crisis and increased complication rate. Our paper aims to highlight preoperative, intraoperative and postoperative hurdles encountered in performing THA in sicklers and the short term outcome using cementless implants.

MATERIALS AND METHODS

Thirty-nine patients with SC disease, who had osteonecrosis of the femoral head, were operated between 2007 and 2011. The mean age of patients was 22 years (range 13-49 years). There were twenty eight females and 11 males. Bilateral cementless total hip replacement (THR) was performed in 11 patients (22 hips) and in the rest unilateral (28 hips). Preoperative and postoperative modified Harris hip score was evaluated. The average followup was 3.8 years (range 2-6 years).

RESULTS

The average operating time was 96 min (range 88-148 min). The average blood loss was 880 ml (range 650-1200 ml). The average intraoperative blood transfused was 2.3 units (range 2-5 units). All patients showed an improvement in Harris hip score from 42 points preoperatively to 92 points at latest followup. Intraoperatively, one patient had a periprosthetic fracture. Six patients developed acute SC crisis and were managed in intensive care unit. Three patients developed wound hematoma. Three patients developed limb length discrepancy less than 1 cm. None had early or late dislocations, infection, heterotopic ossification, sciatic nerve palsy and aseptic loosening.

CONCLUSION

THA in sicklers involves considerable challenge for the orthopedic surgeon. Management requires a multidisciplinary approach involving the anesthetist, hematologist and the orthopedic surgeon. Contrary to previous reports, THA in sicklers now has a predictable outcome especially with the use of cementless implants.

[Atraumatic hip pain in young adults]

Hip pain in the young adult is a disabling pathophysiological process may be related to multiple etiologies. The process must be determined in order to make a diagnosis and follow-up treatment. The case is presented of a 29 year old woman with anemia, atraumatic hip pain on the right side, and a limp of one month onset. The differential diagnosis includes infectious, rheumatological, tumor, avascular necrosis of hip, hip impingement, hip dysplasia, osteoarthritis and other syndromes.

Microparticles as biomarkers of osteonecrosis of the hip in sickle cell disease

Osteonecrosis of the femoral head (ONFH) is a common complication of sickle cell disease (SCD). To examine the association between microparticles and ONFH in SCD, we compared plasma microparticle levels in 20 patients with and without ONFH. Microparticles were quantified using nanoparticle tracking analysis and found to be 2·3-fold higher in patients with ONFH compared to patients without ONFH, and 2·5-fold higher than in healthy controls. These results suggest that microparticles may be a clinically useful biomarker of ONFH in SCD. Further investigations are needed to determine the functional relevance of microparticles in the pathogenesis of ONFH in SCD.

Sickle cell disease: management options and challenges in developing countries

Sickle Cell Disease (SCD) is the most common genetic disorder of haemoglobin in sub-Saharan Africa. This commentary focuses on the management options available and the challenges that health care professionals in developing countries face in caring for patients with SCD. In a developing countries like Ghana, new-born screening is now about to be implemented on a national scale. Common and important morbidities associated with SCD are vaso-occlusive episodes, infections, Acute Chest Syndrome (ACS), Stroke and hip necrosis. Approaches to the management of these morbidities are far advanced in the developed countries. The differences in setting and resource limitations in developing countries bring challenges that have a major influence in management options in developing countries. Obviously clinicians in developing countries face challenges in managing SCD patients. However understanding the disease, its progression, and instituting the appropriate preventive methods are paramount in its management. Emphasis should be placed on early counselling, new-born screening, anti-microbial prophylaxis, vaccination against infections, and training of healthcare workers, patients and caregivers. These interventions are affordable in developing countries.

Tuberculous spondylodiscitis in a patient with a sickle-cell disease: CT findings

Background:

Although sickle-cell anemia (SCA) is common in black Americans, Sub-Saharan Africa and in the Mediterranean area, the disease is rare in the temperate climate zone. The manifestations of the disease are related mainly to the production of abnormal hemoglobin that leads to organ ischemia and increased susceptibility to infection caused by functional asplenia.

Case Report:

The authors present CT findings in a 39-year-old black woman diagnosed due to abdominal pain, lymphadenopathy and fever. CT of the thorax and abdomen demonstrated changes in the liver, spleen, and skeletal system suggestive of SCA complicated with spondylodiscitis in the thoracic spine.

Discussion:

Hepatomegaly and small calcified spleen are typical findings in older homozygotic patients with SCA. The lesions in the skeleton may be related either to intramedullary hematopoiesis or osteonecrosis and osteomyelitis. In the latter case, diffuse osteosclerosis and H-shaped vertebrae are most typical. Tuberculous spondylodiscitis is characterized by the location in the thoracic region, preferential involvement of anterior elements, relative sparing of intervertebral discs, and cold abscesses.

The role of hypercoagulability in the development of osteonecrosis of the femoral head

Despite the large number of the outstanding researches, pathogenesis of osteonecrosis remains unknown. During the last decades the hypothesis that increased intravascular coagulation may be the pathogenetic mechanism which leads to osteonecrosis is gaining constantly support. Both primary factors of hyper-coagulability, such as resistance to activated protein C, protein C and protein S deficiency, low levels of tissue plasminogen activator, high levels of plasminogen activator inhibitor, von Willebrand factor, lipoprotein (a), and secondary factors of hypercoagulability with factors potentially activating intravascular coagulation, such as pregnancy, antiphospholipid antibodies, systemic lupus erythematosus, hemoglobinopathies and sickle cell disease, and hemato-oncologic diseases are discussed in this article. Although coagulation abnormalities in patients with hip osteonecrosis might represent increased risk factors for the development of bone necrosis by predisposing the patient to thromboembolic phenomena, further investigation is needed to indicate the definite correlation between factors leading to increased intravascular coagulation and pathogenesis of osteonecrosis.

Osteonecrosis in children after allogeneic hematopoietic cell transplantation: study of prevalence, risk factors and longitudinal changes using MR imaging

Osteonecrosis after hematopoietic SCT (HCT) has seldom been addressed in pediatric populations. At our institution, since January 2002, children undergoing allogeneic HCT (alloHCT) receive yearly follow-up magnetic resonance imaging (MR) of hips and knees. To estimate the prevalence, longitudinal changes and associated risk factors for osteonecrosis after alloHCT, we reviewed MRs for children who underwent single alloHCT during the study period. We analyzed 149 of 344 patients who had post-HCT MR imaging performed (84 males; median age 11 years (range, 0.5-21 years)), median follow-up time was 32.6 months (range, 2.8-97.2 months). In all, 44 (29.5%) developed osteonecrosis of hips and/or knees; of those, 20 (45%) had at least 30% epiphyseal involvement. In 23 (52%), osteonecrosis lesions were identified in the first and in 43 (98%) by the third yearly scan. Knees were more frequently involved than hips; severity of osteonecrosis was greater in hips. Those who had pre-alloHCT osteonecrosis, two patients' hips and six patients' knees resolved completely; three patients' osteonecrosis lesions regressed after alloHCT. On risk factor analysis, age at time of alloHCT (P=0.051) and osteonecrosis identified by MRs before alloHCT (P=0.001) were the primary risk factors. This analysis shows that preventive strategies for osteonecrosis in this population should focus on measures to minimize risk factors before alloHCT.

Osteonecrosis in children after allogeneic hematopoietic cell transplantation: study of prevalence, risk factors and longitudinal changes using MR imaging

Osteonecrosis after hematopoietic stem cell transplantation (HCT) has seldom been addressed in pediatric populations. At our institution, since January 2002, children undergoing allogeneic HCT (alloHCT) receive yearly follow-up magnetic resonance imaging (MR) of hips and knees. To estimate the prevalence, longitudinal changes and associated risk factors for osteonecrosis after alloHCT, we reviewed MRs for children who underwent single alloHCT during the study period. We analyzed 149 of 344 patients who had post HCT MRI imaging performed [84 males; median age11 years (range, 0.5–21years)], median follow-up time was 32.6 months (range, 2.8–97.2 months). Forty-four (29.5%) developed osteonecrosis of hips and/or knees; of those, 20 (45%) had at least 30% epiphyseal involvement. In 23 (52%) osteonecrosis lesions were identified in the first, and 43 (98%) by the third yearly scan. Knees were more frequently involved than hips; severity of osteonecrosis was greater in hips. Those who had pre-alloHCT osteonecrosis, two patients’ hips and six patients’ knees resolved completely; three patients’ osteonecrosis lesions regressed after alloHCT. On risk factor analysis, age at time of alloHCT (p=0.051) and osteonecrosis identified by MRs before alloHCT (p=0.001) were the primary risk factors. This analysis shows that preventive strategies for osteonecrosis in this population should focus on measures to minimize risk factors before alloHCT.

The impact of a multidisciplinary pain management model on sickle cell disease pain hospitalizations

BACKGROUND

Sickle cell disease (SCD) pain is acute or chronic, leads to school absenteeism, impaired health-related quality of life and early mortality. Given that little is known about children with SCD and chronic pain, we (1) described characteristics of these children and (2) evaluated the impact of a multidisciplinary pain management model on health care utilization.

PROCEDURE

A retrospective cohort study of children with SCD evaluated and treated in our institution's multidisciplinary pain clinic between 1999 and 2008 was conducted. Referrals occur when children require chronic opioids and/or have frequent pain hospitalizations. Descriptive statistics evaluated patient characteristics and Wilcoxon-Signed Rank evaluated change in median number of pain hospitalizations 1 year before and after referral.

RESULTS

Median age of 19 children identified was 15 years (IQR 11-17); significantly more were female (78.9% vs. 21.1%; P = 0.012). At time of referral, all patients reported taking opioids, 68.4% were taking hydroxyurea, half of those not on hydroxyurea started it (n = 3), none were chronically transfused and one initiated transfusions upon referral. Majority (89.5%) learned non-pharmacologic pain management techniques. Median number of pain hospitalizations between the year before and after referral significantly decreased [5(IQR 3-6) to 1(IQR 0-4); P = 0.006]. To further delineate the pain clinic's effect, analysis was repeated after removing children initiating hydroxyurea/transfusions upon referral. The significant decrease in hospitalizations persisted [5(IQR 3-6) to 1(IQR 0-4; P = 0.022].

CONCLUSIONS

A multidisciplinary pain management model appears to have decreased SCD pain hospitalizations. Results of this retrospective study will need to be tested in a prospective randomized trial.

Musculoskeletal manifestations of sickle cell anaemia: a pictorial review

Sickle cell anaemia is an autosomal recessive genetic condition producing abnormal haemoglobin HbS molecules that result in stiff and sticky red blood cells leading to unpredictable episodes of microvascular occlusions. The clinical and radiological manifestations of sickle cell anaemia result from small vessel occlusion, leading to tissue ischemia/infarction and progressive end-organ damage. In this paper we discuss and illustrate the various musculoskeletal manifestations of sickle cell disease focusing primarily on marrow hyperplasia, osteomyelitis and septic arthritis, medullary and epiphyseal bone infarcts, growth defects, and soft tissue changes.

Spectrum of musculo-skeletal disorders in sickle cell disease in Lagos, Nigeria

BACKGROUND

Sickle cell anemia (SCA) is a common genetic disease in Nigeria. Past studies from West Africa focused on isolated aspects of its medical and surgical presentations. To the best of our knowledge, the musculo-skeletal presentations amongst Nigerians with SCA have not been documented in a single all encompassing study. This work aims to prospectively document the musculo-skeletal disease burden among SCA patients.

METHODS

In a prospective study of 318 consecutive patients with genotype-confirmed SCA at the Lagos University Teaching Hospital (LUTH), the musculo-skeletal pathologies, anatomic sites, grade of disease, age at presentation and management outcome were recorded over a one-year period. Data obtained were analyzed using Epi-Info software version 6.0. Data are presented as frequencies (%) and mean values (SD) as appropriate.

RESULTS

The HbSS genotype occurred in 296 (93.0%), while 22 (7.0%) were HbSC. 100 (31.4%) patients with average presenting haemoglobin concentration of 8.2 g/100 ml in the study group, presented with 131 musculo-skeletal pathologies in 118 anatomic sites. Osteomyelitis 31 (31%) and septic arthritis 19 (19%) were most commonly observed in children less than 10 years. Skin ulcers and avascular necrosis (AVN) occurred predominantly in the older age groups, with frequencies of 13 (13.0%) and 26 (26.0%) respectively. 20 (71.5%) of diagnosed cases of AVN presented with radiological grade 4 disease. The lower limbs were involved in 84 (71.1%) of sites affected. Lesions involving the spine were rare 11 (0.9%). Multiple presentations occurred in 89 (28.0%) of patients; 62 (69.7%) of which were children below 10 years.

CONCLUSIONS

Musculo-skeletal complications are common features of sickle cell anaemia seen in 31.4%. Infectious aetiologies predominate with long bones and joints of lower limbs more commonly affected by osteomyelitis and septic arthritis. Healthcare providers managing SCA should be aware of the potential morbidity and mortality of these conditions to ensure early diagnosis and adequate management.

Treatment of sickle cell disease's hip necrosis by core decompression: a prospective case-control study

INTRODUCTION

The young age of patients, total arthroplasties complications risks, and implant costs justify evaluation of the results of core decompression in the treatment of sickle-cell disease avascular necrosis of the femoral head (ONFH).

HYPOTHESIS

In sickle-cell disease necrosis, core decompression offers good relief from pain and delays the use of total arthroplasty in comparison to a conservatively treated control group by a simple non-weight bearing protocol.

MATERIALS AND METHODS

From 1994 to 2008, among 215 drepanocytic adults, 42 patients (22 genotype SS, 20 genotype SC; 15 men, 27 women) presented symptomatic ONFH. We report the data from a prospective study of two patients' groups: a non-operated group (16 patients aged 36.5+/-6.5 years, 23 hips) and an operated group (26 patients aged 30.3+/-2.8 years, 42 hips). The results were considered on the basis of change in clinical status according to the numeric evaluation of pain scale, the functional score of Merle d'Aubigné-Postel (MAP), the radiological progression of lesions, and the time delay to total arthroplasty.

RESULTS

Twenty-three hips were conservatively treated by discharge (a pair of canes). After a follow-up period of 13.4+/-0.5 years, no pain improvement was noted (p=0.76), and MAP score was unchanged (p=0.27). Out of 23 hips managed by discharge, 9 stage IV hips (degenerative arthritis, 39.1%) underwent arthroplasty after an average delay of 2.6+/-2.4 years. Forty-two hips were treated by core decompression. The duration of follow-up was 11.3+/-1.8 years. Postoperatively, pain reduction and MAP score improvement were significant in 39 out of 42 hips (93%, p<0.0001). Twenty-nine out of these 42 hips had a favorable evolution. Ten hips (23.8%) progressed to total arthroplasty, after a period of 7.4+/-2.7 years, longer than the one of the non-operated group (p=0.0007). By comparing the two groups (operated and non-operated), the benefit of core decompression appeared very significant (p<0.0001). In addition to allocating patients osteonecrosis stages, the Koo and Kim Index estimated the severity and evolution of necrotic lesions in both groups. It indicated decline in the non-operated group (p=0.002) and improvement for operated patients (p=0.0002).

DISCUSSION

Core decompression had a favorable clinical and radiological outcome superior to surgical abstention. Stages I and II ONFH remained stable after drilling, necessitating no arthroplasty (considered as a failure of drilling). The Koo and Kim Index above 30 degrees in the non-operated group was a significant indicator of lesions degradation (p=0.002). In addition to the indolence obtained by core decompression, the benefit of drilling was manifested by the prolonging the adjournment before arthroplasty end-point. It was respectively 7.4+/-2.7 years in the operated group versus 2.6+/-2.4 years in the non-operated group (difference of 4.8 years, p<0.01).

CONCLUSION

The technique of core decompression remains a valid option place in the treatment sickle-cell disease avascular necrosis of the femoral head (ONFH). It may be especially recommended in under-equipped regions where drepanocytosis and its osteo-articular complications are frequent.

LEVEL OF EVIDENCE

Level III case-control therapeutic study.

Sickle cell disease in North Europe

The numbers of patients with sickle cell disease in Northern Europe are steadily increasing due to migration, leading to a need for improved healthcare services for these patients. We outline the role of neonatal and antenatal screening programmes in the diagnosis of sickle cell disease, clinical aspects of care and the therapeutic options available. The clinical areas discussed in detail are pain management, the management of stroke and other neurological complications and the management of pulmonary and splenic complications. The role of hydroxyurea, blood transfusion and bone marrow transplantation are also discussed.

Managing femoral head osteonecrosis in patients with sickle cell disease

With an increasing number of people immigrating between different countries, sickle cell disease (SCD) is spreading all over the world. Due to improved health care, the life span of SCD patients has increased and many of them live to adulthood and middle-age. Osteonecrosis of the femoral head is one of the most common musculo-skeletal problems in SCD patients. Once osteonecrosis starts in the femoral head, it can progress from early to late stages in just a few years. Managing osteonecrosis of the femoral head in young-adults is a challenging problem and, in many situations, it requires major surgical procedures. In the early stages of the disease it is advisable to treat it by femoral head preserving procedures. In advanced stages, hip replacement arthroplasty (HPA) is indicated. In SCD patients, the incidence of operative complications and failure rates are higher than that for osteonecrosis due to other causes. Understanding the problems of SCD patients; appropriate diagnosis, prognosis, implications of the procedure performed and taking the necessary precautions, can reduce the complications and delay the failure of surgical procedures.

Musculoskeletal Manifestations of Sickle Cell Disease

Sickle cell disease results from the presence of abnormal beta globin chains within hemoglobin and may be manifested in anemia, vaso-occlusion, and superimposed infection. The gene that causes sickle cell disease is particularly prevalent in populations of African origin; approximately 8% of African Americans and 40% of the members of some African tribes carry the gene for hemoglobin S. Over time, the disease produces various musculoskeletal abnormalities as a result of chronic anemia; these include marrow hyperplasia, reversion of yellow marrow to red marrow, and, occasionally, extramedullary hematopoiesis. Familiarity with the imaging features of sickle cell disease is important for the diagnosis and management of complications. Ischemia and infarction are common complications that may have long-term effects on the growth of bone; these conditions have characteristic radiographic appearances. Infection may be more difficult to identify. Both infection and infarction may occur in muscle and soft tissue alone, without involving bone. However, osteomyelitis must be diagnosed early and treated immediately to prevent bone destruction and deformity; therefore, care must be taken to achieve an accurate diagnosis by identifying or excluding bone involvement. The clinical and radiographic features of acute osteomyelitis may be particularly difficult to distinguish from those of bone infarction. In that context, magnetic resonance (MR) imaging may be useful. At MR imaging, findings of cortical defects, adjacent fluid collections in soft tissue, and bone marrow enhancement are suggestive of infection.

Bone involvement in sickle cell disease

Bone involvement is the commonest clinical manifestation of sickle cell disease both in the acute setting such as painful vaso-occlusive crises, and as a source of chronic, progressive disability such as avascular necrosis. Management of these problems is often difficult because of the diagnostic imprecision of most laboratory and imaging investigations and because of the lack of evidence for most surgical procedures in sickle cell disease. This review first discusses the acute problems related to bone involvement in sickle cell disease, with particular reference to differentiating infection from infarction, and then describes the long-term effects of sickle cell disease on bone mineral density, growth, and chronic bone and joint damage.

MRI follow-up and natural history of avascular necrosis of the femoral head in Kuwaiti children with sickle cell disease

PURPOSE

: To document the MRI progression and the natural history of avascular necrosis of the femoral head (AVNFH) in Arab children with sickle cell disease.

PATIENTS AND METHODS

Twenty-three SS and 7 SbetaThal patients (aged 6-17 years) were screened for AVNFH between 1998 and 1999. Eight (26.7%) were identified with varying degrees of AVNFH. Seventeen of the original 30 patients have now been followed for 1 to 4 (mean 2.0 +/- 1.2) years, with repeat MRI of the hips. Spin-echo T1-and T2-weighted images and T2 fat-saturation sequences were obtained using a 1.5-Tesla GE unit with superconductors. AVNFH was graded I (mild), II (moderate), or III (severe).

RESULTS

Eleven (64.7%) of the 17 patients had significant progression of their lesions; at the initial study, 9 were normal, 7 were grade I, 1 was grade II, and none was grade III. At the end of the follow-up period, two were normal, seven were grade I, one was grade II, and seven were grade III. Of the nine who were initially normal, two still had no lesions, while four were grade I and three were grade III on follow-up. Of the seven who were classified as grade I initially, four remained at grade I, one moved to grade II, and two became grade III. The one patient who was initially grade II progressed to III.

CONCLUSIONS

AVNFH is a common, chronic, and unrelenting complication in children with sickle cell disease, and it is usually progressive.

Slipped capital femoral epiphysis in a child with sickle cell disease

Slipped capital femoral epiphysis in a child with sickle cell disease has not been reported previously. The diagnostic challenges, role of imaging techniques, and the medical treatment of this patient are discussed. The presentation of acute hip or leg pain in a child with sickle cell disease should alert the treating physician to the possibility of a vaso-occlusive crisis as the likely source of the child's pain. The goal of the current case report is to emphasize the need to maintain a high index of suspicion for other potential causes of hip, thigh, or knee pain such as slipped capital femoral epiphysis in an adolescent. Preoperative and postoperative care for a child with sickle cell disease needs to be modified to minimize the risks of vaso-occlusive complications.

Pathogenesis and natural history of osteonecrosis

BACKGROUND AND OBJECTIVES

Osteonecrosis (avascular necrosis) is a relatively common disorder seen by both rheumatologists and orthopedic surgeons. The vast majority of cases are secondary to trauma. However, for non-traumatic cases, there often remains a diagnostic challenge in defining the cause of bone death. The goal of this article is to review data extensively in the medical literature with respect to the pathogenesis of osteonecrosis, its natural history, and treatment.

METHODS

A review of 524 studies on osteonecrosis was performed, of which 213 were selected and cited.

RESULTS

Non-traumatic osteonecrosis has been associated with corticosteroid usage, alcoholism, infections, hyperbaric events, storage disorders, marrow infiltrating diseases, coagulation defects, and some autoimmune diseases. However, a large number of idiopathic cases of osteonecrosis have been described without an obvious etiologic factor. Although corticosteroids can produce osteonecrosis, careful history is always warranted to identify other risk factors. The pathogenesis of non-traumatic osteonecrosis appears to involve vascular compromise, bone and cell death, or defective bone repair as the primary event. Our understanding of the pathogenesis of osteonecrosis is now much better defined and skeletal scintigraphy and magnetic resonance imaging have enhanced diagnosis greatly. Early detection is important because the prognosis depends on the stage and location of the lesion, although the treatment of femoral head osteonecrosis remains primarily a surgical one.

CONCLUSIONS

Osteonecrosis has been associated with a wide range of conditions. Many theories have been proposed to decipher the mechanism behind the development of osteonecrosis but none have been proven. Because osteonecrosis may affect patients with a variety of risk factors, it is important that caregivers have a heightened index of suspicion. Early detection may affect prognosis because prognosis is dependent on the stage and location of the disease. In particular, the disease should be suspected in patients with a history of steroid usage, especially in conjunction with other illnesses that predispose the patient to osteonecrosis.

RELEVANCE

A better understanding of the pathophysiology, diagnosis and treatment of osteonecrosis will help the physician determine which patients are at risk for osteonecrosis, facilitating early diagnosis and better treatment options.

Sickle cell disease

Sickle cell disease is a serious and life threatening disease that affects approximately 1 in 600 African-Americans. Since its first description in 1910 by Herrick, our understanding and treatment of this disease has grown tremendously. Most pediatricians will encounter one or more children with sickle cell disease and should have a thorough understanding of the disease, its complications, and treatment. This article summarizes present day knowledge about the complications and potential treatments for patients with sickle cell disease.

The comprehensiveness care of sickle cell disease

Millions of people across the world have sickle cell disease (SCD). Although the true prevalence of SCD in Europe is not certain, London (UK) alone had an estimated 9000 people with the disorder in 1997. People affected by SCD are best managed by a multidisciplinary team of professionals who deliver comprehensive care: a model of healthcare based on interaction of medical and non-medical services with the affected persons. The components of comprehensive care include patient/parent information, genetic counselling, social services, prevention of infections, dietary advice and supplementation, psychotherapy, renal and other specialist medical care, maternal and child health, orthopaedic and general surgery, pain control, physiotherapy, dental and eye care, drug dependency services and specialist sickle cell nursing. The traditional role of haematologists remains to co-ordinate overall management and liase with other specialities as necessary. Co-operation from the affected persons is indispensable to the delivery of comprehensive care. Working in partnership with the hospital or community health service administration and voluntary agencies enhances the success of the multidisciplinary team. Holistic care improves the quality of life of people affected by SCD, and reduces the number as well as length of hospital admissions. Disease-related morbidity is reduced by early detection and treatment of chronic complications. Comprehensive care promotes awareness of SCD among affected persons who are encouraged to take greater control of their own lives, and achieves better patient management than the solo efforts of any single group of professionals. This cost-effective model of care is an option for taking haemoglobinopathy services forward in the new millennium.

Sickle cell anemia

Sickle cell anemia (SCA) is a disease caused by production of abnormal hemoglobin, which binds with other abnormal hemoglobin molecules within the red blood cell to cause rigid deformation of the cell. This deformation impairs the ability of the cell to pass through small vascular channels; sludging and congestion of vascular beds may result, followed by tissue ischemia and infarction. Infarction is common throughout the body in the patient with SCA, and it is responsible for the earliest clinical manifestation, the acute pain crisis, which is thought to result from marrow infarction. Over time, such insults result in medullary bone infarcts and epiphyseal osteonecrosis. In the brain, white matter and gray matter infarcts are seen, causing cognitive impairment and functional neurologic deficits. The lungs are also commonly affected, with infarcts, emboli (from marrow infarcts and fat necrosis), and a markedly increased propensity for pneumonia. The liver, spleen, and kidney may experience infarction as well. An unusual but life-threatening complication of SCA is sequestration syndrome, wherein a considerable amount of the intravascular volume is sequestered in an organ (usually the spleen), causing vascular collapse; its pathogenesis is unknown. Finally, because the red blood cells are abnormal, they are removed from the circulation, resulting in a hemolytic anemia. For the patient with SCA, however, the ischemic complications of the disease far outweigh the anemia in clinical importance.

Osteonecrosis induced by a single administration of low-dose lipopolysaccharide in rabbits

We succeeded in developing a novel rabbit model of nonsteroid and nontraumatic osteonecrosis (ON) by use of a single- and low-dose lipopolysaccharide (LPS) injection. This model is simple and highly reproducible for the frequent development of multifocal and widespread ON lesions. Male adult Japanese white rabbits intravenously injected with a single injection of 10 microg/kg body weight of LPS were histopathologically examined in the early phase (3 [n = 3], 5 [n = 3], and 24 h [n = 3]) and at 4 weeks (n = 22). Seventy-seven percent of the rabbits developed multifocal ON 4 weeks after LPS injection. ON was also observed in the femoral and humeral condyle. The average percentage of necrotic area/total area examined was 86.7 +/- 29.1% and 78.8 +/- 16.7% in the proximal one third of both the femoral and humeral bones, respectively. Organized thrombi in the intraosseous small-sized arteries and arterioles were frequently seen in and around the necrotic tissues. In the early phase, LPS treatment prominently induced thrombocytopenia, hyperlipidemia, and increased plasma levels of plasminogen activator inhibitor-1 (PAI-1). The plasma level of PAI-1 was significantly higher in the rabbits with ON than in those without ON (p < 0.01). The immunohistochemical expression of tissue factor was exaggerated in monocytes/macrophages and adipocytes in both the femoral and humeral bones of the LPS-treated rabbits. Histologically, marrow necrosis and fibrin thrombi could be observed at 24 h. In addition, pretreatment with an anticoagulant, warfarin potassium, significantly decreased the incidence of LPS-induced ON (33%, n = 9, p < 0.05) associated with elongation of prothrombin time. The results of our study show that a single administration of low-dose lipopolysaccharide induces multifocal and widespread ON characterized by the pathophysiological participation of hypercoagulability in ON development. Therefore, this model would be useful for elucidating the pathogenesis of nonsteroid ON in humans especially inflammatory hypercoagulability-induced as well as for developing preventive and therapeutic strategies.

Frequency of the 677 C-->T mutation of the methylenetetrahydrofolate reductase gene among Kuwaiti sickle cell disease patients

Sickle cell disease (SCD) is relatively mild among Kuwaiti Arabs. However, an atypical subset of patients exists with frequent, severe vaso-occlusive crisis and osteonecrosis. The thermolabile variant of MTHFR, resulting from a C-->T mutation at nucleotide 677, has been shown to be associated with hyperhomocysteinemia, which is an important risk factor for premature vascular disease. We have screened an unselected group of 41 Kuwaiti SCD patients (33 SS and 8 Sbeta(0)-thal) attending the Hematology Clinic of Kuwait University Teaching Hospital for the MTHFR mutation, using a PCR-RFLP method. The patients were aged 2-41 years (mean of 12.8 +/- 8.6). One (2.4%) individual was homozygous for the mutation while 15 (36.6%) were heterozygous, giving an allele frequency of 20.7%. Twenty-one patients (14 SS and 7 Sbeta(0)-thal) were screened for osteonecrosis using MRI of the hip (spin-echo T1- and T2-weighted images). Seven (33.3%) had varying degrees of osteonecrosis, among whom the frequency of the 677 C-->T allele was 21.4%. The frequency was identical among those without osteonecrosis. Although the allele frequency is higher among our patients compared to American SS patients, our results do not suggest an association with osteonecrosis.

Core decompression in avascular necrosis of the hip in sickle-cell disease

Sickle-cell disease (SCD) is the most common cause of avascular necrosis (AVN) of the hip in childhood. It results in significant physical impairment and chronic pain, and often progresses to require hip replacement. Conservative therapy is ineffective. We evaluated whether core decompression can arrest progression of AVN. We performed 13 coring procedures in 10 patients with SCD and AVN. Patients ranged from age 9-21 years at diagnosis (mean, median age, 15 years); five hips were stage I, six hips were stage II, and two hips were stage III. Mean follow-up on these patients was 3.7 years. Efficacy of the procedure was evaluated by clinical improvement in pain, radiographic progression, and need for further surgery. All 5 stage I patients had substantial improvement in pain, and only one showed X-ray progression. Five of the 6 (83%) stage II patients had improvement in pain, and 2 patients progressed on X-ray. Both stage III patients progressed on X-ray, but one was clinically improved. None of the 10 patients has required further surgery. Our results demonstrate that in early AVN, core decompression was beneficial for almost all patients, even with progression on X-ray. Core decompression should be considered in the management of SCD patients with early AVN.

Osteonecrosis: current perspectives on pathogenesis and treatment

Nontraumatic osteonecrosis results from impairment of circulation to the affected bone. The femoral head is affected most frequently. The underlying cause for the circulatory defect in osteonecrosis varies and may involve both local and systemic changes. Steroid use, alcohol consumption, pancreatitis, and lipid disorders appear to lead to bone death either by development of fat emboli in the microcirculature surrounding the affected bone or by fatty infiltration of the marrow. Decompression syndrome results from the presence of gaseous emboli in the microcirculature. In Legg-Calvé-Perthes disease other associated features are present such as short stature, suboptimal growth velocity, and/or hormonal imbalances, and it is likely that osteonecrosis may be secondary to systemic abnormalities, although specific factors have not been identified. Other frequently suggested pathogenic factors that play a role in the development of osteonecrosis include increased intraosseous pressures, the presence of cytotoxic cellular factors, intravascular coagulation, venous stasis, and the hyperviscosity syndrome. Some investigators have attempted, without success, to find a common etiology for all cases of osteonecrosis. In addition, patients have developed osteonecrosis without any known risk factors; this syndrome has been coined idiopathic avascular necrosis. In advanced stages of femoral head osteonecrosis, total hip arthroplasty appears to be the best therapeutic modality, particularly in older individuals.