Prospective reevaluation of the association between thrombotic diathesis and legg-perthes disease

Network Analysis of Legg-Calve-Perthes Disease and Its Comorbidities

Background/Objectives: Legg-Calvé-Perthes disease (LCPD) is characterized by idiopathic avascular necrosis of the femoral head in children. There are several hypotheses regarding the cause of LCPD; however, the exact cause remains unclear. Studies on comorbidities can provide better insight into the disease. We aimed to perform a network analysis to identify the associations between LCPD and comorbidities. Methods: We analyzed patients aged ≤ 12 years with LCPD as defined by ICD-10 codes M91.1, M91.8, and M91.9 registered in the National Health Insurance Service cohort database from 2002 to 2015. A control group was designed using propensity score matching. Comorbidities were identified and network analysis was performed. The identified comorbidities were reclassified into clinical disease groups considering their clinical relevance, and a network map was created using odds ratios. Results: In total, 23 significant disease clusters were identified. Injury-related disease clusters with ICD-10 codes starting with "S" were the most frequent. They were reclassified into 11 disease groups based on clinical relevance. Among these, congenital deformities of hip (Q65) had the highest odds ratio. Congenital deformities of feet (Q66) and other anemia (D64) had a single association with LCPD in the comorbidity network analysis. Conclusions: We confirmed the association between LCPD and comorbidities using a network analysis. The LCPD comorbidity network identified in this study is expected to serve as the basis for future research on LCPD.

A retrospective study describing the acetabular consequences of Legg- Calve-Perthes disease

PURPOSE

Legg Calve Perthes disease (LCPD) is a paediatric hip disorder caused by ischemia of the femoral epiphysis, causing femoral head deformity when untreated. This study aims to determine if previously validated pelvic obliquity radiographic parameters, used for assessing acetabular retroversion in developmental dysplasia of the hip, are applicable to patients with LCPD and its prognostic value.

METHOD

A retrospective study of patients with Legg Calve Perthes disease was carried out, analysing 4 pelvic parameters: Ilioischial Angle, Obturator Index, Sharp's Angle and Acetabular Depth-Width Ratio (ADR). The differences between healthy and affected hips were studied, and subsequently, it was assessed whether these parameters have prognostic value in the disease outcome.

RESULTS

Statistically significant differences have been obtained in the ilioischial angle, obturator index and ADR, between the affected and healthy hip. However, only the Acetabular Depth-Width Ratio showed predictive value for the disease outcome.

CONCLUSION

Although this study revealed differences in pelvic parameters between healthy and diseased hips, with only the ADR showing statistical significance in the disease's evolution and prognosis, further studies with larger sample sizes are necessary.

Legg-Calvé-Perthes disease overview

Background

Legg–Calvé–Perthes Disease (LCPD) is a necrosis of the femoral head which affects the range of motion of the hips. Its incidence is variable, ranging from 0.4/100,000 to 29.0/ 100,000 children. Although LCPD was first described in the beginning of the past century, limited is known about its etiology. Our objective is to describe the main areas of interest in Legg–Calve–Perthes disease.

Methods

A review of the literature regarding LCPD etiology was performed, considering the following inclusion criteria: Studies reporting clinical or preclinical results. The research group carried out a filtered search on the PubMed and Science Direct databases. To maximize the suitability of the search results, we combined the terms ‘‘Perthes disease” OR “LCPD” OR “children avascular femoral head necrosis” with “diagnostic” OR “treatment” OR “etiology” as either key words or MeSH terms.

Results

In this article been described some areas of interest in LCPD, we include topics such as: history, incidence, pathogenesis, diagnosis, treatment and possible etiology, since LCPD has an unknown etiology.

Conclusions

This review suggests that LCPD has a multifactorial etiology where environmental, metabolic and genetic agents could be involved.

Is Legg-Calvé-Perthes Disease a Local Manifestation of a Systemic Condition?

BACKGROUND

Osteochondrosis includes numerous diseases that occur during rapid growth, characterized by disturbances of endochondral ossification. One example, Legg-Calvé-Perthes disease, is characterized by disruption of the blood supply to the femoral head epiphysis, and a systemic etiology often has been suggested. If this were the case, secondary osteochondroses at locations other than the hip might be expected to be more common among patients with Legg-Calvé-Perthes disease, but to our knowledge, this has not been evaluated in a nationwide sample.

QUESTIONS/PURPOSES

(1) Do patients with Legg-Calvé-Perthes disease have an increased prevalence of secondary osteochondroses at locations other than the hip? (2) Is the concept of Legg-Calvé-Perthes disease a systemic etiology supported by a higher prevalence of the metabolic diseases obesity and hypothyroidism?

METHODS

We designed a retrospective population-based cohort study with data derived from the Swedish Patient Registry (SPR). The SPR was established in 1964 and collects information on dates of hospital admission and discharge, registered diagnoses (categorized along the International Classification of Diseases [ICD]), and applied treatments during the entire lifetime of all Swedish citizens with high validity. Analyzing the time span from 1964 to 2011, we identified 3183 patients with an ICD code indicative of Legg-Calvé-Perthes disease and additionally sampled 10 control individuals per patient with Legg-Calvé-Perthes disease, matching for sex, age, and residence, resulting in 31,817 control individuals. The prevalence of secondary osteochondroses, obesity, and hypothyroidism was calculated separately for patients with Legg-Calvé-Perthes disease and control individuals based on the presence of ICD codes indicative of these conditions. Using logistic regression analysis, we compared the adjusted relative risk of having either of these conditions develop between patients with Legg-Calvé-Perthes disease and their matched control subjects. The mean followup was 26.1 years (range, 2.8-65 years).

RESULTS

The prevalence of secondary osteochondroses was greater among patients with Legg-Calvé-Perthes disease (3.11%) than among control subjects (0.31%), resulting in an increased adjusted risk of an association with such lesions in the patients (relative risk [RR], 10.3; 95% confidence interval [CI], 7.7-13.6; p < 0.001). When stratified by sex, we attained a similarly increased risk ratio for females (RR, 12.5; 95% CI, 6.1-25.8; p < 0.001) as for males (RR, 9.9; 95% CI, 7.3-13.5; p < 0.001). Patients with Legg-Calvé-Perthes disease had an increased adjusted risk of an association with obesity (RR, 2.8; 95% CI, 1.9-4.0; p < 0.001) or hypothyroidism (RR, 2.6; 95% CI, 1.7-3.8; p < 0.001) when compared with control subjects.

CONCLUSIONS

To our knowledge, this is the first population-based description of a robust association of Legg-Calvé-Perthes disease with osteochondroses at locations other than the hip, and we also found increased risk estimates for an association with obesity and hypothyroidism in patients with Legg-Calvé-Perthes disease. Our findings strengthen the hypothesis that Legg-Calvé-Perthes disease is the local manifestation of a systemic disease, indicative of an underlying common disease pathway that requires further investigation. Physicians should be aware that patients with Legg-Calvé-Perthes disease may present with secondary osteochondroses and metabolic comorbidities.

LEVEL OF EVIDENCE

Level III, prognostic study.

Legg-Calvé-Perthes disease

Current knowledge of the causes and risk factors of Legg-Calvé-Perthesdisease (LCPD) does not allow effective preventive strategies. The outcome in adulthood is usually good. Hip osteoarthritis rarely develops before 50 years of age. The risk of osteoarthrosis depends chiefly on the final degree of joint incongruence. Age at onset and the lateral pillar classification are the two main outcome predictors and serve to guide the surgical indications based on the studies by Herring's group. Non-operative treatment is not effective. In contrast, femoral varus osteotomy and Salter's innominate osteotomy provide good outcomes. In severe forms, however, combining these two techniques or performing a triple pelvic osteotomy seem preferable. Surgery is now performed considerably less often than in the past, as it is effective only in patients with lateral pillar group B or B/C disease with onset after eight years of age. In other situations, therapeutic abstention is recommended.

[Aseptic osteonecrosis in children and adolescents]

BACKGROUND

Aseptic osteonecrosis (AO) in children and adolescents has been described in all parts of the skeleton. The disease is presumed to be caused by local blood circulation disorders, the reasons for which are multifactorial and occur more often in times of stronger growth intensity.

DISEASE SEQUELAE

The disease leads to bone catabolism which can affect the epiphyses, metaphyses, apophyses, carpal and tarsal bones of the hands and feet. The more stretched the form alteration of the bone at the end of the diseases is, the earlier arthritic alterations occur due to the incongruence of the corresponding joint partner. If a growth plate is affected, a growth disorder can be the result.

DIAGNOSTICS AND THERAPY

The diagnostics and therapeutic measures are oriented to the site and extent of the disease and the age of the child. For early forms of AO magnetic resonance imaging (MRI) is the imaging method of choice. In recent years the medicinal therapy of AO has been described as an additional option. The disease lasts at least several months up to years and more commonly affects boys than girls with the exception of necrosis of the foot tarsals.

CONCLUSION

The early diagnosis and immediate initiation of adequate therapy which must take the age and stage of the disease into consideration, can reduce a possible joint destruction. Prostaglandin therapy, as an off label use, leads to a reduction of pain and improvement in mobility.

Histological confirmation and biological significance of cartilage canals demonstrated using high field MRI in swine at predilection sites of osteochondrosis

Cartilage canal vessels in epiphyseal cartilage have a pivotal role in the pathogenesis of osteochondrosis/osteochondritis dissecans. The present study aimed to validate high field magnetic resonance imaging (MRI) methods to visualize these vessels in young pigs. Osteochondral samples from the distal femur and distal humerus (predilection sites of osteochondrosis) of piglets were imaged post-mortem: (1) using susceptibility-weighted imaging (SWI) in an MRI scanner, followed by histological evaluation; and (2) after barium perfusion using µCT, followed by clearing techniques. In addition, both stifle joints of a 25-day-old piglet were imaged in vivo using SWI and gadolinium enhanced T1-weighted MRI, after which distal femoral samples were harvested and evaluated using µCT and histology. Histological sections were compared to corresponding MRI slices, and three-dimensional visualizations of vessels identified using MRI were compared to those obtained using µCT and to the cleared specimens. Vessels contained in cartilage canals were identified using MRI, both ex vivo and in vivo; their locations matched those observed in the histological sections, µCT images, and cleared specimens of barium-perfused tissues. The ability to visualize cartilage canal blood vessels by MRI, without using a contrast agent, will allow future longitudinal studies to evaluate their role in developmental orthopedic disease.

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

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

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

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

Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease is an idiopathic hip disorder that produces ischemic necrosis of the growing femoral head. Permanent femoral head deformity is the most significant sequela. Experimental studies indicate that the pathologic repair process, which is marked by an imbalance of bone resorption and formation, contributes to the pathogenesis of femoral head deformity. Important prognostic factors include degree of deformity, age at disease onset, extent of head involvement, head-at-risk signs, and lateral pillar collapse. Treatment should be guided by age at disease onset, current best evidence, and prognostic factors. Patients aged <6 years at onset are best managed nonsurgically, whereas older patients may benefit from surgical treatment. Good surgical results have been reported in 40% to 60% of older patients (>8 years), indicating the need to develop more effective treatments based on the pathobiology of the disease.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Coagulation abnormalities in Legg-Calvé-Perthes disease

BACKGROUND

Legg-Calvé-Perthes disease is a pediatric disorder characterized by osteonecrosis of the proximal femoral epiphysis. The etiology probably involves successive vascular occlusions, in which hypercoagulable disorders may play a role. We evaluated the etiologic role of thrombophilia in Legg-Calvé-Perthes disease in a pediatric population.

METHODS

One hundred and sixty-nine consecutive patients who had been diagnosed with Legg-Calvé-Perthes disease at two centers in Rotterdam, the Netherlands, when they were between 1.5 and 13.5 years of age were identified between 2000 and 2003. The study also included two control groups: 474 subjects (16.3 to 73.1 years of age) from a population-based case-control study on the etiology of venous thrombosis as well as thirty-eight children (1.8 to 18.8 years of age) who were treated for asthma at one of the centers. We determined levels of protein C, protein S, factor VIII, and fibrinogen and tested for the factor V Leiden and prothrombin G20210A mutations. We calculated age and sex-adjusted odds ratios as measures of the relative risk of the development of Legg-Calvé-Perthes disease.

RESULTS

The incidence of Legg-Calvé-Perthes disease was increased in the presence of the factor V Leiden mutation (odds ratio, 3.3; 95% confidence interval, 1.6 to 6.7), in the presence of the prothrombin G20210A mutation (odds ratio, 2.6; 95% confidence interval, 1.0 to 6.3), in association with elevated levels of factor VIII (>150 IU/dL) (odds ratio, 7.5; 95% confidence interval, 2.2 to 25.2), and in association with protein S deficiency (<67 U/dL) (odds ratio, 2.8; 95% confidence interval, 0.7 to 10.8). Neither high levels of fibrinogen (>4.0 g/L) nor protein C deficiency (< or =55 U/dL) had an apparent effect on the risk of Legg-Calvé-Perthes disease. (Odds ratios were adjusted for age and sex.) Overall, males had a 2.4 times higher risk of Legg-Calvé-Perthes disease developing than did females. The effect of the factor V Leiden mutation, high levels of fibrinogen, and increasing levels of factor VIII was stronger in males than in females. The risk of Legg-Calvé-Perthes disease increased with an increasing number of coagulation abnormalities in males but not in females.

CONCLUSIONS

There appears to be a thrombotic component in the etiology of Legg-Calvé-Perthes disease.

Fator V de Leiden na doença de Legg-Calvé-Perthes

Trobofilias hereditárias têm sido implicadas na patogênese da doenca de Legg-Calvé-Perthes. Uma investigação do fator de risco hereditário mais comum para hipercoagulabilidade - a mutação no gene do fator V (fator V de Leiden) - foi conduzida em 20 pacientes com Legg-Calvé-Perthes e 214 controles sadios. A prevalência do fator V de Leiden foi maior nos pacientes com Legg-Calvé-Perthes que no grupo controle (30 vs. 1,87%). A razão de chances (odds ratio) para o desenvolvimento de Legg-Calvé-Perthes foi de 22,5 (p<0,05; intervalo de confiança: 5,68- 89.07). Estes dados sugerem, o fator V de Leiden como fator de risco hereditário para hipercoagulabilidade associada ao desenvolvimento da doença de Legg-Calvé-Perthes.

Perthes' disease and the search for genetic associations: collagen mutations, Gaucher's disease and thrombophilia

The role of heritable thrombophilic risk factors in the pathogenesis of the Perthes' disease is controversial. The clinical and radiological findings of Perthes' disease may be indistinguishable from those of Gaucher's disease, and the most common Jewish N370S Gaucher mutation is threefold greater in patients with Perthes' disease. Familial osteonecrosis of the femoral head is associated with variant mutations of collagen type II (COL2A1 mutations). We therefore studied the potential role of genetic thrombophilia and the Gaucher and COL2A1 mutations in children with Perthes' disease. Genomic DNA of 119 children with radiologically-confirmed Perthes' disease diagnosed between 1986 and 2005 was analysed for the thrombophilic polymorphisms Factor V Leiden, 677T-MTHFR and FIIG20210A. The results were compared with those of a group of 276 children without Perthes' disease. DNA was also analysed for the Gaucher mutations N370S, G insertion (84GG), L444P, Intron 2 (IVS2+1G>A) and R496H. Enzymic assays confirmed the Gaucher disease status. Collagen (COL2A1) mutations of the 12q13 gene were also analysed. The prevalence of thrombophilic markers was similar among the 119 patients with Perthes' disease and the 276 control subjects. The prevalence of the Gaucher mutation was consistent with Israeli population carriership data and did not confirm an earlier-claimed association with Perthes' disease. All 199 patients were negative for the studied COL2A1 mutations. We found no genetic association between Perthes' disease and either Gaucher's disease or COL2A1 mutations or increased genetic thrombophilia among our patients compared with the control group. A systematic review of case-control studies suggested that there was a positive association between Perthes' disease and Factor V Leiden. The impact of this association upon the disease, although not consistent across the studies, remains unclear.

Legg-Calve-Perthes disease, venous and arterial thrombi, and the factor V Leiden mutation in a four-generation kindred

In a 4-generation kindred identified through a 12-year-old female proband with Legg-Calve-Perthes Disease (LCPD) who was found to be heterozygous for the G1691A factor V Leiden mutation (FV), our specific aim was to assess associations of FV with LCPD and with venous and arterial thrombotic events. Despite lethal thromboembolism in 3 family members at ages 21, 35, and 38, retinal artery thrombosis, and deep venous thrombosis, no family members had previously been studied for the FV mutation until kindred screening-genetic counseling was prompted by the discovery of the FV mutation in a child proband with LCPD.

METHODS

In a 4-generation kindred identified through a 12-year-old female proband with LCPD and found to be heterozygous for the FV mutation, we assessed the FV genotype and its association with thromboembolism in 14 of 16 living first- and second-degree relatives.

RESULTS

There was 3-generation vertical and horizontal transmission of heterozygosity for the FV mutation. Of 14 living first- and second-degree relatives, 10 were heterozygous for the FV mutation, including the proband's sister, mother, and maternal grandmother. Of the 14 living relatives, 2 had thrombotic events (retinal artery thrombosis and deep venous thrombosis of the leg). The proband's maternal great-grandfather had a lethal pulmonary embolus at age 35, as did her maternal great aunt at age 38, and a female third cousin at age 21.

CONCLUSIONS

In a large kindred identified by a child with LCPD who was found to have the FV mutation, FV heterozygosity was found in 3 generations of previously undiagnosed family members and was associated with venous and arterial thrombosis throughout the kindred. We suggest that FV mutation be studied in children with LCPD facilitate diagnosis and genetic counseling for thrombophilia in their parents, siblings, and other kindred members, and because the proband LCPD child with the FV mutation is at increased risk for other thromboembolic abnormalities as an adult.

LEVEL OF EVIDENCE

1.

Protein C levels in patients with Legg-Calve-Perthes disease: is it a true deficiency?

A hyper-coagulable state due to protein C deficiency has been postulated to be the cause of avascular necrosis of the capital femoral physes in Legg-Calve-Perthes disease (LCPD). In order to test this hypothesis, plasma protein C levels were analyzed from 51 unselected cases of LCPD. These were compared with a control group. Our findings showed that the levels were less than the mean for age in 38 (74.5%) of the cases, though were within the normal range. We conclude that clinical thrombosis could be triggered off in these susceptible individuals by prothrombotic insults such as passive smoking, ultimately leading to LCPD.

Legg-perthes disease and heritable thrombophilia

The etiology of Perthes' disease is unclear. Recent reports have suggested that inheritable thrombophilic disorders may be one of its pathogenetic causes. The G20210A prothrombin gene, factor V Leiden, and MTHFR C677T mutations have been identified as predisposing genetic factors for thrombosis. Ninety children diagnosed with Perthes' disease were studied. A family history of thrombosis and any other personal thromboembolic events were researched. PCR and endonuclease digestion were used to analyze factor V Leiden, prothrombin G20210A, and MTHFR C677T. Two hundred healthy donors were included as a control group. No patient had a family or personal history of early thrombotic events. Four children with Perthes' disease (4.4%) were heterozygous for G20210A polymorphism compared with controls (odds ratio: 2.07; 95% confidence interval: 0.40-8.46). No association between factor V Leiden and Perthes' disease was observed. Three patients (3.33%) were heterozygous for factor V Leiden (odds ratio: 1.36; 95% confidence interval: 0.32-5.84). The prevalence of different genotypes of C677T MTHFR did not show statistical differences compared with controls. Eleven patients were homozygous for this polymorphism (odds ratio: 1.02; 95% confidence interval: 0.42-2.44). This study does not support the screening of this group of polymorphism in patients with Perthes' disease.

Enhanced tissue factor pathway inhibitor response as a defense mechanism against ongoing local microvascular events of Legg-Calve-Perthes disease

The precise pathogenetic basis of Legg-Calve-Perthes disease (LCPD) is currently unknown. Hemostatic abnormalities, i.e., hypercoagulability and/or hypofibrinolysis, were proposed in the genesis of the LCPD. Deficiency of tissue factor pathway inhibitor (TFPI), a critical natural anticoagulant molecule, may lead to a prothrombotic state in a wide variety of conditions. The aim of this study is to assess the circulating TFPI pool in the LCPD. Group I consisted of 44 patients with LCPD and group II comprised 38 healthy children. Median (IQR) TPFI concentration was significantly higher in the group I (p < .0001). Enhanced TFPI response could be regarded as a compensatory defense mechanism against ongoing local microvascular events of occlusion and revascularization of LCPD. TFPI molecule may be an important link between the crossroads of the LCPD genesis and pathogenetic microvascular changes in the disease course. Further investigations are needed to shed light on the endothelial anticoagulant kinetics, the unique microvascular compromise, and the self-limiting nature of the disease.

Enoxaparin prevents progression of stages I and II osteonecrosis of the hip

In a prospective pilot study, we hypothesized that enoxaparin (60 mg/day for 12 weeks) would prevent progression of Stages I and II osteonecrosis of the hip associated with thrombophilia or hypofibrinolysis or both over > or = 108 weeks of followup versus untreated historic controls, with different treatment responses in primary versus corticosteroid-associated secondary osteonecrosis. Patients with one or more thrombophilic-hypofibrinolytic disorder and Ficat Stages I or II osteonecrosis of at least one hip were included. A blinded committee interpreted anteroposterior and frog-leg lateral radiographs at entry in the study and every 36 weeks to > or = 108 weeks. Maintenance of the disease at Stages I and II versus progression of the osteonecrosis to Stages III and IV requiring total hip replacement was the major end point. Sixteen patients had primary osteonecrosis (25 hips; 13 Stage I, 12 Stage II), and 12 had secondary osteonecrosis (15 hips; five Stage I, 10 Stage II). With no Enoxaparin-related complications, 19 of 20 hips (95%) with primary osteonecrosis were unchanged from Stages I and II osteonecrosis at > or = 108 weeks; 12 of 15 hips (80%) with secondary osteonecrosis progressed to Stages III and IV osteonecrosis. In primary osteonecrosis at > or = 108 weeks, survival of 95% hips, or 76% (19/25 hips, based on intent to treat), compared favorably with untreated historical controls (approximately 20% 2-year survival), comparable to 20% survival in secondary hip osteonecrosis. Enoxaparin may prevent progression of primary hip osteonecrosis, decreasing the incidence of total hip replacement.

LEVEL OF EVIDENCE

Therapeutic study, II-1 (prospective cohort study).

Evaluation of anticoagulant system in Turkish children with Perthes disease

BACKGROUND

Perthes Disease (PD) is generally a self-limiting disease of childhood but it causes severe pain and may lead to deformity of the femoral head. Intravascular thrombosis seems to form the main mechanism in the pathogenesis of the disease. The aim of this study was to determine hereditary thrombotic risk factors in Turkish children with PD.

METHODS

In 46 Perthes patients (35 male, 11 female), family history of thrombotic events was investigated, Protein C (PC), free-Protein S (f-PS), antithrombin (AT) activities, fibrinogen level, and resistance to activated Protein C (APC) were measured. The results were compared with a healthy control group of 79 children matched by age and sex. The relationship between the severity of disease and coagulation system abnormalities was evaluated.

RESULTS

While the mean PC and AT activities were significantly lower in the patients than those of the controls, the proportions of patients with low AT activity, resistance to APC, and a history of hereditary thrombophilia were significantly higher than those of the controls. No difference was observed in coagulation system disorders relative to severity of the disease and bilateral or unilateral disease involvement.

CONCLUSIONS

This study shows that a possible association between PD and inherited hypercoagulability. Determination of thrombotic risk factors in these patients may bring a new approach to the treatment. Most importantly, this may be a stimulant to take precautions for other thrombotic events, which patients may face later in life.

Factor V Leiden and the prothrombin 20210A gene mutation and osteonecrosis of the knee

INTRODUCTION

The pathogenesis behind osteonecrosis of the knee is still unknown. Circulatory impairment of the bone secondary to thrombosis in the microcirculation has been suggested as a mechanism. The purpose of this study was to examine the association between osteonecrosis of the knee and abnormalities in the thrombotic pathway in the form of factor V Leiden and the prothrombin 20210A gene mutation.

MATERIALS AND METHODS

Thirty-eight consecutive patients (13 men and 25 women) with osteonecrosis of the knee without a history of knee trauma or surgery to the knee were enrolled in this study. Assays for the detection of factor V Leiden and the prothrombin 20210A gene mutation were performed, and the results were compared with those from 282 healthy volunteers.

RESULTS

Six patients were diagnosed with secondary osteonecrosis, four corticosteroid-induced and two alcohol-induced. In 32 patients, no aetiological factor was found, and these patients were diagnosed with primary osteonecrosis of the knee. Twelve patients had 14 gene mutations, 11 factor V Leiden and 3 prothrombin 20210A gene mutations. Factor V Leiden and the prothrombin 20210A gene mutation occurred significantly (p=0.006) more frequently in patients with osteonecrosis than in a population of 282 healthy volunteers (odds ratio 3.1, 95%CI 1.4-6.6).

CONCLUSION

The results of this study suggest that coagulation abnormalities in the form of factor V Leiden and the prothrombin 20210A gene mutation might play a role in osteonecrosis of the knee.

Legg-Calve-Perthes disease and thrombophilia

BACKGROUND

Thrombophilia has previously been identified as a potential etiologic factor in Legg-Calve-Perthes disease. We prospectively studied the association between Legg-Calve-Perthes disease and coagulation abnormalities by comparing seventy-two children who had the disease with 197 healthy controls.

METHODS

A nonselected, consecutive series of seventy-two patients with Legg-Calve-Perthes disease (mean age [and standard deviation], 6.6 +/- 2.6 years) was studied in their order of referral and compared with 197 healthy controls (mean age, 7.6 +/- 5.1 years). Assays were done for factor-V Leiden, prothrombin G20210A, methylenetetrahydrofolate reductase C677T, and plasminogen activator inhibitor-1 4G/5G gene mutations. Levels of anticardiolipin antibodies immunoglobulin G and M (IgG and IgM), homocysteine, protein C, protein S, antithrombin III, and plasminogen activator inhibitor-1 were also measured.

RESULTS

The factor-V Leiden mutation was more common in the patients (eight of seventy-two) than in the controls (seven of 197) (chi-square = 5.7, p = 0.017). After we controlled for the false-discovery rate, the case-control difference remained significant (p = 0.017). The odds ratio for the development of Legg-Calve-Perthes disease in the presence of the factor-V Leiden mutation was 3.39 with a 95% confidence interval of 1.18 to 9.73. A high level of anticardiolipin antibodies (IgG and/or IgM) was found in nineteen of the seventy-two patients compared with twenty-two of the 197 controls (chi-square = 9.5, p = 0.002). After we controlled for the false-discovery rate, the case-control difference remained significant (p = 0.002). The odds ratio of patients with Legg-Calve-Perthes disease having one or more abnormalities in factor V, anticardiolipin antibody IgG, or anticardiolipin antibody IgM as opposed to normal values for all three variables was 3.29 (95% confidence interval, 1.73 to 6.24; p = 0.0003).

CONCLUSIONS

Two thrombophilic risk factors, the factor-V Leiden mutation and anticardiolipin antibodies, are associated with Legg-Calve-Perthes disease, an association that may reflect causality.

LEVEL OF EVIDENCE

Prognostic study, Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.

Smoking and socio-economic status in the etiology and severity of Legg-Calvé-Perthes' disease

BACKGROUND

The etiology of Legg-Calvé-Perthes disease is poorly understood. An association has been found in the past between Legg-Calvé-Perthes disease and smoking as well as low socio-economic status.

METHODS

A prospective study was carried out in which families with a child diagnosed with Legg-Calvé-Perthes' disease were interviewed about the presence and duration of household second-hand smoke exposure to children. A control group of randomly selected families seen at our institution were interviewed with identical questions. The radiographs of children with Legg-Calvé-Perthes disease were reviewed and classified according to the Herring lateral pillar classification system.

RESULTS

Thirty-eight of the 60 patients (63.3%) with Legg-Calvé-Perthes disease were noted to have at least one smoker living in the child's household with a mean of 1.03 smoker-years per year of life exposure to smoke. The median income of the patients with Legg-Calvé-Perthes disease was USD 20,300. The median income of the patients in the control group was USD 17,000. Thirty-eight of the 96 control patients (39.6%) were noted to have at least one smoker living in the child's household with a mean of 0.48 smoker-years per year of life. A significant association was noted between living with a smoker and Legg-Calvé-Perthes disease as well as between increasing smoke exposure and increased risk of developing Legg-Calvé-Perthes disease. No significant association was noted between lower income and Legg-Calvé-Perthes disease. There was no association between increased smoke exposure and increased severity of Legg-Calvé-Perthes disease as measured by the lateral pillar classification.

CONCLUSIONS

The presence of second-hand smoke seems to be a significant risk factor in the development of Legg-Calvé-Perthes disease. The presence of second-hand smoke may represent the 'unknown industrial factor' that has been discussed.