Anticoagulant therapy for osteonecrosis associated with heritable hypofibrinolysis and thrombophilia

Identification of hub genes and therapeutic drugs in osteonecrosis of the femoral head through integrated bioinformatics analysis and literature mining

Osteonecrosis of the femoral head (ONFH) is a multifactorial disease leading to severely limited function. By far, the etiology and pathogenesis of ONFH are not fully understood, and surgery is the only effective way to treat ONFH. This study aims to identify hub genes and therapeutic drugs in ONFH. Two gene expression profiles were downloaded from the gene expression omnibus database, and the hub genes and candidate drugs for ONFH were identified through integrated bioinformatics analysis and cross-validated by literature mining. A total of 159 DEGs were identified. PTGS2, LRRK2, ANXA5, IGF1R, MCL1, TIMP2, LYN, CD68, CBL, and RUNX2 were validated as 10 hub genes, which has considerable implications for future genetic research and related research fields of ONFH. Our findings indicate that 85 drugs interact with ONFH, with most drugs exhibiting a positive impact on ONFH by promoting osteogenesis and angiogenesis or inhibiting microcirculation embolism, rather than being anti-inflammatory. Our study provides novel insights into the pathogenesis, prevention, and treatment of ONFH.

Osteonecrosis of the Jaws in Patients with Hereditary Thrombophilia/Hypofibrinolysis-From Pathophysiology to Therapeutic Implications

Osteonecrosis of the jaws (ONJ) usually has a clear etiology. Local infection or trauma, radiotherapy and drugs that disrupt the vascular supply or bone turnover in the jaws are its major contributors. The thrombotic occlusion of the bone’s venous outflow that occurs in individuals with hereditary thrombophilia and/or hypofibrinolysis has a less known impact on jaw health and healing capability. Our research provides the most comprehensive, up-to-date and systematized information on the prevalence and significance of hereditary thrombophilia and/or hypofibrinolysis states in ONJ. We found that hereditary prothrombotic abnormalities are common in patients with ONJ refractory to conventional medical and dental treatments. Thrombophilia traits usually coexist with hypofibrinolysis traits. We also found that frequently acquired prothrombotic abnormalities coexist with hereditary ones and enhance their negative effect on the bone. Therefore, we recommend a personalized therapeutic approach that addresses, in particular, the modifiable risk factors of ONJ. Patients will have clear benefits, as they will be relieved of persistent pain and repeated dental procedures.

Osteonecrosis of the Femoral Head in Patients with Hypercoagulability-From Pathophysiology to Therapeutic Implications

Osteonecrosis of the femoral head (ONFH) is a debilitating disease with major social and economic impacts. It frequently affects relatively young adults and has a predilection for rapid progression to femoral head collapse and end-stage hip arthritis. If not diagnosed and treated properly in the early stages, ONFH has devastating consequences and leads to mandatory total hip arthroplasty. The pathophysiology of non-traumatic ONFH is very complex and not fully understood. While multiple risk factors have been associated with secondary ONFH, there are still many cases in which a clear etiology cannot be established. Recognition of the prothrombotic state as part of the etiopathogeny of primary ONFH provides an opportunity for early medical intervention, with implications for both prophylaxis and therapy aimed at slowing or stopping the progression of the disease. Hereditary thrombophilia and hypofibrinolysis are associated with thrombotic occlusion of bone vessels. Anticoagulant treatment can change the natural course of the disease and improve patients' quality of life. The present work focused on highlighting the association between hereditary thrombophilia/hypofibrinolysis states and ONFH, emphasizing the importance of identifying this condition. We have also provided strong arguments to support the efficiency and safety of anticoagulant treatment in the early stages of the disease, encouraging etiological diagnosis and prompt therapeutic intervention. In the era of direct oral anticoagulants, new therapeutic options have become available, enabling better long-term compliance.

Management of osteonecrosis of the femoral head

Aims

Earlier studies dealing with trends in the management of osteonecrosis of the femoral head (ONFH) identified an increasing rate of total hip arthroplasties (THAs) and a decreasing rate of joint-preserving procedures between 1992 and 2008. In an effort to assess new trends in the management of this condition, this study evaluated the annual trends of joint-preserving versus arthroplasties for patients aged < or > 50 years old, and the incidence of specific operative management techniques.

Methods

A total of 219,371 patients with ONFH were identified from a nationwide database between 1 January 2009 and 31 December 2015. The mean age was 54 years (18 to 90) and 105,298 (48%) were female. The diagnosis was made using International Classification of Disease, Ninth revision, Clinical Modification (ICD-9-CM) and Tenth Revision, Clinical Modification (ICD-10-CM) procedure codes. The percentage of patients managed using each procedure during each year was calculated and compared between years. The trends in the use of the types of procedure were also evaluated.

Results

The rate of joint-preserving procedures was significantly higher in patients aged < 50 years compared with those aged > 50 years (4.93% vs 1.52%; p < 0.001). For the overall cohort, rates of arthroplasty were far greater than those for joint-preserving procedures. THA was the most commonly performed procedure (291,114; 94.03%), while osteotomy (3,598; 1.16%), partial arthroplasty (9,171; 2.96%), core decompression (1,200; 0.39%), and bone graft (3,026; 0.98%) were performed markedly less frequently. The annual percentage of patients managed using a THA (93.56% to 89.52%; p < 0.001), resurfacing (1.22% to 0.19%; p < 0.001), and osteotomy (1.31% to 1.05%; p < 0.001) also decreased during the study period.

Conclusion

We found that patients with ONFH have been most commonly managed with non-joint-preserving procedures. Our findings provide valuable insight into the current management of this condition and should increase efforts being made to save the hip joint. Cite this article: Bone Joint J 2020;102-B(7 Supple B):122–128.

Prevalence of glucocorticoid induced osteonecrosis in the mouse is not affected by treatments that maintain bone vascularity

Objective

Determine if LLP2A-Ale or PTH (1–34) affects the prevalence of glucocorticoid-induced osteonecrosis (ON) in a mouse model.

Methods

Eight-week-old young adult male BALB/cJ mice were weight-randomized into Control (Con), glucocorticoid (GC)-only, or concurrent treatments with GC and LLP2A-Ale (250 μg/kg or 500 μg/kg, IV, Days 1, 14, 28) or parathyroid hormone hPTH (1–34) (40 μg/kg, 5×/week). Mice were necropsied after 45 days for qualitative evaluation of prevalent ON and quantitative evaluation of vascularity in the distal femoral epiphysis (DFE); and quantitative evaluation of bone mass, microarchitecture, and strength in the distal femoral metaphysis and lumbar vertebral body.

Results

The prevalence of ON was 14% in the Con group and 36% in the GC-only group (P = 0.07). The prevalence of ON did not differ among GC-only, GC + LLP2A-Ale, and GC + PTH groups. GC-only mice had significantly lower trabecular and cortical bone strength than Con, while GC + LLP2A-Ale (500 μg/kg) and GC + PTH (1–34) groups had significantly greater trabecular bone strength than the GC-only group. GC + LLP2A-Ale (250 μg/kg and 500 μg/kg) and GC + PTH had significantly higher trabecular bone volume than GC-only mice at the vertebrae, distal femoral epiphyses and distal femoral metaphyses. DFE vascularity was lower in GC-only mice than in all other groups.

Conclusion

Neither LLP2A-Ale nor hPTH (1–34) reduced the prevalence of GC-induced ON, compared to GC-only mice. However, GC-treated mice given LLP2A-Ale or hPTH (1–34) had better bone mass, microarchitecture, and strength in trabecular-rich regions, and higher levels of vascularity than GC-only mice.

Combined pharmacotherapy for osteonecrosis of the femoral head after severe acute respiratory syndrome and interstitial pneumonia: two and a half to fourteen year follow-up

PURPOSE

The purpose of this study was to retrospectively analyze the clinical, functional, and radiological outcomes of combined pharmacotherapy to ONFH after high-dose corticosteroid therapy.

METHOD

From August 2003 to June 2015, five patients (ten hips) of ONFH in ARCO stage I, after SARS and Interstitial pneumonia, were treated by combined pharmacotherapy. Lipo-prostaglandin E₁ 10 μg iv Bid × 28 days, enoxaparin 6000 iu H QD × 12 weeks, alendronate sodium tablet 10 mg QD × 1 year. The patients were fully weight-bearing following completion of the follow-up.

RESULT

For these five patients (ten hips), Harris score was 100 from the diagnosis to final follow-up time. Radiologic findings show no signs of collapse, necrotic focus was repaired, and ARCO stages were changed from I_C into II_B.

CONCLUSION

This combined pharmacotherapy has promising treatment results for delaying or preventing collapse of ONFH in ARCO stage I.

T786C Mutation in the Endothelial Nitric Oxide Synthase Gene in Patients With Primary Osteonecrosis

Mutations in the T786C endothelial nitric oxide synthase gene (eNOS) are associated with osteonecrosis and Prinzmetal's angina. Nitric oxide is necessary for bone health and ameliorates Prinzmetal's angina. This study compared mutations of T786C eNOS in 146 patients with primary osteonecrosis, 114 patients with Prinzmetal's angina, and 83 normal control subjects. Patients with osteonecrosis had more mutant eNOS alleles than control subjects (42% vs 22%, respectively; P<.0001) but had the same number of mutant alleles as patients with Prinzmetal's angina (42% vs 41%, respectively; P=.7), who in turn had more mutant eNOS alleles than control subjects (41% vs 22%, respectively; P=.0001). Of 146 patients with primary osteonecrosis, 65 (45%) had none of the 5 thrombophilias (Factor V Leiden heterozygosity, high levels of Factors VIII and XI, anticardiolipin antibody immunoglobulin M, and homocysteine) that otherwise distinguished patients with osteonecrosis from control subjects (P<.05). No associations were found between eNOS hetero-homozygosity and the 5 major thrombophilias in primary osteonecrosis. Of the 65 patients who had osteonecrosis but no major thrombophilias, for 41 (28% of the total sample of 146), eNOS hetero-homozygosity was the only abnormality. Normalization of nitric oxide levels with l-arginine 9 g/d or l-citrulline 800 mg/d, both of which relieve vasospastic angina in Prinzmetal's angina, which has the same eNOS genotype as primary osteonecrosis, may slow or stop the progression of osteonecrosis. Placebo-controlled trials of patients with primary osteonecrosis who are hetero-homozygous for the T786C eNOS mutation and have no major thrombophilias are needed to assess the safety and efficacy of this treatment. [Orthopedics. 2017; 40(5):e898-e903.].

Role of coagulopathy in glucocorticoid-induced osteonecrosis of the femoral head

The two major theories of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) are apoptosis and ischaemia. The traditional theory implicates ischaemia as the main aetiological factor because the final common pathway of ONFH is interruption of blood supply to the bone. The most common causes of interruption of blood supply include fat embolism and coagulation disorders. GCs can directly or indirectly lead to coagulation disorders, producing a hypercoagulable state, followed by poor blood flow, ischaemia, and eventually ONFH. This review summarizes the existing knowledge on coagulation disorders in the context of GC-induced ONFH, including hypofibrinolysis and thrombophilia, endothelial cell dysfunction and damage, endothelial cell apoptosis, lipid metabolism, platelet activation, and the effect of anticoagulant treatment.

Diagnostic ramifications of ocular vascular occlusion as a first thrombotic event associated with factor V Leiden and prothrombin gene heterozygosity

AIM

This study aimed to assess the diagnostic ramifications of vascular occlusion of the ocular vein and artery as a first thrombotic event associated with factor V Leiden (FVL) and/or prothrombin gene (PTG) heterozygosity.

METHODS

Patients with ocular vein (n=191) and artery (n=74) occlusion, free of cardioembolic etiologies, were sequentially referred from vitreoretinal specialists for measurement of thrombophilia-hypofibrinolysis and compared to 110 healthy normal controls.

RESULTS

Of the 265 patients, 29 (11%; 17 women, 12 men) of all referred ocular vascular occlusion (OVO) cases were found to be heterozygous for FVL and/or PTG, including 16 with FVL, 12 with PTG, and 1 with both. Of the 29 cases, 16 had central retinal vein occlusion (CRVO), 2 branch retinal vein occlusion (BRVO), 5 nonarteritic anterior ischemic optic neuropathy (NA-AION), 3 retinal artery occlusion (RAO), 2 amaurosis fugax (AF), and 1 had both CRVO and RAO. Of the 16 FVL cases, 15 (94%) had OVO as a first thrombotic event without prior deep venous thrombosis (DVT) or pulmonary embolism (PE); 6 (38%) also had other thrombotic events, including recurrent miscarriage, osteonecrosis, ischemic stroke, and/or ischemic colitis; and 5 (31%) had immediate family members with previous venous thromboembolism (VTE). Of the 12 PTG cases, 9 (75%) had OVO as a first thrombotic event, 5 (42%) experienced VTE other than DVT or PE, and 6 (50%) had immediate family members with VTE. In one patient with both FVL and PTG, DVT occurred before BRVO. Of the 17 women with FVL and/or PTG mutations, 7 (41%) experienced ≥1 miscarriage, 6 (35%) were on estrogen therapy, and 1 (6%) was on clomiphene.

CONCLUSION

Of the 265 patients with OVO, 29 (11%) had FVL and/or PTG, and 83% of these 29 cases presented with OVO as their first thrombotic event. By diagnosing thrombophilia as an etiology for OVO, the ophthalmologist opens a window to family screening and preventive therapy.

Management of femoral head osteonecrosis: Current concepts

Osteonecrosis of femoral head (ONFH) is a disabling condition of young individuals with ill-defined etiology and pathogenesis. Remains untreated, about 70-80% of the patients progress to secondary hip arthritis. Both operative and nonoperative treatments have been described with variable success rate. Early diagnosis and treatment is the key for success in preserving the hip joint. Once femoral head collapses (>2 mm) or if there is secondary degeneration, hip conservation procedures become ineffective and arthroplasty remains the only better option. We reviewed 157 studies that evaluate different treatment modalities of ONFH and then a final consensus on treatment was made.

Medical treatment of osteonecrosis of the knee associated with thrombophilia-hypofibrinolysis

In 6 patients with stage II knee osteonecrosis, all 6 with thrombophilia and 4 with concurrent hypofibrinolysis, the authors prospectively determined whether anticoagulation with enoxaparin could prevent collapse and progression to osteoarthritis, ameliorate pain, and restore function. The 6 patients were treated with enoxaparin (40 to 60 mg/d for 3 or more months) as mandated by a US Food and Drug Administration-approved protocol. In post-enoxaparin prospective follow-up, patients were reassessed clinically every 4 to 6 months, and radiographs were obtained every year. The 6 patients followed up at 15.1, 7.5, 3.9, 2.25, 2, and 1 year, respectively. None progressed to joint collapse or severe osteoarthritis. Four became and remained asymptomatic at 2-, 3.9-, 7.5-, and 15.1-year follow-up, respectively. A fifth patient did not progress to collapse or severe osteoarthritis but had residual pain at 2.25-year follow-up. The sixth patient had no symptomatic benefit on enoxaparin but improved on rivaroxaban at 1-year follow-up. Two patients had recurrences of knee pain 1 and 4 years after their initial treatment with enoxaparin. One resolved after a second course of enoxaparin, and the other, with a second recurrence 1 year after the second course, resolved after a third course. Pretreatment, all 6 patients required canes, crutches, or wheelchairs, but after enoxaparin, no patient required them, and walking was unrestricted. Thrombophilia-hypofibrinolysis contributes to the pathogenesis of knee osteonecrosis. Thrombophilic-hypofibrinolytic patients with stage II knee osteonecrosis treated with enoxaparin have had no collapse or progression to severe osteoarthritis, and most have had resolution of pain and restoration of full function. This represents a major improvement compared with the natural history of untreated spontaneous knee osteonecrosis.

Treatment of femoral head osteonecrosis in the United States: 16-year analysis of the Nationwide Inpatient Sample

BACKGROUND

Many surgical interventions are used to treat osteonecrosis of the femoral head. The instance and distribution of these various procedures may give some insight into the practicing community's understanding of the efficacy of these treatments. We therefore sought to determine trends in the types and numbers of procedures performed for atraumatic osteonecrosis from 1992 through 2008 in the United States.

QUESTIONS/PURPOSES

(1) How has the overall incidence of surgical treatment for atraumatic osteonecrosis changed over this time period; and (2) how has the percentage of THA performed for osteonecrosis (compared with joint-preserving procedures) changed over this time period?

METHODS

The Nationwide Inpatient Sample database was used to collect information for all patients who had an International Classification of Diseases, 9(th) Revision diagnosis of hip osteonecrosis between 1992 and 2008. Procedures were collated according to frequency, and trends were analyzed for joint-preserving and joint-replacing procedures.

RESULTS

The total number of procedures performed over this time period for osteonecrosis of the hip increased from 3570 procedures to 6400 procedures per year. In 1992, 75% (n = 2678) of the procedures performed to treat osteonecrosis of the hip were THA, which increased to 88% (n = 5632) in 2008. The percentage of joint-preserving procedures consequently decreased from 25% to 12% over this period.

CONCLUSIONS

Previously, THA was believed to have poor survivorship and clinical results for the treatment of osteonecrosis of the hip, but reports since 1993 have suggested improved survivorship of these reconstructions. Our study suggests that surgeons have incorporated this into their practice patterns, in that an increasing percentage of patients with this diagnosis are treated with THA. Additionally, the total number of procedures performed for osteonecrosis has increased, which may reflect an improved awareness of this disease and more aggressive approaches to diagnosis and treatment.

Thrombophilia, hypofibrinolysis, the eNOS T-786C polymorphism, and multifocal osteonecrosis

BACKGROUND

We examined the hypothesis that thrombophilia, hypofibrinolysis, and the endothelial nitric oxide synthase (eNOS) T-786C polymorphism are common, potentially treatable, and similar pathophysiologic causes of multifocal (three sites or more) and unifocal (single-site) osteonecrosis.

METHODS

We prospectively evaluated twenty-six consecutively referred adults with multifocal osteonecrosis, who included thirteen with idiopathic multifocal osteonecrosis and thirteen with secondary multifocal osteonecrosis (resulting from steroid therapy in ten and alcoholism in three). We compared these patients with race, sex, and age-matched normal control subjects and with patients with idiopathic unifocal and secondary unifocal osteonecrosis, respectively. Using polymerase chain reaction and serologic measures, we studied thrombophilic and hypofibrinolytic mutations and the eNOS T-786C polymorphism.

RESULTS

The total number of polymerase chain reaction and serologic thrombophilic-hypofibrinolytic abnormalities and the eNOS T-786C polymorphism did not differ between patients with idiopathic (p > 0.5) or secondary (p > 0.5) multifocal and unifocal osteonecrosis. The frequency of low free protein-S levels (<66%) in patients with secondary multifocal osteonecrosis (four of eleven patients) was higher than that in the control subjects (one of fifty-nine) (risk ratio = 21.5; 95% confidence interval, 2.6 to 174; p = 0.0016, Benjamini-Hochberg adjusted p [Bp] = 0.004). Factor-V Leiden heterozygosity was present in two of thirteen patients with secondary multifocal osteonecrosis compared with none of sixty-four control subjects (p = 0.027, Bp = 0.008). For eleven patients with secondary multifocal osteonecrosis, the eNOS T-786C polymorphism was present in nine of twenty-two alleles compared with eight of forty-four alleles in twenty-two normal control subjects (risk ratio = 2.3; 95% confidence interval, 1.0 to 5.0; p = 0.047, Bp = 0.016). The frequency of homocystinemia (>13.5 mumol/L) was higher in patients with idiopathic multifocal osteonecrosis (two of thirteen patients) than in normal controls (none of fifty-one) (p = 0.039, Bp = 0.004). A high level of factor VIII (>150%) was seen in four of eight patients with idiopathic multifocal osteonecrosis and in seven of forty-eight normal controls (risk ratio = 3.4; 95% confidence interval, 1.3 to 9.1; p = 0.04, Bp = 0.008). The eNOS T-786C mutant allele was present in seven of twelve alleles in the six patients with idiopathic multifocal osteonecrosis who were tested, compared with twenty-five of 108 alleles in fifty-four control subjects (risk ratio = 2.5; 95% confidence interval, 1.4 to 4.5; p = 0.015, Bp = 0.008).

CONCLUSIONS

Limited by the small numbers of patients with multifocal osteonecrosis, this exploratory study suggested that thrombophilia was associated with both idiopathic multifocal osteonecrosis and secondary multifocal osteonecrosis, as was the eNOS T-786C polymorphism. Multifocal and unifocal osteonecrosis are similarly associated with thrombophilia, hypofibrinolysis, and the eNOS T-786C polymorphism, which are potentially treatable pathophysiologic conditions, requiring further study.

Ocular vascular thrombotic events: a diagnostic window to familial thrombophilia (compound factor V Leiden and prothrombin gene heterozygosity) and thrombosis

In a 12-member, 3-generation kindred with conjoint inheritance of G1691A factor V Leiden (FVL) and G20210A prothrombin gene (PTG) mutations, identified through a proband with amaurosis fugax and his father with nonarteritic ischemic optic neuropathy (NAION), the authors' hypothesis was that ocular thrombosis was a diagnostic window to familial thrombophilia-thrombosis. The authors used polymerase chain reaction (PCR) measures for thrombophilia (FVL, PTG, C677T-A1298C methylenetetrahydrofolate reductase [MTHFR], platelet glycoprotein PLA1A2) and hypofibrinolysis (plasminogen activator inhibitor-1 4G4G). The 39-year-old white male proband, with amaurosis fugax and transient ischemic attacks (TIA), was found to be a compound heterozygote for FVL and PTG mutations. His symptoms resolved only after coumadin. His 44-year-old brother (deep venous thrombosis [DVT]) and 46-year-old sister (DVT, pulmonary embolus [PE]) were compound FVL-PTG gene heterozygotes. Of 4 asymptomatic children born to these 3 siblings, 2 were FVL heterozygotes and 2 PTG heterozygotes. The proband's 69-year-old father, with NAION and ischemic stroke, had PTG heterozygosity, familial high factor VIII, and compound MTHFR C677T-A1298C mutation with homocysteinemia. The proband's 61-year-old aunt had PTG heterozygosity, recurrent DVT, and mesenteric artery thrombosis. The proband's 67-year-old mother, free of thrombotic events, was a FVL heterozygote, had high factor VIII, and PAI-1 4G4G homozygosity. In this extended kindred, ocular thrombotic events (amaurosis fugax, NAION) were associated with variegated thrombotic events, including TIA, ischemic stroke, DVT, PE, and mesenteric artery thrombosis, and opened a diagnostic window to family screening and treatment for complex thrombophilias, which had previously been undiagnosed.

Heritable thrombophilia-hypofibrinolysis and osteonecrosis of the femoral head

We hypothesized that inherited thrombophilia and hypofibrinolysis were risk factors for osteonecrosis of the femoral head. We compared measures of thrombophilia and hypofibrinolysis in referred new adult patients with idiopathic osteonecrosis (n = 71) or secondary osteonecrosis (n = 62) with the same measures in sex- and race-matched healthy control subjects. Heritable thrombophilic Factor VIII and hypofibrinolytic Lp(a) were more frequently high in the 71 patients with idiopathic osteonecrosis than in control subjects. High Factor VIII, Factor V Leiden heterozygosity, and resistance to activated protein C, all heritable thrombophilias, were more frequently present in the 62 patients with secondary osteonecrosis than in control subjects. Our data suggest inherited thrombophilia and hypofibrinolysis are risk factors for both idiopathic and secondary osteonecrosis of the head of the femur.

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.

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).

Maintenance immunosuppression use and the associated risk of avascular necrosis after kidney transplantation in the United States

BACKGROUND

Avascular necrosis (AVN) after renal transplantation has been largely attributed to the use of corticosteroids. However, other risk factors such as microvascular thrombosis and hyperlipidemia have been well described and may be of increased importance in the era of early steroid cessation and avoidance. We hypothesized that maintenance immunosuppressive medications known to be associated with these risk factors for AVN would also be associated with a higher risk of AVN.

METHODS

By using the U.S. Renal Data System database, we studied 27,772 primary patients on Medicare who received a solitary kidney transplant between January 1, 1996, and July 31, 2000. Cox proportional hazards regression models were used to calculate adjusted hazard ratios (AHRs) for patient- and transplant-related factors (including allograft rejection) with Medicare claims for AVN. The intensity and duration of corticosteroid use could not be assessed.

RESULTS

Among patients who were prescribed sirolimus at discharge, 3.5% of patients who received the combination of sirolimus-cyclosporine A (CsA) demonstrated AVN, compared with 1.4% of patients who received the combination of sirolimus-tacrolimus (P=0.06 by chi). In Cox regression, CsA use (vs. tacrolimus) (AHR 1.36, 95% confidence interval, 1.09-1.71) was independently associated with an increased risk of AVN. Sirolimus use showed a trend toward significance (AHR 1.59, 95% confidence interval, 0.99-2.56), with no significant interaction with CsA.

CONCLUSIONS

Compared with other maintenance immunosuppression, AVN was significantly more common after use of CsA prescribed at the time of discharge for renal transplantation. Whether this increased risk of AVN was directly attributable to hyperlipidemia, microvascular thrombosis, or differences in corticosteroid dosing could not be determined.

Risk factors for pulmonary emboli after total hip or knee arthroplasty

Because it is difficult to predict which patients may sustain a pulmonary embolism after total hip or knee arthroplasty, we assessed multiple thrombophilic and hypofibrinolytic parameters to identify risk factors. Twenty-nine patients who survived a known pulmonary embolism after total knee or total hip arthroplasty were matched by age, gender, race, arthritic diagnosis, procedure, and surgery date with 29 patient-controls who had a total hip or knee arthroplasty but who did not have a symptomatic known pulmonary embolism or deep vein thrombosis. Twenty-one serologic measures and five genes associated with thrombophilia, hypofibrinolysis, or both were assessed without knowledge of group assignment. All patients with pulmonary embolism had at least one abnormality of plasminogen activator inhibitor activity, dilute Russell's viper venom time, prothrombin time, or total cholesterol versus 13 of 27 (48%) control patients. Forty-seven percent of patients who experienced pulmonary embolism had at least two abnormalities of plasminogen activator inhibitor activity, dilute Russell's viper venom time, prothrombin time, or total cholesterol, versus 7% of control patients. Preoperatively, to identify patients at high risk of pulmonary embolism, plasminogen activator inhibitor activity, dilute Russell's viper venom time, prothrombin time, and cholesterol levels were most predictive. Using at least one abnormality of these four measures as a screening test to detect risk of pulmonary embolism, the test is sensitive (100%), and the predictive value of a negative test is high (100%). After additional prospective study, this may allow identification of patients at low risk (the majority of patients) in whom anticoagulation may not be required and a small group of patients at high risk for pulmonary embolism in whom prophylactic anticoagulation should be provided.