The role of the factor V Leiden mutation in osteonecrosis of the hip

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.

Development and validation of a nomogram for predicting the probability of nontraumatic osteonecrosis of the femoral head in Chinese population

Although corticosteroids and alcohol are two major risk factors for nontraumatic osteonecrosis of the femoral head (NONFH), the effects of other factors have rarely been studied, thereby making early diagnosis and treatment of NONFH difficult. This study aimed to develop and validate a nomogram to NONFH, but patients with alcohol- and steroid-related NONFH are not at all taken into account in this study. A training cohort of 790 patients (n = 434, NONFH; n = 356, femoral neck fractures [non-NONFH]) diagnosed in our hospital from January 2011 to December 2016 was used for model development. A least absolute shrinkage and selection operator (lasso) regression model was used for date dimension reduction and optimal predictor selection. A predictive model was developed from univariate and multivariate logistic regression analyses. Performance characterisation of the resulting nomogram included calibration, discriminatory ability, and clinical usefulness. After internal validation, the nomogram was further evaluated in a separate cohort of 300 consecutive patients included between January 2017 and December 2018. The simple prediction nomogram included five predictors from univariate and multivariate analyses, including gender, total cholesterol levels, triglyceride levels, white blood cell count, and platelet count. Internal validation showed that the model had good discrimination [area under the receiver operating characteristic curve (AUC) = 0.80] and calibration. Good discrimination (AUC = 0.81) and calibration were preserved in the validation cohort. Decision curve analysis showed that the predictive nomogram was clinically useful. The simple diagnostic nomogram, which combines demographic data and laboratory blood test results, was able to quantify the probability of NONFH in cases of early screening and diagnosis.

Transient Familial Factor V Leiden-Linked Hip Osteoporosis

INTRODUCTION

Transient osteoporosis of the hip (THO) is a rare disease of unknown pathogenesis that has traditionally been considered an early and reversible stage of avascular necrosis (AN). Thrombophilia or familial hypofibrinolysis is considered a risk factor for the development of AN and THO. Factor V Leiden is one of the most common hereditary hypercoagulability disorders.

CLINICAL CASES

Case series study. The development and course of 3THO cases in 3siblings (two males and one female) aged between 40 and 43 years are described consecutively. Clinical and nuclear magnetic resonance imaging (MRI) studies confirmed the diagnosis of THO and ruled out the presence of AN. The G1691A mutation of factor v Leiden was positive in all cases. The clinical and radiological outcome was favourable, with healing without sequelae and disappearance of bone oedema on control MRI at 6 months in all cases.

DISCUSSION

The results of this study support the ischaemic aetiology and establish HTO as an early and reversable stage of hip AN. Factor V Leiden causes a state of hypercoagulability and hypofibrinolysis that encourages the development of THO due to ischaemic causes.

CONCLUSIONS

This study outlines the first familiar description of factor v Leiden-linked THO.

Prevalence of CAM deformity and its influence on therapy success in patients with osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) and CAM-type femoroacetabular impingement (FAI) present two different pathologies of the hip joint. The aim of this study is to describe the prevalence of CAM-FAI in a collective of ONFH hips and to evaluate its influence on ONFH therapy outcome. A cohort of 86 ONFH hips with a mean follow-up of 46.7 months (±20.5) after advanced core decompression (ACD) was evaluated regarding CAM deformity by measuring the alpha angle (α) and head-neck offset. The influence of CAM-type FAI was investigated using the Kaplan-Meier estimator and the Cox regression model. The mean α was 60.4° (±13.8) with 41 hips (47.7%) being ≥60°. The mean head-neck offset was 4.5 mm (±3.2), with 78 hips (90.7%) being ≤9 mm. Survival analysis indicated noticeably better ACD results for α < 60° versus α ≥ 60° (p = 0.07). Treatment failure within the first 2 years was statistically estimated as 27.7% for α < 60° versus 40.7% for α ≥ 60°: The hazard ratio for α ≥ 60° was 1.94. Head-neck offset-dependent survival showed better, though not significant, results for offset >9 mm (p = 0.38, hazard ratio 1.89 for offsets ≤9 mm). The prevalence of CAM-type deformity is greatly increased in patients with concomitant ONFH. There is a strong indication that CAM-type FAI has a negative influence on ONFH therapy outcome. The risk that ONFH treatment will fail seems to be twice as high for α ≥ 60° as for α < 60°. We recommend cotreatment of pathological head-neck offset in patients with ONFH.

Etiologic Classification Criteria of ARCO on Femoral Head Osteonecrosis Part 1: Glucocorticoid-Associated Osteonecrosis

BACKGROUND

Glucocorticoid usage, a leading cause of osteonecrosis of the femoral head (ONFH), and its prevalence was reported in 25%-50% of non-traumatic ONFH patients. Nevertheless, there have been no unified criteria to classify glucocorticoid-associated ONFH (GA-ONFH). In 2015, the Association Research Circulation Osseous addressed the issue of developing a classification scheme.

METHODS

In June 2017, a task force was set up to conduct a Delphi survey concerning ONFH. The task force invited 28 experts in osteonecrosis/bone circulation from 8 countries. Each round of the Delphi survey consists of questionnaires, analysis of replies, and feedback reports to the panel. After 3 rounds of the survey, the panel reached a consensus on the classification criteria. The response rates were 100% (Round 1), 96% (Round 2), and 100% (Round 3), respectively.

RESULTS

The consensus on the classification criteria of GA-ONFH included the following: (1) patients should have a history of glucocorticoid use >2 g of prednisolone or its equivalent within a 3-month period; (2) osteonecrosis should be diagnosed within 2 years after glucocorticoid usage, and (3) patients should not have other risk factor(s) besides glucocorticoids.

CONCLUSION

Association Research Circulation Osseous established classification criteria to standardize clinical studies concerning GA-ONFH.

Etiologic Classification Criteria of ARCO on Femoral Head Osteonecrosis Part 2: Alcohol-Associated Osteonecrosis

BACKGROUND

Although alcohol is a leading risk factor for osteonecrosis of the femoral head (ONFH) and its prevalence reportedly ranges from 20% to 45%, there are no unified classification criteria for this subpopulation. In 2015, Association Research Circulation Osseous decided to develop classification criteria for alcohol-associated ONFH.

METHODS

In June of 2017, Association Research Circulation Osseous formed a task force to conduct a Delphi survey. The task force invited 28 experts in osteonecrosis/bone circulation from 8 countries. Each round of the Delphi survey included questionnaires, analysis of replies, and feedback reports to the panel. After 3 rounds of the survey, consensus was reached on the classification criteria. The response rates for the 3 Delphi rounds were 100% (round 1), 96% (round 2), and 100% (round 3).

RESULTS

The consensus on the classification criteria of alcohol-associated ONFH included the following: (1) patients should have a history of alcohol intake >400 mL/wk (320 g/wk, any type of alcoholic beverage) of pure ethanol for more than 6 months; (2) ONFH should be diagnosed within 1 year after alcohol intake of this dose; and (3) patients should not have other risk factor(s).

CONCLUSION

ARCO-established classification criteria to standardize clinical studies concerning AA-ONFH.

Testosterone Therapy, Thrombophilia, Venous Thromboembolism, and Thrombotic Events

In our sequential studies of 67 and 21 patients, testosterone therapy (TT) interacted with thrombophilia⁻hypofibrinolysis, leading to venous thromboembolism (VTE). Compared to 111 VTE controls not taking TT (VTE-no TT), the 67 and 21 cases were more likely (p < 0.05 for all) to have Factor V Leiden (FVL) heterogeneity (24% and 33% vs. 12%), the lupus anticoagulant (14% and 33% vs. 4%), and high lipoprotein(a) (33% vs. 13%, n = 21). After a first VTE and continuing TT, 11 thrombophilic cases had a second VTE despite adequate anticoagulation, 6 of whom, still anticoagulated, had a third VTE. The greatest density of thrombotic events was at three months after starting TT, with a rapid decline by 10 months. From <1 to 8 months after starting TT, 65% of VTE occurred, which may reflect TT-induced depletion of susceptible thrombophilic patients, leaving a winnowed residual group with fewer VTE events despite the continuation of TT. Before starting TT, we suggest screening for FVL, lipoprotein(a), and the lupus anticoagulant to identify patients at increased VTE risk, with an adverse risk-to-benefit ratio for TT. We suggest that TT should not be started in patients with known thrombophilia⁻hypofibrinolysis, and should not be continued after a first VTE. When TT is given to patients with thrombophilia⁻hypofibrinolysis, VTE may occur and then recur despite adequate anticoagulation.

Thromboembolism peaking 3 months after starting testosterone therapy: testosterone–thrombophilia interactions

We assessed time of thrombotic events (venous thromboembolism (VTE)) after starting testosterone therapy (TT) in 21 men who sustained 23 VTE. The density of thrombotic events was greatest at 3 months after starting TT, with a rapid decline in events by 10 months. The 21 cases with VTE on TT differed from 110 patient controls with unprovoked VTE, not taking TT (VTE-no TT) for Factor V Leiden heterozygosity (FVL) (33 per cent vs 13 per cent, P=0.037), for high lipoprotein (a) (Lp(a)) (55 per cent vs 17 per cent, P=0.012), and for the lupus anticoagulant (33 per cent vs 4 per cent, P=0.003). These differences between cases and VTE-no TT controls were independent of age and gender. TT can interact with underlying thrombophilia–hypofibrinolysis promoting VTE. We suggest that TT should not be started in subjects with known thrombophilia. Coagulation screening, particularly for the FVL , Lp(a), and the lupus anticoagulant should be considered before starting TT, to identify men at high VTE risk who have an adverse risk/benefit ratio for TT.

Case report: primary osteonecrosis associated with thrombophilia-hypofibrinolysis and worsened by testosterone therapy

Background

Familial and acquired thrombophilia are often etiologic for idiopathic hip and jaw osteonecrosis (ON), and testosterone therapy (TT) can interact with thrombophilia, worsening ON.

Case presentation

Case 1: A 62-year-old Caucasian male (previous deep venous thrombosis), on warfarin 1 year for atrial fibrillation (AF), had non-specific right hip-abdominal pain for 2 years. CT scan revealed bilateral femoral head ON without collapse. Coagulation studies revealed Factor V Leiden (FVL) heterozygosity, 4G/4G plasminogen activator inhibitor (PAI) homozygosity, high anti-cardiolipin (ACLA) IgM antibodies, and endothelial nitric oxide (NO) synthase (eNOS) T786C homozygosity (reduced conversion of L-arginine to NO, required for bone health). Apixaban 5 mg twice daily was substituted for warfarin; and L-arginine 9 g/day was started to increase NO. On Apixaban for 8 months, he became asymptomatic. Case 2: A 32-year-old hypogonadal Caucasian male had 10 years of unexplained tooth loss, progressing to primary jaw ON with cavitation 8 months after starting TT gel 50 mg/day. Coagulation studies revealed FVL heterozygosity, PAI 4G/4G homozygosity, and the lupus anticoagulant. TT was discontinued. Jaw pain was sharply reduced within 2 months.

Conclusions

Idiopathic ON, often caused by thrombophilia-hypofibrinolysis, is worsened by TT, and its progression may be slowed or stopped by discontinuation of TT and, thereafter, anticoagulation. Recognition of thrombophilia-hypofibrinolysis before joint collapse facilitates anticoagulation which may stop ON, preserving joints.

Testosterone Therapy Can Interact With Thrombophilia, Leading to Osteonecrosis

Although this effect is not widely recognized, testosterone therapy can interact with thrombophilia, causing osteonecrosis. In 12 men and 4 women who had idiopathic osteonecrosis a median of 6 months after the onset of testosterone therapy, the authors examined the interaction between testosterone therapy and previously undiagnosed thrombophilia. The authors hypothesized that patients who had osteonecrosis after starting testosterone therapy were more likely than 110 normal control subjects or 48 patients who had osteonecrosis and were not receiving testosterone therapy to have thrombophilia. Measures of thrombophilia included Factor V Leiden, prothrombin, PAI-1 gene mutations, Factor VIII, Factor XI, anticardiolipin antibody immunoglobulin G or immunoglobulin M, and homocysteine values. In 10 cases, osteonecrosis occurred 6 months or less after the onset of testosterone therapy, and in all 16 cases, it occurred after a median of 6 months of testosterone therapy. Of the 16 cases, 5 (31%) were Factor V Leiden heterozygotes vs 2 of 109 (2%) healthy control subjects (P=.0003) and 4 of 48 patients who had osteonecrosis and were not receiving testosterone therapy (P=.04). Of the 16 cases, 4 (25%) had high (>150%) Factor VIII levels vs 7 of 103 (7%) healthy control subjects (P=.04), and 3 (19%) had high (>150%) Factor XI levels vs 3 of 101 (3%) healthy control subjects (P=.03). Of the 16 patients with osteonecrosis, 14 (88%) had at least 1 abnormal procoagulant value (of the 8 measured) vs 47 of 110 (43%) healthy control subjects (P=.0009). Of the 5 men whose serum estradiol level was measured while they were receiving testosterone therapy, this level was high (≥42.6 pg/mL) in 4. When testosterone therapy is given to patients with thrombophilia, they are at increased risk for osteonecrosis.

Thrombophilia in 67 Patients With Thrombotic Events After Starting Testosterone Therapy

We compared thrombophilia in 67 cases (59 men and 8 women) with thrombotic events after starting testosterone therapy (TT) versus 111 patient controls having unprovoked venous thrombotic events without TT. In the 67 patients, thrombosis (47 deep venous thrombosis-pulmonary embolism, 16 osteonecrosis, and 4 ocular thrombosis) occurred 6 months (median) after starting TT. Cases differed from controls for factor V Leiden heterozygosity (16 of the 67 [24%] vs 13 [12%] of the 111, P = .038) and for lupus anticoagulant (9 [14%] of the 64 vs 4 [4%] of the 106, P = .019). After a first thrombotic event and continuing TT, 11 cases had a second thrombotic event, despite adequate anticoagulation, 6 of whom, still anticoagulated, had a third thrombosis. Screening for thrombophilia before starting TT should identify men and women at high risk for thrombotic events with an adverse risk-benefit ratio for TT. When TT is given to patients with familial and acquired thrombophilia, thrombosis may occur and recur in thrombophilic men despite anticoagulation.

The development of thromboembolism may increase the risk of osteonecrosis in children with acute lymphoblastic leukemia

Previous studies indicate pathophysiological and epidemiological parallels between osteonecrosis (ON) and thromboembolism (TE), two common treatment-related morbidities in acute lymphoblastic leukemia (ALL). To elucidate risk factors for ON and explore the relationship between ON and TE, we undertook a retrospective study of children (n = 208) with ALL. Twenty-one (10.1%) children developed ON and 42 (20.2%) TE on therapy. Thromboembolism was a significant predictor of ON on univariate (OR 8.85) and multivariate analysis, along with older age and PEGylated asparaginase. This observation supports a role for hypercoagulability in the pathogenesis of ON. Larger prospective studies are needed to further test these findings.

Testosterone, thrombophilia, thrombosis

We screened previously undiagnosed thrombophilia (V Leiden-prothrombin mutations, Factors VIII and XI, homocysteine, and antiphospholipid antibody [APL] syndrome) in 15 men and 2 women with venous thromboembolism (VTE) or osteonecrosis 7 months (median) after starting testosterone therapy (TT), gel (30-50 mg/d), intramuscular (100-400 mg/wk), or human chorionic gonadotropin (HCG) (6000 IU/wk). Thrombophilia was studied in 2 healthy control groups without thrombosis (97 normal controls, 31 subjects on TT) and in a third control group (n = 22) with VTE, not on TT. Of the 17 cases, 76% had ≥1 thrombophilia vs 19% of 97 normal controls (P < 0.0001), vs 29% of 31 TT controls (P = 0.002). Cases differed from normal controls by Factor V Leiden (12% vs 0%, P = 0.021), by high Factor VIII (>150%) (24% vs 7%, P = 0.058), by high homocysteine (29% vs 5%, P = 0.007), and from both normal and TT controls for APL syndrome (18% vs 2%, P = 0.023, vs 0%, P = 0.04). Despite adequate anticoagulation with TT continued after the first deep venous thrombosis-pulmonary embolus (DVT-PE), 1 man sustained 3 DVT-PEs 5, 8, and 11 months later and a second man had 2 DVT-PEs 1 and 2 months later. Of the 10 cases with serum T measured on TT, 6 (60%) had supranormal T (>800 ng/dL) and of 9 with estradiol measured on TT, 7 (78%) had supranormal levels (>42.6 pg/mL). TT interacts with thrombophilia leading to thrombosis. TT continuation in thrombophilic men is contraindicated because of recurrent thrombi despite anticoagulation. Screening for thrombophilia before starting TT should identify subjects at high risk for VTE with an adverse the risk to benefit ratio for TT.

Long term anticoagulation (4-16 years) stops progression of idiopathic hip osteonecrosis associated with familial thrombophilia

In 6 patients with familial thrombophilia (5 Factor V (FV) Leiden heterozygotes, 1 with resistance to activated protein C (RAPC)), we prospectively assessed whether continuous longterm (4–16 years) anticoagulation would prevent progression of idiopathic osteonecrosis (ON), ameliorate pain, and facilitate functional recovery. Four men and 2 women (9 hips, 8 Ficat stage II, 1 stage I) were anticoagulated with enoxaparin (60 mg/day) for 3 months and subsequently with Coumadin, Xarelto, or Pradaxa, warranted by ≥2 prior thrombotic events. Anticoagulation was continued for 4, 4, 9, 13, 13, and 16 years, with serial clinical and X-ray follow-up. On 4–16-years anticoagulation, 9 hips in the 6 patients (8 originally Ficat II, 1 Ficat I) remained unchanged, contrasted to untreated ON Ficat stage II, where 50%–80% of hips progress to collapse (Ficat stages III-IV) within 2 years after diagnosis. Within 3, 3, 3, 9, and 16 months after starting anticoagulation, 5 patients became pain-free and remained asymptomatic throughout follow-up; the 6th patient required Percocet for pain. There were no significant bleeding episodes. Long term (4–16 years) anticoagulation initiated in Ficat stages I-II of idiopathic hip ON in patients with FV-RAPC changes the natural history of ON, stopping progression, resolving pain, and restoring function.

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.

Testosterone therapy, thrombosis, thrombophilia, cardiovascular events

There are similar time intervals between starting testosterone therapy (TT) and development of thrombotic (~4.5 months) or cardiovascular (CVD) events (~3 months) which may, speculatively, reflect a shared pathophysiology. We have described thrombotic events 5 months (median) after starting TT in 38 men and 4 women, including 27 with deep venous thrombosis-pulmonary embolism, 12 with osteonecrosis, 1 with central retinal vein thrombosis, 1 with amaurosis fugax, and 1 with spinal cord infarction. In 8 men whose TT was continued, second thrombotic events occurred despite adequate anticoagulation with Coumadin in 8 men, 3 of whom had a third thrombotic event. Of these 42 cases, 40 had measures of thrombophilia-hypofibrinolysis, and 39 were found to have previously undiagnosed thrombophilia-hypofibrinolysis. Before beginning TT, especially in men with previous history of thrombotic events, we suggest that, at a minimum, measurements be made for the Factor V Leiden and Prothrombin mutations, Factors VIII and XI, and homocysteine, to identify men who should not receive TT. We need prospective data focused on whether there should be pre-TT screening based on history of previous venous thromboembolism or for all subjects for major gene thrombophilias. To better resolve questions about TT and all cause and cardiovascular morbidity and mortality and thrombosis, a long term, prospective, randomized, blinded study following the example of the Women's Health Initiative is needed. While we wait for prospective placebo-controlled TT outcome data, TT should be restricted to men with well-defined androgen deficiency syndromes.

Enoxaparin prevents steroid-related avascular necrosis of the femoral head

Nontraumatic osteonecrosis of the femoral head is still a challenging problem in orthopedic surgery. It is responsible for 10% of the 500,000 hip replacement surgeries in the USA and affects relatively young, active patients in particular. Main reasons for nontraumatic osteonecrosis are glucocorticoid use, alcoholism, thrombophilia, and hypofibrinolysis (Glueck et al., 1997; Orth and Anagnostakos, 2013). One pathomechanism of steroid-induced osteonecrosis is thought to be impaired blood flow to the femoral head caused by increased thrombus formation and vasoconstriction. To investigate the preventive effect of enoxaparin on steroid-related osteonecrosis, we used male New Zealand white rabbits. Osteonecrosis was induced by methylprednisolone-injection (1 × 20 mg/kg body weight). Control animals were treated with phosphate-buffered saline. Treatment consisted of an injection of 11.7 mg/kg body weight of enoxaparin per day (Clexane) in addition to methylprednisolone. Four weeks after methylprednisolone-injection the animals were sacrificed. Histology (hematoxylin-eosin and Ladewig staining) was performed, and empty lacunae and histological signs of osteonecrosis were quantified. Histomorphometry revealed a significant increase in empty lacunae and necrotic changed osteocytes in glucocorticoid-treated animals as compared with the glucocorticoid- and Clexane-treated animals and with the control group. No significant difference was detected between the glucocorticoid and Clexane group and the control group. This finding suggests that cotreatment with enoxaparin has the potential to prevent steroid-associated osteonecrosis.

High prevalence of prothrombotic abnormalities in multifocal osteonecrosis: description of a series and review of the literature

Multifocal or multiple osteonecrosis (ON), defined by the involvement of 3 or more anatomic sites, is unusual, being observed in only 3%-10% of patients diagnosed with ON. We report the clinical characteristics of a cohort of 29 patients with multifocal ON from a single center and evaluate the prevalence of associated prothrombotic abnormalities in 26 of these patients. We conducted a retrospective study of all patients diagnosed with multifocal ON evaluated in our institution during the last 20 years. We recorded clinical manifestations and underlying diagnoses. A wide thrombophilic profile was performed, including antithrombin, protein C, protein S, lupus anticoagulant, anticardiolipin antibodies, activated protein C resistance, factor V Leiden, mutation G-20210-A of the prothrombin gene, and factor VIII. Coagulation test results were compared with those in a healthy control group and a group of patients with history of lower-extremity deep venous thrombosis. The mean age of the patients was 49.2 ± 15 years (range, 28-81 yr). The mean number of ON localizations per patient was 5.2 ± 2.3 (range, 3-11). Hips were the most commonly affected joint (82%), followed by knees (58%), shoulders (37%), and ankles (13%). Most patients had an underlying disease process, and 12 of 25 (48%) patients had coagulation test abnormalities. The most common alterations were high factor VIII levels and antiphospholipid antibody (aPL) positivity in 24% and 20% of cases, respectively. These abnormalities were more prevalent in patients with multifocal ON compared with patients in the control groups. Sixty-one percent of patients had a history of corticosteroid treatment. Patients with coagulation abnormalities had a higher number of ON localizations per patient (6.5 ± 2.7 vs. 3.88 ± 0.8; p = 0.002) and a higher prevalence of atypical ON localizations (25% vs. 0%; p = 0.05). In conclusion, in the present cohort of patients with multifocal ON, 48% of the patients had at least 1 prothrombotic factor, especially high levels of factor VIII and aPL. These findings have major implications for the diagnosis and treatment of multifocal ON and clearly indicate the need to perform a thrombophilic profile in these patients.

Meta-analysis of Factor V Leiden G1691A polymorphism and osteonecrosis of femoral head susceptibility

Testing for genetic risk associations between Factor V Leiden (FVL) and the osteonecrosis of femoral head (ONFH) is common, however, inconsistent results have been previously obtained. To summarize results on the association of FVL mutation polymorphism with ONFH in various populations and to calculate the overall genetic risk factors, we performed a search of electronic databases including PubMed, Elsevier Science Direct, Chinese National Knowledge Infrastructure and the Chinese Biomedical Database to identify published studies correlating the FVL mutation with ONFH. Statistical analysis was performed using Review Manager (RevMan) version 5.0 and Stata statistical software (version 10). We identified 57 titles and included 7 studies comprising 481 cases and 867 controls in this meta-analysis. The groups were pooled, and a significant association between FVL mutation and increased ONFH was found (OR=4.55, 95% CI, 2.75-7.52, P<0.00001). This meta-analysis demonstrated that FVL plays an important role in non-Asian populations. Large sample studies including different ethnic groups and age- and gender-matched groups, as well as multiple gene polymorphism detection should be considered to clarify the association of FVL mutation polymorphism and ONFH susceptibility in the future.

Bone vascularization in normal and disease conditions

Bone vasculature is essential for many processes, such as skeletal development and growth, bone modeling and remodeling, and healing processes. Endothelium is an integral part of bone tissue, expressing a physiological paracrine function via growth factors and chemokines release, and interacting with several cellular lines. Alterations of the complex biochemical interactions between vasculature and bone cells may lead to various clinical manifestations. Two different types of pathologies result: a defect or an excess of bone vasculature or endothelium metabolism. Starting from the molecular basis of the interactions between endothelial and bone cells, the Authors present an overview of the recent acquisitions in the physiopathology of the most important clinical patterns, and the modern therapeutic strategies for their treatments.