A Rabbit Model of Hormone-induced Early Avascular Necrosis of the Femoral Head

Objective To establish an experimental model of early stage avascular necrosis of the femoral head （ANFH） caused by corticosteroid in adult rabbits and to observe the pathological changes with various imaging techniques. Methods ANFH was induced by a combination of hypersensitivity vasculitis caused by injection of horse serum and subsequent administration of a high dose of corticosteroid. The pathological changes were detected with digital radiography （DR）, computed tomography （CT）, magnetic resonance imaging （MRI）, ink artery infusion angiography, hematoxylin-eosin staining, and immunohistochemistry. Results The imageological and pathological changes corresponded to the clinical characteristics of early stage ANFH. DR showed bilaterally increased bone density, an unclear epiphyseal line, and blurred texture of cancellous bone. CT showed spot-like low-density imaging of cancellous bone, thinner cortical bone, osteoporosis, and an unclear epiphyseal line. MR! showed bone marrow edema and spot-like high signals in T2-weighted imaging in cancellous bone. Ink artery infusion angiography showed fewer obstructed blood vessels in the femoral head. HE staining of pathological sections showed fewer trabeculae and thin bone, an increased proportion of empty osteocyte lacunae, decreased hematopoiesis, thrombosis, and fat cell hypertrophy. Immunohistochemistry showed attenuated expression of vascular endothelial growth factor in osteoblasts and chondrocytes, and on the inner membrane of blood vessels. Conclusion Experimental rabbit model of early stage ANFH caused by corticosteroid can be successfully established and provide the foundation for developing effective methods to treat early stage ANFH.

Experimental Study of Vascular Endothelial Growth Factor Gene Therapy for Avascular Necrosis of the Femoral Head

To explore a new method for the therapy of the avascular necrosis of the femoral head, the recombinant plasmid pCD-hVEGF 165 was mixed with collagen and was implanted in the necrotic femoral head The expression of vascular endothelial growth factor (VEGF) was detected by RNA dot hybridization and immunohistochemical method The repair of the femoral head was observed by histological method The results showed that the expression of VEGF was detectable in the femoral head treated with VEGF gene Angiogenesis in these femoral heads was more abundant than the control Bone repairing was augmented in the femoral head treated with VEGF gene The results suggest that angiogenesis in bone tissue could be augmented by gene transfection of VEGF and bone repairing would be accelerated accordingly

Regulation of Quan Du Zhong capsule on VEGF/bFGF and expression of Bcl‑2/Bax and Caspase‑3 protein in the repairing process of canine femoral head necrosis

Objective:To explore the repair and treatment effect of Quan Du Zhong capsule on necrosis of femoral head in dogs.Methods:Totally 12 beagles were randomly divided into normal group,model group,Quan Du Zhong capsule group and Xianlinggubao capsule group,with three in each group.In addition to the normal group,the other groups established the femoral head necrosis model by liquid nitrogen alternative freezing.The normal group and the model group did not have any intervention during the modeling period,and the Quan Du Zhong group began to receive the Quan Du Zhong by gavage on the day of modeling;Xianlinggubao capsule group was given Xianlinggubao capsule by gavage once a day for 12 consecutive weeks on the day of modeling.The levels of VEGF and bFGF in the blood vessels of each group at the 12th week were compared,and the ratios of BMD,BS/BV,BV/TV,Tb.Th,Tb.N were measured by Micro CT,and the expressions of Bcl-2,Bax,Caspase-3 proteins were detected by immune reaction.Results:1.Compared with the normal group,the level of serum VEGF and bFGF in the model group decreased after 12 weeks of modeling(P<0.05);Compared with the model group,the levels of serum VEGF and bFGF water in the Xianlinggubao capsule group and the Quan Du Zhong capsule group increased on average at the 12th week of modeling,with statistical difference(P<0.05).The level of the Quan Du Zhong capsule group was the highest,followed by the Xianlinggubao capsule group.2.Compared with the normal group,BMD,BS/BV,BV/TV,Tb.Th and Tb.N in the model group were lower,and Tb.SP were higher,the results were statistically significant(P<0.05).Compared with the model group,the BMD,BV/TV,Tb.Th and Tb.N of Xianlinggubao capsule group and the total eucommia capsule group increased,while the BS/BV and Tb.SP decreased(P<0.05).3.The Quan Du Zhong capsule group and Xianlinggubao capsule group could significantly increase the expression of bcl-2 protein in the femoral head of dogs,which was significantly different from the model group(P<0.05).The expression of bax protein in the femoral head of dogs in the Quan Du Zhong capsule group and the Xianlinggubao capsule group was significantly reduced compared with the model group(P<0.05).The expression of caspase-3 protein in the femoral head of dogs was significantly reduced in the Quan Du Zhong capsule group and Xianlinggubao capsule group,which was significantly different from the model group(P<0.05).Conclusion:Quan Du Zhong capsule can increase the expression of VEGF and bFGF in serum,increase the expression of bcl-2,inhibit the expression of bax,and reduce the expression of caspase-3,which plays a synergistic role in the treatment of avascular necrosis of the femoral head,and has potential targets.

Effect of Yang-Warming and Kidney-Tonifying Prescription on Expression of Osteogenic and Angiogenic Factors and H-Type Vascular Markers in Steroid-Induced Avascular Necrosis of Femoral Head in Rabbits

Objective: To investigate the effect of Yang-warming and Kidney-tonifying Prescription (YKP) on the treatment of steroid-induced avascular necrosis of the femoral head (SANFH) in rabbits. And to further explore whether its therapeutic mechanism is related to the expression of HIF-1α and VEGF (angiogenic factors), BMP2 and Osterix (osteogenic factor), CD31 (type H vascular marker) and MMP13 (bone destruction-related factor). Methods: Twenty-seven healthy male New Zealand white rabbits were divided into a normal group, model group, traditional Chinese medcine (TCM) group (clinical equivalent dose group of YKP), miR-130a inhibitor group and TCM + inhibitor group. The SANFH model was established by combining horse serum with methylprednisolone. After the model is successfully established, TCM group was given 6.44 g/kg·d YKP by gavage, and the miR-130a gene inhibitor group was intraperitoneally injected with 25 mg/kg miR-130a inhibitor, locked nucleic acid (LNA)-anti-miR-130a. TCM + inhibitor group was treated with YKP intragastrically and miR-130a inhibitor intraperitoneally. The rabbits in the normal group and the model group were intragastrically administered with normal saline 10 ml/d. Once a day for 4 weeks. The avascular necrosis was detected by HE staining. The contents of HIF-1α, VEGF, BMP2 and Osterix in rabbit tissues were detected by qRT-PCR kit, and the expression of CD31 and MMP13 was detected by immunofluorescence staining. Results: In the normal group, the surface of the cartilage layer of the femoral head was smooth, the bone trabeculae were intact and densely arranged, the cells of each layer were neatly arranged, the morphology of the bone cells, the chondrocytes and the adipocytes were normal. In the model group, cartilage surfaces of the femoral head showed exfoliative cracks. The bone trabecular structure was loose and incomplete, chondrocytes, osteoblasts and bone marrow cells were significantly reduced, and the number of empty bone traps was significantly increased. In the TCM-treated group, more chondrocytes, thicker cartilage layer, and more regular bone trabeculae were detected as compared to model rabbits. In contrast, the cartilage layer was thinner, the destruction and fracture of bone trabeculae was more serious, chondrocytes and osteocytes were decreased as compared to model group. The expression of HIF-1α, VEGF, BMP2, and Osterix in the model group decreased significantly as compared to the normal group (P Conclusion: YKP can regulate the expression of angiogenic-related factors (VEGF and HIF-α), osteogenic-related factors (BMP2 and Osterix), and H-type vascular marker CD31, resulting in increased expressions of VEGF, HIF-α, BMP2, and Osterix, which promote intra-femoral head revascularization. Meanwhile, YKP decreased the expression of bone-destruction-related factor MMP13, thus enhancing the ability of bone tissue to repair itself. Regulation of these molecules’ expression may be one of the mechanisms of YKP in the treatment of hormonal femoral head necrosis.

Current Status of Research on Treatment of Osteonecrosis of Femoral Head with Traditional Chinese Medicine from the Perspective of Security-based Chinese Medicine

The publication of"Evidence-based Chinese Medicine"and the establishment of the Chinese Traditional Medicine Evidence-based Medicine Center mark that evidentiary-based Chinese medicine has stood in front of all Chinese medicine practices in the form of new disciplines,greatly promoting the modernization of Chinese medicine.It will always give Chinese medicine a powerful impetus to the world.Femoral head necrosis is the dominant disease in the treatment of TCM.Chinese medicine practices should seize the optionality to active learn the content of evidentiary-based Chinese medicine and apply it to clinical and scientific research practice.This article review the development status of femoral head necrosis treatment by TCM medicine from the perspective of event-based Chinese medicine.It provides a reference for the event-based development of Chinese medicine in the treatment of femoral head necrosis,and continues to develop advantages and make up for the shortcomings.

Vascular endothelial growth factor gene transfection to enhance the repair of avascular necrosis of the femoral head of rabbit

Objective To explore a new method for the therapy of avascular necrosis of the femoral head. Methods The recombinant plasmid pCD-hVEGF 165 was mixed with collagen and was implanted in the necrotic femoral head. The expression of vascular endothelial growth factor (VEGF) was examined by RNA dot hybridization and immunohistochemical techniques. Repair of the femoral head was observed by histological and histomorphometric analysis.Results The expression of VEGF was detected in the femoral head transfected with the VEGF gene. The femoral head transfected with the VEGF gene showed a significant increase in angiogenesis 2 and 4 weeks after gene transfection and a significant increase in bone formation 6 and 8 weeks after gene transfection on histomorphometric analysis ( P <0.01).Conclusions Transfection of the VEGF gene enhances bone tissue angiogenesis. Repair of osteonecrosis could be accelerated accordingly,thus providing a potential method for therapy of osteonecrosis.

Association of sterol regulatory element binding protein 2 and insulin-like growth factor binding protein 3 genetic polymorphisms with avascular necrosis of the femoral head in the Chinese population

Background Sterol regulatory element binding protein （SREBP）-2 plays a key role in lipid homeostasis by stimulating gene expression of cholesterol biosynthetic pathways. The insulin-like growth factor binding protein （IGFBP） family regulates growth and metabolism, especially bone cell metabolism, and correlates with osteonecrosis. However, association of their gene polymorphisms with risk of avascular necrosis of the femoral head （ANFH） has rarely been reported. We determined whether SREBP-2 and IGFBP-3 gene polymorphisms were associated with increased ANFH risk in the Chinese population. Methods Two single nucleotide polymorphisms of SREBP2 gene, rs2267439 and rs2267443, and one of IGFBP-3 gene, rs2453839, were selected and genotyped in 49 ANFH patients and 42 control individuals by direct sequencing assay. Results The frequencies of rs2267439 TT and rs2267443 GA of SREBP2 and rs2453839 TT and CT of IGFBP-3 in the ANFH group showed increased and decreased tendencies （against normal control group）, respectively. Interaction analysis of genes revealed that the frequency of carrying rs2267439 TT and rs2267443 GA genotypes of SREBF-2 in ANFH patients was significantly higher than in the control group （P 〈0.05）. Association analysis between polymorphisms and clinical phenotype demonstrated that the disease course in ANFH patients with the rs2453839 TT genotype of IGFBP-3 was significantly shorter than that of CT＋CC carriers （P 〈0.01）. CT＋CC genotype frequency in patients with stage Ill/IV bilateral hip lesions was significantly higher than in those with stage Ill/IV unilateral lesions and stage II/111 bilateral lesions （P 〈0.05-0.02）. Conclusions Our results suggested that interaction of SREBP-2 gene polymorphisms and the relationship between the polymorphisms and clinical phenotype of IGFBP-3 were closely related to increased ANFH risk in the Chinese population. The most significant finding was that the CT＋CC genotype carriers of IGFBP-3 rs2453839 were highly associated with the development of ANFH.

BASIC FIBROBLAST GROWTH FACTOR GENE TRANSFECTION TO ENHANCE THE REPAIR OF AVASCULAR NECROSIS OFTHE FEMORAL HEAD

Objective To explore a new method for the therapy of avascular necrosis of the femoral head. Method The recombinant plasmid pCD-rbFGF was mixed with collagen and was implanted in the necrotic femoral head. Expression of basic fibroblast growth factor (bFGF) was examined by RT-PCR and immunohistochemical method. Re-pair of the femoral head was observed by histological and histomorphometric analysis. Result Expression of bFGF was detected in the femoral head transfected with bFGF gene, indicating significant increase of angiogenesis 2 weeks after gene transfection and increased new bone formation 8 weeks after gene transfection on histom-orphometric analysis (P< 0.01). Conclusion Transfection of bFGF gene enhances bone tissue angiogenesis. Repair in osteonecrosis would be accelerated accordingly.

Microstructures and properties of cancellous bone of avascular necrosis of femoral heads

The aim of this study is to investigate microscopic structure and characterize cancellous bone of avascular necrosis of the femoral head （ANFH）. The rabbit model of the ANFH is established. The histopathologic features are studied successfully. The differences between the steroidinjection group （S.G.） and the controlled group （C.G.） are examined, including the weight of rabbits, the hematological examination and the three-dimensional stnactures. It is found that the plasma levels of cholesterol （CHO）, high-density lipoprotein （HDL） and low-density lipoprotein （LDL） in S.G. are lower than those in C.G. when the triglyceride （TG） increased in the S.G.; but the bone mineral content （BMC） and the structural model index （SMI） of the organ and tissue decreased significantly in S.G. Three-dimensional structures of the femoral head are obtained using micro-computed tomography （CT） scanning and the mechanical model is established to analyze the influences of these structural changes on the mechanical properties of the cancellous bone.

Avascular osteonecrosis of the femoral head during HIV infection and antiretroviral therapy: a case report

Avascular osteonecrosis of the femoral head is increasingly affecting HIV-infected patients. Several factors may contribute to its occurrence, including antiretroviral therapy and its complications. We report a case of avascular necrosis of the femoral head in a black woman infected with HIV and treated with antiretroviral drugs in Lomé, Togo, for about 13 years at the time of consultation and with therapeutic success. The antiretroviral treatment included a protease inhibitor initiated 3 years before the onset of the symptomatology which was marked by bilateral hip pain. Biochemical tests showed hypercholesterolemia (total and LDL-cholesterol) and a slight increase in triglycerides. Antiretroviral treatment with a protease inhibitor was changed to an integrase inhibitor. The surgical treatment that was indicated could not be performed because of the patient’s lack of financial means.

Osteonecrosis of the femoral head: An update in year 2012

Osteonecrosis is a phenomenon involving disruption to the vascular supply to the femoral head, resulting in articular surface collapse and eventual osteoarthritis. Although alcoholism, steroid use, and hip trauma remain the most common causes, several other etiologies for osteonecrosis have been identified. Basic science research utilizing animal models and stem cell applications continue to further elucidate the pathophysiology of osteonecrosis and promise novel treatment options in the future. Clinical studies evaluating modern joint-sparing procedures have demonstrated significant improvements in outcomes, but hip arthroplasty is still the most common procedure performed in these affected younger adults. Further advances in joint-preserving procedures are required and will be widely studied in the coming decade.

Modified porous tantalum rod technique for the treatment of femoral head osteonecrosis

AIM: To study a modified porous tantalum technique for the treatment of osteonecrosis of the femoral head.METHODS: The porous tantalum rod was combined with endoscopy,curettage,autologous bone grafting and use of bone marrow aspirates from iliac crest aspiration in 49 patients(58 hips) with a mean age of 38 years.The majority of the patients had idiopathic osteonecrosis,followed by corticosteroid-induced osteonecrosis.Thirtyeight hips were of Steinberg stage Ⅱ disease and 20 hips were of stage Ⅲ disease.Patients were followed for 5 years and were evaluated clinically with the Merle D'Aubigne and Postel score and radiologically.The primary outcome of the study was survival based on the conversion to total hip arthroplasty(THA).Secondary outcomes included deterioration of the osteonecrosis to a higher disease stage at 5 years compared to the preoperative period and identification of factors that were associated with survival.The Kaplan-Meier survival analysis was performed to evaluate the survivorship ofthe prosthesis,and the Fisher exact test was performed to test associations between various parameters with survival.RESULTS: No patient developed any serious intraoperative or postoperative complication including implant loosening or migration and donor site morbidity.During the 5-year follow up,1 patient died,7 patients had disease progression and 4 hips were converted to THA.The 5-year survival based on conversion to THA was 93.1% and the respective rate based on disease progression was 87.9%.Stage Ⅱ disease was associated with statistically significant better survival rates compared to stage Ⅲ disease(P = 0.04).The comparison between idiopathic and non-idiopathic osteonecrosis and between steroid-induced and non-steroid-induced osteonecrosis did not showed any statistically significant difference in survival rates.The clinical evaluation revealed statistically significantly improved Merle d'Aubigne scores at 12 mo postoperatively compared to the preoperative period(P < 0.001).The mean preoperative Merle d'Aubigne score was 13.0(SD: 1.8).The respective score at 12 mo improved to 17.0(SD: 2.0).The 12-mo mean score was retained at 5 years.CONCLUSION: The modified porous tantalum rod technique presented here showed encouraging outcomes.The survival rates based on conversion to THA are the lowest reported in the published literature.

Vascular endothelial growth factor for the treatment of femoral head osteonecrosis: An experimental study in canines

AIM To evaluate the treatment of osteonecrosis of the femoral head(ONFH) with the use of vascular endothelial growth factor(VEGF).METHODS In 30 mature beagles(6 groups of 5 beagles) ONFH was induced cryosurgically and one of the following solutions was administered locally in the femoral head(FH) in each group: Single injection of 500 μg VEGF(t-VEGFμ group); single injection of 500 ng VEGF(t-VEGFn group); continuous delivery of 500 μg VEGF through osmotic micropump(t-VEGFpump-μ group); continuous delivery of 500 ng VEGF through osmotic micropump(t-VEGFpump-n group); single injection of 0.9% sodium chloride(t-NS group), while one group that served as control group did not receive any local solution(No-t group). FHs were retrieved 12 wk postoperatively, underwent decalcification and hematoxylin/eosin and toluidine blue staining. In two canines per group, one half of FH was processed without decalcification and stained with modified Masson Trichrome. Histological sections were observed by light microscopy and measured with a semi-automatized bone histomorphometry system and Bone Volume/Total Volume(BV/TV), Marrow Volume/Total Volume(MaV/TV), and Trabecular Thickness(TbT h) were assessed. Standard and robust tests(Welch, Brown Forsythe) of analysis of variance along with multiple comparisons, were carried out among the categories.RESULTS The untreated(No-t) group had signs of osteonecrosis, whereas the VEGF groups revealed reversal of the osteonecrosis. Statistical analysis of the decalcified specimens revealed a significantly better BV/TV ratio and a higher Tb Th between the VEGF treatment groups(except the t-VEGFn group) and the No-t group or the control t-NS group. Single dose 500 μg VEGF group had significantly better BV/TV ratio and higher Tb Th when compared to the No-t group(50.45 ± 6.18 vs 29.50 ± 12.27, P = 0.002 and 151.44 ± 19.07 vs 107.77 ± 35.15, P = 0.161 respectively) and the control t-NS group(50.45 ± 6.18 vs 30.9 ± 6.67, P = 0.004 and 151.44 ± 19.07 vs 107.14 ± 35.71, P = 0.151 respectively). Similar differences were found for the prolonged VEGF delivery/pump groups of 500 μg and 500 ng. Analysis of the totality of specimens(decalcified/non-decalcified) enhanced the aforementioned differences and additionally revealed significant differences in the comparison of the TbT h.CONCLUSION In an experimental model of ONFH in canines it was found that local treatment with VEGF leads to bone tissue remodeling and new bone formation.

The changes of nitric oxide and hemorheology in steroid-induced avas-cular necrosis of femoral head

Objective: To explore the pathogenesis of avascular necrosis of femoral head (ANFH), the early diagnosis index and the treatment effective index of ANFH in clinical practice. Methods: Twenty-four Japanese rabbits were divided into 2 groups: model group and control group. ANFH models were produced by intramuscular injection of large dosage of steroid to rabbits for 8 weeks. On the 4 th, 8 th week after the injection, two rabbits each time from each group were taken to observe the structure of femoral head by light microscope and scanning electron microscope. Four other stomach-empty rabbits from each group were also used to test the contents of Nitric Oxide (NO), contents of the hemorheology indexes. Results: Compared with the control group, the rabbits in the model group exhibited osteoporosis of femoral head and more bone lacuna and more fat cells through light microscope. Through scanning electron microscope observation bone trabecula were broken and sunk, and collagen fibers on the surface of bone matrix became loosen and broken, more osteocyte had pyknosis, adipocyte in the medullary cavity were enlarged and subchondral arterioles and capillaries of the femoral head were pressed by adipocyte. Compared with the control group, the model rabbits contained less NO and obvious increase of the plasma viscosity (PV), low blood viscosity (LBV), erythrocyte hematocrit (HCT), indices of erythrocyte rigidity (TK) and indices of erythrocyte aggregation (AI), plasma fibrin level (PFL) (P<0. 01) and an increase of erythrocyte electrophoresis rate (ERT) (P< 0.05). High blood viscosity (HBV), and erythrocyte sedimentation rate (ESR) were unchanged. Conclusion: The steroid-induced ANFH might be related to less NO and the abnormal hemorheology; and NO and hemorheology should be considered as an early diagnosis index for ANFH in clinical practice.

DIAGNOSIS AND TREATMENT OF IDIOPATHIC NECROSIS OF THE FEMORAL HEAD

Fifteen cases,27 hips,of idiopathic necrosis of the femoral head (INFH) were included iour series.The role of radiography,isotopic bone scanning,intraosseous pressure measure-ment and intraosseous venography in the diagnosis of INFH were evaluated.Radiologicalexamination could not reveal early cases,while isotopic bone scanning was more sensitive.There was an increase of intraosseous pressure in most of the diseased hips.and intraos-seous venography showed abnormalities in all examined hips.The latter two tests couldtherefore detect early INFH.Core decompression was performed in 23 hips,21 of whichwere followed for 7 to 27 months.Functional evaluation was good or excellent in 18 hips.Radiological re-examination remained unchanged in 19 hips.Postoperative intraosseouspressure measurement and intraosseous venography revealed a decrease of intraosseous pres-sure and improvement of venous drainage.Core decompression is therefore an ideal methodof treatment for early INFH.

Avascular necrosis of the first metatarsal head in a young female adult:A case report and review of literature

BACKGROUND This case study describes an atypical presentation of avascular necrosis(AVN)of the first metatarsal head,which is largely unfounded in the literature.CASE SUMMARY A healthy 24-year-old female initially presented with pain at the first metatarsophalangeal joint(MTPJ)and was diagnosed with AVN by physical examination and magnetic resonance imaging.The patient demonstrated atypically poor progress in recovery,despite being in otherwise good health and being of young age,with no history of corticosteroid or alcohol use.The patient also did not have any history or clinical features of autoimmune disease or vasculitis,such as systemic lupus erythematosus.The patient was managed with conservative treatment for 18 mo,which allowed for gradual return of full range of motion of the first MTPJ and subsiding pain,permitting the patient to return to highintensity sports training and full weight-bearing.Throughout her recovery,many differential diagnoses were ruled out through specific investigations leading to further reinforcement of the diagnosis of AVN of the 1st metatarsal head.CONCLUSION Atypical AVN may occur with no predisposing risk factors.Treatment is mainly conservative,with unclear guidelines in literature on management.

TREATMENT OF ISCHEMIC NECROSIS OF FEMORAL HEAD BY THE FREE TRANSFERRING FIBULAR BONE GRAFT WITH VASCULAR PEDICLE IN ADULTS：A

cases (97 hips) with avascular necrosis of femoral head caused by variors factors treated by the free transferring fibular graft with vascular pedicle in the Second Teaching Hospital of Xi'an Medical University are reported. All patients have ben followed up for 2 to 11 years. Excellent and good rate of operative results was 86. 6%. A long observation indicated that this procedure was superior to the other operations for the osteonecrosis of femoral head. Successful interim and final operative results can warrant its continued use in management of this kind of patients.

Analysis of the Development of Avascular Necrosis in Slipped Capital Femoral Epiphysis

Introduction: Slipped capital femoral epiphysis (SCFE) is a common hip disorder in adolescents. The most serious complication is avascular necrosis (AVN), which has lasting sequelae. The objective of this study was to determine the rate of AVN in stable slips. Method: We reviewed retrospectively all the children treated for SCFE between 2004 and 2008 at Princess Margaret Hospital. Results: Of a total of 67 patients, 51 (76%) were stable slips and 16 (24%) unstable. Avascular necrosis developed in 3 patients with stable slip (5.9%) and in 6 with unstable slip (37.5%). There was no statistically significant association found between AVN and age, weight, slip severity, pin position, number of pins used, experience of the surgeon or side affected. Those with stable presentations can develop AVN2, males are more likely and the possibility of developing AVN increases as the time from presentation to operation increased. Conclusion: AVN can occur in stable slips without joint penetration. This combined with male sex and increased time to operation, increases the risk of AVN.

Superior Retinacular Artery Did Not Occlude in a Rat Model of the Non-Traumatic Osteonecrosis of the Femoral Head

Non-traumatic osteonecrosis of the femoral head (ONFH) is believed to be avascular necrosis. Certainly, a disruption of a supplying artery induces necrosis in the supplying artery-dominant region. However, when an abnormality such as cell apoptosis, or another reason, is developed in the supplying artery-dominant region, it induces a disruption of the supplying artery. Therefore, to prove that ONFH is avascular necrosis, it is necessary to demonstrate the disruption of the supplying artery prior to histological osteonecrosis development. Here we investigate histologically, using a rat model, whether disruption of the supplying artery occurs before the initial development of ONFH following corticosteroid treatment. Rats were given imiquimod and methylprednisolone, and were sacrificed 1, 2, 3, 7 or 14 days after the last injection. At the sacrifice, the rat was perfused with 20 ml black Indian ink through the left ventricle. ONFH was observed in the Imiquimod + Methylprednisolone group at 7 and 14 days. The osteonecrotic area was not stained with perfused black Indian ink. However, the lateral portion of the femoral head near the superior retinacular artery was stained with the ink. In conclusion, the present study shows that the superior retinacular artery did not occlude before the initial development of ONFH histologically in rats.