[Study on the relationship between sclerosis rim and bone morphogenetic proteins of osteonecrosis of the femoral head].

OBJECTIVES: To analyze retrospectively the formation and histological changes of sclerosis rim in patients with osteonecrosis of the femoral head (ONFH), and to study the relationship between bone morphogenetic proteins (BMP4) and sclerosis rim, so as to acquire experimental and theoretical basis on individualized treatment for ONFH patients. METHODS: From November 2005 to November 2007, 184 hips of steroid-induced ONFH inpatients were collected. The mean age was (47 ± 7) years, the patients were divided into high (more than 54 years old), middle (40 - 54 years old) and low (less than 40 years old) age groups. Their clinical data were analyzed retrospectively according to gender and age. Parts of the femoral heads were selected for the study, including 18 hips in high age group, 11 hips in low age group and 20 hips in middle age group. Each 10 hips were selected with or without sclerosis rim. The femoral heads were cut along middle coronal plane, their weight-bearing and non-weight-bearing areas were used for the study. The specimens were processed by routine HE staining and picric acid-Sirius red staining and electron microscopy preparation and immunohistochemistry stain. The average optical density of BMP4 protein was calculated by image analysis software. RESULTS: The trabecular of sclerosis rim was thickening and disorder. But its osteocytes were normal and with high secretion. The ratio of sclerosis rim was 71.4% (105/147) in middle age ONFH patients, which was significantly higher than the low age group patients (45.5%, 5/11) and high age group patients (38.5%, 10/26) (P < 0.01). The optical density of BMP4 in middle age ONFH patients was 0.32 ± 0.14, which was significantly higher than the low age group 0.20 ± 0.17 and high age patients 0.19 ± 0.27 (P < 0.05). The optical density was 0.16 ± 0.11 in ONFH patients without sclerosis rim, which was significantly lower than with sclerosis rim (0.28 ± 0.13) (P < 0.01). The time from hip pain to joint replacement in patients with sclerosis rim was (49 ± 11) months, and (15 ± 2) months without sclerosis rim. There was significant difference between the two groups (P < 0.01). CONCLUSIONS: The formation of sclerosis rim is positively related to the expression of BMP4, and high expression of BMP maybe promote the formation of sclerosis rim.

[The effect of subchondral bone defect in femoral head on structure and metabolism of article cartilage].

OBJECTIVE: To investigate the changes of structure and metabolism of the cartilage of femoral head overlying the bone defect in animal model and analyse the possible effect of the necrotic area of the femoral head on the cartilage overlying there. METHODS: 18 adult hybrid dogs was applied for bone defect model of femoral head. Of the femoral heads, the left was applied for bone defect model, the right for shame-operation. 5, 5, and 8 animals were sacrificed respectively 4, 12 and 24 weeks after operation and the femoral heads were received for examinations. The X-rays films were taken just before the animals were sacrificed. After the cartilage specimens were decalcified, dehydrated and embedded, sections 6, u thick were made. They were stained with hematoxylin-eosin, sirius-red and toilude blue. The biochemical assay were performed. RESULTS: 12 and 24 weeks after operation of bone defect, cartilage histology and biochemistry demonstrated the signs of articular cartilage pathological changes. The arrangement of chondrocytes were disorder. The number of chondrocytes decreased. The cartilage surface lost its smoothness, and these kinds of changes were more severe in the area next to the bone defect. Fibrosis and vasi formation were found. Tidemark had the changes of discontinuation and veil. Glycosaminoglycans decreased. CONCLUSION: The bone defect, whose damaged structure strength and decreased blood supply is similar, had effect on the structure and metabolism of the articular cartilage near the bone defect, and suggest osteonecrosis at the stage of pro-collapse may affect the cartilage overlying it.

[In vitro study of combination rhOPG-Fc and alendronate on inhibition osteoclast].

OBJECTIVE: To study the effect of combination rhOPG-Fc and alendronate on mature osteoclasts. METHODS: Recombinant human osteoprotegerin secretory expression in P. pastoris was performed. Osteoblasts were got from new born mouse skeletal bone and proved by ALP staining and incubated together with osteoclasts precursor cell line Raw 264.7 in 96 well plate. After 9 d, 10 micromol/L ALN, 10(-5) g/L rhOPG-Fc, 10 micromol/L ALN + 10(-5) g/L rhOPG-Fc, 5 micromol/L ALN + 5 x 10(-6) g/L rhOPG-Fc were added to these coculture systems. Osteoblasts cultured without the drugs mentioned above served as controls. TRAP stain positive cells counting and cortical bone pit formation counting were preformed in the following the 3rd and 7th d. RESULTS: SDS-PAGE and Western blot showed that molecular weight of the expressed protein was about 55 KD, and it could reach specifically with anti-IgG antibody. Many multi-nuclear TRAP stain positive cells were found in the coculture control group after 9 d incubation, and proved to be mature osteoclasts by TRAP stain. In the 3rd and 7th d after the addition of rhOPG-Fc, ALN or both, TRAP stain positive cells counting and cortical bone pit formation counting decreased significantly in the rhOPG-Fc, ALN or both groups than in the control group, and the combine group (10(-5) g/L rhOPG-Fc + 10 micromol/L ALN) decreased most significantly when compared with rhopG-FC or ALN single. CONCLUSIONS: rhOPG-Fc can decrease the number of osteoclasts and inhibit their function. The combination of both rhOPG-Fc and ALN shows the significant inhibition effect on mature osteoclasts.