The extent of osteocyte death in the proximal femur of patients with osteonecrosis of the femoral head.
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Our aim was to assess the local extent of osteocyte death in the proximal femur of 16 patients with osteonecrosis of the femoral head. We performed histological examination of the femoral heads and cancellous bone biopsies from four regions of the proximal femur in patients undergoing total hip arthroplasty. A control group consisted of 19 patients with osteoarthritis. All histological specimens were examined in a blinded fashion. Extensive osteonecrosis was shown in the proximal femur up to 4 cm below the lesser trochanter in the group with osteonecrosis. There was an overall statistically significant difference in the extent of osteocyte death distal to the femoral head between the two groups (p < 0.001). We discuss the implications of these findings as possible contributing factors in regard to the early failure of total hip arthroplasty reported in patients with osteonecrosis of the femoral head. (+info)
Volumetric analysis of osteonecrosis of the femur. Anatomical correlation using MRI.
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We tested the accuracy of MRI for the precise quantification of the volume of osteonecrosis in 30 hips (stage III). The values were compared with direct anatomical measurements of the femoral heads obtained after total hip replacement. When the area of osteonecrosis was determined visually, and manually outlined on each slice, the accuracy of the measurement of volume was satisfactory, and the mean absolute deviation between MRI and anatomical measurements was similar to that between two MRI data sets. For ten of the hips which were measured by MRI, both before and after collapse, the volume did not appear to change significantly. Our findings suggest that the volume of osteonecrosis can be determined with accuracy by MRI, both before and after collapse. (+info)
Apoptosis and expression of stress protein (ORP150, HO1) during development of ischaemic osteonecrosis in the rat.
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Using in situ hybridisation and the terminaleoxynucleotidyl transferase-mediated biotin-dUTP nick end-labelling (TUNEL) reaction in rats with osteonecrosis of the femoral head we have studied the effect of ischaemia on the gene expression of the stress proteins oxygen-regulated protein 150 (ORP150) and haemoxygenase 1 (HO1) and the death mechanism of the cells involved in osteonecrosis. Both ORP150 and HO1 have been reported to have important roles in the successful adaptation to oxygen deprivation. ORP150 and HO1 mRNA expression was induced by ischaemia in osteoblasts and osteocytes. In proliferative chondrocytes, these signals were detected constitutively. During the development of ischaemic osteonecrosis, the mechanism of cell death was apoptosis as indicated by DNA fragmentation and the presence of apoptotic bodies in osteocytes, chondrocytes and bone-marrow cells. After the initial ischaemic event, expression of ORP150 and HO1 mRNA, the TUNEL-positive reaction and empty lacunae were found sequentially. These findings were exclusive and may be considered to be markers for each stage in the development of osteonecrosis. (+info)
The timing of reduction and stabilisation of the acute, unstable, slipped upper femoral epiphysis.
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We reviewed the management of 100 cases of slipped upper femoral epiphysis treated over a period of 26 years. A total of 14 slips was identified as unstable on admission. These underwent reduction and stabilisation within 24 hours of the onset of severe symptoms. Of the 86 stable slips four progressed to avascular necrosis (AVN), which was not seen in the unstable slips. The literature on slipped upper femoral epiphysis suggests that the acute unstable slip is at higher risk of developing AVN. We recommend reduction and stabilisation of unstable slips within 24 hours of the onset of symptoms in order to reduce the risk of AVN. (+info)
Osteonecrosis in patients with systemic lupus erythematosus develops very early after starting high dose corticosteroid treatment.
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OBJECTIVES: To investigate the actual time of onset of osteonecrosis (ON) after high dose corticosteroid treatment in systemic lupus erythematosus (SLE). METHODS: 72 patients with active SLE, who received high dose corticosteroid for the first time, for the development of ON at hips and knees were monitored by magnetic resonance imaging for at least 12 months. RESULTS: ON lesions were detected in 32/72 patients (44%) between one and five months (3.1 months on average) after starting high dose corticosteroid treatment. No osteonecrotic lesion was newly detected from the sixth month of treatment until the end of the follow up period. CONCLUSION: The findings suggested that the actual time of onset of ON in SLE is within the first month of high dose corticosteroid treatment. (+info)
Tracer accumulation in femoral head during early phase of bone scintigraphy after renal transplantation.
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Nontraumatic osteonecrosis of the femoral head (ONF) is a complication of renal transplantation. The pathogenic mechanism of ONF is thought to be an ischemic event. The purpose of this study was to investigate whether 3-phase bone scintigraphy can reveal early hemodynamic changes associated with ONF after renal transplantation. METHODS: We performed 3-phase bone scintigraphy on 19 renal allograft recipients between 3 and 9 wk after they underwent renal transplantation. Regions of interest (ROI) were assigned bilaterally in the femoral heads, diaphyses, and soft tissue. The head-to-diaphysis ratio (HD) in each phase was then calculated. RESULTS: ONF occurred in 8 femoral heads of 4 patients. Three of the 4 ONF patients had no abnormal MRI findings at the time of bone scintigraphy. In phase 1, no significant difference in HDs was observed between the ONF patients (mean HD +/- SD, 0.62 +/- 0.44) and the non-ONF patients (0.31 +/- 1.40). The difference between the mean counts for bone and soft tissue was small in both instances, and the HD had a large dispersion. In phase 2, the HDs for the ONF patients (0.70 +/- 0.27) and the non-ONF patients (1.31 +/- 0.43) were significantly different (P = 0.0005). The HD was <1.00 in all femoral heads of the ONF patients, whereas 9 non-ONF heads had an HD that was <1.00. In phase 3, the HD of the ONF patients was significantly lower than that of the non-ONF patients (ONF patients, 0.92 +/- 0.17; non-ONF patients, 1.62 +/- 0.46; P = 0.0002). CONCLUSION: All ONF patients were in the group with a low HD in phase 2, suggesting a reduction in blood flow or blood pool. Phase 2 accumulation in 3-phase bone scintigraphy can be used to estimate early hemodynamic changes in patients with ONF after renal transplantation. (+info)
Elastic modulus and strength of emu cortical bone.
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The emu (Dromaius novaehollandiae) shows potential as a unique animal model for replicating the femoral head collapse process seen in end-stage human osteonecrosis. Since the collapse phenomenon (and interventions to prevent it) involve mechanical processes, it is important to elucidate the similarities and differences of emus versus humans in terms of hip joint biomechanics. A first step for comparison is the intrinsic mechanical properties of the respective bone tissues, as reflected in cortical bone flexural stiffness and strength. In four-point bending, emu cortical bone was found to have an elastic modulus of 13.1 GPa. Its yield stress was determined to be 113 MPa and the ultimate strength was 146 MPa. Emu cortical bone's elastic modulus was similar to that of other avian species, and falls approximately 25% below that of the human (17.3 GPa). (+info)
Early lesions of the labrum and acetabular cartilage in osteonecrosis of the femoral head.
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Osteonecrosis of the femoral head can be caused by a variety of disorders and affects the relatively young patient. Most studies have concentrated on the femoral changes; the sites of early lesions of the labrum and acetabular cartilage have not been recorded. We studied 17 hips with osteonecrosis and a wide congruent joint space on radiographs and by direct inspection of the femoral head, labrum and acetabular cartilage during surgery. All of the femoral heads had some anterosuperior flattening which reduced the head-neck ratio in this area. A consistent pattern of damage to the labrum and the acetabular cartilage was seen in all hips. Intraoperatively, impingement and the cam-effect with its spatial correlation with lesions of the labrum and acetabular cartilage were observed. These findings could be helpful when undertaking conservative surgery for osteonecrosis, since the recognition of early radiologically undetectable acetabular lesions may require modification of the surgical technique. (+info)