The Importance of Increased Intraosseous Pressure in the Development of Osteonecrosis of the Femoral Head: Implications for Treatment

Alcohol-induced adipogenesis in a cloned bone-marrow stem cell

BACKGROUND

Alcohol has been shown to be associated with osteoporosis and osteonecrosis in patients and in animal models. Recent studies have demonstrated that alcohol contributes to abnormal lipid metabolism in the stromal cells of bone marrow, but the mechanisms have not been defined. The purpose of this study was to evaluate the effects of alcohol on the differentiation of a stem cell that was cloned from bone marrow.

METHODS

D1 cells (cloned bone-marrow stem cells from a BALB/c mouse) were treated either with increasing concentrations of ethanol (0.09, 0.15, and 0.21 mol/L) or without alcohol to serve as controls. Morphologic features of the cells were monitored with use of a phase-contrast microscope. Alkaline phosphatase activity was determined with use of a colorimetric assay. The expression of genes that are indicators of adipogenesis [422(aP2), PPARgamma] and osteogenesis (osteocalcin) was evaluated using Northern blot and reverse transcription-polymerase chain reaction assays.

RESULTS

The cells treated with ethanol started to accumulate triglyceride vesicles at day seven. The number of adipocytes and the percentage of the area that contained the cells with fat vesicles increased significantly (p < 0.05), and the level of alkaline phosphatase activity diminished with longer durations of exposure to ethanol and with higher concentrations. Analysis of gene expression showed diminished expression of osteocalcin. This occurred without a significant increase in the expression of either the fat-cell-specific gene 422(aP2) or PPARgamma in cells treated with ethanol, suggesting that adipogenesis may occur at a point downstream in the fatty-acid-metabolism pathway.

CONCLUSIONS

Alcohol treatment decreases osteogenesis while enhancing adipogenesis in a cloned bone-marrow stem cell, indicating that alcohol abuse may be one of the mechanisms leading to osteoporosis and osteonecrosis. This finding explains the clinical observation that there is increased adipogenesis in alcohol-induced osteoporosis and osteonecrosis.

CLINICAL RELEVANCE

The inhibition of bone-marrow adipogenesis and the concomitant enhancement of osteogenesis may provide a novel approach to the prevention or treatment of osteonecrosis and osteoporosis.

Association of corticosteroids and factor V, prothrombin, and MTHFR gene mutations with avascular osteonecrosis in renal allograft recipients

The mechanism of posttransplantation avascular osteonecrosis (AVN) is controversial. Besides an increased bone marrow pressure due to reduced blood supply, enhanced coagulation has been considered. We investigated the associations of factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations as well as cumulative corticosteroid doses with AVN in renal allograft recipients. The records of 39 volunteer patients and 11 patients in whom osteonecrosis was previously identified were reviewed for cumulative corticosteroid dosages during the first year. All patients were screened for factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations by direct sequencing of genomic DNA. The cumulative corticosteroid dosages at 3, 6, and 12 months in the osteonecrotic group (5033.5 +/- 1565.3, 7164.9 +/- 2063.1, 8835.1 +/- 2216.8 mg) were significantly higher than in the control group (3629 +/- 1504.1, 4784.5 +/- 1568.7, 6322.4 +/- 1686.6 mg; P = .013, P = .001, P = .001, respectively). No significant difference in factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations was observed between the osteonecrotic and control groups (P > .05). In conclusion, an association between the first year (3, 6, and 12 month) cumulative corticosteroid dosages and AVN was demonstrated in renal transplant recipients. However, no correlation was determined between factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations and osteonecrosis.

Alterations in the differentiation ability of mesenchymal stem cells in patients with nontraumatic osteonecrosis of the femoral head: comparative analysis according to the risk factor

It has been suggested that decreased replication capacity of mesenchymal stem cells (MSCs) or decreased MSCs activity in the bone marrow is related to nontraumatic osteonecrosis (ON). However, little is known about differentiation ability of MSCs according to the risk factor of nontraumatic ON. We hypothesize that differentiation abnormalities in MSCs of the bone marrow of the proximal femurs might be related to nontraumatic ON of the femoral head. The purpose of this study was to investigate the osteogenic and adipogenic differentiation ability of MSCs in patients with nontraumatic ON of the femoral head. We examined the differentiation ability of MSCs in cultures derived from the bone marrow of the proximal femurs obtained from 10 patients with hip osteoarthritis (OA) and 37 patients with nontraumatic ON of the femoral head undergoing hip replacement surgery. We analyzed the osteogenic and adipogenic differentiation ability of MSCs according to the risk factor [alcohol-induced (15 patients), idiopathic (12 patients) and steroid-induced (10 patients)] of nontraumatic ON of the femoral head separately and compared it with patients with hip OA. The osteogenic activity was measured as the extracellular matrix calcification by alizarin red S staining and the alkaline phosphatase activity, and the adipogenic activity was measured as the accumulation of Oil red O-positive lipid vacuoles. The osteogenic differentiation ability of MSCs in patients with alcohol-induced and idiopathic ON was significantly reduced compared with that in patients with OA (p < 0.05 and p < 0.05, respectively). In patients with steroid-induced ON, the osteogenic differentiation ability was found to be increased, but the difference was not statistically significant. The adipogenic differentiation ability of MSCs was not significantly changed in patients with alcohol-induced, idiopathic, and steroid-induced ON compared to patients with OA. Our results indicate that altered osteogenic differentiation ability in MSCs is related to nontraumatic ON of the femoral head and the differentiation potential of MSCs in patients with nontraumatic ON differs according to its risk factor.

Finding the unexpected: pathological examination of surgically resected femoral heads

OBJECTIVE

To study the clinically diagnosed disease process but also identify additional, clinically undetected pathologies in femoral heads resected for replacement arthroplasty.

DESIGN AND MATERIAL

A retrospective review was carried out of the pathological findings in 460 surgically resected femoral heads. Serial sections were submitted to low-energy fine-detail radiography, then decalcified sections stained by the WHO method were examined. The preoperative clinical and imaging diagnoses were compared with the pathological findings and special interest was placed on assessing the clinical significance of any unexpected, clinically undetected findings.

RESULTS

The most common findings included the presence of bone islands (solitary osteomas) and areas of avascular necrosis in addition to the primary joint disease for which the patient underwent surgery. The preoperative symptomatology did not distinguish between the known primary disease and the additional pathological findings.

CONCLUSION

Some of the clinically unidentified lesions were of a size that fell below the ability of current clinical investigations to detect. However, the finding of lesions by tissue fine-detail radiography indicates that current, more sensitive clinical imaging techniques may identify them. Careful examination of surgically resected femoral heads is important to ensure that all pathologies are identified and assessed for clinical relevance.

Decreased osteogenic differentiation of mesenchymal stem cells in alcohol-induced osteonecrosis

We postulated that osteogenic and adipogenic differentiation ability of the mesenchymal stem cells isolated from the bone marrow could be altered in patients with alcohol-induced osteonecrosis of the femoral head. To examine this hypothesis, we investigated the differentiation ability of the mesenchymal stem cells isolated from the bone marrow from the proximal end of the femur during hip replacements in patients with alcohol-induced osteonecrosis of the femoral head and compared it with the differentiation ability of patients with femoral neck fractures. Marrow was collected from the proximal femurs of 33 patients having hip replacement for either alcohol-induced osteonecrosis of the femoral head or femoral neck fractures. The mesenchymal stem cells were isolated and the culture was expanded from the marrow. The cell populations were compared in terms of the doubling time and the differentiation ability to the osteoblasts and adipocytes. The cells obtained from the patients with alcohol-induced osteonecrosis of the femoral head showed a reduced ability to differentiate the osteogenic lineages compared with the cells obtained from the patients with femoral neck fractures. Such changes may play a role in the development of alcohol-induced osteonecrosis of the femoral head. The altered function of mesenchymal stem cells can be responsible for the pathogenesis of osteonecrosis.

Glucocorticoid-induced osteoporosis: from basic mechanisms to clinical aspects

Glucocorticoid (GC)-induced osteoporosis (GCOP) is the most common cause of osteoporosis in adults aged 20-45 years as well as the most common cause of iatrogenic osteoporosis. GC excess, either endogenous or exogenous, induces bone loss in 30-50% of cases. Indeed, bone loss leading to fractures is perhaps the most incapacitating, sometimes partially irreversible, complication of GC therapy. Nevertheless, GCOP is often underdiagnosed and left untreated. The following article provides an update on the cellular and molecular mechanisms implicated in the pathophysiology of GC-induced bone loss, as well as some guidelines on diagnostic, preventive and therapeutic strategies for this medical condition, in an effort to promote a better knowledge and greater awareness of GCOP by both the patient and the physician.

Steroid effects on osteogenesis through mesenchymal cell gene expression

We have studied the mechanism of steroid-induced osteonecrosis by examining the effect of dexamethasone on a multipotential cell line, D1, which is derived from bone marrow and is capable of differentiating into either the osteoblast or the adipocyte lineage. The expression of bone cell and fat cell transcription factors Cbfa1/Runx2 and PPARgamma2, were determined. Osteocalcin promoter activity was measured by co-transfecting the cells with the phOC-luc and pSV beta-Gal plasmids. Dexamethasone increased PPARgamma2 gene expression 2-fold, while Cbfa1/Runx2 gene expression and osteocalcin promoter activity decreased by 50-60%, and VEGF protein, measured by ELISA, decreased by 55%. These changes indicate enhanced adipogenesis and decreased osteogenesis by mesenchymal cells in vitro, together with a decrease in VEGF, a potent angiogeneic factor, suggesting that dexamethasone may shunt uncommitted osteoprogenitor cells in marrow from osteoblastic differentiation into the adipocytic pathway, leading to diminished vascularization and eventual osteonecrosis.

Analysis of failures after vascularized fibular grafting in femoral head necrosis

Evaluation of graft-host bone interactions after failed vascularized fibular grafting of femoral head necrosis may elucidate the reasons for failure of the procedure. According to the authors' study, the vascularized fibula implanted into the femoral head before collapse has the potential for restructuring the major segment of the affected head and delaying joint degeneration for many years if circumferential graft-host union is established. Asymmetric bone healing and non-union between the graft and the necrotic subchondral bone in the weight-bearing area lead to failure, progression of symptoms, and subsequent early hip replacement.

Avascular necrosis and bone marrow edema syndrome

MR imaging is the most accurate modality for the diagnosis of AVN, bone marrow edema syndrome, and femoral head insufficiency fractures. When the particular demographics of the patient are considered, the specificity of this examination is high. The reported success rates of joint-sparing operative intervention are variable. When compared with conservative management, the outcome of joint-sparing operative intervention in patients who have early (stage I, II) AVN lesions is improved. This is impetus for screening programs for patients who are known to be at high risk for AVN, such as patients who have undergone renal transplants and others who are on long-term, high-dose corticosteroid treatment. There is strong evidence that bone marrow edema syndrome (TO) is a distinct entity with demonstrable unique histopathology and well-defined demographics. Increased spatial resolution revealed typical subchondral findings of AVN in lesions that were once believed to represent irreversible TO. SIF of the femoral head is a new concept with a seemingly distinct population and with clinical presentation and imaging characteristics that should permit its differentiation from AVN.

Avascular necrosis of the femoral head after surgery for lumbar spinal stenosis

STUDY DESIGN

Case report.

OBJECTIVE

To report a previously undescribed complication of lumbar spinal surgery under prolonged hypotensive anesthesia.

BACKGROUND DATA

Avascular necrosis of bone most commonly affects the femoral head. The etiology of the condition is understood in only 75% of cases. There have been no prior reports of this condition following lumbar spine surgery carried out under hypotensive anesthetic.

METHODS

Notes review, clinical examination, plain radiographs, and magnetic resonance imaging diagnosed three patients who developed avascular necrosis of the femoral heads (five joints in total) after surgery for lumbar spinal stenosis. All three were treated with total hip replacement (five joints), and the diagnosis of avascular necrosis was confirmed in two by histopathological examination.

RESULTS

All three patients have recovered full mobility following hip replacement surgery. None had any residual symptoms of lumbar spinal stenosis or hip disease, and none of them had shown any clinical evidence of avascular necrosis in any other bone.

CONCLUSIONS

The development of avascular necrosis of the femoral heads following surgery for spinal stenosis may be due to hypotensive anesthesia, prone positioning on a Montreal mattress, or a combination of the two. Careful intraoperative positioning may reduce the risk of this occurring after spinal surgery. However, close postoperative surveillance and a high index of suspicion of worsening hip pathology in patients who appear to mobilize poorly after lumbar spinal surgery may be the only method of early detection and treatment for this condition.

Cementation for femoral head osteonecrosis: a preliminary clinic study

Treatment for femoral head osteonecrosis has been less successful in late stages of the disease, after progression to collapse. The current authors treated 21 patients (22 hips) with Stage III osteonecrosis by a technique of open reduction and fixation with methylmethacrylate cement (cementation). The followup ranged from 1 to 3 years (average, 1.7 years). Patient progress was followed using preoperative and postoperative Harris hip scores, Western Ontario and McMaster Universities Osteoarthritis Index, and a health status questionnaire (Short Form-36). Patients were staged preoperatively using the Association Research Circulation Osseous international classification system and radiographic evaluation was done intraoperatively and postoperatively. The Harris hip score, Western Ontario and McMaster Universities Osteoarthritis Index, and Short Form-36 physical health scores improved significantly from 53.5 to 78.0, 66.0 to 48.1, and 27.0 to 40.0, respectively. The outcome was worse for patients with more advanced disease. Six patients, all with severe disease, had total hip arthroplasty. Cementation is technically simple, enables patients' immediate postoperative pain relief and improvement in mobility, and has the potential to restore and maintain the sphericity of the femoral head after collapse. The high failure rate (27%) at short-term followup, although comparable with other reported techniques, does not support generalized use for Stage III disease. Currently the use of this procedure is restricted to symptomatic, young patients (younger than 40 years), preferably with mild to moderate Stage III disease (degree of head involvement < 30% and degree of collapse < 4 mm).

Alcohol-induced adipogenesis in bone and marrow: a possible mechanism for osteonecrosis

The effect of alcohol on rabbit bone marrow and on the differentiation of mouse bone marrow stromal cells was investigated. Alcohol was administered intragastrically at a dose of 10 mL/kg/day for 1 to 6 months. Alcohol induced a significant increase in serum lipid peroxides, triglyceride, and cholesterol, and a reduction in superoxide dismutase activity. Fatty infiltration in the liver and adipogenesis in bone marrow were found histologically after alcohol administration. Fat cell hypertrophy and proliferation and diminished hematopoiesis in the subchondral area of the femoral head were observed. Triglycerides were deposited in osteocytes, which became pyknotic, and the percentage of empty osteocyte lacunae increased. None of these abnormal changes were detectable in the control group. In the in vitro study, the marrow stromal cells were treated with increasing (0.03, 0.09, and 0.15 mol/L) concentrations of ethanol for 4 to 21 days. Alcohol induced the differentiation of the cells into adipocytes. The number of adipocytes increased with longer durations of exposure to ethanol and with higher concentrations. Cells treated with ethanol also showed diminished alkaline phosphatase activity and expression of osteocalcin. These novel findings indicate that alcohol can directly induce adipogenesis, decrease osteogenesis in bone marrow stroma, and produce intracellular lipid deposits resulting in the death of osteocytes, which may be associated with the development of osteonecrosis, especially in patients with long-term and excessive use of alcohol.

Pathogenesis and natural history of osteonecrosis

BACKGROUND AND OBJECTIVES

Osteonecrosis (avascular necrosis) is a relatively common disorder seen by both rheumatologists and orthopedic surgeons. The vast majority of cases are secondary to trauma. However, for non-traumatic cases, there often remains a diagnostic challenge in defining the cause of bone death. The goal of this article is to review data extensively in the medical literature with respect to the pathogenesis of osteonecrosis, its natural history, and treatment.

METHODS

A review of 524 studies on osteonecrosis was performed, of which 213 were selected and cited.

RESULTS

Non-traumatic osteonecrosis has been associated with corticosteroid usage, alcoholism, infections, hyperbaric events, storage disorders, marrow infiltrating diseases, coagulation defects, and some autoimmune diseases. However, a large number of idiopathic cases of osteonecrosis have been described without an obvious etiologic factor. Although corticosteroids can produce osteonecrosis, careful history is always warranted to identify other risk factors. The pathogenesis of non-traumatic osteonecrosis appears to involve vascular compromise, bone and cell death, or defective bone repair as the primary event. Our understanding of the pathogenesis of osteonecrosis is now much better defined and skeletal scintigraphy and magnetic resonance imaging have enhanced diagnosis greatly. Early detection is important because the prognosis depends on the stage and location of the lesion, although the treatment of femoral head osteonecrosis remains primarily a surgical one.

CONCLUSIONS

Osteonecrosis has been associated with a wide range of conditions. Many theories have been proposed to decipher the mechanism behind the development of osteonecrosis but none have been proven. Because osteonecrosis may affect patients with a variety of risk factors, it is important that caregivers have a heightened index of suspicion. Early detection may affect prognosis because prognosis is dependent on the stage and location of the disease. In particular, the disease should be suspected in patients with a history of steroid usage, especially in conjunction with other illnesses that predispose the patient to osteonecrosis.

RELEVANCE

A better understanding of the pathophysiology, diagnosis and treatment of osteonecrosis will help the physician determine which patients are at risk for osteonecrosis, facilitating early diagnosis and better treatment options.

Nontraumatic osteonecrosis of the humeral head

The humeral head is the second most common site for nontraumatic osteonecrosis after the femoral head, yet it has attracted relatively little attention. Osteonecrosis is associated with many conditions, such as corticosteroid use, sickle-cell disease, alcoholism, dysbarism (or caisson disease), Gaucher's disease, and other systemic conditions. The diagnosis is a clinical and radiographic one, the latter forming the basis for its staging. Treatment depends on the chronicity and severity of symptoms, as well as the degree of clinical and radiographic progression. Surgical treatment includes arthroscopic debridement and core decompression for early osteonecrosis and hemiarthroplasty or total shoulder arthroplasty for more advanced disease. This report reviews osteonecrosis of the humeral head, with an emphasis on current treatment options.

Corticosteroid osteoporosis

Corticosteroids are widely used and effective agents for the control of many inflammatory diseases, but corticosteroid osteoporosis is a common problem associated with their long term high dose use. Prevention of corticosteroid osteoporosis is preferable to treatment of established corticosteroid bone loss. Several large double-blind controlled clinical trials in patients with corticosteroid osteoporosis have recently been published that provide new insights into its treatment. Based upon available evidence, the rank order of choice for prophylaxis would be a bisphosphonate followed by a vitamin D metabolite or an oestrogen type medication. Calcium alone appears to be unable to prevent rapid bone loss in patients starting corticosteroids, especially with prednisolone doses at 10 mg a day or greater. If an active vitamin D metabolite is used, calcium supplementation should be avoided unless dietary calcium intake is low. Hormone replacement therapy should be considered if hypogonadism is present. Since vertebral fracture is a common and important complication of high dose corticosteroid therapy, these findings suggest that rapid bone loss and hence fractures, can be prevented by prophylactic treatment. Although the follow-up data is limited, it is likely that such therapy needs to be continued beyond 12 months whilst patients continue significant doses of corticosteroid therapy.

Classification of osteonecrosis of the femoral head. Reliability, reproducibility, and prognostic value

The purpose of the current investigation was to determine interobserver and intraobserver reliability of the classification system of Steinberg et al for osteonecrosis of the femoral head. Sixty-five anteroposterior and lateral radiographs of hips were selected randomly from a pool of patients with confirmed osteonecrosis of the femoral head. Six fellowship-trained observers viewed the radiographs (Reading 1). The observers used six main stages of the classification excluding A, B, and C subgroups. The same observers viewed the radiographs 4 months later in reverse order (Reading 2). Reading 1 was used to calculate interobserver kappa values. Reading 2 was used to calculate intraobserver kappa values. Stage-specific kappa values for interobserver variation between all viewers were as follows: Stage I, k = 0.64; Stage II, k = 0.51; Stage III, k = 0.21; Stage IV, k = 0.49; Stage V, k = 0.36; and Stage VI, k = 0.80. Stage-specific kappa values for intraobserver variation between all viewers were as follows: Stage I, k = 0.74; Stage II, k = 0.60; Stage III, k = 0.46; Stage IV, k = 0.59; Stage V, k = 0.27; and Stage VI, k = 0.78. An average of 10 of 21 (48%) of these errors involved Stage III. An average of 6.3 of 21 (30%) intraobserver errors involved Stage V. The presence of the crescent sign in Stage III and joint space narrowing in Stage V markedly diminished the overall reliability of any four- to six-stage classification system. Based on the authors' experience and analysis of the current classifications of osteonecrosis of the femoral head, an easy and reproducible Pittsburgh classification system is proposed.

The effect of freezing and intraosseous fluid on the stiffness behavior of canine trabecular bone

The effect of disrupting the intraosseous fluid compartment and freezing on the mechanical stiffness of trabecular bone in intact canine femoral head specimens was investigated. Twenty-four skeletally mature dogs were divided into two groups. Twelve paired fresh femora were tested and 12 paired femora were tested after freezing at -20 degrees C. The intact femoral head specimens were subjected to a load of physiologic magnitude, and then the stiffness of the underlying trabecular bone was determined in intact femora, in drilled femora with a disrupted intraosseous fluid compartment, and subsequently after refilling the compartment with fluid. Drilling of the femoral head and disrupting its bony fluid compartment resulted in a 40% decrease in stiffness (P<.001). This effect was seen only with fresh specimens and not frozen specimens. Refilling the bony compartment with fluid restored the stiffness of the fresh femoral head. These results demonstrate the mechanical properties of trabecular bone in canine femoral head specimens in vitro are affected by intraosseous fluid and freezing. Removal of the intraosseous fluid decreases the mechanical stiffness of canine trabecular bone, and freezing the specimens appears to alter the intraosseous fluid compartment behavior. It is necessary to gain a better understanding of the dynamic mechanical properties of intact bone to improve the existing analytical and experimental mechanical bone models. The effect of intraosseous fluid and freezing should be considered in these models.

An update on glucocorticoid-induced osteoporosis

In general, bone loss from glucocorticoid treatment occurs rapidly within the first 6 months of therapy. Glucocorticoids alter bone metabolism by multiple pathways; however, the bone loss is greatest in areas rich in trabecular bone. Preventive measures should be initiated early. It is the author's opinion that all subjects initiating treatment with prednisone at 7.5 mg or greater require calcium supplementation (diet plus supplement) at a dose of 1500 mg and vitamin D at a dose of 400 to 800 IU/d. If the patient is going to remain on this dose of glucocorticoid for more than 4 weeks, an antiresorptive agent should be started (e.g., estrogen, bisphosphonate, raloxifene). If a patient has established osteoporosis and is either initiating glucocorticoid therapy or is chronically treated with prednisone at 5 mg d or greater in addition to calcium and vitamin D supplementation, a potent antiresorptive agent (bisphosphonate) should be started. A bone mineral density measurement of either the lumbar spine or the hip may be helpful is assessing an individual's risk of osteoporosis, may improve compliance with treatment, and can be used to monitor the efficacy of the prescribed therapy. There is no reason to withhold treatment for glucocorticoid-induced bone loss until a bone mass measurement is taken, however. In motivated patients, a weight-bearing and resistance exercise program should be prescribed to help retain muscle strength and prevent depression. If hypercalciuria develops with glucocorticoid use, either thiazide diuretics or sodium restriction may be helpful. In patients who continue to lose bone or experience fracture's despite antiresorptive therapy while on glucocorticoids, bone-building anabolic agents (e.g., hPTH 1-34 or PTH 1-84) may be available someday soon.

Osteonecrosis as a complication of treating acute lymphoblastic leukemia in children: a report from the Children's Cancer Group

PURPOSE

To determine the incidence, risk factors, and morbidity for osteonecrosis (ON) in children with acute lymphoblastic leukemia (ALL) treated with intensive chemotherapy including multiple, prolonged courses of corticosteroid.

PATIENTS AND METHODS

The occurrence of symptomatic ON was investigated retrospectively in 1, 409 children ages 1 to 20 years old receiving therapy for high-risk ALL on Children's Cancer Group (CCG) protocol CCG-1882.

RESULTS

ON was diagnosed in 111 patients (9.3% +/- 0.9%, 3-year life-table incidence). The incidence was higher for older children (> or = 10 years: 14.2% +/- 1.3% v < 10 years: 0.9% +/- 0.4%; P: <.0001), especially females 10 to 15 years old and males 16 to 20 years old (19.2% +/- 2.3% and 20.7% +/- 4.7%, respectively). In patients 10 to 20 years old, the incidence of ON was higher for females versus males (17.4% +/- 2.1% v 11.7% +/- 1.6%, respectively; P: =.03) and for patients randomized to receive two 21-day dexamethasone courses versus one course (23.2% +/- 4.8% v 16.4% +/- 4.3%, respectively; P: =.27). Among ethnic groups, whites had the highest incidence and blacks the lowest, with other groups intermediate (16.7% +/- 1.4% v 3.3% +/- 2.3% v 6.7% +/- 2.2%, respectively; P: =.003). There was no difference in event-free survival in patients with or without ON. ON was diagnosed within 3 years of starting ALL therapy in all but one patient, involved weight-bearing joint(s) in 94% of patients, and was multifocal in 74% of patients. Symptoms of pain and/or immobility were chronic in 84% of patients, with 24% having undergone an orthopedic procedure and an additional 15% considered candidates for surgery in the future.

CONCLUSION

Children ages 10 to 20 years who receive intensive ALL therapy, including multiple courses of corticosteroid, are at significant risk for developing ON.

Pluripotential marrow cells produce adipocytes when transplanted into steroid-treated mice

The effect of steroids on adipogenesis by D1-BAG, a pluripotent cell cloned from mouse bone marrow and transfected with traceable genes encoding beta-galactosidase and neomycin resistance, was investigated in vitro in culture and in vivo after injection into mice. Treatment of D1-BAG cells in culture with dexamethasone produced an accumulation of lipid vesicles and stimulated expression of the fat cell-specific 422(aP2) mRNA. Fifty-six mice each received 1 x 10(6) D1-BAG cells, either by tail-vein injection or by direct injection into the marrow of the right femur. Another 38 mice received either saline injection or no treatment as controls. Half of the animals in each group were treated with 3 mg/kg of methylprednisolone per week. Analysis of marrow blow-outs by flow cytometry, DNA analysis by PCR, and X-gal stain of histological sections indicated that cells transplanted by either intravenous or intramedullary injection had appeared and persisted in the marrow of host mice. Cell sorting by flow cytometry and staining with Sudan IV demonstrated that steroid treatment produced adipogenesis in 5-9% of transplanted cells. The results indicate that steroid-induced differentiation of potentially osteogenic marrow cells into adipocytes in vivo may contribute to the development of osteoporosis and osteonecrosis.

The Nicolas Andry award. The pathogenesis and prevention of steroid-induced osteonecrosis

The effects of steroids on a cloned pluripotential cell from bone marrow stroma were examined in vitro in culture and in vivo after the cells were transfected with a traceable gene and transplanted into host mice. Bipedal chickens were treated with steroids to establish a model for osteonecrosis. The effects of a lipid lowering agent, lovastatin, on the prevention of steroid induced adipogenesis in vitro in cell culture, and on adipogenesis and osteonecrosis in vivo in chickens, were evaluated. On treatment with dexamethasone, cloned pluripotential cells began to differentiate into adipocytes and expressed a fat specific gene, whereas the expression of Type I collagen and osteocalcin messenger ribonucleic acid decreased. Addition of lovastatin in culture inhibited steroid induced fat gene expression and counteracted the inhibitory effect of steroids on osteoblastic gene expression. Cloned pluripotential cells were transduced with a traceable retrovirus vector encoding the beta-galactosidase and neomycin resistance genes. The transfected cells were administered to mice either by tail vein or by direct intramedullary injection. Half of the animals in each group were treated with steroids. Histologic sections showed the appearance of transplanted cells in the marrow. Analysis of marrow blowouts by flow cytometry revealed that steroid treatment produced adipogenesis in transplanted cells. Evidence of osteonecrosis was observed in steroid treated chickens, whereas sections from animals treated with steroids and lovastatin showed less adipogenesis and no bone death. The results indicate that steroid induced adipogenesis in the marrow may contribute to osteonecrosis and that lovastatin may be helpful in preventing the development of steroid induced osteonecrosis.

Osteonecrosis of the humeral head: relationship of disease stage, extent, and cause to natural history

One hundred fifty-one patients with 200 shoulders affected with osteonecrosis of the humeral head were evaluated for associated factors, the need for prosthetic replacement surgery, the state of the unoperated shoulder, and the existence of prognostic factors. Associated factors included corticosteroid use in 112 shoulders, trauma in 37, Gaucher's disease in 3, sickle cell disease in 3, and radiation necrosis in 1. No cause was evident in 44 shoulders. Ninety-seven shoulders had replacement surgery. The need for replacement surgery was found to be related to extent and stage of humeral head involvement and to diagnosis. Shoulders with a traumatic cause of osteonecrosis required surgery more often (cumulative rate of 77.8% by 3 years). Advancing stage of disease was also related to the need for surgery. By 3 years the cumulative replacement rate was performed in 42% for shoulders with stage 2 disease, 29% with stage 3 disease, 55% with stage 4 disease, and 79% with stage 5 disease. In a similar manner, surgical frequency increased with increasing extent of humeral head involvement. In 60 shoulders not surgically treated that were monitored an average of 8.6 years (range 3.4 to 14.5 years), there was none to occasional moderate pain in 46 and moderate to severe pain in 14. The mean American Shoulder and Elbow Surgeons score was 64.8.

Indications, technique, and results of shoulder arthroplasty in osteonecrosis

The most common causes of osteonecrosis of the humeral head are steroid use and trauma. Corticosteroids produce osteonecrosis by alterations in fat metabolism, and trauma, by injury to the anterolateral ascending artery. The need for replacement surgery is influenced by stage and extent of the disease, as well as a history of trauma. Results of replacements are superior in steroid-induced osteonecrosis compared to posttraumatic osteonecrosis.

The science and therapy of glucocorticoid-induced bone loss

Glucocorticoids are critical in the management of chronic, noninfectious, inflammatory diseases. Bone loss is a most devastating side effect of these powerful medications. Glucocorticoids produce bone loss by altering calcium metabolism, suppressing gonadal hormone production, and inhibiting bone formation. Now that the mechanism of glucocorticoid-induced bone loss is understood and effective medications are available, this disease can be prevented and reversed.

Spontaneous osteonecrosis of the femoral condyle: causal treatment by early core decompression

In 16 patients with an average age of 64.6 +/- 9.8 years and sudden onset of severe knee pain, the initial stage of Ahlbäck disease (spontaneous osteonecrosis of a femoral condyle) was verified by magnetic resonance imaging (MRI) and subsequent histology. The first radiological sign of osteonecrosis (flattening of the affected femoral condyle) was present in only one case. All patients were treated surgically by extra-articular drilling into the affected femoral condyle to achieve core decompression. The knee pain disappeared immediately after surgery in all patients. Successful healing was confirmed by normalization of the bone marrow signal on MRI (on average, 35.8 months follow-up). Core decompression by extra-articular drilling into the femoral condyle can be recommended as an effective treatment in initial osteonecrosis of the knee (still radiologically invisible). However, if radiologically a flattening of the affected femoral condyle becomes apparent, progression of this disease cannot be avoided.

The Otto Aufranc Award. Lovastatin prevents steroid induced adipogenesis and osteonecrosis

Osteonecrosis of the femoral head was induced experimentally in chickens after the administration of a high dose of corticosteroids. Lovastatin was used to prevent the effects of the steroid on adipogenesis in cultured cells, and adipogenesis and osteonecrosis in chickens. The in vitro study, with marrow cells in culture, showed that Lovastatin inhibited steroid induced fat specific gene expression and counteracted the inhibitory effects of steroids on osteoblastic gene expression. For the in vivo study, 83 adult chickens were used: 48 received methylprednisolone 3 mg/kg weekly via intramuscular injection (Group A). Fifteen received the steroid (as in Group A) plus Lovastatin 20 mg per animal per day orally (Group B). Ten chickens received Lovastatin only (Group C). Another 10 received no medication and served as the control group (Group D). Evidence of osteonecrosis was observed in specimens from Group A, including subchondral bone death and resorption, fat cell proliferation, and new bone formation. Conversely, sections from Group B showed less adipogenesis and no bone death. It is concluded that the bipedal chicken is a useful animal model for studies of osteonecrosis and that lipid clearing agents, such as Lovastatin, may be helpful in preventing the development of steroid induced osteonecrosis.

Osteonecrosis of the Humeral Head

Current understanding of osteonecrosis of the humeral head is largely based on previous studies of the femoral head. Similarities between the two sites are numerous, but the shoulder has many unique characteristics. The anatomy of the glenohumeral joint, motion at the scapulothoracic joint, the rich vascular supply of the surrounding soft tissues, and the accommodations for the different forces (shear, compression) exerted across the glenohumeral joint all allow the shoulder to tolerate a greater amount of deformity. A number of pathologic agents can cause bone death by disrupting the blood supply, among them corticosteroid use, trauma, dysbarism, hemoglobinopathies, and various systemic diseases that disrupt the vascular system, such as Gaucher's disease and systemic lupus erythematosus. Management is similar to that of femoral osteonecrosis; the earlier stages respond well to nonoperative approaches, and the more advanced stages require surgical intervention. Hemiarthroplasty and total shoulder arthroplasty have produced good outcomes. Surgical intervention with core decompression, vascular flaps, and arthroscopic debridement have also shown promise, but further studies are necessary to define their optimal use.

Management of osteonecrosis of the femoral head

Osteonecrosis of the femoral head continues to pose a therapeutic challenge to orthopedic surgeons. This pathologic process results from the death of living components of bone from mechanical and biologic factors. Diagnosis, clinical symptoms, and classification systems are discussed. Several treatment regimens and their controversies are explored in this article.

Bone disorders in sickle cell disease

The bony skeleton of the patient with sickle cell disease is a frequent target of the consequences of sickling. Bone marrow necrosis, bone infarcts osteomyelitis, and aseptic necrosis are common complications in patients with sickle cell disease. An understanding of the pathogenesis, prevalence, diagnosis, and management of these conditions is therefore important for those involved in the care of such patients.

Core decompression for osteonecrosis of the femoral head

A retrospective++ review of core decompression of the femoral head for treatment of osteonecrosis was done. Cause of osteonecrosis, radiographic stage and progression, complications, and clinical results were evaluated. The study was based on 54 hips in 45 patients (98.2% followup rate). All patients reported pain preoperatively. Thirty-five hips (30 patients) were considered to have failed. Of these, 26 hips (23 patients) underwent total hip arthroplasty. The remaining 9 hips (7 patients) had little or no relief of pain and no improvement in function, but had not undergone total hip arthroplasty at last followup. The average time to failure was 11.1 months (2-34 months). Nineteen hips (16 patients) were considered successful. Fifteen hips (12 patients) were graded good to excellent and 4 hips (4 patients) were graded fair in terms of clinical results with an average followup of 47.5 months (12.4-95.7 months). The mean preoperative Hospital for Special Surgery hip score improved from 24.6 points (range, 18-38 points) to 34.2 points (range, 20-40 points). There were 2 intertrochanteric femur fractures in this group (5 and 6 weeks postoperatively). The overall success rate of core decompression in this series was 35.2% (19 of 54 hips, 45 patients). The results of core decompression in this study were poor in general and had an unpredictable effect on disease progression.

Femoral head reconstruction and revascularization. Treatment for ischemic necrosis

There is no solution to ischemic necrosis of the femoral head, a condition that leads to collapse, rapid degenerative changes, and subluxation of the hip joint. Core decompression, osteotomy, and various means of femoral head reconstruction have been tried, but the results have been mixed. When ischemic necrosis has led to cartilage indentation and marked collapse, any means of reconstructing the femoral head could be too late. However, if the collapse is not severe, the logical treatment may be the removal of the dead bone and restoration of the bony contents with chip grafts and a vascularized bone strut. A new method of treatment using a vascular pedicled iliac crest strut graft has been used for 13 years. Followup assessments 4 to 12 years later have shown good results with the early involvements, whereas the late collapsed cases showed good control of pain but unsatisfactory maintenance of femoral head integrity. Thus, the technique is recommended for restoring and maintaining femoral head integrity for Stage 3 and early Stage 4 of the disease.

Microvascular obstruction in avascular necrosis. Immunohistochemistry of 14 femoral heads

14 femoral heads with late stage avascular necrosis of different etiologies were histologically examined, with special attention to vascular structures. Decalcified slices were stained with hematoxylin-eosin, safranin-O, van Gieson stain, and Martius Scarlet Blue. Immunohistochemical techniques with antibodies against Factor VIII, and Ulex Europeus Lectin were used to visualize the endothelium of the blood vessels. 5 distinct zones of the necrotic femoral head could be identified. The necrotic zone contained areas with richly vascularized connective tissue. In the transitional zone, several areas with intravascular aggregations of newly formed and older fibrin clots were noticed, mainly on the venous side of the vascular system. Other small vessels were collapsed, with a few endothelial cells clumped together in the center of a concentric fibrous tissue. We suggest that obstruction to the venous outflow due to intravascular thrombosis as well as to perivascular fibrosis is important in the pathogenesis of non-traumatic avascular necrosis of the femoral head.

Steroid-induced osteonecrosis of the humeral head

Steroid-induced osteonecrosis is a disease of modern medicine. Prevention remains the hallmark of management; however, as long as there are medical conditions requiring steroid therapy, osteonecrosis will remain a problem. An understanding of the pathophysiology, in addition to the clinical and radiographic manifestations of this disease process, will aid the physician in the unique challenge of diagnosing and treating osteonecrosis of the humeral head.

Osteonecrosis: current perspectives on pathogenesis and treatment

Nontraumatic osteonecrosis results from impairment of circulation to the affected bone. The femoral head is affected most frequently. The underlying cause for the circulatory defect in osteonecrosis varies and may involve both local and systemic changes. Steroid use, alcohol consumption, pancreatitis, and lipid disorders appear to lead to bone death either by development of fat emboli in the microcirculature surrounding the affected bone or by fatty infiltration of the marrow. Decompression syndrome results from the presence of gaseous emboli in the microcirculature. In Legg-Calvé-Perthes disease other associated features are present such as short stature, suboptimal growth velocity, and/or hormonal imbalances, and it is likely that osteonecrosis may be secondary to systemic abnormalities, although specific factors have not been identified. Other frequently suggested pathogenic factors that play a role in the development of osteonecrosis include increased intraosseous pressures, the presence of cytotoxic cellular factors, intravascular coagulation, venous stasis, and the hyperviscosity syndrome. Some investigators have attempted, without success, to find a common etiology for all cases of osteonecrosis. In addition, patients have developed osteonecrosis without any known risk factors; this syndrome has been coined idiopathic avascular necrosis. In advanced stages of femoral head osteonecrosis, total hip arthroplasty appears to be the best therapeutic modality, particularly in older individuals.

A comparison of modern imaging modalities in osteonecrosis of the femoral head

Eleven symptomatic and seven asymptomatic patients, considered to be at high risk of osteonecrosis of the hip, were studied using plain radiography, scintigraphy, computed tomography (CT) with multiplanar reconstruction (MPR), and magnetic resonance imaging (MRI), to determine the precise roles of the various imaging modalities in detecting and staging femoral head osteonecrosis, and to evaluate the incidence in an asymptomatic high-risk patient group. Osteonecrosis was best detected by MRI and was particularly useful for the diagnosis of early disease when other imaging modalities were negative. It is recommended that MRI be performed for the detection of early osteonecrosis, while CT/MPR be used for accurate staging and treatment planning in the established disease.

Uncemented surface replacement for osteonecrosis of the femoral head

From 1973 to 1982, we performed 40 uncemented surface arthroplasties using 27 Thomine and 13 Gerard cups in 32 patients with osteonecrosis of the femoral head (Ficat Stages 3 and 4). The median follow-up was 8 (3-12) years, with a median age at operation of 35 (19-60) years. Walking ability and mobility were improved, but relief from pain was the most significant improvement. In 28 of the 40 hips the result was excellent or good according to the scoring system of Merle d'Aubigné. The clinical outcome was not influenced by varus angulation, axial resorption, or acetabular protrusion of the cup. As compared with other methods of treatment for osteonecrosis with loss of sphericity of the femoral head, we conclude that the cup arthroplasty is a good choice of treatment in the young patient.