Core decompression with bone grafting for osteonecrosis of the femoral head.

Although core decompression is one of the more popular procedures for treating avascular necrosis, considerable controversy exists concerning its safety and effectiveness. The current authors review the results of a prospective study of 406 hips in 285 patients treated by one surgeon with core decompression and bone grafting. Patients were followed up for 2 to 14 years. The outcome was determined by the change in the Harris hip score, quantitative radiographic measurements, and need for total hip replacement. These hips were compared with 55 hips in 39 patients treated non-operatively and with historic controls. Five complications occurred after 406 procedures including two fractures that resulted from falls during the first postoperative month. Of the 312 hips in 208 patients with a minimum 2-year followup, 36% of hips (113 hips in 90 patients) required hip replacement at a mean of 29 months: 18 of 65 hips (28%) with Stage I disease; 45 of 133 hips (34%) with Stage II disease; three of 13 hips (23%) with Stage III disease; and 45 of 92 hips (49%) with Stage IV disease. Before femoral head collapse (Stages I and II combined) hip replacement was performed in 10 of 77 hips (14%) with small lesions (A), 33 of 68 hips (48%) with intermediate lesions (B), and 20 of 48 hips (42%) with large lesions (C). Results as determined by changes in Harris hip scores and radiographic progression were similar. Patients who underwent core decompression and bone grafting have a very low complication rate. In patients treated before femoral head collapse, the outcome is significantly better than in patients who received symptomatic treatment. The results are correlated with the stage and the size of the necrotic lesion.

Magnetic resonance venography versus contrast venography to diagnose thrombosis after joint surgery.

Magnetic resonance venography is a recently developed, noninvasive means of visualizing the proximal veins of the lower extremity and pelvis. Magnetic resonance venography is compared with standard contrast venography in the diagnosis of proximal deep vein thrombosis after total joint arthroplasty. Two hundred seven extremities were evaluated in a blinded study 5 to 7 days after surgery. Standard contrast venography identified 11 proximal deep vein thromboses. Initial interpretations of the magnetic resonance venographies by staff radiologists identified 5 of the proximal vein thromboses (sensitivity 45%). Two patients with negative standard contrast venographies were identified as positive (specificity 99%). A retrospective review of all magnetic resonance venographies by a dedicated magnetic resonance angiographer identified 10 of 11 deep vein thromboses seen on standard contrast venography (sensitivity 91%). Both false negatives were identified as positives. Standard contrast venography remains the gold standard for identifying proximal vein thromboses. Emerging magnetic resonance imaging techniques have created a potential alternative modality by which to identify deep vein thrombosis. The present study suggests that standard contrast venography continues to be the most accurate modality currently available. Although magnetic resonance venography seems to be accurate, its interpretation requires experience. As costs diminish and experience increases, magnetic resonance venography will have increased importance in the clinical recognition of deep vein thrombosis.

TPA induces differentiation of purified human myeloblasts in the absence of proliferation.

Normal granulocyte-monocyte progenitor cells have an absolute requirement for colony-stimulating factor (CSF) for proliferation and differentiation in vitro. In contrast, cells derived from acute myeloblastic leukemia patients are often defective in their response to CSF, but can be induced to undergo terminal differentiation by exposure to 12-o-tetradecanoyl phorbol-13-acetate (TPA) by a process that does not require cell proliferation. To investigate the relationship between TPA-induced leukemic cell differentiation and CSF-induced myeloid cell differentiation we investigated the effects of TPA on myeloblasts highly enriched from normal bone marrow and stable-phase chronic myeloid leukemia peripheral blood. TPA (10(-6)-10(-9) M) induced the rapid appearance of macrophage characteristics in the majority of myeloblasts in the absence of proliferation. The mechanisms of TPA- and CSF-induced myeloblast differentiation were compared by examining the requirement for DNA synthesis. Exposure of myeloblasts to CSF induced increased triatiated thymidine (3H-TdR) incorporation within a few hours, while TPA did not induce 3H-TdR incorporation by itself and was inhibitory to CSF-induced 3H-TdR uptake. This requirement for DNA synthesis was further investigated by reversibly inhibiting DNA synthesis by depleting intracellular polyamines with difluoromethylorinithine (DFMO). DFMO inhibited both CSF-induced proliferation and differentiation of myeloblasts, but had no effect on TPA-induced differentiation. These results demonstrate that the process of differentiation of myeloblasts induced by TPA is distinct from CSF-induced differentiation.

Differential expression of HLA-DR antigens in subsets of human CFU-GM.

Expression of HLA-DR surface antigens by granulocyte/monocyte colony-forming cells (CFU-GM) may be important in the regulation of proliferation of these cells. Using immunological techniques to enrich for progenitor cells, we investigated the expression of HLA-DR in subsets of CFU-GM. "Early" (day 14) CFU-GM express higher levels of HLA-DR than do "late" (day 7) CFU-GM. Among late CFU-GM, cells destined to form monocyte (alpha-naphthyl acetate esterase-positive) colonies express higher levels of HLA-DR than do CFU-GM destined to form granulocyte (chloroacetate esterase-positive) colonies. Because high-level expression of DR antigen was a marker for monocyte differentiation, we examined several lymphokines for their effects on both DR expression and in vitro commitment to monocyte differentiation by myeloid precursor cells. DR antigen density could be increased by more than twofold over 48 hours upon exposure to gamma-interferon (gamma-IFN), whereas colony-stimulating factors had no effect. This was associated with a dose-dependent inhibition of total CFU-GM number, and a relative, but not absolute, increase in the ratio of monocyte colonies to granulocyte colonies. Similarly, in day 7 suspension cultures of purified myeloid precursor cells, gamma-IFN inhibited cell proliferation and increased the ratio of monocytes to granulocytes. Thus, despite the induction of high levels of HLA-DR antigen on precursor cells (a marker of monocyte commitment), the dominant in vitro effect of gamma-IFN was inhibition of granulocyte differentiation.

Expression of Ia antigens on myeloid progenitor cells in chronic myeloid leukemia: direct analysis using partially purified colony-forming cells.

The regulation of Ia (HLA-DR) antigen expression on myeloid progenitor cells may be closely related to the control of myelopoiesis in both normal individuals and chronic myeloid leukemia (CML) patients. In an effort to study directly the expression and behavior of Ia surface molecules on myeloid progenitor cells, we used an immunologic purification technique to enrich these cells approximately 100-fold from the peripheral blood of CML patients. The majority of cells in this blast population expressed HLA-DR antigens. Thirty percent to 40% of cells could form a granulocyte or monocyte colony in agar, and these cells tended to express the highest levels of HLA-DR. The number of HLA-DR molecules per cell increased about twofold as the cells tranversed the cell cycle from G0/G1 to G2/M. This was true for unstimulated cells or cells exposed to colony-stimulating factors. Some of this increase was related to a corresponding increase in cell size and is also seen with other cell surface antigens such as beta-2-microglobulin. Ia antigen expression was not modified by culture with colony-stimulating factors, fetal calf serum, or serum-free, prostaglandin-free medium for periods of up to 24 hours. These results demonstrate that Ia antigens are expressed on the myeloid progenitor cells of CML, are increased in the S and G2/M phases of the cell cycle, and are stable under most in vitro culture conditions for at least 24 hours of culture.

Heterogeneity of clonogenic cells in acute myeloblastic leukemia.

The expression of differentiation-associated surface antigens by the clonogenic leukemic cells from 20 patients with acute myeloblastic leukemia (AML) was studied with a panel of seven cytotoxic monoclonal antibodies (anti-Ia, -MY9, -PM-81, -AML-2-23, -Mol, -Mo2, and -MY3). The surface antigen phenotypes of the clonogenic cells were compared with the phenotypes of the whole leukemic cell population, and with the phenotypes of normal hematopoietic progenitor cells. In each case the clonogenic leukemic cells were found within a distinct subpopulation that was less "differentiated" than the total cell population. Clonogenic leukemic cells from different patients could be divided into three phenotype groups. In the first group (7 of 20 cases), the clonogenic cells expressed surface antigens characteristic of the normal multipotent colony-forming cell (Ia, MY9). These cases tended to have "undifferentiated" (FAB M1) morphology, and the total cell population generally lacked expression of "late" monocyte antigens such as MY3 and Mo2. A second group (seven cases) of clonogenic cells expressed surface antigens characteristic of an "early" (day 14) colony-forming unit granulocyte-monocyte (CFU-GM), and a third group (six cases) was characteristic of a "late" (day 7) CFU-GM. The cases in these latter two groups tended to have myelomonocytic (FAB M4) morphology and to express monocyte surface antigens. These results suggest that the clonogenic cells are a distinct subpopulation in all cases of AML, and may be derived from normal hematopoietic progenitor cells at multiple points in the differentiation pathway. The results further support the possibility that selected monoclonal antibodies have the potential to purge leukemic clonogenic cells from bone marrow in some AML patients without eliminating critical normal progenitor cells.

Induction of proliferation of purified human myeloid progenitor cells: a rapid assay for granulocyte colony-stimulating factors.

The proliferation and differentiation of granulocyte and monocyte progenitor cells (CFU-C) in vitro is dependent on the presence of a group of closely related glycoproteins termed colony-stimulating factors (CSF). In order to investigate the interaction of these factors with CFU-C, we purified CFU-C from the peripheral blood of chronic myeloid leukemia patients with an immune rosette technique using specific monoclonal antibodies (mean 74-fold enrichment, 45% cloning efficiency). Colony formation by purified CFU-C demonstrated an absolute dependence on an exogenous source of CSF. Liquid culture of small aliquots of enriched CFU-C with CSF-containing medium resulted in a rapid, time- and concentration-dependent induction of DNA synthesis as measured by 3H-thymidine incorporation. This specific CSF induction of DNA synthesis by enriched CFU-C was used to develop a microassay system for CSF activity. CSF activity could be reproducibly quantitated in 24-48 hr. The proliferating cells in this assay system were shown to be myeloid progenitor cells by examining the morphology of their progeny and by determining the surface antigen phenotype of the responding cells (Ia+, T3-, B1-, Mo1-). This microassay provides a quantitative assessment of CSF activity that may be useful in the purification of human CSF and in the generation of monoclonal antibodies to CFU-C surface structures.

A monoclonal antibody reactive with normal and leukemic human myeloid progenitor cells.

Anti-MY9 is an IgG2b murine monoclonal antibody selected for reactivity with immature normal human myeloid cells. The MY9 antigen is expressed by blasts, promyelocytes and myelocytes in the bone marrow, and by monocytes in the peripheral blood. Erythrocytes, lymphocytes and platelets are MY9 negative. All myeloid colony-forming cells (CFU-GM), a fraction of erythroid burst-forming cells (BFU-E) and multipotent progenitors (CFU-GEMM) are MY9 positive. This antigen is further expressed by the leukemic cells of a majority of patients with AML and myeloid CML-BC. Leukemic stem cells (leukemic colony-forming cells, L-CFC) from most patients tested were also MY9 positive. In contrast, MY9 was not detected on lymphocytic leukemias. Anti-MY9 may be a valuable reagent for the purification of hematopoietic colony-forming cells and for the diagnosis of myeloid-lineage leukemias.

Use of surface markers to identify a subset of acute myelomonocytic leukemia cells with progenitor cell properties.

The expression of differentiation-associated surface antigens was used to identify subsets of human acute myelomonocytic leukemia cells. The leukemic colony-forming cells expressed antigens characteristic of very immature myeloid cells (Ia, MY7), while the majority of leukemic cells also expressed an antigen (MY4) characteristic of later myeloid cells. The highly proliferative MY4 negative colony-forming cells may serve as progenitor cells for the less proliferative MY4 + leukemic cells.