Rotationplasty is a compromise between amputation and limb salvage most commonly used for osteosarcomas of the distal femur. It is essentially an intercalary amputation where the neurovascular structures and distal aspect of the limb (leg) are retained, and re-attached to the proximal portion (proximal femur and hip) after the tumor has been removed. For functional purposes, the distal segment is turned 180 degrees so that the ankle joint functions as a knee joint, thus converting an above-knee to a below-knee amputation in order for prosthetic use to be maximized (see Figure 6).
Osteosarcomas are the most common primary, non-hematologic malignant tumors in childhood and adolescence, comprising almost 60% of all bone sarcomas. Although these tumors are osteoblastic in nature, the characteristics of the specific tumor-initiating cells are unclear. Osteosarcomas contain highly proliferative undifferentiated malignant cells with a disrupted bone differentiation program. Cancer stem cells (CSCs) that have tumor-initiating properties and capacity of symmetric and asymmetric division have now been described in many solid tumors. For osteosarcomas, the CSC hypothesis has received support from recently reported findings that both human and murine osteosarcomas contain a sub-population of multipotent cells that that express various mesenchymal stem cell surface markers and are capable of undergoing differentiation in multiple mesenchymal lineages such as osteoblasts and adipocytes. Differentiation into these different lineages can be easily assessed by growing cells in specific medium and assaying for differentiation markers.
Many reports have proved that traditional Chinese herbal medicines (TCM) have become popular used in disease prevention and as alternatives to cancer chemotherapy. In this study, we purified a polysaccharide (ABP-Ia) from the fruiting bodies of Agaricus blazei and identified its molecular weight to be ×10(5)Da. ABP-Ia was a heteropolysaccharide fraction consisting of glucose, mannose, and galactose in a molar ratio of 1:1:1, along with trace of rhamnose. The effect of ABP-Ia at three concentrations of 100, 200 and 400 μg/mL on the cell growth and apoptosis was evaluated in osteosarcoma cell lines HOS and a normal human osteoblast cell line NHOst. ABP-Ia had a significant inhibitory effect against the growth of HOS cells, whereas a mild cytotoxicity to the HOS cells mediated by ABP-Ia was observed, which was in accordance with the results that ABP-Ia substantially induced apoptosis in a dose-dependent fashion in the HOS cells. However ABP-Ia had no or minor inhibitory and cytotoxic effects on the viability of NHOst cells even at the high concentration of 400 μg/mL. Base on all the observations, we could conclude that ABP-Ia had an evident inhibitory effect on the growth of HOS cells mainly through induction of apoptosis, with a minor toxicity to normal human osteoblast cell.