![]() ![]() We believe that a cement with an elasticity modulus similar to cancellous bone and large interconnected pores would offer favorable conditions for bone remodeling. However, almost all evaluated bone defects remodeled without any graft filling or other substitute. 13 stated that bone defects smaller than 60 mm 3 do not require filling with bone substitutes because they remodel with a low risk of fracture (5%), while larger defects require stabilization due to increased risk of fracture (17%). There is a natural tendency to fill bone defects triggered by mechanical stimuli. 10 However, only two of these techniques allow intraoperative modeling of the block, allowing perfect adaptation to the defect: a mixture of immiscible absorbable or soluble substances 4 and adding of effervescent components. 9 Many pore-forming techniques have been reported, especially for use in tissue engineering. 8 It is believed that macropores favor bone intrusion. In addition to the recognized characteristics which are important for this purpose (for example, early mechanical strength and its unlimited availability), there are specific features that can be enhanced regarding solid cement, such as free diffusion of growth factors and other osteoinductive substances interconnected through pores 7 and reducing the difference between the modulus of elasticity of cancellous bone and the cement. Porous cements can be seen as reasonable alternatives to solid cement and many options based on PMMA 4, 5 and calcium phosphate (CPC) 6 have been reported. 2 The high temperatures reached during cement drying, the decrease in blood supply due to the confinement of the subchondral bone between the articular cartilage and the cement and the elasticity discrepancy between bone and cement are considered causes of the appearance of a radiolucent region around the block and eventually, its failure. 1 Solid PMMA blocks allow immediate load support, but are related to complications such as bone and cartilage necrosis leading to arthrosis, when implanted in the periarticular subchondral region. Other bone substitutes in different cement presentations do not provide immediate mechanical stability and their ability to remodel is not well established in the literature. They are often filled with solid blocks of polymethylmethacrylate (PMMA). The curettage of benign bone tumors produce large defects that are at risk of fracture. ![]()
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