BMP2 and osteonecrosis: In another steroid-induced osteonecrosis model, bone morphogenetic protein-2 (BMP-2)-loaded poly-L-lactic acid/polylactic-co-glycolic acid/poly-ε-caprolactone (PLLA/PLGA/PCL) composite scaffolds stimulated by LIPUS could facilitate osteoblast differentiation, vascularization, and bone formation [109].