A review on external physical stimuli with biomaterials for bone repair

Bone repair is a complex process that involves the inflammatory response, angiogenesis, and bone remodeling. The traditional bone defect treatment process suffers from a lack of donors, immune rejection and a high cost of treatment. Recently, external physical stimulation, including electrical, magnetic, and mechanical forces; heat; ultrasound; and shock waves, has been widely used in bone defect repair in a noninvasive and nonpouring manner. It can promote bone regeneration through different pathways such as Wnt/beta-catenin signaling pathway conduction, activation of Ca2+ channels, and integrin signaling. Importantly, different stimulation methods are related to each other rather than completely independent. And it is a promising strategy to apply multiple external stimuli to bone defect repair or to combine them with endogenous biomaterials. This review briefly describes the applications and mechanisms of external stimulation in bone tissue engineering. In the end, we proposed a strategy to combine external stimulation with biomaterials and cells for bone repair and look forward to the further application of external stimulation in future medicine.