An implant system that includes small cross-section implant elements that can be introduced into targeted bone regions wherein the elements self-assemble into a large cross-section, higher modulus monolith. The implant elements are configured with properties engage one another, such as surface features or magnetic properties. The implants and methods can be used to treat bone abnormalities such as compression fractures of vertebrae, bone necrosis, bone tumors, cysts and the like.