According to a 2009 article in the Indian Journal of Orthopaedics, bone growth stimulation is a method of internal or external electrical and electromagnetic manipulation used to promote the healing of difficult bone fractures. Stimulation includes the application of low electrical currents or ultrasound to the fracture. Ultrasound is noninvasive, but bone growth stimulation can also be applied to fractures from inside the body through the use of implantable devices.
In the article, Galkowski et al. notes that bone growth stimulation has been proven to heal fresh fractures and osteotomies, spine fusions and delayed and nonunion of fractures that do not heal on their own. In some cases, invasive stimulators are surgically implanted in a patient's body. Anodes and cathodes deliver positive and negative electromagnetic currents to the site of injury.
Galkowski et al. explains that the cathode is placed into the site of bone repair, while the anode is placed in nearby soft tissues. The advantage of invasive stimulators is that they provide constant electric currents directly to the bone fracture and require little intervention or operation on the part of the patient. Noninvasive stimulators apply external electromagnetic coils to each side of the fracture and are held in place by a strap or cuff. Patients are responsible for adhering to a prescribed treatment schedule, which makes noninvasive stimulation more inconvenient.