The purpose of bone-growth stimulators is to support the healing of bone after spinal surgery, according to Spine-health. After spinal fusion surgery, bits of bone are supposed to heal or fuse together. Internal or external bone-growth stimulators help them to do this.
Bone-growth stimulators aren't used on every patient who has bone graft surgery, says Spine-health. They are used for people who are at risk for a failed fusion. These patients have had a failed fusion in the past, have a multiple-level fusion, smoke or have a severe case of spondylolisthesis.
An internal bone-growth stimulator is placed during the surgery, according to Spine-health. It is inserted in soft tissue beside the spine and just under the skin. It delivers tiny amounts of electrical current to the bone fragments, which encourages them to fuse. It is not painful, though some patients claim they can feel it. The electrical current is so low that they can pass through metal detectors. The bone-growth stimulator is removed after the bones are fused, which can be anywhere from six months to one year.
An external bone-growth stimulator uses skin pads or electrodes placed over the fusion area or treatment coils that are installed in a brace and put on the skin, according to Spine-health. An external bone-growth stimulator is worn for several hours a day for about three to nine months after spinal surgery.