In the past, spinal fusions of the lumbar spine were performed without any internal fixation. The surgeon simply roughed up the bone, placed bone graft material around the vertebrae, and hoped the bones would fuse. Sometimes, patients were placed in a body cast to try to hold the vertebrae still while healing. The patient was lucky to have a 70 percent chance of successful fusion.
Surgery of the spine continues to be a challenging and difficult area. The vertebrae are small, so there is not much room to place small instruments. Also, many nerves can get in the way of putting screws into the vertebral body. And a large amount of stress is put on the lower back, so finding a metal device that is able to hold the bones together can be difficult.
Over the past two decades, some very inventive devices have been designed that have changed the way surgeons perform spinal fusions.
Pedicle Screws and Rods
The surgeon may use some type of metal screws, plates, and rods to hold the vertebrae in place while the spine fusion heals. Designed to stabilize and hold the bones together while the fusion heals, these devices have greatly improved the success rate of fusion in the lower back.
“Pedicle screws” are placed through the pedicle bone on the back of the spinal column. The screw inserts through the pedicle and into the vertebral body, one on each side. The screws grab into the bone of the vertebral body, giving them a good solid hold on the vertebra. Once the screws are placed they are attached to metal rods that connect all the screws together. When everything is bolted together and tightened, this creates a stiff metal frame that holds the vertebrae still so that healing can occur. The bone graft is then placed around the back of the vertebrae.