Glossary: Pedicle screws

Provide a means of gripping onto a vertebral segment and limiting its motion. The pedicle screw, which is sometimes used as an adjunct to spinal fusion surgery, provides a means of gripping a spinal segment. The screws themselves do not fixate the spinal segment, but act as firm anchor points that can then be connected with a rod. The screws are placed at two or three consecutive spine segments (e.g. lumbar segment 4 and 5) and then a short rod is used to connect the screws. This construct prevents motion at the segments that are being fused.

After the bone graft grows, the screws and rods are no longer needed for stability and may be safely removed with a subsequent back surgery. However, most surgeons do not recommend removal unless the pedicle screws cause discomfort for the patient (5% to 10% of cases).

While there was a rod and screw breakage rate of approximately 10% in the 1980's, with modern pedicle screws the breakage rate has now been reduced to about one in 1,000.

An analysis of 2,500 patients by 350 physicians conducted by the North American Spine Society found that the complication rate with using pedicle screws in spinal fusion surgery is low. There is about a one in 1,000 chance of nerve root damage, and a 2% to 3% chance of infection.