[[Pedicle screw]] [[pull-out]] strength is determined in part by the major [[screw]] diameter which should be 70–80% of [[pedicle]] diameter (in adults, larger screws can break through the [[pedicle wall]] or can burst the pedicle; in peds, larger screws may be used as the pedicle can expand). The minor diameter determines the strength of the screw and should be ≥ 5.5 mm in the adult [[lumbar spine]].