[Stability of pedicle screws. 1: Maximum pullout force in healthy bony spine trunks with reference to drilling...

Pullout direction was axial and oblique to screw axis. Two different techniques of preparing the screw bed are matched: 1) 3.2 mm AO drill and 6.0 mm screws for D7-S1 and 4.5 mm screws for D11-D6, 2) resection of cancellous bone of the pedicle tube and 6.0 mm, 7.0 mm, 8.0 mm screws, which were inserted after measuring each level. With the better technique 1 (saving the cancellous bone) 620N-161N were reached from D1-S1, even if bigger screws could be used with technique 2.