Fig. 5From: Modified mini-open SRS-Schwab grade 4 osteotomy combined with percutaneous pedicle screws fixation in post-traumatic thoracolumbar kyphosisclassification of pedicle screws. Grade 0: accurate pedicle screw; Grade 1: pedicle screws with < 2 mm perforation; Grade 2: pedicle screws with 2–4 mm perforation, Grade 3: pedicle screws with > 4 mm perforationBack to article page