Study design: The shape and size of the pedicles of the human spine differs within different races. The authors studied the diameters and angles of the spine pedicle from the T1 to L5 levels in Koreans. The following measurements were made 1) transverse diameter, 2) superoinferior diameter, 3) anteroposterior pedicle angle, 4) horizontal pedicle angle, and 5) pedicle axis angle.
Objectives: This study obtained indices of pedicle morphology in Koreans to use in transpedicular screw fixation and to explain the difference between other races and Koreans.
Summary of background data: Internal fixators for vertebrae fixation have been developed. Knowledge of pedicle morphology is essential for pedicle screw use. The use of pedicle screws in Asians is questionable. Few reports exist regarding pedicle morphology, and in those few reports, the pedicle isthmus diameter, pedicle angles, and the depth to the anterior cortex are emphasized.
Methods: The following measurements of the diameter and length of the human cadaver pedicle were done with vernier and dial calipers: 1) transverse diameter of pedicles, 2) superoinferior diameter of pedicles, 3) anteroposterior pedicle angle, and 4) horizontal pedicle and pedicle axis angles.
Results: The widest transverse diameter of the pedicle was seen at the L5 level and the narrowest was at the T4 level. The widest superoinferior diameter of the pedicle was seen at the T12 level, the narrowest was at the T1 level. In the transverse plane, the angles of the pedicles of T11 and T12 were faced laterally. The anteroposterior angle increased rapidly at the T4 level, with the T1 level having the greatest. In the sagittal plane, the horizontal angle of the lumbar vertebra was almost parallel to the horizontal plane. The pedicle axis was longest at the L3 level and shortest at the T1 level. In all areas, the transverse diameter of the pedicle in males was wider than the that in the female.
Conclusions: The results suggest that using 6-mm screws can violate the cortex of the pedicles in a significant number of levels of the upper lumbar spine. Using a screw longer than 40 mm is dangerous in the lower thoracic spine of a Korean. A statistical difference exists between the transverse diameter of the pedicles of Westerners and Koreans.