OBJECTIVESTo investigate the spatial structure of pedicle rib units in normal thoracic human spines and to compare the dimensions of the pedicle rib unit with corresponding dimensions.

METHODSThoracic spine specimens in four fresh adult cadaveric were used. Computerized tomographic (CT) images (including two-dimensional, three-dimensional reconstruction) of the thoracic spines were obtained. Measurement parameters include:the width, the height, the chord length and the sagittal angles of the pedicle rib unit compared with pedicle, especially for the pedicle-rib overlapping height.

RESULTSThe pedicle rib unit was not a simple two-dimensional structure but a three-dimensional structure. The shortest height of pedicle rib unit was (12.6 ± 0.8) mm (T(1)), while the longest was (16.9 ± 1.1) mm (T(11)). The shortest height of pedicle-rib overlap was (7.2 ± 0.3) mm (T(1)), while the longest was (11.8 ± 1.0) mm (T(10)). The height of pedicle rib unit and the height of pedicle were significantly larger than that of the pedicle-rib overlap (P < 0.05), while there was no significantly difference between the height of pedicle rib unit and the height of pedicle (P > 0.05).

CONCLUSIONSThe pedicle rib unit is a complicated spatial structure, and the longitudinal height of pedicle-rib overlap should be taken as the real height of the unit.