目的　探讨合并腰骶移行椎时骶1、2椎弓根的形态学特点，为应用骶髂螺钉固定提供形态学基础。  方法　选取生前资料完整的标本共79例。对骶1、骶2椎体前后径、椎体高度、椎体横径、椎弓根前高、椎弓根后高、椎弓根宽度、进针深度、进针角度进行测量。  结果　正常骶1椎弓根前高(18.1± 　3.8)mm，后高(20.6±3.6)mm，宽度(27.7±3.1)mm；Ⅱ型骶1椎弓根前高(19.9±2.0)mm，后高(19.2±2.6)mm，宽度(29.9±2.2)mm；Ⅲ型骶1椎弓根前高(18.5±3.0)mm，后高(16.9±3.1)mm，宽度(27.8±2.2)mm。正常骶2椎弓根前高(12.4±2.3)mm，后高(14.34±2.9)mm，宽度(22.2±3.1)mm，Ⅱ型骶2椎弓根前高(10.4±1.5)mm，后高　(14.4±2.4)mm，宽度(19.5±2.7)mm；Ⅲ型骶2椎弓根前高(9.5±2.0)mm，后高(14.0±3.0)mm，宽度(18.6±3.4)　mm。Ⅱ型骶1椎弓根大于正常，Ⅲ型与正常接近。正常骶2椎弓根大于Ⅱ型和Ⅲ型。  结论　合并腰骶移行椎时可应用骶髂螺钉固定，骶1椎弓根可容纳1~2枚螺钉，骶2椎弓根可容纳1枚螺钉。

Objective　To study morphologic characteristics of S1 and S2 pedicles of sacrum co-existing lumbosacral transitional vertebra, and provide anatomic basis for sacroiliac screw fixation.　Methods　79 specimens were selected and measured in this study. Anatomic measurements included the anteroposterior diameter of S1, the height and transverse diameter of S1 and S2, the anterior and posterior heights of S1and S2 pedicles, the width of S1 and S2 pedicles, and the depth and the angle of screw in S1 and S2.　Results　For normal specimens, anterior heights of S1 and S2 pedicles were about (18.1±3.8)mm and (12.4±2.3)mm，the posterior heights (20.6±3.6)mm and (14.34±2.9)mm, the width (27.7±3.1)mm and (22.2±3.1)mm；For typeⅡ specimens, anterior heights of S1 and S2 pedicles were about (19.9±2.0)mm and (10.4±1.5)mm，the posterior heights (19.2±2.6)mm and (14.4±2.4)mm，the width (29.9±2.2)mm and (19.5±2.7)mm；For type Ⅲ specimens, anterior heights (18.5±3.0)mm and (9.5±2.0)mm，the postreior heights (16.9±3.1)mm and (14.0±3.0)mm，the width (27.8±2.2)mm and (18.6±3.4)mm respectively. The size of normal S1 pedicle was less than type Ⅱ，however, that of type Ⅲ was similar to the normal. The size of normal S2 pedicle exceeded that of type Ⅱ and type Ⅲ.　Conclusions　sacroiliac screws fixation is reliable for treating lumbosacral transitional vertebre. One or two screws can be hold in S1 pedicle, however, only one screw can be hold in S2 pedicle.