目的　为经坐骨小切迹髋臼后柱打钉入路提供解剖依据。  方法　用66侧成人髋骨标本，男36侧，女30侧；CT扫描男、女各30例骨盆，图像用Mimics软件行三维重建。根据坐骨小切迹的形态进行分型。   结果　髋骨标本分型：男性“）”型44.4%；“C”型30.6%；“『”型16.7%；“丿”型8.3%。女性“）”型73.3%；“C”型占3.3%； “『”型占6.7%；“丿”型1%。Mimics三维重建分型：男性“）”型56.7%； “C”型26.7%； “『”型13.3% “丿”型3.3%。女性“）”型76.7%；； “C”型10.0%； “『”型6.7%；“丿”型6.7%。   结论　坐骨小切迹“C”型时，坐骨小切迹的下端影响打钉，要用骨刀切下坐骨小切迹下端，打入导针；如坐骨小切迹为“『”型时，打导针易打滑，需要在坐骨小切迹的进钉点做一个台阶。

　Objective　To provide anatomy basis for the placement of lag screw in the acetabular posterior column via lesser sciatic notch.　Methods　The morphology of lesser sciatic notch was observed on 66 sides of innominatum bone specimens (36males and 30 females). Pelvic CT scanning data from 60 adults (30males and 30 females) were imported to Mimics 14.1 for 3D image reconstruction. On the basis of this result, the morphology of lesser sciatic notch was classified.　Results　According to skeleton classification, type “）” “C” “『” “丿” of each station were 44.4%, 30.6% ,16.7%, 8.3% in male respectively. Type“）”“C” “『”“丿”of each station were 73.3%, 3.3%,6.7%,1% in female respectively. According to three-dimensional reconstruction of Mimics classification, type “）” “C” “『” “丿” of each station were 56.7%, 26.7% , 13.3%, 3.3% in male respectively. Type “）” “C” “『” “丿” of each station were 76.7%, 10.0% , 6.7%,6.7% in female respectively.　Conclusion　If type “C”was encountered, the inferior extremity of lesser sciatic notch will affect placement of the lag screw and into a guide pin should be placed after osteotomy. The guide pin is easy to slip and a “step” should be made at pin- point of lesser sciatic notch if the type is “『”.