OBJECTIVESTo study the best entry points, direction and length of screw in acetabular posterior column plate technique, and to prevent the serious complications of screw penetrating the joint surface.

METHODSFebruary to July 2008 20 male cadaveric adult semi-pelvic specimen were taken.Serial cross-sections of the acetabular posterior column were determined and made. The safe angle of screw entry and the length on all entry points of each cross-section were measured. And put all data into software SPSS 10.0 for statistics process.

RESULTSOn margin of acetabulum, lateral-middle 1/4 point, midpoint, medial-middle 1/4 point and medial margin of posterior column of each cross-section, safe entry angle of inclination was 39 degrees , 57 degrees , 74 degrees , 90 degrees and 106 degrees respectively, the length of the screw was 39, 57, 74, 90 and 106 mm respectively.

CONCLUSIONOn lateral 1/4 region, lateral-middle 1/4 region, medial-middle 1/4 region and medial 1/4 region, screw posterior column angle is 40 degrees to 60 degrees , 60 degrees to 75 degrees , 75 degrees to 90 degrees , 90 degrees to parallel to the quadrilateral plate, and the length of the screw is 30 mm.