Analysis of Danger Zone of the Posterior Column of Acetabulum and Morphological Data of the Isehial Tuberosity

Kyung, Hee Soo; Kim, Poong Taek; Rho, Han Kee; Kim, Yong Goo

Abstract

Ten emhalmed cadaveric adult bony hemipelvis specimens were ohtained to evaluate the configuration of the posterior column of acetabulum and to find a safe path for screw placement into it as well as to report on the morphological data of the ischial tuherosity and to determine the most optimaI technique for ischial tuberosity screw placement for open reduction and internal fixation of posterior acetabular fracture. Cadaveric studies were performed analyzing icm cross-sections through the acetabulum for the purpose of studying the anatomical configuration of the danger zone. The plane of the cross-section was perpendicular to the posterior column. Each cross-section had the medial boundary ot the acetabulum projected onto the posterior column. By analysing the projections on the posterior column, the exact configuration of the danger zone was determined. In this study, the average width of the posterior column at the mid-acetabular Ievel was 3.9cm. Computed tomography scan of the acetabulum yielded valuable int'ormation regarding screw placement in the posterior column. The average width, height and depth of the ischial tuberosity were 25.7 mm, 33. 1 mm and 31.7mm, respectively. The average angles hetween the posterior and medial aspects and hetween the posterior and lateral aspects of the ischial tuherosities were 79.5degreesand 111.5degrees, respectively. The entry point of the screw should be Smm or 10mm medial to the lateral margin of the ischial tuherosity and the screws should be directed 35-40degrees, 45-50degrees and 50-55degrees caudally at the level of the inferior acetahular margin and lcm and 2cm below it, respectively. to obtain the most favorable bony purchase.