Anatomical Study Of Screw Placement Into The Posterior Column Of The Acetabulum Security And The Application Of Clinical

The first part: The anatomical study of screw placement into the posterior column of the acetabulum security.Objective:To provide an applied anatomical basis for the placement of screw of the acetabular posterior column and explore a safe path for screw placement into it during the procedure of open reduction and internal fixation of the acetabulum fractures through anatomical study of the posterior column of acetabulum.Methods:15 adult pelvis (30 hips)specimens of China were used in this study.The top point of acetabular margin was named point A, the fundus point of acetabular margin was named point B,the midpoint line A-B was named C.The top point of greater sciatic notch was named A',the top point of sciatic spina was named point B',the midpoint line A'-B'was named C'.The original plane(middle plane of acetabulum)was through point C and C'and perpendicular to the surface of posterior column.parallel the original plane, sectioned the specimens at 10mm intervals ,there were two plane up (down)the original plane.We can obtain 5 planes(contain anterior column and posterior column of the acetabulum).The width of posterior column and the width of acetabulum were obtained by analysis of each cross-section. On each cross-section measured the safe angulation and length of screw , at the point of 10,20mm medial to the margin of acetabular . Results:1. The width of the acetabulum of middle plane is the widest ,the average width of middle plane was 20.7±1.5mm. The ratios from the superior to the inferior of the width of acetabulum and the width of posterior column were :38.67%, 55.80%, 61.12%, 49.68%, 28.65%. On each cross-section the projection point of the medial acetabular boundary on the posterior were marked. Connected these marks,point A and point B there was area of arc.This area was the danger zone of acetabular on the posterior column.2. On each of the cross-section,the average maxima angulation of screw for 10,20mm points medial to the acetabular brim:①On the 20mm plane superior to the middle plane of acetabulum: 62.7±2.5o,87.8±2.8o.②On the 10mm plane superior to the middle plane of acetabulum: 52.3±5.5o,82.7±4.3o.③On the middle plane of acetabulum: 54.9±4.0o,81.4±5.0o.④On the 10mm plane inferior to the middle plane of acetabulum: 59.7±2.7o,85.3±3.2o.⑤On the 20mm plane inferior to the middle plane of acetabulum: 76.4±4.8o,90.0±0.0 o.3. On each of the cross-section,the proper length of screw for 10,20mm points medial to the acetabular brim:①On the 20mm plane superior to the middle plane of acetabulum: 38.9±2.1mm,49.4±4.9mm.②On the 10mm plane superior to the middle plane of acetabulum: 33.2±2.6mm,39.6±2.2mm.③On the middle plane of acetabulum: 28.9±2.7mm,35.9±4.1mm.④On the 10mm plane inferior to the middle plane of acetabulum: 30.9±2.9mm,35.4±4.1mm.⑤On the 20mm plane inferior to the middle plane of acetabulum: 38.6±2.2mm,40.3±1.0mm.Conclusions:1.The safe angulation of screw placement for the point 10mm medial to the acetabular brim should smaller than 50 o ,the safe length should smaller than 28mm. 2. The safe angulation of screw placement for the point 20mm medial to the acetabular brim should smaller than 80 o ,the safe length should smaller than 35mm.The second part :The study of clinical applicationObjective:Use the data that we obtained from the study of the acetabulum posterior column guided the treatment of acetabulum fractures.To prove the clinic significance of the study of the acetabulum posterior column.Methods:Clinical analysis was done on 21 patients with fractures of posterior column and(or)posterior wall of acetabular .Treated from April 2005 to October 2006.Treated by open reduction and internal fixation with reconstruction plate-screw and(or) ATMS.Used the data we obtained from the anatomical study of posterior column of the acetabular, guided our treatment.Results:21 cases were followed up ,according to Matta anatomic criteria ,14 cases with anatomic reduction, 6 cases with satisfied reduction,1 case with unsatisfied reduction and evaluated to D'Aubigne-pestel criteria for joint functions, 13 cases with excellent,4 cases with fine, 3 cases with fair ,1 case with poor. There were not the complications of screw penetration the hip joint and the injure of organ of pelvis.Conclusions:The date we obtained from the posterior column anatomical study of the acetabulum could guide the screwing placement safety duaring the procedure of open reduction and internal fixation.