| BackgroundWith the rapid development of our country’s economy and society,fractures of acetabulum caused by high-energy injuries such as industry,construction and traffic accidents is increasing.The classic view in acetabular fracture surgery indicates that the choice of surgical approach is decided by the types of fractures.The fractures of acetabular anterior column should be fixed through anterior approach,and the fractures of acetabular posterior column should be fixed through posterior Kocher-Langenback approach.Since Hirvensalo etc.and Cole etc.first reported the great curative effect on treatment of pelvic and acetabular fractures through modified Stoppa approach,a growing number of orthopedic surgeons have started to use this technology.Modified Stoppa approach has obvious advantages over traditional anterior or posterior approaches,with little trauma,safe in operation and less complications.It can expose the whole pelvis,from the pubic symphysis to the front of sacroiliac joint,so the plate can be directly placed on the surface of quadrilateral plate for better stability.Based on the further understanding of the anatomical relationship between the acetabular posterior column and the quadrilateral plate,our research group considered that the area ahead of the greater sciatic notch was the projection portion of acetabular posterior column on quadrilateral plate.Therefore,the fractures of acetabular posterior column could be fixed in the projection area,and it has been verified by good clinical treatment result.The plate,used to fix posterior column fracture of the acetabulum on the quadrilateral plate side,was named as medial iliosciatic plate.This technology overturned the traditional treatment concept of posterior column fractures,and provided a novel method for treatment of acetabular fractures.In clinic,it’s difficult to insert the screws of the medial iliosciatic plate safely.Orthopedic surgeons often place screws according to the operation experience and the understanding of the anatomical relationship between acetabulum and quadriilateral plate.Once the screw penetrated the acetabular joint,serious complications might happen,including articular cartilage injury,traumatic arthritis and so on.To our knowledge,there is little research about the safe screw placement of the medial iliosciatic plate through modified Stoppa approach so far.In this study,we aimed to measure the safe zone and safe angles for screw placement of the medial iliosciatic plate by computer 3D reconstruction technology.We hope to provide anatomical basis for orthopedic surgeons to place medial iliosciatic plate and screws safely and speedily.Objective1.Feasibility analysis of the treatment of the acetabular posterior column fractures by the medial iliosciatic plate.By using the software Mimics and Geomagic Studio,the safe zone of the medial iliosciatic plate for fixation of acetabular posterior column fractures was.defined,and the absolute and relative size of it were measured as well.2.Safety analysis of the treatment of the acetabular posterior column fractures by the medial iliosciatic plate.Within the safe zone,the general safe angulations of the screw placement of the medial iliosciatic plate were measured at different positions,which could provide anatomical reference for orthopedic surgeons to place medial iliosciatic plate and screws safely.Materials and methodsNormal pelvic CT scans of 52 adults(27 males and 25 females)were obtained to create pelvic 3D models.The acetabulum was extracted,5mm-thickened and recombined into the pelvic model.The width(d)of the safe zone for placement of the medial iliosciatic plate was measured.The vertical distance(w)between the vertex of the obturator canal and the greater sciatic notch was measured and the ratio(r)of d/w was calculated.Through the center of the acetabulum,the recombined innominatum model was cut with a plane perpendicular to the quadrilateral plate and the greater sciatic notch.The cross-section was marked as M.In males,4 points at distances of 1.0 cm,1.5 cm,2.0 cm and 2.5 cm anterior to the greater sciatic notch were marked.At each points,the angulations(∠a,∠b,∠c and ∠d)between the quadrilateral plate and tangent line of the outer edge of the thickened acetabulum model were measured in the cross-section M.In females,3 points at distances of 1.0 cm,1.5 cm and 2.0 cm anterior to the greater sciatic notch were marked,and ∠a,∠b,and ∠c were measured.The differences of parameters mentioned above were compared between males and females.ResultsThe width(d)of the safe zone for placement of the medial iliosciatic plate were(28.56±2.44)mm and(24.36±2.47)mm in males and females respectively,the ratio(r)were about 3/5(0.61)and 1/2(0.54).In males,the safe angulations of screw placement ∠a,∠b,∠c and ∠d were 88.04°±3.18°,77.81°± 3.85 °,68.01°± 4.11°and 56.81°±4.81°.In females,∠a,∠b and ∠c were 91.29°±4.52°,76.23°±3.82°and 62.790 ±3.51°.The values of d,r,∠a and ∠c were of statistical significance between males and females(P<0.05).ConclusionMedial surface of the acetabular posterior colomn have enough space to place the the medial iliosciatic plate.Inserting the screws at a certain angle in the safe zone can completely avoid penetrating to the hip joint. |
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