| BackgroundWith the high-speed development of China’s modernization and industrialization industrialization,Industrial buildings and traffic accidents and the incidence of all kinds of natural disasters increasing year by year,made acetabulum fracture caused by serious violence commonly significantly increased than in the past.Traumatic hip arthritis, femoral head necrosis, heterotopic ossification, and complications such as fracture malunion seriously limits the prognosis of acetabulum fracture, the patient’s quality of life has a very bad influence.Because anatomy structure is complex, deep around the acetabulum, the acetabulum fracture treatment increasingly taken seriously by traumatic orthopedic surgeon, and also is a difficult point to trauma orthopaedics doctor.Complex anatomical structures of acetabulum, and the complexity of the injured mechanism make the acetabulum fracture way also rich variety,To have a better understanding of acetabulum fracture, help making clinical diagnosis, be auxiliary for surgical treatment. Since1961, when the state of Massachusetts general hospital Rowe and Lowell reported93cases of acetabulum fracture, appeared on the international classification method of many kinds of acetabulum fracture, Of which1964Judet and by Letournel modified Judet-Letournel classification method is more popular. Fracture which is cumulative to anterior column including pure anterior column fracture, transverse fractures, T fracture, double column fracture, anterior column with second half fractures. According to the fracture line direction, anterior column fractures often can be divided into high, medium and low anterior column fractures, High anterior column fractures involving the front of iliac crest or iliac spine, which can lead to bad head mortar matching, low involvement before iliac spine, only in the anterior column fracture between high and low.The operative method of anterior column fracture is commonly used by tension screw fixation and open reduction and internal fixation with the steel plate. They each have advantages and disadvantages, tension screw has advantages such as small trauma, simple operation, less complications, while the indications are relatively limited. To the cases that acetabulum anterior column fracture simply tension screw dose be a better chance. It is much easier to be toleranced for elder patients cause of litter damage and functional reduction. And that elder patients have the problem of osteoporosis,so the fixtion using steel plate lose efficacy sometimes. In the other way,it is easier to take the THR for patients which were fixed with tension screw. The cases that acetabulum anterior column fracture terribly, having obvious displacement, tension screw cannot achieve good reduction and fixation effect, and now open reduction and plate fixation will be the preferred. Iliac groin approach is commonly used as a surgical approach for anterior column fracture, and intraoperative approach cannot show joint surface, making serious complications such as the steel plate bolt penetrating the articular surface often happened. Therefore, some scholars study and use various methods to prevent this complication, such as expanding the exposure and cutting open joint capsule making articular surface under direct observation, or through the activity of the hip using a stethoscope to auscultation in ilium board, and increasing the frequency of intraoperative fluoroscopy. But these methods increased the trauma, or increase the operation time, and increase the radiation hazard.As far as possible close to the edge of acetabulum not dozen screw concept was put forward by some scholars, this means that try not to twist the screw in the screw hole near the fracture line. But studies have shown by Shazar, With steel plate fixed acetabulum fracture, away from the fracture end placed screw is fixed intensity50%lower than placed near the fracture end screw. Some cases of the acetabulum fracture reset lost probably has to do with this reason. On the other hand, elastic steel plate now is uesd for anterior wall fractures at the expense of much longer operation time and much more money.So it is very important for surgeons to be familiar with the anatomical structure of acetabulum.Quantitative anatomy data about the anterior acetabular column plating technology is very little. Shiramizu’s study suggest laying the steel plate along the pelvis boundaries, as long as the hole depth and length of screw are controled in12-14mm, rarely namely screw into the joint. We found in all part of the anterior column using short screw, the strength of the internal fixation is slightly insufficient. In Benedetti’s study, the the perpendicular line of surface of anterior column anterior surface is setting as a screw nail into a point of reference, but the anterior column surface, not a flat surface, as a reference to reliability is poorer. Wang Xianquan cutting pelvic specimen, choose relatively flat quadrilateral district for reference. But the quadrilateral district also have multiple radian, and there is still a space distance from quadrilateral district to the needle point. Using quadrilateral district plane as a reference, there would also be rich in experience for performer and procedure for multiple X-ray irradiation. No specimen is measured and compared between women in Wang Xianquan test. Sample size is limited, the repeatability is not high while using specimen, the error is bigger by manual cutting, also can cause great influence to the experimental results.Understanding the anterior column in the acetabulum anatomy to preventing screw through the joints is very necessary. Quantitative anatomy data about the anterior acetabular column plating technology is very little. Integrated the advantages and disadvantages of previous studies, we design new experiments and conduct a preliminary study. The pelvis three-dimensional model was established based on digital orthopaedic technology, to provide anatomical basis for screwing placement safely in acetabular anterior column plate by precisely cutting and measurement.Objective1. By collecting complete, healthy adult pelvic CT data, using Mimics software reconstruction, getting detailed and complete model of pelvic through digital cutting, measurement to the model, provides a new method for the further understanding of acetabulum anatomy.2. When we reduction and fixtion acetabulum anterior column fractures using open reduction and plate internal fixation technology. Quantization the scope of cotyle using the number of screw hole of pelvic reconstruction plate produced by Synthes. So that we can define the danger zone for placing the acetabulum anterior column plate accurately and intuitively, and to provide the anatomical evidence for the selection of the length of the screw.3. According to the experimental data, it provides the anatomical basis for the the direction and the length of the screw.4. For acetabulum anterior column fractures with open reduction and plate internal fixation of individualized preoperative preparation provides an experimental method.Materials and methods 1. Collection of images and reconstruct3-dimensional model of pelvis Obtained156adult models randomly, who took complete CT scan of pelvis in our hospital between July2010and August2013. Excluded the models with fractures, bony or anatomy abnormality of pelvic, we collected40models finally, including20males and20females. Scan condition:tube current200-300mA, tube tension120kV, matrix512x512, slice increment1.25mm. All the images were saved as DICOM format and imported to the personal computer. All the sequent tomoscan images of pelvis were imported into the Materialise’s Interactive Medical Image Control System (Mimics) in personal computer as DICOM format. The3-dimensonal models were reconstructed by the same calculated parameter.2. Within the acetabulum simulation into a sphere, the use of line drawing tool to draw the sphere diameter of L, and the diameter parallel to the corresponding line of the pelvis, To draw the vertical surfaceline at the two endpoints of the line,which is tangent to acetabulum edge called PI and P3, intersect to pelvic boundaries in two points B and D. Drawing the plano perpendicular of the sphere’s diameter through the point of anterior inferior spine, intersect to pelvic boundaries in points C. The pubic symphysis is defined as point A and sacroiliac joint is defined as point E. To measute the distance of AB,BC,CD,BD,DE respectively.3. Select common AO reconstruction plate (Synthes,3.5mm reconstruction bone plate), which is scaned by spiral CT (GE MediCal systems/lightsDeed type16), getting427copies of the original data in CT images of the steel plate. The DICOM format is stored and imported into the MediCal imaging interactive software (10.01) Mimics, defined threshold (Thresholding), then use regional growth (Region growing) for3d reconstruction, the reconstruction plate to. STL format file backup.4. Steel file of the STL format is imported into the pelvis of reconstruction of3d model. Moving and rotating plate to place it in front of the pelvis flange surface. According to the former planes, the steel plate model is divided into three parts. Pubic security zone is from the pubic symphysis to P3plane, of which the steel plate screw holes are safe to put screw, while not into the joint. Count the number and record it as N. Steel plate between P1and P3is the danger zone for acetabulum.5. According to the observation we found that the5th and the10th hole positions are not fixed, sometimes pass into the joint, sometime not, so they can’t be defined as the boundary of the danger zone of acetabulum. But the4th hole and11th holes must be outside the joint, and be safe to nail the bolts. The6th and9th holes are located in the danger zone of acetabulum, and are close to the edge of the acetabulum, according to the research of Shazar etc. Which has shown that near the fracture line nailing has obvious significance to increase the intensity of fixed. So we nail bolts in6th and9th holes simulatedly, make sure they are tangent with the acetabulum outer wall. Read the screws’parameters, pythagorean theorem is used to calculate the angles between screws with coronary plane, namely our mastery of tail direction in operation. The length of the screw is measured from starting point to exit point.6. Process Statistical Analysis to all result of a measurement. Independent sample t test is processed bewteen male and female, left and right (It was statistically significant when P<0.05). All data were putted into software SPSS13.0for statistics process.Results1. The distance of BD from anterior acetabular margin to posterior acetabular margin was male:(56.63±2.05) mm, female:(49.07±5.08) mm; The distance of BC and CD from anterior inferior spine to anterior acetabular margin and posterior acetabular margin was male:(27.71±1.34) mm,(29.38±1.79) mm,female:(27.74±3.75) mm,(23.24±4.24) mm;The distance of AB from pubic symphysis to anterior acetabular margin was male:(52.16±1.71)mm,female:(57.52±3.46)mm;The distance of DE from pubic symphysis to posterior acetabular margin was male:(21.39±5.61)mm,female:(26.14±4.77) mm.2. The number of nailing holes from pubic symphy sis to anterior acetabular margin was male:(4.56±0.51), female:(4.86±0.36).Because the statistical object is enumeration data, the first4holes of the steel plate are safe to nail screw bolts.3. The6th and9th holes are located in the danger zone of acetabulum, and are close to the edge of the acetabulum, When we nail bolts in the6th and9th holes simulatedly, make sure they are tangent with the acetabulum outer wall, the angle between screws with coronary plane is male:(64.72±5.79)°,(34.98±4.18)°;female:(56.33±6.02)°,(34.70±8.91)°.4. The6th and9th holes are located in the danger zone of acetabulum, and are close to the edge of the acetabulum, When we nail bolts in the6th and9th holes simulatedly, make sure they are tangent with the acetabulum outer wall, the length of screw bolt is male:(28.89±2.77) mm,(45.98±3.36) mm;female:(21.74±1.83) mm,(35.43±2.62) mm.Conclusions1. By collecting completly, healthy adult pelvic CT data, using Mimics software reconstruction, getting detailed and complete model of pelvic through digital cutting, measurement to the model, provides a new method for the further understanding of acetabulum anatomy.2. When we reduction and fixtion acetabulum anterior column fractures using open reduction and plate internal fixation technology. Quantization the scope of cotyle using the number of screw hole of pelvic reconstruction plate produced by Synthes. So that we can define the danger zone for placing the acetabulum anterior column plate accurately and intuitively.3. According to the experimental data, it provides the anatomical basis for the the direction and the length of the screw.4. For acetabulum anterior column fractures with open reduction and plate internal fixation of individualized preoperative preparation provides an experimental method. |
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