| Background：Acetabular fracture has a variety of Classification systems, the most widely usedclassification system is Judet-Letournel classification. However, this classification systemdoes not involve the weight-bearing area of acetabular roof. In fact, both column fracture,transverse fracture or T-type fracture may involve weight-bearing area. The majority ofscholars believe that whether the fracture involves the weight-bearing area are essential forthe choice of treatment strategy and the judgment of prognosis.Zhang Chuncai, the leader of MO group，based on the systematic concept ofLetournel and Judet in two columns, put forward the theory of acetabular three-columninnovatively, which on the basis of the evolution of acetabulum, the integrity of the pelvisand the head-mortar counterparts. The theory focuses on the weight-bearing area whichcorresponding the middle column as an important part of the acetabulum. We put forwarda specific classification system by ABC damage variable and positioning system foracetabular fracture. Then providing a more intuitive impression for clinicians. You canroughly determine the type of fracture, the severity, treatment options prognosis, even theproximal femoral fractures which often combined with acetabular fractures due to highenergy injuries by the classification of fracture.Given the importance of acetabular roof fracture, but there is very few anatomicalmeasurements corresponding that. The purpose of this study is to further understand theanatomy characteristics of the weight-bearing area by measuring the acetabular wall of themiddle column, namely the weight-bearing area. To study the loading characteristics ofmiddle column of acetabulum of the body’s normal standing position, we use thethree-dimensional finite element, which verify the particular importance of the middlecolumn wall and provide a theoretical evidence for the three-column acetabular theory andABC damage variable positioning system. So we could guide clinicians to choose bettertreatment options and judgement of prognosis.Part I Anatomic measurements and quantitative analysis ofthe middle wall of acetabular middle columnObjective：To further understand and quantitatively analyze the anatomy characteristics of theweight-bearing area by measuring the acetabular wall of the middle column, namely the weight-bearing area, which verify the particular importance of the middle column wall andprovide a theoretical evidence for the three-column acetabular theory and ABC damagevariable positioning system. So we could guide clinicians to choose better treatmentoptions and judgement of prognosis.Methods：15formalin-preserved cadaveric pelvises（8males and7females） were used for thisinvestigation。The whole acetabular middle walls were marked with―angle‖sector methodand the thickness was measured with caliper in different levels of the different split points.The measurement results were validated and analyzed.Results：1、At5mm away from the acetabular rim，the average thickness of anterior wall ofacetabular middle column fluctuated between7.71±0.47mm and8.27±0.49mm； theaverage thickness of posterior wall of acetabular middle column fluctuated between6.47±0.42mm and7.43±0.45mm；the average thickness of the wall of acetabular middlecolumn fluctuated between6.47±0.42and8.27±0.49mm； the average thickness ofposterior wall of acetabular posterior column fluctuated between5.62±0.37mm and6.33±0.41mm. Comparatively,no statistically significant difference was found between theaverage thickness of anterior wall of acetabular middle column and posterior wall ofacetabular middle column（P>0.05），and no statistically significant difference was foundbetween the average thickness of posterior wall of acetabular middle column and posteriorwall of acetabular posterior column（P>0.05），and no statistically significant differencewas found between the average thickness of the wall of acetabular middle column andposterior wall of acetabular posterior column（P>0.05），but the average thickness of theanterior wall of acetabular middle column was significantly larger than posterior wall ofacetabular posterior column（P<0.05）；At10mm away from the acetabular rim，the averagethickness of anterior wall of acetabular middle column fluctuated between14.47±0.65mmand17.05±1.05mm；the average thickness of posterior wall of acetabular middle columnfluctuated between8.81±0.66mm and13.35±0.71mm；the average thickness of the wall ofacetabular middle column fluctuated between8.81±0.66and17.05±1.05mm；the averagethickness of posterior wall of acetabular posterior column fluctuated between7.02±0.27mm and7.87±0.29mm. Comparatively，the average thickness of the anterior wallof acetabular middle column was significantly larger than posterior wall of acetabularmiddle column（P<0.01）；the average thickness of the posterior wall of acetabular middle column was significantly larger than posterior wall of acetabular posterior column（P<0.05）；the average thickness of the wall of acetabular middle column wassignificantly larger than posterior wall of acetabular posterior column（P<0.05）；At15mmaway from the acetabular rim，the average thickness of anterior wall of acetabular middlecolumn fluctuated between23.23±1.10mm and26.01±1.26mm；the average thickness ofposterior wall of acetabular middle column fluctuated between12.08±0.71mm and19.84±0.96mm；the average thickness of the wall of acetabular middle column fluctuatedbetween12.08±0.71and26.01±1.26mm；the average thickness of posterior wall ofacetabular posterior column fluctuated between10.17±0.35mm and11.26±0.52mm.Comparatively，the average thickness of the anterior wall of acetabular middle column wassignificantly larger than posterior wall of acetabular middle column（P<0.01）；the averagethickness of the posterior wall of acetabular middle column was significantly larger thanposterior wall of acetabular posterior column（P<0.01）；the average thickness of the wallof acetabular middle column was significantly larger than posterior wall of acetabularposterior column（P<0.01）；2、At5mm away from the acetabular rim，the average thickness of anterior wall ofacetabular middle column fluctuated between7.71±0.47mm and8.27±0.49mm. At10mmaway from the acetabular rim，the average thickness of anterior wall of acetabular middlecolumn fluctuated between14.47±0.65mm and17.05±1.05mm. At15mm away from theacetabular rim，the average thickness of anterior wall of acetabular middle columnfluctuated between23.23±1.10mm and26.01±1.26mm. Comparatively，with the increase ofthe measured distance, the thickness of anterior wall of acetabular middle column had asignificant increas（eP<0.01）；At5mm away from the acetabular rim，the average thicknessof posterior wall of acetabular middle column fluctuated between6.47±0.42mm and7.43±0.45mm. At10mm away from the acetabular rim，the average thickness of posteriorwall of acetabular middle column fluctuated between8.81±0.66mm and13.35±0.71mm. At15mm away from the acetabular rim，the average thickness of posterior wall of acetabularmiddle column fluctuated between12.08±0.71mm and19.84±0.96mm. Comparatively，with the increase of the measured distance, the thickness of posterior wall of acetabularmiddle column had a significant increase（P<0.05）；At5mm away from the acetabularrim，the average thickness of the wall of acetabular middle column fluctuated between6.47±0.42mm and8.27±0.49mm. At10mm away from the acetabular rim，the averagethickness of the wall of acetabular middle column fluctuated between8.81±0.66mm and 17.05±1.05mm. At15mm away from the acetabular rim，the average thickness of the wallof acetabular middle column fluctuated between12.08±0.71mm and26.01±1.26mm.Comparatively，with the increase of the measured distance, the thickness of the wall ofacetabular middle column had a significant increase（P<0.05）；At5mm away from theacetabular rim，the average thickness of posterior wall of acetabular posterior columnfluctuated between5.62±0.37mm and6.33±0.41mm. At10mm away from the acetabularrim，the average thickness of posterior wall of acetabular posterior column fluctuatedbetween7.02±0.27mm and7.87±0.29mm. At15mm away from the acetabular rim，theaverage thickness of posterior wall of acetabular posterior column fluctuatedbetween10.17±0.35mm and11.26±0.52mm. Comparatively，with the increase of themeasured distance, the thickness of posterior wall of acetabular posterior column had asignificant increase（P<0.05）；Conclusion：Whether the anterior wall of acetabular middle column, the posterior wall ofacetabular middle column or posterior wall of acetabular posterior column, with themeasurement distance increases, the average thickness had a significant increase. Of them,the average thickness of the anterior wall of acetabular middle column had the mostsignificant increase. That means the acetabular lip of the anterior wall of acetabular middlecolumn is short and thick, and the acetabular lip of the posterior wall of acetabularposterior column is thin and long. Anatomical measurements confirmed the view that theanterior wall of acetabular middle column, rather than the posterior wall of acetabularmiddle column, assume a major role in weight-bearing in the acetabulum. The fracture ofthe anterior wall of acetabular middle column has more significant biomechanical effects. Part II Three-dimensional finite element analyzing theloading characteristics of middle column of acetabulum of thebody’s normal standing positionObjective:To study the loading characteristics of middle column of acetabulum of the body’snormal standing position, we use the three-dimensional finite element, which verify theparticular importance of the middle column wall and provide a theoretical evidence for thethree-column acetabular theory and ABC damage variable positioning system. So we couldguide clinicians to choose better treatment options and judgement of prognosis.Methods：Choose healthy adult male, human pelvis entity model is set up. After pre-processing byfinite element, we set conditions as follows: normal nondestructive pelvis model withupright position, gradually loading preature to500N and1600N within2hours. Recordaverage pressure, peak pressure, and stress distribution of the joint surface, and analyze theresult.Results：1、When the load uniformly increased to500N load within two hours, the central peakload force of one side of the hip joint had no significant increase during the first30min.After that, it increased uniformly；When the load uniformly increased to1600N load withintwo hours, the central peak load force of one side of the hip joint had no significantincrease during the first30min. After that, it increased first slow after the fast；When theload uniformly increased to500N load within two hours, the central peak intensity ofpressure of one side of the hip joint had no significant increase during the first30min.After that, it increased uniformly; When the load uniformly increased to1600N load withintwo hours, the central peak intensity of pressure of one side of the hip joint had nosignificant increase during the first30min. After that, it increased first slow after the fast.2、Under the load of500N, the weight-bearing area roughly distributed within the scopeof the middle column wall of the acetabulum, the posterior wall of acetabular posteriorcolumn only partly involved in weight-bearing. The weight-bearing pressure stepwisedecreasing from the center to the surrounding. The acetabular rim and the anterior andposterior wall beyond does not participate in the range of weight-bearing; Under the loadof1600N, the weight-bearing area roughly distributed within the scope of the middlecolumn wall of the acetabulum, the posterior wall of acetabular posterior column only partly involved in weight-bearing. The weight-bearing pressure stepwise decreasing fromthe center to the surrounding. With the increase of the load pressure, the loading ofacetabular roof increased significantly, the range of weight-bearing area within the middlecolumn wall increased, but the anterior and posterior wall beyond still does not participatein the range of weight-bearing.3、Under the load of500N, the average intensity of pressure of anterior wall ofacetabular middle column fluctuated between0.4591±0.5036Mpa and0.8185±0.6331Mpa;The average intensity of pressure of posterior wall of acetabular middle column fluctuatedbetween0.4488±0.5345Mpa and0.6518±0.5168Mpa; The average intensity of pressure ofthe wall of acetabular middle column fluctuated between0.4488±0.5345Mpa and0.8185±0.6331Mpa; The average intensity of pressure of posterior wall of acetabularposterior column fluctuated between0±0Mpa and0.4438±0.4599Mpa; The averageintensity of pressure of Acetabular notch is0. Of them, the posterior wall of acetabularposterior column where near the boundary of middle column and posterior columnwithin a30°range can be measured pressure distribution, its intensity of pressurefluctuated between0.0065±0.0195Mpa and0.4438±0.4599Mpa. Under the load of500N,no statistically significant difference was found between the average intensity of pressureof anterior wall of acetabular middle column and posterior wall of middle column（P>0.05）；The average intensity of pressure of the posterior wall of middle column andthe posterior wall of acetabular posterior column where near the boundary of middlecolumn and posterior column within a30°range has a significant difference（P<0.05）;The average intensity of pressure of the anterior wall of middle column and the posteriorwall of acetabular posterior column where near the boundary of middle column andposterior column within a30°range has a significant difference（P<0.05）; The averageintensity of pressure of the the wall of middle column and the posterior wall of acetabularposterior column has a significant difference（P<0.05）;Under the load of1600N, the average intensity of pressure of anterior wall of acetabularmiddle column fluctuated between1.2231±1.0234Mpa and2.1362±1.3158Mpa; Theaverage intensity of pressure of posterior wall of acetabular middle column fluctuatedbetween0.9969±0.8183Mpa and2.0690±1.0476Mpa; The average intensity of pressure ofthe wall of acetabular middle column fluctuated between0.9969±0.8183Mpa and2.1362±1.3158Mpa; The average intensity of pressure of posterior wall of acetabularposterior column fluctuated between0±0Mpa and0.8158±0.7246Mpa; The average intensity of pressure of Acetabular notch is0. Of them, the posterior wall of acetabularposterior column where near the boundary of middle column and posterior columnwithin a30°range can be measured pressure distribution, its intensity of pressurefluctuated between0.0314±0.0943Mpa and0.8158±0.7246Mpa. Under the load of1600N,no statistically significant difference was found between the average intensity of pressureof anterior wall of acetabular middle column and posterior wall of middle column（P>0.05）；The average intensity of pressure of the posterior wall of middle column andthe posterior wall of acetabular posterior column where near the boundary of middlecolumn and posterior column within a30°range has a significant difference（P<0.05）;The average intensity of pressure of the anterior wall of middle column and the posteriorwall of acetabular posterior column where near the boundary of middle column andposterior column within a30°range has a significant difference（P<0.05）; The averageintensity of pressure of the the wall of middle column and the posterior wall of acetabularposterior column has a significant difference（P<0.05）;4、Under the load of500N, the average intensity of pressure of anterior wall ofacetabular middle column fluctuated between0.4591±0.5036Mpa and0.8185±0.6331Mpa.Under the load of1600N, the average intensity of pressure of anterior wall of acetabularmiddle column fluctuated between0.4591±0.5036Mpa and0.8185±0.6331Mpa. Theyhave a significant difference（P<0.05）; Under the load of500N, the average intensity ofpressure of posterior wall of acetabular middle column fluctuated between0.4488±0.5345Mpa and0.6518±0.5168Mpa. Under the load of1600N, the averageintensity of pressure of posterior wall of acetabular middle column fluctuated between0.9969±0.8183Mpa and2.0690±1.0476Mpa. They have a significant difference（P<0.05）;Under the load of500N, the average intensity of pressure of the wall of acetabular middlecolumn fluctuated between0.4488±0.5345Mpa and0.8185±0.6331Mpa. Under the load of1600N, the average intensity of pressure of the wall of acetabular middle columnfluctuated between0.9969±0.8183Mpa and2.1362±1.3158Mpa. They have a significantdifference（P<0.05）; Under the load of500N, the average intensity of pressure of posteriorwall of acetabular posterior column fluctuated between0±0Mpa and0.4438±0.4599Mpa.Under the load of1600N, the average intensity of pressure of posterior wall of acetabularposterior column fluctuated between0±0Mpa and0.8158±0.7246Mpa. They have asignificant difference（P<0.05）; Under the load of500N, the average intensity of pressureof the posterior wall of acetabular posterior column where near the boundary of middle column and posterior column within a30°range fluctuated between0.0065±0.0195Mpaand0.4438±0.4599Mpa. Under the load of1600N, the average intensity of pressure of theposterior wall of acetabular posterior column where near the boundary of middle columnand posterior column within a30°range fluctuated between0.0314±0.0943Mpa and0.8158±0.7246Mpa. They have a significant difference（P<0.05）;In summary, with the load force increased, the intensity of pressure of different parts ofthe wright-bearing surface increased significantly, but the scope of the wright-bearingsurface has no significant increase.Conclusion：1、Under the load of500N, the weight-bearing area roughly distributed within the scopeof the middle column wall of the acetabulum, the posterior wall of acetabular posteriorcolumn only partly involved in weight-bearing. The weight-bearing pressure stepwisedecreasing from the center to the surrounding. The acetabular rim and the anterior andposterior wall beyond does not participate in the range of weight-bearing; Under the loadof1600N, the weight-bearing area roughly distributed within the scope of the middlecolumn wall of the acetabulum, the posterior wall of acetabular posterior column onlypartly involved in weight-bearing. The weight-bearing pressure stepwise decreasing fromthe center to the surrounding. With the increase of the load pressure, the loading ofacetabular roof increased significantly, the range of weight-bearing area within the middlecolumn wall increased, but the anterior and posterior wall beyond still does not participatein the range of weight-bearing. So whether under the load of500N or1600N, it is themiddle column,which participate in the range of weight-bearing, the posterior wall ofacetabular posterior column only partly involved in weight-bearing.2、The weight-bearing area mainly located in the scope of the middle column wall,include the anterior wall of acetabular middle column and the posterior wall of acetabularmiddle column. The posterior wall of acetabular posterior column only partly involved inweight-bearing. Whether under the load of500N or1600N, no statistically significantdifference was found between the average intensity of pressure of anterior wall ofacetabular middle column and posterior wall of middle column（P>0.05）, the averageintensity of pressure of the posterior wall of middle column and the posterior wall ofacetabular posterior column where near the boundary of middle column and posteriorcolumn within a30°range has a significant difference（P<0.05）, the average intensity ofpressure of the anterior wall of middle column and the posterior wall of acetabular posterior column where near the boundary of middle column and posterior columnwithin a30°range has a significant difference（P<0.05）, the average intensity of pressureof the the wall of middle column and the posterior wall of acetabular posterior column hasa significant difference（P<0.05）;That is, the average intensity of pressure of the posteriorwall of middle column is larger than the posterior wall of posterior column, but it has nostatistically significant difference between the average intensity of pressure of anterior wallof acetabular middle column and posterior wall of middle column. We found that with theload force increased, the intensity of pressure of different parts of the wright-bearingsurface increased significantly, but the scope of the wright-bearing surface has nosignificant increase. |
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