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鎖定鋼板以不同偏轉(zhuǎn)角度固定股骨干粉碎骨折的有限元分析

發(fā)布時(shí)間:2018-08-03 15:02
【摘要】:目的:結(jié)合鎖定螺釘?shù)臉蚪咏庸前迨悄壳爸委煿晒歉煞鬯楣钦鄣某R?jiàn)內(nèi)固定器材之一,在良好的骨折端復(fù)位的前提下盡量使用閉合復(fù)位內(nèi)固定技術(shù)已成為治療共識(shí),然而在臨床實(shí)踐中,閉合復(fù)位后放置鋼板時(shí),由于暴露不夠充分,會(huì)出現(xiàn)接骨板中線與股骨長(zhǎng)軸成角度固定。本研究通過(guò)運(yùn)用三維有限元分析技術(shù),模擬粉碎骨折斜置鋼板固定,對(duì)其固定的力學(xué)效果進(jìn)行對(duì)比及評(píng)價(jià),以及探討斜置鋼板固定股骨粉碎骨折的風(fēng)險(xiǎn),從而為臨床治療提供理論依據(jù)。方法:利用64排螺旋CT掃描正常成年人股骨,獲取股骨DICOM數(shù)據(jù),將DICOM數(shù)據(jù)導(dǎo)入Mimics醫(yī)學(xué)建模軟件進(jìn)行三維重建,并建立股骨干粉碎骨折模型;運(yùn)用Pro/E Wildfire 5.0軟件,依據(jù)股骨解剖鎖定鋼板建立接骨板模型,將此模型STL文件導(dǎo)入Mimics,同時(shí)結(jié)合股骨粉碎骨折模型進(jìn)行模擬內(nèi)固定手術(shù),然后將鋼板分別置于不同偏轉(zhuǎn)角度,依據(jù)近端螺釘偏前及偏后分為接骨板前傾及后傾兩組,每組分別依據(jù)遠(yuǎn)近端螺釘距離皮質(zhì)的距離分為2mm、4mm、6mm、8mm、10mm五個(gè)亞組,以及加上正常中置鋼板總共11組。分別通過(guò)3-matic及Mimics進(jìn)行網(wǎng)格劃分和賦值,對(duì)各個(gè)內(nèi)固定模型施加模擬70kg成人雙足站立時(shí)的載荷及約束,觀察各個(gè)分組間的股骨及內(nèi)植物的等效應(yīng)力、位移的分布變化。結(jié)果:對(duì)于各個(gè)亞組在相同的載荷及約束下,隨鋼板傾斜程度的增大,斜置組1、5、6號(hào)釘-骨界面的應(yīng)力峰值逐漸遞增:(1)在前傾2組及前傾4組中1、5、6號(hào)釘孔處骨皮質(zhì)均出現(xiàn)了應(yīng)力集中且大于股骨皮質(zhì)的強(qiáng)度。在前傾6組中,5、6號(hào)釘孔皮質(zhì)出現(xiàn)了應(yīng)力集中,且大于股骨皮質(zhì)的強(qiáng)度;(2)在后傾2組、后傾4組、后傾6組中的1號(hào)、5號(hào)及6號(hào)釘孔處骨皮質(zhì)和后傾8組中的5號(hào)、6號(hào)釘孔處骨皮質(zhì)出現(xiàn)應(yīng)力集中且超過(guò)骨皮質(zhì)的強(qiáng)度;(3)在各個(gè)亞組中,鎖定鋼板及螺釘?shù)姆逯祽?yīng)力及應(yīng)變均位于3號(hào)螺釘?shù)尼?板交界處,且未超出鈦合金的強(qiáng)度;(4)在鋼板前傾組,隨鋼板傾斜程度的增大,骨折斷端軸向位移增大;(5)在鋼板后傾組,隨鋼板傾斜程度的增大,軸向位移減小,剪切位移增大。結(jié)論:股骨鎖定鋼板近端向前傾斜放置時(shí),當(dāng)螺釘距離骨皮質(zhì)表面小于等于6mm時(shí),在負(fù)重的過(guò)程中,最遠(yuǎn)端兩個(gè)螺釘會(huì)因螺釘附近骨質(zhì)破壞而失去把持力;當(dāng)螺釘距離骨皮質(zhì)距離小于4mm時(shí),最遠(yuǎn)端的兩個(gè)螺釘及近端螺釘處的骨皮質(zhì)存在疲勞斷裂的可能,會(huì)導(dǎo)致遠(yuǎn)近端螺釘同時(shí)失效導(dǎo)致內(nèi)固定失敗;股骨鎖定鋼板近端向后傾斜放置時(shí),當(dāng)螺釘距離骨皮質(zhì)表面小于8mm時(shí),在負(fù)重的過(guò)程中,最遠(yuǎn)端兩個(gè)螺釘會(huì)因螺釘附近骨質(zhì)破壞而失去把持力;當(dāng)螺釘距離骨皮質(zhì)小于6 mm時(shí),最遠(yuǎn)端的兩個(gè)螺釘及近端螺釘處的骨皮質(zhì)存在疲勞斷裂的可能,會(huì)導(dǎo)致遠(yuǎn)近端螺釘同時(shí)失效導(dǎo)致內(nèi)固定失敗;鋼板前傾放置后在負(fù)重后會(huì)導(dǎo)致骨折斷端軸向穩(wěn)定性下降,而鋼板后傾后負(fù)重會(huì)導(dǎo)致其骨折斷端剪切向穩(wěn)定性大大降低,同樣不利于骨折愈合。以上結(jié)論提示我們?cè)诶肕IPO技術(shù)處理股骨干部位的粉碎骨折時(shí),出于固定效果的考慮,應(yīng)當(dāng)盡量將鋼板與股骨干長(zhǎng)軸平行放置,以獲得最佳的固定效果。當(dāng)術(shù)中放置鋼板后,鋼板近端向前傾斜時(shí),則應(yīng)保證其遠(yuǎn)近端螺釘距離骨皮質(zhì)表面均應(yīng)大于6mm,而當(dāng)鋼板近端向后傾斜放置時(shí),其遠(yuǎn)近端螺釘距離骨皮質(zhì)表面均應(yīng)大于8mm,否則在術(shù)后恢復(fù)期的功能鍛煉存在鋼板周圍骨折的風(fēng)險(xiǎn)。如鋼板放置后雖然傾斜,但在上述安全范圍內(nèi),則可以不需反復(fù)調(diào)整鋼板位置,以避免過(guò)度損傷軟組織、破壞骨折斷端血運(yùn),避免不必要的醫(yī)源性輻射的損害。鋼板傾斜放置時(shí),骨折斷端的微動(dòng)均大于鋼板與股骨縱軸平行放置的情況,因此骨折愈合前應(yīng)避免下地負(fù)重以避免骨折不愈合。
[Abstract]:Objective: the bridging plate combined with locking screws is one of the common internal fixators for the treatment of femoral shaft comminuted fractures. The closed reduction and internal fixation technique has become a common understanding on the premise of good fracture reduction. However, in clinical practice, when the plate is placed after closed reduction, the exposure is not sufficiently exposed. In this study, the three-dimensional finite element analysis (3D finite element analysis) was used to simulate the fixation of the comminuted fracture of the steel plate, to compare and evaluate the mechanical effect of the fixation, and to explore the risk of the fixation of the femoral fracture with oblique plate, and to provide a theoretical basis for clinical treatment. Method: 64 Spiral CT scan normal adult femur, obtain femur DICOM data, introduce DICOM data into Mimics medical modeling software for three-dimensional reconstruction, and establish the model of femoral shaft comminuted fracture; use Pro/E Wildfire 5 software to establish the plate model based on the locking plate of femur, and introduce this model STL file into Mimics, and combine the femur with the femur. The fracture model was performed by simulated internal fixation, and then the plate was placed at different deflection angles. According to the anterior and posterior partial screws, the two groups were divided into two groups, which were the anterior and posterior inclination of the plate. Each group was divided into five subgroups of 2mm, 4mm, 6mm, 8mm, 10mm respectively according to the distance of the distant and proximal screw distance cortex, and 11 groups were added to the normal medium plate. Grid division and assignment were carried out through 3-matic and Mimics respectively, and the load and constraint of simulated 70kg adult bipedal standing were applied to each internal fixation model. The equivalent stress and displacement of the femur and inner plant between the groups were observed. The stress peak value of 1,5,6 nail bone interface increased gradually in the oblique group: (1) the stress concentration of the bone cortex appeared in the 2 groups and the front 4 groups, and the intensity of stress concentration was greater than that of the femoral cortex. In the 6 groups, the stress concentration of the 5,6 nail hole cortex appeared, and was greater than the strength of the femoral cortex; (2) in the 2 groups, the backward 4 groups, and the posterior inclination 6. In the group 1, No. 5 and No. 6, the cortical bone and the 8 groups of the posterior tilt were 5. The cortical bone cortex appeared stress concentration and exceeded the strength of the bone cortex. (3) in each subgroup, the peak stress and strain of the locking plate and screw were located at the nailed plate junction of No. 3 screw and did not exceed the strength of the titanium alloy; (4) (4) in the steel plate forward group, (4) The axial displacement of the broken end of the fracture increased, and (5) the axial displacement decreased and the shear displacement increased as the steel plate tilted. Conclusion: when the proximal end of the locking plate of the femur is placed forward, when the distance of the screw is smaller than 6mm, the two most distal screw will be in the process of weight negative. When the distance of the screw distance to the bone is less than 4mm, the bone cortex of the two distal screws and the proximal screws may have fatigue fracture when the distance of the screw is less than the cortical bone, which leads to the failure of the internal fixation of the distal end screw and the proximal end of the locking plate when the screw is placed in the bone cortex. When the surface is less than 8mm, the most distal two screws will lose the holding force due to the bone destruction near the screw during the loading process. When the screw is less than 6 mm, the bone cortex of the distal two screws and the proximal screws may have fatigue fracture, which will lead to the failure of the internal fixation of the distal end screw and the plate before the screw. After placing weight, the axial stability of fracture end will decrease after loading, and the weight of the plate behind the plate will lead to the reduction of the fracture end of the fracture to the stability, which is also not conducive to the fracture healing. The above conclusion suggests that we should use the MIPO technique to deal with the broken bone fracture in the femoral shaft. The plate should be placed in parallel with the long shaft of the femoral shaft to obtain the best fixation effect. When the steel plate is placed during the operation, the proximal end of the plate should be more than 6mm when the proximal end of the plate is tilted forward, and the distance to the proximal end screw should be greater than 8mm when the proximal end of the plate is tilted. Otherwise, the distal end screw of the plate should be greater than that of the bone. In the post recovery period, there is a risk of fracture around the plate. If the plate is placed after the plate is placed, the position of the steel plate can not be repeatedly adjusted to avoid excessive damage to the soft tissue, damage the fractured end blood transport and avoid unnecessary iatrogenic radiation damage. When the steel plate is tilted, the fracture ends micro The movement is greater than that of the plate placed parallel to the longitudinal axis of the femur, so the lower weight bearing should be avoided before fracture healing to avoid nonunion.
【學(xué)位授予單位】:天津醫(yī)科大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2015
【分類號(hào)】:R687.3

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