全膝关节置换术中股骨假体屈曲对髌股关节生物力学影响的实验研究

目的]探讨全膝置换术中股骨假体矢状位上屈曲对髌股关节生物力学的影响,为临床指导人工膝关节置换的手术技术提供实验依据,以减少术后髌股关节的并发症。方法]取正常国人新鲜冷冻尸体的5个膝关节作为研究对象,模拟膝关节自站立位屈膝下蹲的动作,设计制作膝关节实验架,与生物力学测试仪共同搭建实验平台。人工膝关节采用DePuy PFC假体全膝系统,手术由同一位有经验的术者实施以控制实验误差,置换髌骨。比较股骨假体相对于按下肢力线位、前屈5°、10°及后屈5°、10°、15°位置时的髌股关节的生物力学指标。选择屈膝30°、60°、90°、120°为观察角度,采用美国Tecscan公司生产的感测片测定髌股关节接触压峰值,最后软件处理得到数字化的结果。结果]除了在膝关节屈曲30°、60°、90°,股骨假体前屈5°时,髌股关节内侧间隙接触压峰值与下肢力线位相比较无显著性差异(P>0.05),其余各种屈膝角度下,股骨假体不同屈曲角度所致髌股关节内外侧间隙接触压峰值与下肢力线位比较有显著性差异(P<0.05)。股骨假体后屈角度越大,峰值的升高越明显。结论]全膝关节置换术中,股骨假体在矢状位上争取按下肢力线位置入,以降低术后并发症的发生。

Experimental study on biomechanical effects of femoral prosthesis flexion on patellofemoral joint in total knee arthroplasty

Objective]To study the the effects of femoral prosthesis flexion on patellofemoral biomechanics in total knee arthroplasty demonstrated on autopsy specimes,as the guide for surgeons to choose the correct referenc of proper flex degree on sagittal plane of femoral prosthesis and to reduce postoperative complications. Methods]Five frozen fresh human cadaver knees without gross deformities or instabilities were selected and a patellofemoral joint testing jig was made connected to biomechanical testing instrument.Standard TKA was performed in each specimen by the same senior surgen using DePuy PFC Total Knee System.All knees received replacement and then was flexed 5°forward、10°forward、5°backward、10°backward、15°backward.Peak contact pressure of patellofemoral joint was measured using Tecscan sensing film(U.S.) at 30°、 60°、90°、 120° of knee flexion respectively.The digital values were obtained by Tecscan systems and Autocad software. Results]Except the group of femoral prosthesis flex 5°forward,the intra-patellofemoral contact knee flexion at 30°、60° and 90°,the other any groups of femoral prosthesis flex forward or backward,knee flexion at 30°、60°、90° and 120° lead to the higher peak value of patellofemoral contact force than the position across to the line of leg force(P<0.05).The higher flexion degree backward of the prosthesis was,the higher h peak value of patellofemoral contact force was. Conclusion]It’s reliable for surgeons to position femoral prosthesis across to the line of leg force on sagittal plane,to avoid the complication of patellofemoral joint in TKA.