应用钛板修复髋臼大面积骨缺损的生物力学研究

Treatment of severe acetabular bone defect using titanium mesh: a biomechanical research

[目的]比较应用钛板修复髋臼不同面积骨缺损与初次全髋关节置换术时髋臼周围生物力学变化及初始稳定性的研究。[方法]选取12具30~50岁男性尸体骨盆。随机分成四组,每组3具,于髋臼负重区人工制造出占整个髋臼50%、60%、70%的三种混合型骨缺损（AAOSⅢ型）,作为骨缺损组;应用钛板＋植骨＋骨水泥＋高分子聚氯乙烯杯固定,对三种程度的骨缺损进行髋臼重建;无骨缺损组行单侧骨水泥型假体髋关节置换术。试验模拟人体单足直立位,在CSS-44020型生物力学试验机上进行。应用双页型压敏纸测定各标本在轴向加载,持续加压下,髋臼顶负重区在不同程度骨缺损应用钛板修补与正常初次髋关节置换的应力变化情况。[结果]（1）载荷200 N时,骨缺损组50%,60%,70%和无骨缺损组平均应力分别为267.628 6 N;268.635 2 N;270.691 4 N,266.463 8N。经方差分析,F=0.715,P〉0.05,按α=0.05水准,各组应力值无明显差异;（2）以钛板重建髋臼严重骨缺损,臼顶负重区的应力变化规律相同。在50%骨缺损组,载荷200 N,400 N,600 N受到应力分别为267.628 6 N,507.831 4 N,693.177 1 N。[结论]（1）在同一载荷下,应用钛板重建修复50%~70%髋臼缺损组间与初次髋关节置换组髋臼应力变化无明显差异。随加载负荷的增加,臼顶负重区压应力随之增加。在生物力学方面未出现应力集中及假体不稳等现象;（2）钛板具有良好的生物相容性和力学性能,强度高,可根据髋臼缺损修剪,使其完全贴附于缺损臼壁,金属网孔能够刺激并且允许新生骨组织长入形成＂锚固效应＂,使金属网架和髋臼壁合为一整体,既增加髋臼抗压强度,又降低金属网架的断裂和疲劳的可能性。

[Objective]The aim of our study is to compare the strain changes among different bone defects around the operated acetabular during the total hip athroplasty.[Method]A total of twelve fresh male cadaveric pelvic specimens including bilateral superior femur were used.All soft issue was removed,but ligaments and sacroiliac joint were kept intact.Specimens were separated into four groups： normal,50%,60%,and 70% defect,and defects of acetabular were made artificially.The test groups with severe bone defects were reconstructed using Ti-mesh,bone grafting,bone cement and acetabular prosthesis.Total cemented hip arthroplasty were performed in specimens without bone loss as control group.The loading mode of single-leg stand was simulated.Increasing vertical stress was loaded on the fixed pelvis and strain measurements were made by CSS 44020 biomechanical machine.[Result]1.There was no biomechanical difference among the defective acetabulum of varied degrees,which had been repaired by the titanium mesh and the hip replacement for the first time,At the weight-bearing of 200 N,the mean stress of the acetabulum of 50%,60%,70% defects were 267.628 6 N,268.635 2 N,270.691 4 N,respectively.Little difference was shown among these groups according to the analysis of variance and outcome,with standard of α = 0.05,that was F = 0.715,P 0.05.2.After the reconstruction of acetabulum by the titanium plate,the stress on bearing region of acetabulum top varied almost the same,with the increase of the weight.For example,stress was 267.628 6 N at the bearing of 200 N,while reached 507.831 4 N as the weight doubled.Finally it continued to rise up to 693.1771 N when the weight increased to 600 N in 50% defect group.[Conclusion]1.The titanium mesh has a remarkable biocompatibility and biomechanics.It can be remodeling according to the shape of acetabulum without diminish the strength.The titanium mesh serves to stimulate the neoformative bone tissue as well as precipitate an anchoring effect by growing in,eventually combining the metal mesh and the acetabulum as a whole.Titanium plate not only greatly increases its compressive strength,but also considerablely reduces the possibility of the metal mesh＇s dis1858 ruption or fatigue.2.Although with the first total hip replacement,there are little differences between test group and control group under the same loading.Mechanical problems of titanium plate such as stress concentration,prosthetic loosing was not found during the reconstruction of the defective acetabulum.Titanium mesh is an ideal internal fixation for the seriously acetabular defects reparations.