人工全髋关节置换术中偏心距重建与聚乙烯内衬应力分布的三维光弹性研究

Three-dimensional-photoelasitc Investigate on the Relationship between Femoral Offset and Hip Stress in Total Hip Arthroplasty

目的通过建立全髋关节三维光弹模型来研究人工全髋关节置换术中,偏心距重建与术后髋关节应力、稳定性、以及聚乙烯内衬磨损的关系。方法建立包括第3腰椎、骨盆、股骨、人工全髋关节假体以及外展肌在内的三维光弹模型。通过改变假体颈长(25,30,35,40mm)达到重建偏心距的目的。通过应力冻结和对聚乙烯内衬切片的光弹分析来测定聚乙烯内衬假体的应力分布情况。结果颈长和偏心距与最大应力区的分布有较强的正相关性(r=0.926,P<0.01),与最大应力值的大小呈较强的负相关性(r=-0.950,P<0.01),与髋臼聚乙烯内衬应力分布的均匀程度呈较强的正相关(r=0.922;P<0.01)。颈长和偏心距变化时聚乙烯内衬的应力总体水平有差别(F=3.210>F0.0(53,60),P<0.05),并呈下降趋势(r=-0.978,P<0.05)。结论偏心距与人工全髋关节内的应力分布有密切关系,人工全髋关节置换术前应细致测量,适当地增加假体颈的长度,尽量使偏心距恢复到术前解剖水平。

Objective To investigate the relationships between femoral offset rebuilding in the total hip arthroplasty and the hip stress,hip stability and polyethylene liner abrasion after operation by three-dimensional photoelastic models. Methods Photoelastic models of human pelvis were made by light-sensatory material. To rebuild the femoral offset, the femoral neck was changed to 25,30,35,40 mm. The weight was put on the model to perform froze stress, the distribution of model stress and morphological change were observed, and the data were analyzed by the SPSS （P 〈 0.05 means）. There was statistical significance of observed data. The profile curve of the stress was drawn with the AutoCAD. Results There was a strong linear correlation between the femoral offset and the stress area （r = 0.926, P 〈 0.01 ）, the femoral offset and the peaking stress （r = -0.950,P 〈 0.01 ）. Simple correlation analysis showed that femoral offset was significantly and positively related to the uniformity of the contact stress of the hip （ r = 0.922,P 〈 0.01 ）. The analysis of the four groups＇ variance showed that there was a variance （F = 3.210〉 F 0.05 （3,60）, P 〈 0.05 ）. Simple correlation analysis showed that the total stress of hip depended on the offset （r = -0.978,P 〈 0.05）. Conclusion Femoral offset is very important in THA,so we should measure exactly the length of femoral neck before THA and try to rebuild the offset as its state before THA.