基于偏髓分型应用骨水泥型长短柄假体置换治疗高龄偏髓Ⅰ型粗隆间骨折的有限元分析（英文）

The comparative analysis with finite element for cemented long-and short-stem prosthetic replacement in elderly patients with a partial marrow type Ⅰ intertrochanteric fracture

[目的]探讨高龄偏髓Ⅰ型粗隆间骨折行骨水泥型股骨假体置换术后的股骨应力分布,并对比分析长、短假体柄置换后的应力分布差异。[方法]利用螺旋CT对志愿者的右侧股骨进行断层扫描获取图像数据,将图像数据经Mimics软件和建模软件处理后重建股骨三维模型。在此基础上,建立偏髓Ⅰ型粗隆间骨折长、短柄股骨假体及骨水泥套的三维实体模型,最后利用有限元分析软件建立长、短柄股骨假体治疗粗隆间骨折的三维有限元模型,并对该模型进行生物力学分析。[结果]长、短柄假体置换后股骨的应力分布没有发生明显改变,依然是由近端向远端逐渐增加,至内外侧中下1/3交界处达到峰值,再向末端又减小。短柄假体骨水泥-假体柄界面在末端内外侧虽形成应力集中区,且外侧峰值为15.3 MPa,但未超过骨水泥疲劳强度;而长柄假体在骨水泥-假体柄界面远端内外侧及内侧中段形成应力集中区,其峰值也均低于骨水泥疲劳强度。骨水泥重建的股骨距部位未见明显的应力集中区。[结论]骨水泥型长、短柄假体置换治疗高龄偏髓Ⅰ型粗隆间骨折不会引起股骨应力分布的明显改变。长柄假体的松动概率与短柄假体基本相当,但后者由于手术时间短、创伤小、并发症少,可能更适合治疗高龄偏髓Ⅰ型粗隆间骨折。

[Objective]This study investigated the stress distribution in a femur after a cemented prosthetic replacement surgery in elderly patients with a partial marrow type I intertrochanteric fracture and compared the differences in stress distribution between a long-and short-stem prosthetic replacement.[Method]A spiral computed tomography（CT） scan was used on the volunteer＇s right femur to obtain image data,which were processed with the Mimics software and the modeling software to reconstruct a three-dimensional model of the femur.On this basis,the three-dimensional physical models for a partial marrow type intertrochanteric fracture,long-and short-stem femoral prostheses,and the mantle layer of cement were established.Finally,the three-dimensional finite element models of the long-and short-stem femoral prostheses as a treatment of an intertrochanteric fracture were established using the software for finite element analysis,and the biomechanical analysis was implemented for the models.[Result]The stress distribution in the femur after the cemented long-or short-stem prosthetic replacement did not change significantly;it still gradually increased from the proximal end to the distal end,reaching the peak value at the lower 1 /3 of the medial and lateral junction,and then decreased to the end.Although a stress concentration zone formed in the medial and lateral end of the bone cement-prosthetic stem interface in the short-stem prosthesis,which had a lateral peak value of 15.3 MPa,it did not exceed the fatigue strength of the bone cement.Alternatively,a stress concentration zone formed in the distal medial and lateral end of the bone cement-prosthetic stem interface and the medial middle part of the shaft in the long-stem prosthesis,which showed a peak value that was also lower than the fatigue strength of the bone cement.No significant stress concentration zones were found in the femoral calcar reconstructed by bone cement.[Conclusion]The stress distribution in the femur did not change significantly after cemented long-and short-stem prosthetic replacements were used for elderly patients with a partial marrow type I intertrochanteric fracture.The probability of loosening of the cemented long-stem prosthesis was comparable to that of the short-stem prosthesis,but the latter may be more suitable for treating elderly patients with a partial marrow type I intertrochanteric fracture due to the shorter surgery time,minor trauma,and fewer complications.