Objective To investigate the stress distribution in a cemented femoral component in elderly patients with a partial marrow type Ⅰ intertrochanteric fractures and to compare differences in the stress distribution after a long-and short-stem prosthetic replacement.Methods Spiral CT images of right femur of the volunteer were obtained and processed with Mimics software and modeling software to reconstruct a three-dimensional model of the femur.Based on this,a three-dimensional physical model for partial marrow type Ⅰ intertrochanteric fractures,long-and short-stem femoral prostheses,and cement mantle was established.Subsequently,a three-dimensional finite element model of long-and short-stem prosthetic replacement for intertrochanteric fractures was established using the finite element analysis software,and biomechanical analysis was implemented for the model.Results No significant changes in stress distribution of the femur occurred after long-or short-stem prosthetic replacement.Stress on the femur still presented a gradual increase from the proximal end to the distal end,peaked at the lower 1/3 of the medial and lateral junction and then decreased at the end.A stress concentration zone formed in the medial and lateral end of cement-stem interface in short-stem prosthetic replacement.Besides,the maximum value of stress in the lateral interface reached 15.3 MPa,but without surpassing the fatigue strength of the bone cement.Whereas,a stress concentration zone formed in the distal medial and lateral part of cement-stem interface and the medial middle part of the interface in long-stem prosthetic replacement and the maximum value was also lower than the fatigue strength of bone cement.No significant stress concentration zones were found in the femoral calcar reconstructed using bone cement.Conclusions Cemented long-or short-stem prosthetic replacement achieves no significant alteration in stress distribution of the femur.Loosening probability of the cemented long-or short-stem prosthesis is almost the same,but the latter has advantages of shorter surgery time,minor trauma,and fewer complications and may be more suitable for treatment of the elderly patients with a partial marrow type Ⅰ intertrochanteric fractures.