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

Abstract

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. Methods: 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. Results: 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. © Springer Science+Business Media Dordrecht 2014.