The effect of the hip joint endoprosthesis length after a total hip arthroplasty: A biomechanical study

Background/purpose: Total hip arthroplasty is a safe, cost-effective surgical intervention which restores mobility and alleviates pain from most kinds of hip arthritis. The proposed biomechanical study evaluates the effect of the stem size on the mechanical environment of the hip and its association with aseptic loosening.Methods: Medium left, fourth-generation, composite femoral models were used, and different prosthesis dimensions were examined. Fourteen strain gages were placed at specific positions on the femur. Load cycles were programmed to simulate single-leg stance of gait of a normal-weight subject.Results: Microstrains in the anterior and posterior region of the femur shaft were found to decrease with increasing the stem length, while no specific tendency was observed in the regions of the great and lesser trochanteric as well as in the medial and lateral femur.Conclusion: This study indicates that shorter implants are subjected to higher strains distally to the pertrochanteric area.