To simulate the biomechanical properties of enhanced PFNA and compression interlocking intramedullary nail Intertan in the treatment of elderly anti-trochanteric fractures with osteoporosis.

Three-dimensional finite element method was used to establish the model of enhanced PFNA and Intertan fixation for intertrochanteric fracture (AO classification 3.1). The total stress distribution, peak stress and displacement of the two models were compared.

The equivalent stress of internal fixation in both groups was mainly distributed on the medial side of the main screw. The maximum equivalent stress in the enhanced PFNA group was located at the junction of the main screw and the distal screw, which was 192.76 Mpa, while the maximum equivalent stress in the Intertan group was located at the junction of the oblique screw and the lag screw, which was 395.87; (2) Both the enhanced PFNA group and the Intertan group had different degrees of displacement. The maximum position was located in the femoral head and gradually took effect to the distal end. The peak displacement of the two femoral heads was 4.562 mm in the enhanced PFNA group and 4.68 mm in the Intertan group.

The maximum equivalent stress of the internal fixation in both groups is located on the intramedullary nail, and is far greater than the stress borne on the femur, which indicates that the internal fixation in both groups is effective for the intertrochanteric fracture of the femur. In the early postoperative period, the internal fixation bears the maximum stress, relieves the stress on the femur, and is conducive to fracture healing. However, the maximum equivalent stress in the enhanced PFNA group is smaller, which is more stable than that in the Intertan group, The risk of internal fixation failure is reduced. When using enhanced PFNA fixation, the femur bears less stress and can play a better supporting role. Therefore, enhanced PFNA is a better choice for senile osteoporotic intertrochanteric fracture.