Type a3.3 femoral intertrochanteric fracture with augmented proximal femoral nail anti-rotation in the elderly: Finite element analysis of the optimal amount of bone cement / 中国组织工程研究

ABSTRACT

BACKGROUND: Osteoporosis and fracture type are two important reasons for the postoperative failure of proximal femoral nail anti-rotation. The treatment of elderly patients with type AO31-A3.3 femoral intertrochanteric fractures by bone cement augmented proximal femoral nail anti-rotation can effectively reduce the failure rate, but the specific amount of bone cement injected remains to be discussed. OBJECTIVE: To investigate the optimal amount of bone cement in the treatment of type A3.3 intertrochanteric femur fracture with augmented proximal femoral nail anti-rotation in elderly. METHODS: CT data of one volunteer were imported into Mimics 19.0 and Geomagic studio 2017 to extract and optimize the three-dimensional model of the right femur. Internal fixation model was drawn and assembled with femur model according to the standard operation technology, then imported into Hypermesh 14.0 software to simulate type AO31-3.3 intertrochanteric femur fracture. The spongy bone around the proximal helical blade was redefined as bone cement, obtaining A, B and C models with 2.2 mL, 4.2 mL, and 6.4 mL of bone cement, respectively. The material property parameters, boundary conditions, and applied loads were set and imported into LS-DYNA software for solution. RESULTS AND CONCLUSION: (1) There was no significant difference in the inversion and rotation angles of the head and neck fragment and the overall stress in three models, but the blade cutting in model B and model C was severe and the helical blade was broken, while the blade cutting in model A was slight and did not break. (2) The strong anchoring force of bone cement could stabilize the helical blade, but easily led to local stress concentration. (3) The amount of bone cement injected into the proximal femoral nail anti-rotation for the treatment of type A3.3 intertrochanteric femur fracture in elderly should not be too much, and less than 3 mL may have the best biomechanical effect.