RÉSUMÉ
BACKGROUND:The proximal femoral nail antirotation is the preferred treatment for reverse osteoporotic intertrochanteric fractures.Bone cement enhancement can reduce the probability of proximal femoral nail antirotation cut-out and cut-through,but there are no relevant biomechanical studies demonstrating the effect of bone cement content and location on the stress and displacement of the fracture end. OBJECTIVE:To investigate the effects of different contents and locations of bone cement in cement-reinforced proximal femoral nail antirotation on stress,strain,and displacement of reverse osteoporotic femoral intertrochanteric fractures in the elderly by finite element analysis. METHODS:A healthy adult female right femur model was extracted by Mimics software and smoothed in Geometric software.Five types of internal fixation methods of proximal femoral nail antirotation(cementless,cephalic spherical 1 mL,cephalic spherical 2 mL,cephalic spherical 3.4 mL,and cylindrical 5 mL around spiral blade)and femoral intertrochanteric fracture(AO subtype 31-A3.1 type)model were established in Solidworks software.After assembly,the total stress distribution,peak stress and displacement of the five models of implants with the femur were compared in Ansys software. RESULTS AND CONCLUSION:(1)The peak stresses of proximal femoral nail antirotation with head-end spherical 1 mL,head-end spherical 2 mL,head-end spherical 3.4 mL,and cylindrical 5 mL enhanced proximal femoral nail antirotation around the spiral blade respectively were 571.07 MPa(located at the junction of the spiral blade and the main nail),495.45 MPa(located at the junction of the spiral blade and the main nail),467.20 MPa(located at the junction of the main nail and the distal screw connection),642.70 MPa(located at the junction of the main nail and distal screw connection),and 458.58 MPa(located at the junction of the spiral blade and the main nail).(2)The maximum displacements of proximal femoral nail antirotation with head end sphere 1 mL,head end sphere 2 mL,head end sphere 3.4 mL,and with cylindrical 5 mL enhancement around the spiral blade were 9.260 5,7.589 1,7.316 8,6.790 7,and 6.615 7 mm,respectively,all of which were located at the proximal end of the femoral head.(3)These findings revealed that for reverse femoral intertrochanteric fractures treated with proximal femoral nail antirotation,the bone cement enhancement had significant mechanical stability compared with no enhancement,and the enhancement of the spiral blade 5 mL around the perimeter was the best,which is more preferable for aged unstable intertrochanteric fractures.