Limited V-shaped cement augmentation of the proximal femur to prevent secondary hip fractures

Abstract

Patients with a femoral fracture due to osteoporosis are at high risk of sustaining a secondary fracture on the contralateral side. A prophylactic mechanical reinforcement of the contralateral side during operation of the initial fracture could be of interest for such patients. This biomechanical invitro study investigates the potential of a limited V-shaped bone cement augmentation to prevent secondary hip fractures by targeting the areas of the proximal femur with the highest stresses during a fall. Five pairs of human cadaveric proximal femora were tested in a configuration simulating a fall on the greater trochanter. The femoral neck of one specimen of each pair was augmented with 8-14 ml polymethylmethacrylate from the lateral cortex towards inferior and superior, spanning a V-shaped cement pattern. Clinical relevant fractures were generated with a 45 kg mass in controlled free fall. Load-displacement data were recorded and energy to fracture, fracture load, yield load and stiffness were statistically evaluated. Augmented samples absorbed 124% more energy until fracture compared to their controls (p = 0.043). No significant differences were found between the two groups for fracture load (p = 0.5), yield load (p = 0.35) and stiffness (p = 0.5). Biomechanically, a limited V-shaped prophylactic cement augmentation carries potential to prevent secondary hip fractures indicated by increased energy absorption until fracture. Further investigations are necessary to minimize interference with the biology and to maximize the mechanical benefit of prophylactic augmentation.