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Abstract-Screw cut-out and non-union have been cited as major complications with hip screw systems for the treatment of intertrochanteric femoral fractures. Recently, cement augmentation of hip screw system has been introduced to provide better purchase of the screw. This study investigates the biomechanical efficacy of cement augmentation technique by assessing the changes in stress distributions within the femur and the surgical construct. Finite element models of the operated femur with sliding hip screw assemblies were constructed with and without bone cement augmentation. To simulate the fracture plane and other interfacial regions, 3-D contact elements were used with appropriate friction coefficients. Our results demonstrated the efficacy of the cement augmentation: 80% reduction in stresses was found in the cancellous bone due to cement augmentation, suggesting that the fractures of the cancellous bone and the cut-out of the screw are far less likely to take place. The peak von Mises stress within the cement mantle was about 1/3 of its fatigue strength. The likelihood of cement failure that might lead to osteolysis due to cement debris was not apparent. The micromotion at the hip screw interface was reduced from 0.275mm to 0.008mm, an indication for strong fixation after surgery. / / / / Keywords -Intertrochanteric fractures, Cement-augmentation, Hip screws, Biomechanics, Finite element methods I. INTRODUCTIONRecent findings estimate that intertrochanteric femoral fractures (IFF) occur in more than 200,000 patients each year in the United States alone, with reported mortality rates ranging from 15% to 20% [1]. Most intertrochanteric femoral fractures occur in patients over 70 years of age and they are likely to increase each year as the population of these age group increases. In addition, the traumatic patients from traffic accidents make up the ever-increasing patient group. One of the most commonly used surgical treatments for IFF is using internal fixation devices such as sliding compression hip screws with side plate assemblies. These devices are considered to be safe with minimum amount of drilling of the cancellous bone in the femoral head and neck region. They allow early weight-bearing and limit interfacial movement on the fracture plane by providing strong compressive forces.Clinical studies show, however, that superior cutting-out through the femoral head by the sliding hip screw is one of the major complications [2,3]. Improper screw placement has been cited as one of the major contributing factors. Frequent non-union on the fracture plane often requires revision surgery that can compound more surgical difficulties [2,4]. For patients with severe osteoporosis in which the primary compression trabecular structures have diminished in a great deal can be more prone to this type of complication and add surgical challenges. Strong fixation of the sliding hip screws within the femur and minimum amount of sliding motion must be maintained for the optimal bony-healing.Biomechanical studies have been d...