Kurzfassung

Together with pertrochanteric fractures, femoral neck fractures represent the most frequent fractures in the region of the hip joint. Most often caused by a simple fall on the hip, those fractures occur in elderly people with preexisting conditions. Because of aging society, the proximal femur fracture and its treatment will gain in socio-economic importance in future.
For the stabilization of proximal femoral fractures, there are several different concepts and implants available. We developed...Together with pertrochanteric fractures, femoral neck fractures represent the most frequent fractures in the region of the hip joint. Most often caused by a simple fall on the hip, those fractures occur in elderly people with preexisting conditions. Because of aging society, the proximal femur fracture and its treatment will gain in socio-economic importance in future.
For the stabilization of proximal femoral fractures, there are several different concepts and implants available. We developed a biomechanical setup for testing different implants. After measuring the stiffness of each native femur, in 6 matched pairs of representative cadaver femurs, a standardized femoral neck fracture with a posteromedial defect will be created. The osteosyntheses will be conducted with two different implants (Aesculap “Targon FN” and Synthes “DHS”) according to the guidelines of the manufacturer.
After takeing radiographs, the specimens will be clamped in our servopneumatic testing machine with an angular orientation of 25° adduction, allowing to simulate the joint reaction force in single-legged stance (figure 1). The femoral head will be potted in a cup. The femoral condyles will articulate with an individually manufactured 5-mm-deep polymethylmethacrylate (PMMA) footprint allowing the femur to pivot (figure 2, 3). The biomechanical testing starts with a static loading of 750N for 2 seconds.
After recording a possible deformation of the construct, the specimens will be cyclic loaded in a sinusoidal manner at 2 Hz to 750N for 10, 100, 1.000 and 10.000 cycles with a maintained load-valley at 100N. To compare the stability of the osteosyntheses, the implant position, the change of reduction as well as the displacement of the femoral head will be measured and analyzed after each cycle interval by optical techniques.
After cyclic testing, the ultimate strength of the fixation will be determined in a load to failure test. A displacement of > 10mm in the vertical axis as well as any construct failure like a fracture of the bone or deformation or cut out of the implant from the femoral head will be defined as an end point.» weiterlesen» einklappen