The inherently high stiffness of locked plate constructs is increasingly recognized as a potential cause of deficient healing observed in patients with periarticular locked plating systems. The objective of this study is to perform a biomechanical comparison of distal femur locked plating systems. Biomechanical study using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). Four different locked plate fixation systems were compared (AxSOS, LCP, PERI-LOC, POLYAX). Eight bone implant constructs of each plating system were evaluated in a multiple testing model to examine static failure, stiffness under static and cyclic loading and cyclic fatigue.Background
Methods
Metatarsocuneiform (MTC) fusion is a standard treatment for arthritis, instability, and deformity of these joint. The MTC fusion achieves a good clinical outcome, but nonunion rates up to 12% have been reported. There are different methods for fixation of first MTC joint arthrodesis. Our aim was to compare the biomechanical characteristic of internal and external fixation constructs. Plantar plate fixation provides higher construct stiffness and endurance stability than intraosseous fixation.Introduction
Hypothesis
The proximal geometry and design of trochanteric nails affects initial construct stiffness, fatigue survival, and preservation of biomechanical stability over time. Eight pairs of human cadaveric femora were implanted with two different short intramedullary nails with (Intertan, (S&N)) and without (Gamma 3, (Stryker)) interlocking lag screws. Femoral osteotomies were performed to generate a pertrochanteric multifragmentary unstable fracture (OTA 31-A 2.2). The bones were tested in a cyclic testing protocol with increasing loads of 100 N every 20.000 cycles (start point 50/500 N) simulating one leg stance. The position of the femur was 10° adduction and 10° extension. Stiffness, failure load, and cycles to failure were measured.Hypothesis
Materials & Methods
Common cell based strategies for treating bone defects require time-consuming and expensive isolation and expansion of autologous cells. We developed a novel expedited technology creating gene activated muscle grafts. We hypothesized that BMP-2 activated muscle grafts provide healing capabilities comparable to autologous bone grafting, the clinical gold standard. Two male, syngeneic Fischer 344 rats served as tissue donors. Muscle tissue was harvested from hind limbs and incubated with an adenoviral vector carrying the cDNA encoding BMP-2. Bone tissue was harvested from the iliac crest. Segmental bone defects were created in the right femora of 12 rats and were filled with either BMP-2 activated muscle tissue or bone grafts. After 8 weeks, femora were evaluated by radiographs, microCT, and biomechanical tests. BMP-2 activated muscle grafts and autologous bone grafts resulted in complete mineralization and healing, as documented by radiographs and microCT. Bone volume in the muscle graft defects (33+/-12mm3) was similar to autologous bone graft defects (39+/-5mm3). Torque at failure of the two groups was statistically indistinguishable (240+/-115 Nmm vs. 232+/-108Nmm). In previous experiments we demonstrated that the large segmental defect model in this study will not heal with either empty defects or non-activated muscle grafts. Our findings therefore demonstrate that BMP-2 gene activation of muscle tissue effectively stimulates defect healing similar to autologous bone grafts.
Alpine ski sports changed rapidly in the last decade. Complex fractures of the proximal tibia, typically seen in high energy trauma, has been seen more frequently and more often related to alpine skiing. The aim of our study was to identify reasons for proximal tibia fracture in alpine skiing and observe the outcome. All patients with proximal tibia fractures related to alpine skiing, which were treated in our two trauma centers were included. The patients received a questionnaire at the emergency department, dealing with accident details and the skiing habits. The fractures were classified according to the AO fracture classification scheme. The follow up was performed at least one year after trauma with the Lysholm, the Tegner activity, as well as the WOMAC VAS Score. Between 2007 and 2010 a total of 188 patients with proximal tibia fractures caused by alpine skiing were treated. 43 patients had a type A, 96 patients a type B and 49 a type C injury. The incidence was increasing over the period continuously. The main trauma mechanism was an accident without a third party involvement with an increased rotational and axial compression impact. All outcome scores were related to fracture severity with significant worse results for the type C fractures. In conclusion, proximal tibia fractures are an increasing and serious injury during alpine skiing. Further technical progress in skiing material should focus on these knee injuries in future.
