| Objectives: To manufacture the external fixator and its drilling device for tibial plateau fracture via the measurement of tibial and fibula specimen. To evaluate the biomechanical properties of tibial plateau fracture fixed with homemade external fixator. To verify the security and feasibility of the operation via simulative operation on cadaver.Methods:1. Measured on tibia and fibula: 20 tibia and fibula specimens were measured in the experiment, the anatomical relation between the outmost-benmost Kirschner's wire and the tibial tuberosity and fibular head was confirmed, the angle of outmost and benmost Kirschner's wire was confirmed, too. So, the drilling device was designed then.2. Evaluated the biomechanical properties: 20 homemade catagmatic models were fixed with eight 1.5mm Kirschner's wires, thereby cresting a net-fixation, 20 homemade catagmatic models were fixed with two 3.5mm cortical screws. So, there were two groups. Face- compressed and dot-compressed test were made on each 10 models of the two groups. Then, the maximal force of anti-compress and stiffness were measured and evaluated.3. Simulative operation and external fixator fixation on cadaver. On 4 cadavers, simulative operation and external fixator was fixed one by one. The feasibility of drilling device and the security of the operation were tested.Results:1. The result from the measure on tibia and fibula: Mean length from tibial tuberosity to the up of the tibia was (32.67±3.65)mm, fibular head to the up of the tibia was (25.53±3.54) mm, the dot of outmost Kirschner's wire to F was (10.85±4.29) mm, the dot of benmost Kirschner's wire to H was (5.15±1.26) mm, on the later condyle, the angle of outmost and benmost Kirschner's wire was (89.68_+4.50)°, on the medial condyle, the angle was (100.60±7.25)°, the length of the arch of later condyle was (60.56±8.16) mm, the length of the arch of medial condyle was (74.97±5.89) mm. So, the interval of oriented hole of the drilling device was designed 7.50mm.2. Evaluated the biomechanical properties: In face-compressed test, Mean maximal force of anti-compress and stiffness for screw fixation was (1925.31±444.26) N and (2.28±0.53) N/mm~2, respectively, for net-fixation was (1609.62±277.72) N and (1.90±0.33) N/mm~2, respectively. There was no statistical difference between the two fixation methods (P＞0.05): in dot-compressed test, Mean maximal force of anti-compress and stiffness for screw fixation was (411.13±233.88) N and (2.66±1.52) N/mm~2, respectively, for net-fixation was (1105.58±290.66) N and (7.18±1.89) N/mm~2, respectively, the net-fixation was better than the screw fixation (P＜0.01).3. Simulative operation and external fixator fixation on cadaver: Kirschner's wires can be fixed satisfactorily under the drilling device with arthroscopically and the X-ray machine of "C" arm assisted. The operation was secure and homemade external fixator to be fixed easily.Conclusion: The design of homemade external fixator and drilling device is fit with Chinese. The fracture is fixed biologically and reliably. The operation is secure and homemade external fixator to be fixed easily. Furthermore, it is less invasive and seems an attractive and promising treatment method for tibial plateau fractures.
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