Biomechanical Study Of The Pressure Attenuation Of The Axial Pressurize With The Mosaic External Fixation Device To Treat The Fracture Of The Tibia

Objective: To observe the tendency and the regularity that changedwith the time of the value of the pressure at the broken ends of fracturedtibia treated by the axial pressurize with the mosaic external fixationdevice, and provid the accordance and instruction to use and adjust themosaic external fixation device.Method: Three wet tibia specimens of adult collected, made a modelof dia-fracture. Scaling the the mosaic external fixation device; Pasted thestraining plate at the middle piece of the adjusting rod of the device,lorded 5kg at the beginning, from light to heavy and measured the changeof the voltage and converted force of the adjusting rod. Made thebone-device complex. The p-f dists of the device were 2cm,4cm,6cm.Adjusted the rod to contact the ends of fracture and pressurized, when thequantity of the pressure was 60kg or 30kg(1/2time of weight～1 time ofweight) wrote down the time: to, and collected the data(wrote down valueof the pressure every hours from to to the 12th hour). Used the sametoothed to finished the long period experiment, the quantities of thepressure were 40kg,50kg, and the time of the experiment was 14 days,collected the data three times one day. According to the initial data, wecould get the curves of the pressure that changed with time. According tothe curves we could draw a conclusion. Statistical analyses were performed with LSD-test in the SPSS 13.0.Results: 1. The result of the short period experiment: (1) Thepressure at the end of fractured tibia will attenuate with the change oftime. (2) More length of p-f dist more attenuation of pressure we got, andthe surplus rate of the pressure is more low. (3) More loading at thebeginning more attenuation of pressure we got, the surplus rate of thepressure was more low too. 2. The result of the long period experiment:The pressure was lower than 15kg at the 8th～9th day and tend to zero atthe 12th day.Conclusion: 1. The pressure at the end of fractured tibia willattenuate with the change of time when we used the device to treated thefracture of tibias. 2. We should control the length of p-f dist possiblilywhen we use the device. 3. The loading of the beginning should be 1/2time of weight～1 time of weight. 4. We should adjust de device againat the 8th～9th day after the first loading when the pressure was lower than15kg(this value of pressure is not fit the cure of the fracture).