The Pre-clinical Research Of The Bulge Core Type Rigid Internal Fixation Device

Rigid internal fixation, RIF is a new technique to treat the bone fracture in the later 20 years. Until now, lots of the rigid internal fixation equipments are in use in clinic. Spiral rigid internal fixation is mainly used to treat the bone fracture.Now, I will introduce a new kind of rigid internal fixation, with dilatation force to treat the bone fracture; we did experiments in vitro to research the clinical problems of the new kind of rigid internal fixation: the dilatation position; the effect of the rigid internal fixation equipment length. Our aim is to solve the problems of the new kind of rigid internal to use.This research has three parts:Part one: measurement of the cortical bone thicknessAim: Vernier caliper, cortical bone measurer, X-ray electronic measurements are used to compare the accuracy. We want to find the most suitable method to measure the cortical bone. Method: Caprine tibiaes are chosen randomly. We use micro electric drill to perforate in the caprine tibiaes; then we use 5mm retention pins as measure points, and we use 7.938mm steel bean fixing at the end of caprine tibiaes as a standard. We take X-ray.We get out of the retention pins, then use the Vernier caliper to measure the length of cortical bone.Conclusion: Vernier caliper group: 2.9533±0. 17872mm; X-ray electronic measurement group: 2.9603±0. 18487mm ; cortical bone measure: 2.9567±0.18134mm.We use SPSS11.0 to analysis of variance , P=0.989,P〉0.05;there is no statistical difference between the results.Part two: Part two: The expanding position of the bulge core type rigid internal fixation deviceAim: X-ray, macroscopic observation and sclerous tissues sections are used to ensure the expanding position of the bulge core type rigid internal fixation device. Method: X-ray, macroscopic observation group: Caprine tibiaes are chosen randomly. We used micro electric drill(￠2.0mm) to perforate in the caprine tibiaes; we put 2mm,3m 5mm,6mm,7mm the bulge core type rigid internal fixation device pins into the holes. X-ray pictures are taken to ensure the expanding position of the bulge core type rigid internal fixation device, and then we saw asunder the bone blocks to observe the expanding position of the bulge core type rigid internal fixation device. Slerous tissue section group: Caprine tibiaes are chosen randomly. We used micro electric drill(￠2.0mm) to perforate in the caprine tibiaes; we put 2mm,4mm,6mm,8mm the bulge core type rigid internal fixation device pins into the holes. Slerous tissues sections are taken to ensure the expanding position of the bulge core type rigid internal fixation device.Conclusion: Two groups show that the expanding position of the bulge core type rigid internal fixation device is 1mm to the end. If effective length is the same or thicker than the cortical bone, the expanding effectiveness of the bulge core type rigid internal fixation device is good; and if effective length is thinner than the cortical bone, the expanding effectiveness of the bulge core type rigid internal fixation device is bad.Part three: The mechanic test of the bulge core type rigid internal fixation deviceAim: Bone fracture moulds are fixed by the bulge core type rigid internal fixation device in different length to ensure the length's effectiveness to the fixing. Method: Caprine tibiaes are chosen randomly. We use micro electric drill to see asunder the caprine tibiaes; then we measure the cortical bone thickness with cortical bone thickness measuring scale. We fixed the bone fractures with four group devices: effective length< cortical bone thickness+ Ti-plate thickness; effective length= cortical bone thickness+ Ti-plate thickness; effective length> cortical bone thickness+ Ti-plate thickness.Conclusion: Biomechanical test: effective length< cortical bone thickness+ Ti-plate thickness; effective length= cortical bone thickness+ Ti-plate thickness; effective length> cortical bone thickness+ Ti-plate thickness. The biomechanical stability in three groups was evaluated by testing MBS,MBS and MPS. The bulge core type rigid internal fixation device in optimal length can produce max retention force. In the effective length< cortical bone thickness+ Ti-plate thickness group, the vertical MBS,MAS were100.8±59.95 N,397.2±112.19 N, the effective length= cortical bone thickness+ Ti-plate thickness group MBS,MAS were 141.5±23.97 N,847.5±86.65 N . In the effective length> cortical bone thickness+ Ti-plate thickness group, the vertical MBS,MAS were 55.8±25.36 N,686.58±237.79. So the bulge core type rigid internal fixation device in optimal length can produce max retention force.