Experimental Study Of Biomechanical Properties Change In Compact Bone Traumatic Fracture Natural Healing Process

Fracture healing is an extremely complex biological repair process,5%to10%of the fractures eventually occurred bone healing or non-union for variousreasons.It is reported that the United States had10%of delayed union in56million patients with fractures each year, nonunion patients about15million to20million[1,2].Fracture healing requires not only good contact, the fracturesaround the blood supply, and the pivotal role of biomechanics in the process offracture healing.In recent years, scholar at home and abroad had a largenumber of studies for changes in biomechanical properties of bone fracturehealing process[1-3], but the compact bone Haversian system to re-establish theprocess of healing at the fracture healing callus and various parts of thenon-fracture modulus of elasticity of compact bone changes reported arefew.The purpose of this study is to explore the fracture callus natural healingprocess and the normal compact bone potential of withstand the stress andstrain. The experiment used48health Small Tailed Han and were randomlydivided into four groups of12each.Thiophene xylazine intramuscular injectionof anesthesia, the left hind leg skin preparation, strong iodine disinfection aftertake longitudinal medial incision, about7cm, blunt dissection of the shin boneand soft tissue, rampant through the left tibia amputated to establish fracturefixation model, respectively, a group of animals were sacrificed at2,4,8, and12weeks after surgery, X-ray photographs to check for pseudarthrosis prior tosacrifice. Tick bilateral tibia, double-sealed after saline gauze wrapped, set at-80℃.Surgical limb removal plate and screw fixation, intercept tibia in fracturehealing,the screw holes and steel plate not covered by the normal corticalbone respectively, made of ring bone, sequentially numbered. Each ring bonewere longitudinal fractured, the interception of five uniform size specimens.The contralateral limbs tibia using the same method in the same position with the operative side take the tryout and relatively mark.Careful sanding with finesandpaper, the tryout uniform in size, by force plane and perpendicular to thelong axis. Every small specimen placed on universal mechanical testingmachine compression test, write down the elastic modulus values. after4,8and12weeks select an animal to take the injured side of the fracture zone andcontralateral specimen in the same location, make the ends of the scanningelectron microscope and constant element analysis.At the same time take thesame part of the contralateral normal tibia compact bone as control.The resultsof this study show the elastic modulus of the experimental group fracture callushad downward trend in4weeks and began to rise after4weeks,8and12weeks in ascending order, statistical analysis shows that for2weeks nostatistically significant difference in the4weeks, the other time points pairwisecomparison differences were statistically significant (P <0.05).While the controlgroup throughout the elastic modulus values are higher than the experimentalgroup, and with the fracture healing in the increase of the number of weeks, nosignificant change in the elastic modulus. Based on the results, concluded asfollows:1,Callus elastic modulus of the compact bone fractures at4weeksafter a downward trend began to rise after4weeks,8weeks and12weeksafter ascending order, indicating with healing the increase of the number ofweeks,the fracture callus volume is also increasing, the determination of thebiological changes of mechanical properties of the fracture healing process,can determine fracture healing;2,With the increase in weeks of healing, thefracture fragments department callus organic matter C content graduallyincreased, indicating organic matter increased with increasing time, the bonestrength, fracture strength gradually restored to its original state;3,With theincrease in the number of weeks of healing, fracture fragments callus at theinorganic O, Mg, P, Ca content gradually reduced, indicating that the increaseof a combination of inorganic and collagen, callus healing strength increaseover time increase, also increasing collagen content, help to carry out non-invasive evaluation of fracture healing and fracture fixation, guidance plusnoninvasive intervention within a reasonable period of time, and to determinethe intensity of treatment.