The Biomechanical Comparison Of Different Fixation Methods For Posterolateral Split Depression Tibial Plateau Fracture

Objective: In recent years, with the development of economy, Medicaldiagnostic technology continues to progress, the incidence of Posterior columnfracture in the tibial plateau has been increasing. Congfeng Luo categoriesposterior column fracture into single type based on the theory of CTthree-column,and pointed out that the posterior column fracture should beapplied to posterior approach.We think that patients should be treatedindividually,which is determined by patient’s age, the site of fracture, and thetype of fracture. The tibial plateau posterior column fracture can be dividedinto medial fracture, posterolateral fractures and condylar fractures accordingto the different parts, and also can be divided into splitting fracture, posteriorcolumn compression fracture and splitting compression fracture like the lateraltibial plateau fracture. Splitting fractures are seen the most in posteromedialcolumn,and compression fractures are seen the most in posterolateral column.Based on our experience, the posterolateral shearing tibial plateau fractureshould be fixed with antiglide plate by the posterior surgical approach.Because of the complexity of the local posterior anatomy,the posterolateralsplit depression fractures can be treate with bone graft reduction and fixationpassing through the fracture line, which can shorten surgery time and avoidvascular and nerve injury,While avoiding the trouble to remove afixation.More researches in the past about the biomechanics focused on theshearing tibial plateau fracture. and there are few studies on compressionfractures.The aim of experiment is to compare the biomechanical characterisesof the two surgical methods and provide scientific theory basis for clinicaltreatment, especially in choosing surgery approach.Method: Collect6pairs of full adult anti-corrosion corpse femurspecimens(provided by the department of Anatomy,Hebei Medical University ).specimens deformities, such as fracture and tumor,tuberculosis andsignificant structural damage,were excluded through eye inspection and X-rayobservation. There were no osteoporosis found through Osteocore3-EXA-type absorptiometry(Medileink， Inc， ERA).Remove the skin,subcutaneous, muscle and other soft tissue.The cadavers were sealed andpackaged in double-layer plastic bag. Specimen were preserved in-20℃cryopreservation freezer to ensure that biological characteristics of bone didnot change significantly.Specimen were taken out from freezing and thawed atroom temperature24hours before the experiment. With the pendulum saw,6pairs specimens make the fracture line In accordance with pre-designedposterolateral depression tibial plateau fracture model，We model Madhav A.Karunakar,s method(1),First the lateral tibial platform is divided into anteriorand posterior, drill holes with2mm Kitchener to mark the range ofposterolateral condyle. Open a bone window using the bone knife in thebottom of posterolateral tibial plateau articular surface and remove awedge-shaped bone of the same size while preserving the lateral platformcortex. In order to measure the displacement of the articular surface moreaccurately,300N of force were directly added to the lateral condyle,whichcaused posterolateral collapse fracture model.6pairs of specimens wererandomly divided into two groups: The five-hole reconstruction plate was usedin A group and four screws were placed in order Drilling, sounding tapping.Bgroup used the the L-shaped plate fixation.In order to remove the effect of thebone graft on stability, plasticine were filled in the the bottom of of thecollapsed articular surface.Completion of all these fracture model preparationand plate fixation belonged to the same person. All specimens wereanatomically reconstructed.The two sets of specimens were installed in theCSS.44020bio-mechanical testing machine and the axial load tests wereperformed.Use a continuous axial load at the loading rate of10M/s,measurethe vertical displacement of the posterolateral tibial condyle using theextensometer when the load was respectively500N，1000N and the failureload(the load when posterolateral condyle vertical displacement is2mm）.5 SPSS16.0statistical software were used for statistical analysis，with t-test andP value was set at0.05for the statistical significance.Result:1Comparison of the vertical displacement under different axial loadsWhen the load was500N, the displacement of the posterolateral groupwas（0.187±0.005)mm,(0.186±0.004)mm in anterolateral fixation group,there was no statistically significant difference between twogroups(p=0.525).When the load was1000N, the displacement of the frontgroup is(0.471±0.005)mm,displacement of anterolateral fixation group was(0.498±0.005)mm,there was statistically significant difference between twogroups(p=0.001).2Comparison of failure loadThat fracture displacement was greater than2mm was considered wasthe failure load. It was3430N±201N for posterolateral buttress plate,2959N±151N for the anteromedial There were significant difference between thetwo groups(p<0.05)Conclusions：In this study,the stability of the two methods to fixposterolateral depression tibial plateau fracture models were compared bybiomechanics. The results showed that there was no remarkable differencebetween the posterior group and lateral groups on the stability in thephysiological load，but the failure load of the posterolateral is greater than theanterolateral.Therefore, we recommend using anterolateral approach to treatposterolateral split depression tibial plateau fracture passing through thefracture line bone graft reduction and fixation in clinical studies, the stabilityof fracture can not be influenced.