| Objective: Schatzker Ⅰ type tibial plateau fractures are partialintra-articular fractures. The mechanism of injury is the knee sufferfromvalgus stress that lead to the femoral condyle impact the lateral tibialplateau. When the cancellous bone of the wounded is strong enough, whichalways leads to Schatzker Ⅰtype tibial plateau fractures.They are alwaysoccur in young ages with a high density of cancellous bone and easy to havecollateral ligaments injury. Tibial plateau fractures have a great influence onthe function of the knee joint. Conservative treatment,If the time knee jointimmobilized by cast is more than five weeks, which may developunacceptable knee stiffness and can’t get a better reduction, may lead to a riskof traumatic arthritis. When the displacements are over5mm, most doctorsadvocate operative treatment, which can obtain a better reduction and fixation,and allow early functional exercises.Most patients can get a satisfying curativeeffect. Most doctors use buttress plates as internal fixation to fix the tibialplateau fragment.But as more and more attentions are paid to the concept ofminimally invasive treatment and principal of BO(biological osteosynthesis),itis become the developing trend of orthopaedics that reducing the damage ofsoft tissueand blood supply, lowering the risk of infection and complication asfar as possible on the condition of guaranteeing the treatment effect.Compared to buttress plates,lag screws combined with cortical screw are lesstraumatic, lower infection rate, less pain and lower price in the treatment ofSchatzker Ⅰtype tibial plateau fractures. To study the biomechanicalcharacteristics of lagscrews combined with cortical screw and buttress platesin the treatmentof Schatzker Ⅰtype tibial plateau fractures, we designed thisexperiment，and provided theoretical basis for clinical applications.Method:8pairs of adult corpse lower extremity specimens were chosen (supplied by Department of Anatomy, Hebei Medical University),death age19-46,38on average. Exclude fractures, malformations, tumors, tuberculosisthrough naked eyes and x-rays. Apply osetocore3-EXAabsorptiometry(Medileink, Inc, FRA) in bone density test, osteoporosiswasnot found. Remove the all soft tissue of all specimens and only tibial left.Select a knee joint sample from each pair specimens randomly and namedgroup A, the left named group B, each group have8samples. All specimensare made into the model of Schatzker Ⅰ type tibial plateau fractures(Fig.1).Group A is fixed by two6.5mm lag screws combined with a4.5mm corticalscrew, the lag screws were placed5mm below the surface of cartilage and tobe perpendicular to the fracture line, the cortical screw is placed3mm abovethe distal(Fig.2). Three washer were used to prevent the screws from sinkingin the bone. Group B is fixed by a4.5mm “T” shaped DCP plate,2cancellousscrews were were placed5mm below the surface of cartilage and to beperpendicular tothe fracture line, and3cortical screw were used at distalend(Fig.3). All the specimens were done by the same doctor. Fix the allspecimens on the biomechanical machine, two ends of the displacementmeasurement instrument were inserted in the bone of both sides of the fractureline,ensure that both of them were at the same level(Fig.4). Test the relativedisplacement between the two fragments. Vertical loading biomechanicalexperiment was done on the lateral spilt bone for both group, ensureall theloading was conduct on the lateral spilt fracture fragment. Beforetheexperiment,we used a0-200N preload on the specimens to exclude influenceof the relaxation and creeping effect. We use continuous loading at a speed of5N/s. Recorded the displacements at the loads of300N,500N,700N and thefailure load when the displacements is up to2mm. SPSS19.0statisticsoftware was used to process the data,if P＜0.05,we think difference isobvious significance.Result: When the load was300N,500N,700N,the mean displacements ofgroup A are0.500±0.091mm,0.916±0.124mm,1.603±0.154mm;group B are0.471±0.106mm、0.898±0.118mm、1.543±0.189mm.After paired-sample T test, it turns out to be that the difference is of no significance instatistics(P>0.05);when the displacements is2mm, the mean load of group Ais956±97N, group B is1001±141N. After paired-sample T test,it turns out tobe that the difference is of no significance in statistics(P>0.05).Conclusion:Biomechanical stability of Buttress plate is not better thanlag screws combined with cortical screw in fixing the Schatzker Ⅰ type tibialplateau fractures. Except the same biomechanical stability, Lagscrewcombined whit cortical screw has the advantages of less traumatic,lowerinfection rate, less pain and lower price, and this method is available intreating Schatzker Ⅰ type tibial plateau fractures. |
PDF Full Text Request