Effect Of The Lateral Wall And Femoral Calcar’s Integrity On The Biomechanical Stability Of Pfna Fixation For Intertrochanteric Fracture

Objective: To compare the stability of lateral wall or femoral calcar defect in thePFNA for the treatment of intertrochanteric fracture by biomechanical experiments.Itprovides a clinical theoretical basis for improving the treatment efficacy ofintertrochanteric fractures,and reducing the risk of internal fixation failure.Methods:12whole-length femur specimens of adult body selected to be made intoA1type of intertrochanteric fracture， and then to be divided into2groupsrandomly.Group A removed the femur femoral calcar, group B removed the lateralwall.Both of them are fixed with PFNA,3slices of strain gauge were individuallysticked into below fracture section of medial lesser trochanter,lateral greatertrochanter and the basal parts of the top of femoral neck,marked as1,2,3.Connectedthe strain gauge for axial load testing in the electronic universal test machine,Loadingspeed was20n/S,from0to1200N, recorded the strain value every200N.And at thesame time recorded the corresponding vertical displacement of the femoral head. Thestatistical analysis was performed with SPSS18.0software. P﹤0.05was consideredstatisically significant.Results:1.The relationship between load and displacementThe relationship between load and displacement of the samples under the vertical loadof0to1200N mainly presents linear variation law: with the load increasing, thedisplacement increases gradually.The displacement of group A significant greater thangroup B,That is the displacement of group femoral calcar defect significantly greaterthan group lateral wall.The difference is statistically significant(P<0.05). 2. The relationship between load and strain valueThe strain value of the mark2and3are positive,explaining the force of lateralgreater trochanter and the basal parts of above the femoral neck are tensile stress,thelesser trochanter inside are pressure stress.The relationship between load and strainvalues of the specimen under the vertical load from0to1200N mainly presentslinear variation law.With the load increasing, the strain values increases gradually.Andin the same load conditions,the strain values of group A significant greater than groupB,That is the strain values of group femoral calcar defect significant greater thangroup lateral wall.The difference is statistically significant(P<0.05).Under the samestress conditions,the smaller the strain value,the smaller the stress.Conclusion:The experimental results showed that the prognosis of group lateral walldefect are better than group femoral calcar defect.It reflects that the influence ofbiomechanical stability is smaller, compared with PFNA for intertrochanteric fracturewith the femoral calcar defect.It’s very important to guide the treatment ofintertrochanteric fractures and evaluate prognosis in clinic.