Comparison Of The Clinical Curative Effect Of DHS And Inverted LISS In The Treatment Of Intertrochanteric Fractures And Finite Element Analysis

Objective Compare the clinical curative effect of DHS (dynamic hip screw) and invertedLISS (less invasive stabilization systems) in the treatment of intertrochanteric fractures, establishfinite element models and analysis.Methods1、Retrospectively analysis the clinical data of42patients who did surgicaltreatment of intertrochanteric fractures in orthopedic trauma of Ningxia medical universitygeneral hospital from Jan2008-Dec2012.20cases operated by DHS,22cases operated byinverted LISS. Collect two groups’ data of operation time, intraoperative incision length, amountof bleeding, intraoperative X-ray frequency, fracture healing time, postoperative complications,postoperative Harris score, and compare the curative effect by the statistical analysis.2、Choosethe3D reconstruction CT original data of a normal femoral, establish Evans-Jensen Ⅲ, Ⅳtypeof intertrochanteric fractures and DHS, inverted LISS fixed fracture models, and simulate adultgait cycle joint bearing in the peak time for loading by weight700N after setting boundary andmaterial properties. Analysis the stress value, stress distribution and displacement change of thefemoral near end and fixed things.Results1、Inverted LISS group is shorter operation time, intraoperative X-ray fewerthan DHS group, and no statistically significant difference between the two groups in the lengthof the incision, blood loss, fracture healing time, excellent rate (last follow-up Harris hip score) after10to12months follow-up, average time of10.6months.，and3cases missed. All caseshealed well, one case of the DHS group has coxa vara, one case occurred DHS head nails cut, therest of the review of X-ray showed was the healing of bone, with no complications, andpostoperative complications no statistically significant difference between the two groups.2、Finite element modeling and analysis Evans-Jensen Ⅲ, Ⅳinternal fracture fixation model, DHSstress concentrate in the lag screw and sleeve root, inverted LISS in the lag screw root. Maximumstress value of inverted LISS is smaller than DHS. Compare to DHS, inverted LISS change ofmaximum lateral displacement in the coronal plane (U1), maximum lateral displacement in thehorizontal plane (U2) and maximum subsidence displacement in the sagittal plane (U3) of thefemoral head is smaller in type III. In type IV, inverted LISS change of U1、U3is smaller thanDHS, U2is bigger,but after fixing and inhibiting small tuberositas, U2is smaller.Conclusions1.DHS and inverted LISS are the effective methods in the treatment ofintertrochanteric fractures. Inverted LISS fixed instability of intertrochanteric fracture is moremechanical stability than DHS. It is suitable for can’t tolerate long surgery time, severeosteoporosis, instability fractures.2. Finite element method can establish different types offracture model, to analyze and evaluate the biomechanical characteristics of the bone and internalfixation, and can provide reference of choosing the appropriate treatment and internal fixation.