The Finite Element Analysis And Clinical Application Of Failed Fixation Of Intertrochanteric Femur Fractures Treated With Hip Arthroplasty In Elderly Patients

Part Ⅰ The Finite Element Analysis of Failed Fixation of Intertrochanteric Femur Fractures Treated with Hip Arthroplasty in Elderly PatientsObjectiveTo determine stress distribution of femur after hip replacement and the effect of design parameters on the stress.MethodsThe finite element models of intertrochanteric femur fractures and a femur implanted were developed and stress analysis were carried out after hip replacement.ResultsThese residual holes left by internal fixation device resulted in stress concentrations in the bone in shorter stem。While These residual holes didn’t result in stress concentrations in longer stem.ConclusionsThese residual holes of failed fixation of intertrochanteric femur fractures resulted in stress concentrations in the bone.A distance of40mm between the most distal residual screw hole and the end of femoral prosthesis provide improved stress distribution. Part II A Retrospective Clinic Study of Failed Fixation of Intertrochanteric Femur Fractures Treated with Diaphyseal Locking Hip Arthroplasty in Elderly PatientsBackgroundSalvage treatment with hip arthroplasty may be considered for failed intertrochanteric hip fractures treated with internal fixation. To date no sufficient evidences show the superiority of one type of prosthesis over the other. The purpose of the present study was to respectively analyze the results and complications of diaphyseal locking hip arthroplasty performed as a salvage procedure after the failed treatment of an intertrochanteric hip fracture.MethodsFrom2003to2009,36patients (25females and11males) were treated with diaphyseal locking hip arthroplasty after the failed internal fixation of intertrochanteric femur fractures. Twenty-nine cases underwent total hip arthroplasty (cementless sockets) and seven underwent hemiarthroplasty. Cementless, extensively porous-coated, diaphyseal locking stems were used in all the cases.ResultsThree patients died and five were lost to follow-up in the first year of therapy. Prospective follow-up time of the remaining28cases ranged from2.2to8.2years (mean,4.8years). The average Harris Hip Score was32.8preoperatively and improved to82at the last follow-up postoperatively. No loosening was found in X-ray. According to the criteria of Engh et al, the stability of the femoral stem at the last follow-up was classified into fixation by bone ingrowth in17patients and stable fibrous fixation in11patients. Complications included two cases of deep vein thrombosis and two cases of heterotopic ossification (Brooker Ⅱ). Dislocation and intraoperative femoral fracture were not founded.Conclusion Cementless diaphyseal locking hip arthroplasty is an effective salvage procedure for the elderly patients with failed treatment of an intertrochanteric hip fracture.