Biomechanical Study on Personalized Titanium Alloy Short Femoral Prosthesis / 医用生物力学

Objective To evaluate biomechanical properties of the personalized titanium alloy short femoral prosthesis by finite element analysis. Methods Based on the validated femoral finite element model, the base of the femoral neck was simulated, and by inserting different short femoral prostheses, four total hip replacement (THR) models, namely, the SMF stem model (Model A), BE1 stem model (Model B), MINI stem model (Model C) and personalized stem model (Model D) were established, respectively. The same loads and constraints were applied to four groups of models, and the von Mises stress distribution and deformation were calculated and analyzed, so as to compare mechanical stability of each model. Results The deformation of all THR models was smaller than that of the femur model under physiological state. The deformation of Model B was close to that of Model C, and the deformation of Model A was close to that of Model D. The peak stress of Model C was higher than that of the other 3 models, reaching 9555 MPa. The overall stress trend was Model C > Model B > Model D> Model A > Model under physiological state. Conclusions The peak stress, stress distribution of personalized short femoral stem were similar to that of SMF stem, with reasonable stress distribution, small stress shielding of the proximal femur, minimum overall deformation and shear stress of the prosthesis, and its effectiveness and stability could meet the requirements of human biomechanics, which could provide references for joint surgeons and prosthesis researchers.

Comparative study on curative effect of locking compression plate fixation and anatomical plate in treatment of high-energy distal tibial fractures / 中华创伤杂志

Objective To compare the clinic effect of the locking compression plate (LCP) fixation and the anatomical plate in treatment of high-energy distal tibial fractures. Methods The study involved 42 patients with high-energy distal tibial fractures treated between May 2003 and May 2009. The anatomical plate group included 24 patients ( 16 males and 8 females, at average age of 39 years), of whom there were 13 patients with type A fractures, five with type B and six with type C according to the AO/ASIF classification. The LCP group included 18 patients ( 15 males and 3 females, at average age of 40 years), of whom there were 11 patients with type A fractures, three with type B and four with type C according to the AO/ASIF classification. All the patients were followed up for 8-17 months. Their functional and radiographic outcomes were collected. The operation time, intra-operative blood loss, X-ray exposure, bone healing time, post-operative complications and therapeutic effects were compared between both groups. Mazur's criteria was used to evaluate the function of the ankle. Results The LCP group was followed up for average 11.6 months and the anatomical plate group for average 14.2 months, which showed fracture healing in all the patients. The bone graft in the anatomical plate group was used more frequently than the LCP group, while the X-ray exposure in the LCP group was much more than that in the anatomical plate group. The operation time, incision size, blood loss, postoperative complications and radiographic bone healing time in the LCP group were significantly less than those in the anatomical plate group. Conclusions Both the LCP and anatomical plate are effective methods for the high energy distal tibial fractures. LCP has advantages of less trauma, quick fracture healing and less complications, is consistent with the biomechanics of internal fixation and hence is an ideal method for the treatment of the high-energy tibial fractures.