Intramedullary And Extramedullary Fixation For The Treatment Of Intertrochanteric Fracture:a Biomechanical And Clinical Study

Part one Intramedullary and extramedullary fixation for the treatment of intertrochanteric fracture:a biomechanical studyObjective:To compare the properties of the Proximal femoral nail antirotation (PFNA) and Dynamic hip screw(DHS) fixed intertrochanteric fractures by biomechanical experiments.Methods:After measurements of the normal femur biomechanical properties, we make12adult31-A1,31-A2intertrochanteric fracture model, respectively and randomly fix it by PFNA, DHS. After implant fixed, by the methods of Resistance strain gages and Displacement transducers, the Displacement-Pressure, Pressure-Proximal fracture segment angle displacement statistical tables were produced under the vertical stress. The torsion angle-torque statistical tables was produced under torsional stress.Measurement vertical and torsional stiffness and statistical comparison of the biomechanical properties of two different internal fixation in intertrochanteric fractures. The vertical and torsional stiffness of two specimens groups were Measured and statistically compared. The biomechanical properties of the different kinds of internal fixation in the treatment of intertrochanteric fractures were stastistically compared.Results:1.The compressive stress is mainly distributed at medial femoral and the tensile stress distribution area is mainly distributed at lateral femoral neck and top line. Compressive stress is generally higher than the tensile stress and the middle femur withstand maximum stress.2. DHS major contribution normal femur tensile stress, stress is mainly concentrated in the first screw; PFNA major share compressive stress, stress is mainly concentrated in the reamer and the distal locking nail.3. For the31-A1fractures, there were not exist significant differences between the PFNA-DHS in the proximal femur displacement, angular displacement under the physiological load; when the torsion angle≤4°, there were no significant difference between the PFNA-DHS in torque,but there were significant difference between the two groups when the twist angle≥6°,the torque of PFNA group was significantly greater than that of DHS group.4. For the31-A2type fracture, the specimens that eliminating part of the medial femoral cortex bear the strain were smaller than the31-Al type, plants bear more load than former. There were statistically significant differences exist between PFNA-DHS at vertical and angular displacement.5. Contrasting between the Same kind of internal fixation of intertrochanteric fracture in different types, there were no statistical differences in the proximal femur displacement, angular displacement, torque, torsion angles between the31-A1,31-A2type under the physiological load; while in DHS group, there were significant statistical differences in the proximal femur displacement, angular displacement, torque, torsion angles between the31-A1,31-A2type in the vertical stress regardless of how much displacement of the proximal femur, there were statistically significant.The shear capacity of Intramedullary fixation are stronger and more stable than extramedullary fixation.Conclusion:The capabilities of anti-vertical compression, anti-varus, anti-shear and torsion of PFNA were significantly stronger than DHS. PFNA and DHS could apply to31-A1intertrochanteric fractures associated with small rotor defect under the physiological load, but for the31-A2-type cases, PFNA nail were significantly stronger than the DHS in the resistance to vertical compression, varus, shear and torsion capacity and DHS should not apply for the lesser trochanter defect cases. Therefore, we believe that intramedullary fixation was much smaller affected compared to extramedullary fixation by unstable fractures and relative loaded more than extramedullary, but increased stiffness of intramedullary fixation may exist stress shielding, resulting in a greater likelihood of nonunion.Part two Intramedullary and extramedullary fixation for the treatment of Reverse oblique intertrochanteric fracture:a biomechanical studyObjective:To compare the Proximal femoral nail antirotation (PFNA-), dynamic condylar screw (DCS)and dynamic hip screw (DHS) fixed reverse oblique intertrochanteric fractures by biomechanical experiments.Methods:After measurements of the normal femur biomechanical properties, we make18adult reverse oblique intertrochanteric fracture model, respectively and randomly fix it by PFNA, DHS, DCS. After different implant fixed, by the methods of Resistance strain gages and Displacement transducers, the Displacement-Pressure, Pressure-Proximal fracture segment angle displacement statistical tables were produced under the vertical stress,and the torsion angle-torque statistical tables was produced under torsional stress.Measurement vertical and torsional stiffness and statistical comparison of the biomechanical properties of three different internal fixation in reverse obliquity intertrochanteric fractures. The vertical and torsional stiffness of three specimens groups were Measured and statistically compared. The biomechanical properties of the three different kinds of internal fixation in the treatment of intertrochanteric fractures were stastistically compared.Results:Under the vertical load, when the sinking displacement of proximal femur was no less than1.0mm (vertical stress no less than500N), the axial stress between the PFNA and DCS were not significant difference in physiological load. There was significant difference between the two experimental group when the vertical stress surpass physiological. The resistance to vertical compression capability of PFNA was stronger than DCS, but the stress shielding of PFNA was more obviously. There was significant difference between the PFNA and DCS on resistance to vertical load.Under torsional stress, there were no statistically difference between the DHS and DCS in the presence of torsion angle less than4°. When the torsion angle increasing, the ability of anti-reverse of the PFNA is stronger. Comparison of the stiffness of three different implant, the vertical and torsional stiffness of the PFNA were stronger than DCS and DHS, while no statistically difference between the DCS and DHS on the torsional stiffness.Conclusion:The resistance capability to vertical and torsion stress of PFNA was stronger than DCS and DHS. Under physiological load, PFNA and DCS can be used in the treatment of reverse intertrochanteric fracture, but the stress shielding rate of PFNA was higher than DCS. The DHS was easy to cause the fixation failure and not recommended to the treatment of reverse oblique intertrochanteric fractures.Part three The clinical evaluation of Asian proximal femur intramedullary nail antirotation (PFNAⅡ) in treatment of intertrochanteric fracturesObjective:Investigate the clinical efficacy of the treatment of intertrochanteric fractures in aged people by Asian proximal femur intramedullary nail antirotation (PFNA-Ⅱ).Methods:From March2011to December2012, the PFNAII was applicated to treatment of127cases of elderly patients with intertrochanteric fracture patients. They were49cases of male and female78cases, with a mean age of74.3±15years.127cases of elderly patients were classified by modified Evans:From I to V, followed by37,42,26,15,7respectively. We make the statistics on intraoperative blood loss, operation time, incision length, X-light exposure times, and make evaluation of the efficacy of postoperative, complications by the Harris hip score.Results:Statistics show that the average operation time was42.5min (35to90min), the average intraoperative blood loss was107.5mL (65to410mL), X-light exposure times were2.5±1.4(2-4) and total length of incision was6.5±1.8cm (5.5～11.0cm). All patients received6to24months Follow-up (mean12.5months). The results show that the neck shaft angle was134±13°(120°～150°), fracture healing time was14± 2.5weeks (11to19weeks), the hip Harris score was86.5±19.5points (65～100points), among which were excellent in29cases (22.83%), good in76cases (59.84%), morderate in20cases (15.74%) and poor in2cases (1.57%), good rate of82.67%. There were no hip varus deformity, screw cut out and femoral shaft fractures taken place. Among the patients, there were14cases of patients with thigh pain (11.02%),5cases with inner thigh pain (3.94%),4cases of heavier pain were improved by physical therapyConclusion:PFNAII have the advantages of simple operation, fewer complications, and clinical efficacy to treatment of intertrochanteric fractures, but its long-term efficacy and whether there are other complications or not are needed large sample and multi-center observation.Part four Dynamic condylar screw for treatment of unstable proximal femoral fracturesObjective:To evaluate the efficacy of operative treatment for the Proximal femoral fracture with dynamic condyle screw (DCS).Methods:From January2004to September2012,45cases of patients with Proximal femoral fracture(Reverse intertrochanteric femur fractures in18cases,27cases of intertrochanteric fracture; Male17, Female28) was treated by DCS. All patients were followed up by1to3years.The body mass index, operative time, blood loss, X ray projection times, the number of postoperative blood transfusion, postoperative wound drainage, postoperative neck-shaft angle, fracture healing time (patient began full weight bearing time) was statistics, and make Harris score.Results:All patients were healed and there are no complications such as broken nails, broken boards, and other nonunion take place. All patients were followed up for1-3years. According to Harris score, the result was excellent in16cases, good in18cases, fair in7and not satisfied with4. The excellent rate is79.56%,91.11%pass rate.Conclusion:Dynamic condylar screw is effective methods in treating unstable proximal femoral fractures. Application of DCS should be considered in elderly, obese patients. If you have to use the DCS, full weight-bearing should be extended. Part five A randomly controlled study of unstable intertrochanteric fractures inelderly patients treated by PFNAⅡ and Hemiarthroplasty Objective:The purpose of this study is to compare Asia anti-rotation proximal femur intramedullary nail with cemented hemiarthroplasty in treatment of elderly unstable intertrochanteric fractures.Methods:From January2010to October2012, the average age of77.5to52years (67-92years old), AO classification31-A2type intertrochanteric fractures were included in the study.22patients were randomly using cemented hemiarthroplasty, and30patients were treated with anti-rotation Asia proximal femoral nail (PFNAⅡ).Blood loss, postoperative wound drainage, blood transfusion,operative time, and postoperative start loading time were statistics. We evaluated the effect of treatment on4,6weeks and3、6、12、24months by Harrris score.Results:All patients were followed up for12.5±5.5months (6-24months).For hemiarthroplasty group, the average operation time was82.4min (55～122min), intraoperative blood loss was310.5ml (170-820ml), postoperative wound drainage was210ml (90-340ml), blood transfusion was225ml (0-800ml), part of the weight loading was5.5days (3-9days), last follow Harris score was75.9points (62-86points),excellent rate was77.27%. For PFNA-Ⅱ group, the average operative time was42.5min (35～90min), intraoperative blood loss was102.5mL (65～350mL), postoperative wound drainage was65ml (35-110ml), blood transfusion was85ml (0-400ml), partial weight-bearing after start time was29.3days (25to42days), last follow Harris score was81.9points (71-88) points, excellent rate was80.00%. The two groups have statistical difference in blood loss, operative time, postoperative wound drainage, blood transfusion and postoperative part loading time. The group of PFNA Ⅱ was better than hemiarthroplasty in blood loss, operative time, and Hemiarthroplasty group has earlier weight than PFNA Ⅱ.There were no significant difference between the two groups in the postoperative Harris score.Conclusions:For elderly patients with unstable intertrochanteric fractures, PFNA Ⅱ should be the preferred treatment. For those who have severe osteoporosis or have special requests to early weight-bearing, hemiarthroplasty would be a good choice.