ABSTRACT
Objective:To compare internal fixation with 3 cannulated screws versus with an anteromedial support plate plus 3 cannulated screws using finite element analysis for unstable femoral neck fractures (Pauwels type Ⅲ).Methods:Recruited for this study was a 34-year-old male volunteer with a height of 173 cm and a weight of 75 kg. Continuous thin-layer helical CT was conducted to scan the segment from his hip joint to the middle shaft of his tibia. Digital medical software was used to establish three-dimensional models of the femur based on his femoral CT data. The digital femoral necks were dissected as necessary to simulate femoral neck fractures of Pauwels type Ⅲ. The fractures were fixated with 3 ordinary cannulated screws in a mode of inverted triangle (screw group) and with 3 ordinary cannulated screws in a mode of inverted triangle plus an anteromedial steel plate (screw-plate group). After the 2 groups of models were subjected to identical constraints and 3 kinds of load (slow walking, twisting and standing on one leg), they were compared in terms of distribution of Von Mises stress and deformation.Results:Under various loads in both groups, the maximum deformation occurred in the femoral head. In the condition of slow walking, the deformation in the screw-plate group was 1.97 mm, which was smaller than that in the screw group (2.26 mm). In the conditions of twisting and standing on one leg, similar deformations were observed in both groups. Under all kinds of load, the maximum stress occurred in the middle part of the bottom screw and the fracture line in all the models. In the screw group, the peak stresses were 318.09 MPa, 92.11 MPa and 147.21 MPa for conditions of slow walking, twisting and standing on one leg, greater than those in the screw-plate group (229.86 MPa, 86.94 MPa and 124.48 MPa).Conclusions:The cannulated screws plus an anteromedial support plate are a recommendable fixation method for young adults with unstable femoral neck fracture, because they can effectively share the stress on the cannulated screws, lead to better mechanical stability of the fracture ends than the fixation with merely 3 cannulated screws and effectively prevent shortening of the femoral neck.
ABSTRACT
Objective To compare the curative effects of Orthofix extended external fixator versus Ilizarov external fixator in the treatment of bone defects following post-traumatic tibial osteomyelitis.Methods During the period from January,1996 through January,2015,129 patients were selected for a retrospective analysis.They were 106 males and 23 females,aged from 14 to 60 years (average,36.5 years).Orthofix extended external fixator was used in 43 of them and Ilizarov external fixator in 86.Bone transportation started 7 to 10 dlays after surgery at a speed of 1 mm/d and was completed in 4 turns.The 2 groups were compared in terms of mineralization time for the extended bone,hone lengthening length,fixation time,union indexes,Activity of Daily Living Scale (ADL),Self-Rating Anxiety Scale (SAS),knee range of motion (ROM) and complications.Results The patients were followed up for 13 to 216 months (average,96 months).Orthofix group and llizarov group were not significantly different in mineralization time for the extended bone,bone lengthening length,fixation time or union indexes (P ＞ 0.05).In Orthofix group and Ilizarov group respectively,there were 6 versus 73 patients with mildly limited self-living abilities and 37 versus 13 patients with little limited self-living abilities by ADL scores;there were 33 versus 16 cases of mild anxiety,8 versus 63 cases of moderate anxiety and 2 versus 7 cases of grave anxiety by SAS scores;there were 39 versus 10 cases of limited knee ROM of 15° to 30° and 4 versus 76 cases of limited knee ROM of 30° to 60°.There were significant differences between the 2 groups in the above indexes (P ＜ 0.05).The rate of complications in Orthofix treatment group(79.1％,34/43) was significantly lower than in Ilizarov group (88.4％,76/86) (P ＜ 0.05).Conclusions In the treatment of bone defects following post-traumatic tibial osteomyelitis,the curative effects of Orthofix extended external fixator are similar to those of Ilizarov external fixator.However,they may have different effects on the life and psychology of the patients in the long run.Therefore,specific therapeutic scheme should be decided in consideration of the advantages of the 2 treatments as well as the conditions of specific patients.