| Part 1 A Curative effect analysis of Minimally Invasive "8" Wire Internal Fixation for Transverse Patellar fracturesObjective: To explore the curative effect of minimally invasive "8" wire internal fixation for transverse patellar fractures.Methods: Retrospective analysis of patellar transverse fracture cases treated in Department of Orthopaedics,Affiliated Hospital of Chengdu University from January 2016 to June 2017.They were divided into Minimally invasive "8" wire internal fixation group(Minimally invasive group)and Kirschner wire tension band group(Kirschner wire group).The Lysholm knee function scores in 1 month,3 months,6 months and 12 months after operations,VAS scores at 90°of active knee flexion in 1 week,1 month and 3 months after operations,fracture reduction quality assessments and fracture healings in 12 months after operations were analyzed.The condition of internal fixation and infection of surgical incision were observed during the follow-up period.Results: A total of 52 cases of patellar fracture were collected,which met the inclusion and exclusion criteria.In the Minimally invasive group,there were 29 cases,17 males and12 females,with an average age of 32.28 years.There were 16 left and 13 right sides of the fractures.In the Kirschner wire group,there were 23 cases,12 males and 11 females,with an average age of 32.87 years.There were 14 left and 9 right sides of the fractures.The Lysholm knee joint function score of the Minimally invasive group was higher than that of the Kirschner needle group in 1 month and 3 months after operation(P < 0.05).There was no significant difference in Lysholm knee joint function score between the two groups in 6 months and 12 months after operation(P > 0.05).One week after operation,the VAS score of the Minimally invasive group was lower than that of the Kirschner needle group at 90 degrees of active knee flexion(P < 0.05).There was no significant difference in VAS score between the two groups at 90 degrees of active knee flexion(P > 0.05)in 1 month and 3months after operations.According to the quality evaluation of fracture reduction after operation,11 cases were excellent,12 cases were good and 6 cases were middle in the Minimally invasive group,the excellent and good rate was 79.31%;7 cases were excellent,10 cases were good,5 cases were middle and 1 case was poor in the Kirschner needle group,the excellent and good rate was 83.61%;there was significant difference in the quality grade of fracture reduction between the two groups(P < 0.05);there was no significant difference in the excellent and good rate between the two groups(P > 0.05).In12 months after operations,fracture healings occurred in both groups,and no failure of internal fixator and infection of incision occurred during the follow-up period.Conclusion: Minimally invasive "8" wire internal fixation for transverse patellar fracture can provide effective internal fixation stability,less trauma,less early pain and faster recovery of knee joint function than traditional Kirschner wire tension band technique.Part 2A Finite Element Analysis of Minimally Invasive "8" Wire Internal Fixation for Transverse Patellar fracturesObjective: To explore the effectiveness of minimally invasive "8" wire internal fixation for transverse patellar fractures by finite element analysis,and to analyze the stability and firmness of the internal fixation for fracture fragments.Then to provide data support and theoretical basis for the popularization and use of surgical methods.Methods: Using MIMICS 17.0,Rhinoceros 5.0,Geomagic Studio 12.0 and Hyper Mesh13.0 finite element pre-processing software,three-dimensional models of normal patella-tendons model(model 1)and "8" wire internal fixation for transverse patellar fracture model(model 2)were established respectively.Abaqus/CAE 2017 finite element analysis software was used to constrain the quadriceps femoris tendon and patellar tendon of the two models.The compressive stress of 2.0 MPa,3.5 MPa and 4.4 MPa was respectively applied to the lower,middle and upper 1/3 parts of the facies articularis patellae to simulate the stress of the two models at 20°,45°and 90°degrees of knee flexion.The finite element models were established and the equivalent stress and displacement of the two models are analyzed.Results: 1.The simulated knee flexion was 20 degrees.The maximum stress of patella in model 1 was about 25.0 MPa,and the stress was mainly concentrated in the lower part of patella.The maximum stress of model 2 was about 269.8 MPa,and the maximum stress was located on the steel wire;the maximum stress of patella was about 30.0 MPa,and the stress mainly concentrates on the fracture below the fracture line;the maximum displacement of model 2 was 0.144 mm,which occurs near the fracture line and the inferior pole of patella.2.The simulated knee flexion was 45 degrees.The maximum stress of patella in model 1 was about 34.7 MPa.The stress was mainly concentrated in the middle patella.The maximum stress of model 2 was about 291.2 MPa,and the maximum stress was located on the steel wire;the maximum stress of patella was about 41.0 MPa,and the stress on the fracture block above and below the fracture line was more balanced;the maximum displacement of model 2 was 0.234 mm,which occurred in the area near the fracture line of the upper fracture block.3.The simulated knee flexion was 90 degrees.In model 1,the maximum stress of patella was about 35.5 MPa,and the stress was mainly concentrated in the upper part of patella.The maximum stress of model 2 was about 531.0MPa,and the maximum stress was located on the steel wire;the maximum stress of patella was about 43.0 MPa,and the stress mainly concentrated on the fracture block above the fracture line;the maximum displacement of model 2 was 0.406 mm,which occurred near the upper pole of patella.4.In the three knee flexion angles,the tendon-patella junctions of the two models and the intersection of the steel wires of the model 2 had stress concentration areas.There was also a stress concentration on the facies articularis patella,and the stress concentration region was roughly consistent with the area in which the pressure was applied.In model 2,there was mutual pressure between the two fragments.Conclusion: The finite element analysis showed that the mechanical properties of minimally invasive "8" steel wire internal fixation for transverse patellar fracture were good,the displacement of fracture fragment was small,and the fixation was firm. |
PDF Full Text Request