Abstract:Objective Biomechanical tests were performed on a new type of internal fixator for great tuberosity fractures of the humerus to test the mechanical stability of the internal fixation and the feasibility of the clinical trial and compare the biomechanical stability of cannulated screws,tension band and new type of internal fixation for the treatment of large tuberosity fractures of the humerus.Methods 18 fresh frozen adult cadaveric humeral specimens with rotator cuff muscle and a greater tuberosity fracture model were established.The samples were randomly divided into 3 groups.Hollow screws,tension band and new type of internal fixator were used to fix the great tubercle fracture.Before the test,each model were given 3 times of loading and unloading pretreatment.The loading rate was 10mm/min,and the pressure was between 0 and 80 N.There were 30 seconds between loads to eliminate the muscle relaxation effect and viscoelastic specimen model.The load value was set to zero in the end.Under protective load (900N),each specimen was subjected to constant loading (10 mm/min).The displacement size and the corresponding load condition of the specimen were recorded automatically by computer software of the experimental machine.The greater tuberosity load when fracture had displacement of 2mm and 5mm was chosen to compare.Results The loading of the three groups of specimens (cannulated screws,tension band and new type of internal fixator group) were [(201.18±7.14)N,(238.83±31.04)N and (240.74±5.19)N]respectively,when the greater tuberosity had displacement of 2mm.Compared with the cannulated screw group,the tension band group was statistically significant (P<0.01).Compared with the cannulated screw group,the new internal fixator group had statistical difference (P<0.01),and there was no significant difference between the new internal fixator group and the tension band group (P>0.05).The compressive stress of three groups of specimens (cannulated screw tension band group,model group,new internal fixation group) were [(410.48±32.79)N,(530.48±31.04)N,(728.36±10.43)N]respectively,when the greater tuberosity displacement was 5mm.Between the three groups,the tension band group was statistically significant difference compared with cannulated screws group (P<0.01).Compared with cannulated screws group,the new type of internal fixator group was significantly better(P<0.01) And there was statistical significance of the new internal fixator group compared with tension band group (P<0.01).Conclusion Compared with cannulated screws or tension bands,the new internal fixation device for the greater tuberosity of humerus shows obvious biomechanical advantages.The new type of internal fixator is theoretically stable for the fracture of large tuberosity of humerus and provides the basis for further clinical trials.
薛兆龙,孟艳丽,王勤业,罗亚平. 新型内固定器固定肱骨大结节骨折的生物力学研究[J]. 实用骨科杂志, 2018, 24(3): 234-238.
Xue Zhaolong,Meng Yanli,Wang Qinye,et al. Biomechanical Study of New Internal Fixation Device for the Greater Tuberosity Fracture of Humerus. sygkzz, 2018, 24(3): 234-238.
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