Biomechanical Analysis Of Gamma3 Combined With A Cannulated Compression Screw In The Treatment Of Pauwels Ⅲ Femoral Neck Fracture

Objective: Analysis and comparison biomechanical performance of Cannulated Compression Screw,Gamma3 and Gamma3 combined with a cannulated compression screw to treatment Pauwels Ⅲ femoral neck fracture.Methods: Twelve adult cadaver femora were used as the sample to establish adduction femoral neck fracture models at the Puwel 70°.The femoral samples were divided into three groups at random: group A was fixed with Cannulated Compression Screw,group B was fixed with Gamma3,and group C was fixed with Gamma3 combined with a cannulated compression screw.The specimens were tested on the CCS0-44100 electronic universal testing machine,and the center of the femoral head was marked.First,a single continuous compression test was conducted to obtain load-displacement data of each group within the range of 1000 N.Then cyclic load tests were performed to obtain the femoral head displacement data again.Finally,the ultimate vertical load test was carried out to obtain the ultimate load data of each group.Data were dealt with SPSS 26.0 software by the first author in this study.P<0.05 level was regarded as the significant difference.Results: In a single continuous compression test,the sinking displacement of the femoral head showed a linear variation within the loading range of1000 N.The displacement of femoral head in group C was lower than that in group A and B,and that in group B was lower than that in group A,and the differences were statistically significant(P<0.05).At the same time,the axial stiffness of each group at 800 N was calculated.Group A was 179±9 N/mm,Group B was 371±47 N/mm,and Group C was 1006±293 N/mm.Group C was significantly better than Group A and B,and Group B was better than Group A,the differences were statistically significant(P<0.05).At the end of the cyclic load experiment,the displacement of the femoral head in each group was2.56±0.22 mm in group A,2.35±0.28 mm in group B,and 0.38±0.15 mm in group C.The displacement in group C was significantly lower than that in group A and group B,and the differences were statistically significant(P<0.05),the displacement of group B was smaller than that of group A,but there was no statistically significant difference(P<0.05).The ultimate load values of group A were 2940±276 N,group B 2338±172 N,and group C 3625±167 N.The ultimate load values of group C were significantly higher than those of group A and group B,and group A was higher than group B,the differences were statistically significant(P<0.05),the out-line rotation of the femoral head was obvious in group B,but no obvious rotation of the femoral head in group A and C.Conclusion: For Pauwels Ⅲ femoral neck fracture fixed,relative to Cannulated Compression Screw and Gamma3,Gamma3 combined with a cannulated compression screw has demonstrated superior biomechanical advantages in single continuous compression test,cyclic load tests and extreme vertical load tests.