Comparison Of Biomechanical Effect Between Dynamic Hip Screw And Active Dynamic Hip Screw In Stable Intertrochanteric Fractures

Objective To compare the biomechanical characteristic of Active Dynamic Hip Screw (A-DHS) and Dynamic Hip Screw (DHS) for intertrochanteric fracture of the femur, and evaluate their advantages and disadvantages.To provide a better treatment for stable intertrochanteric fracture of the femur.Methods Ten cadaveric femur specimens instrumented with six strain gauges along the medical and lateral cortices were randomly divided into two groups,and then created A type A1.3intertrochanteric Fracture successively.Lastly, A-DHS (Group A) and DHS (Group B) were implanted respectively.Then press test were carried out on biomechanical experimental machine to compare their press and torsion property,as well as the stain distribution of proximal femurs. At last we evaluate their advantages and disadvantagesResults To compare the biomechanical characteristic of A-DHS and DHS, A-DHS had distinctive advantage over DHS.1) To compare the lateral and inside strength, ADHS is13%and16%higher than DHS respectively.The differences between the two groups were statistically significant(P<0.05).2) To compare rotation-intensity:ADHS is18%higher than DHS;to compare the rotation-rigidity, ADHS is18%higher than DHS. The differences between the2groups were statistically significant(P<0.05).3) To compare rotation-intensity:ADHS is18%higher than DHS;to compare the rotation-rigidity, ADHS is18%higher than DHS. The differences between the2groups were statistically significant(P<0.05).4) To compare the load-strain and laod-displacement, ADHS is10%—11%and20%—60%higher than DHS respectively.The differences between the two groups were statistically significant(P<0.05).5) To compare the fixation failure under static loading, the ultimate loading in ADHS group is3886±388N, and the ultimate loading of DHS group is3028±246N, ADHS is22%higher. The differences between the two groups were statistically significant(P<0.05).6) The mean value of host screw cutout force in ADHS group was (2033.90±181.18) N/mm, significantly higher than (1600.00±152.3) N/mm in DHS group.Conclusion As a new technique, to compare the biomechanical effects between dynamic hip screw and active dynamic hip screw in stable intertrochanteric fractures, A-DHS has the advantages of proper design, good anti-press and anti-rotation property, rigid fixation, little trauma of operation and few complications.It is one of the good choices of treatment of i stable intertrochanteric fractures of the femur.