Evaluation of interlocking intramedullary nails and dynamic compression plate for the fixation of ulnar fracture:a comparative study of their biomechanical properties / 中国矫形外科杂志

ABSTRACT

[Objective]Ulnar fractures fixed by interlocking intramedullary nails or dynamic compression plates were tested to compare their biomechanical function,in order to provide the theoretical basis for clinical practice.[Method]In the experiment,12 pieces of fresh ulnars were used to produce middle-part transverse fracture models;which were fixed by interlocking intramedullary nails or six-hole 3.5 mm dynamic compression plates seperately.The diameter of intramedullary nail was 4mm,and the length was 200-230mm.The specimen was set on the MTS test machine.The rigidity and strength of ulnar fractures fixed by interlocking intramedullary nails were compared with those of ulnar fractures fixed by six-hole 3.5 mm dynamic compression plates in the anti-axial test,anti-bending test,anti-torsional test.[Result]In the anti-axial test,anti-bending test and anti-torsional test,the rigidity of ulnar fractures fixed by interlocking intramedullary nails was 450.00?38.42 N/mm,45.64?5.24 N?cm/Deg,11.42?1.21N?cm/Deg in sequence;while the rigidity fixed by dynamic compression plates was 405.40?29.26 N/mm,41.00?4.78 N.cm/Deg,10.05?1.32 N?cm/Deg accordingly.Burdened 1000N axial pressure,the displacement of interlocking intramedullay nail fixing specimen was 2.20?0.11 mm,and the compression plate fixing specimen was 2.48?0.15 mm.Given a 5 N?M bending burden,the maximum radial bending degree of interlocking intramedullay nailfixing specimen was 3.25?0.15 mm,which was 3.60?0.21 mm of compression plate fixing specimen.In the anti-torsional test,the interlocking intramedullay nail and compression plate fixing specimen could burden 2.40?0.13 N?M and 1.90?0.10 N?M respectively.The experimental data were analyzed by software SPSS.10,which came to a distinguished difference by t-test(P