科研之友
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摘要
To improve proximal plate fixation of periprosthetic femur fractures, a prototype locking plate with proximal posterior angulated screw positioning was developed and biomechanically tested. Twelve fresh frozen, bone mineral density matched human femora, instrumented with cemented hip endoprosthesis were osteotomized simulating a Vancouver B1 fracture. Specimens were fixed proximally with monocortical (LCP) or angulated bicortical (A-LCP) head-locking screws. Biomechanical testing comprised quasi-static axial bending and torsion and cyclic axial loading until catastrophic failure with motion tracking. Axial bending and torsional stiffness of the A-LCP construct were (1,633 N/mm +/- A 548 standard deviation (SD); 0.75 Nm/deg +/- A 0.23 SD) at the beginning and (1,368 N/mm +/- A 650 SD; 0.67 Nm/deg +/- A 0.25 SD) after 10,000 cycles compared to the LCP construct (1,402 N/mm +/- A 272 SD; 0.54 Nm/deg +/- A 0.19 SD) at the beginning and (1,029 N/mm +/- A 387 SD; 0.45 Nm/deg +/- A 0.15) after 10,000 cycles. Relative movements for medial bending and axial translation differed significantly between the constructs after 5,000 cycles (A-LCP 2.09A degrees A A +/- A 0.57 SD; LCP 5.02A degrees A A +/- A 4.04 SD; p = 0.02; A-LCP 1.25 mm +/- A 0.33 SD; LCP 2.81 mm +/- A 2.32 SD; p = 0.02) and after 15,000 cycles (A-LCP 2.96A degrees A A +/- A 0.70; LCP 6.52A degrees A A +/- A 2.31; p = 0.01; A-LCP 1.68 mm +/- A 0.32; LCP 3.14 mm +/- A 0.68; p = 0.01). Cycles to failure (criterion 2 mm axial translation) differed significantly between A-LCP (15,500 +/- A 2,828 SD) and LCP construct (5,417 +/- A 7,236 SD), p = 0.03. Bicortical angulated screw positioning showed less interfragmentary osteotomy movement and improves osteosynthesis in periprosthetic fractures.
- 出版日期2012-10
