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Objective: This study aimed to biomechanically compare the maximum rotational, axial movements, and compression forces between fracture fragments before and after 1-4 mm fracture site resorption among interlocking nails, compression nails, and newly designed compressive anti-resorption (CARES) nails compressed with tube and coil spring.
Methods: We determined the maximum axial/rotational movements and interfragmentary compression loads between fragments on 10 interlocking nails, 10 compression nails, and 10 CARES nails with 30 composite femurs. Using a compression-distraction testing device, 6 N·m external and internal torques were applied, and we evaluated the maximum rotational and axial displacement between fragments after 1-4 mm fracture site resorption.
Results: When 6 N·m of internal–external rotation torque was applied after 2 mm fracture site resorption, the maximum rotational displacement between fragments in the CARES nail was 3 ± 0.52 mm, 101% less than the 6.03 ± 0.83 value in the compression nail and 100% less than the 6 ± 1 mm value measured in the interlocking nail (P=.000). The compression between fragments was 298 ± 72 N in the CARES nail after 1 mm of resorption, while this value was measured as 0 in the other nails. There was a significant difference in rotational, axial stability, and interfragment compression among the different femoral nails after 1-4 mm fracture site resorption.
Conclusion: The CARES nail having additional coil springs seems significantly biomechanically superior to compression nails and interlocking nails, providing maximum rotational, axial stability, and interfragment compression after fracture site resorption.
Cite this article as:Karaarslan AA, Yamak K. A new femur intramedullary nail with tube and coil spring for maximum interfragmentary rotational and axial stability after fracture site resorption. Acta Orthop Traumatol Turc., 2023;57(6):372-377.