Publication: Biomechanical comparison of humeral nails with different distal locking mechanisms: Insafelock nails versus conventional locking nails.
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Date
2019-11-01
Authors
Authors
Erden, T
Kapicioglu, MEHMET
Demirtas, A
Bilsel, K
Akpinar, F
Kuduz, H
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Abstract
Objective: The aim of this study was to compare the biomechanical resistance to rotational and axial
forces of a conventional locking nail with a newly designed intramedullary humeral nail developed for
humeral shaft fractures with a secure locking mechanism through the distal part of the nail.
Methods: InSafeLOCK humeral nail system (group 1, TST, Istanbul, Turkey) and Expert humeral nail
system (group 2, DePuy Synthes, Bettlach, Switzerland) of the same size (9 300 mm) were examined.
In total, 24 fourth-generation humerus sawbones were used in the experiment. Osteotomy was performed
at the humerus shaft, and a defect was created by removing 1 cm of bone. After pre-loading 5000
cycles at a frequency of 2 Hz and a force of 50e250 N for axial loading and 5000 torsion torques between
0.5 Nm and 6.5 Nm at a 2 Hz frequency for torsional loading, the failure load values of each load were
recorded. Distal interlocking was performed with an endopin in group 1, while a double cortex screw was
used in group 2.
Results: All samples successfully passed the cyclic loading. The initial and final stiffness values were
similar between the groups after axial loading (p ¼ 0.873 and p ¼ 0.522, respectively). The mean axial
failure load values in groups 1 and 2 were 2627 ± 164 N and 7141 ± 1491 N, respectively. A significant
difference was found in the axial failure load values (p ¼ 0.004). Significant differences were observed
between the initial and final torsional stiffness between the two groups (p ¼ 0.004 and p ¼ 0.004,
respectively). No significant difference was found in the failure load values after torsional loading
(11791 ± 2055 N.mm and 16997 ± 5440 N.mm) (p ¼ 0.055).
Conclusion: These results provide a biomechanical demonstration of the adequate stability of both nails
after axial and rotational loading. The reliability of the newly developed InSafeLOCK humeral nail system,
which does not require fluoroscopic control and an additional incision for distal locking, supports its use
in the clinic.
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Citation
Erden T., Kapicioglu M., Demirtas A., Bilsel K., Akpinar F., Kuduz H., -Biomechanical comparison of humeral nails with different distal locking mechanisms: Insafelock nails versus conventional locking nails.-, Acta orthopaedica et traumatologica turcica, cilt.53, ss.490-496, 2019