Mechanical evaluation of a novel angle-stable interlocking nail in a gap fracture model.

Abstract

OBJECTIVE: To describe the mechanical characteristics of a novel angle-stable interlocking nail (NAS-ILN) and compare them to those of a locking compression plate (LCP) by using a gap-fracture model. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Synthetic bone models. METHODS: Synthetic bone models simulating a 50&#x2009;mm diaphyseal comminuted canine tibial fracture were treated with either a novel angle-stable interlocking nail (NAS-ILN) or a locking compression plate (LCP). Maximal axial deformation and load to failure in compression and 4-point bending, as well as maximal angular deformation, slack, and torque to failure in torsion, were statistically compared (P&#x2009;<&#x2009;.05). RESULTS: In compression, the maximal axial deformation was lower for NAS-ILN (0.11&#x2009;mm&#x2009;&#xb1;&#x2009;0.03) than for LCP (1.10&#x2009;mm&#x2009;&#xb1;&#x2009;0.22) (P&#x2009;<&#x2009;.0001). The ultimate load to failure was higher for NAS-ILN (803.58&#x2009;N&#x2009;&#xb1;&#x2009;29.52) than for LCP (328.40&#x2009;N&#x2009;&#xb1;&#x2009;11.01) (P&#x2009;<&#x2009;.0001). In torsion, the maximal angular deformation did not differ between NAS-ILN (22.79&#xb0;&#x2009;&#xb1;&#x2009;1.48) and LCP (24.36&#xb0;&#x2009;&#xb1;&#x2009;1.45) (P&#xa0;=&#xa0;.09). The ultimate torque to failure was higher for NAS-ILN (22.45&#x2009;Nm&#x2009;&#xb1;&#x2009;0.24) than for LCP (19.10&#xa0;Nm&#x2009;&#xb1;&#x2009;1.36) (P&#xa0;=&#xa0;.001). No slack was observed with NAS-ILN. In 4-point bending, the maximal axial deformation was lower for NAS-ILN (3.19&#x2009;mm&#x2009;&#xb1;&#x2009;0.49) than for LCP (4.17&#x2009;mm&#x2009;&#xb1;&#x2009;0.34) (P&#xa0;=&#xa0;.003). The ultimate bending moment was higher for NAS-ILN (25.73&#x2009;Nm, IQR [23.54-26.86]&#xa0;Nm) than for LCP (16.29&#x2009;Nm, IQR [15.66-16.47] Nm) (P&#xa0;=&#xa0;.002). CONCLUSION: The NAS-ILN showed greater stiffness in compression and 4-point bending, and a greater resistance to failure in compression, torsion, and 4-point bending, than LCP. CLINICAL IMPACT: Based on these results, NAS-ILNs could be considered as alternative implants for the stabilization of comminuted fractures.