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

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 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 < .05). Results In compression, the maximal axial deformation was lower for NAS-ILN (0.11 mm +/- 0.03) than for LCP (1.10 mm +/- 0.22) (P < .0001). The ultimate load to failure was higher for NAS-ILN (803.58 N +/- 29.52) than for LCP (328.40 N +/- 11.01) (P < .0001). In torsion, the maximal angular deformation did not differ between NAS-ILN (22.79 degrees +/- 1.48) and LCP (24.36 degrees +/- 1.45) (P = .09). The ultimate torque to failure was higher for NAS-ILN (22.45 Nm +/- 0.24) than for LCP (19.10 Nm +/- 1.36) (P = .001). No slack was observed with NAS-ILN. In 4-point bending, the maximal axial deformation was lower for NAS-ILN (3.19 mm +/- 0.49) than for LCP (4.17 mm +/- 0.34) (P = .003). The ultimate bending moment was higher for NAS-ILN (25.73 Nm, IQR [23.54-26.86] Nm) than for LCP (16.29 Nm, IQR [15.66-16.47] Nm) (P = .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.