Biomechanical properties of titanium elastic nail applied to a cadaveric clavicle model.

BACKGROUND: The goal of this study was to examine biomechanical properties of titanium elastic nail fixation method that was applied to cadaveric clavicles with different thicknesses and lengths. METHODS: To test stiffness and failure load of clavicle with titanium elastic nail fixation, 12 pairs of clavicles were obtained. A short oblique fracture line (AO/OTA classification: 15-B1.2) was created at midpoint of the cadaveric bones. They were divided into four groups according to the nails with different thickness and length/diameter ratios. The fixated bones were situated on a jig that allows 3-point bending to measure stiffness and load failure. RESULTS: The stiffness was measured to be mean 3.49 ± 1.49 N/mm in group 1. The stiffness for group 2 was mean 10.41 ± 2.18 N/mm, and for groups 3 and 4, the stiffness was mean 11.89 ± 2.99 N/mm and mean 24.44 ± 4.86 N/mm, respectively. When analyzed with statistics, group 1 had significant differences from groups 2 (P < 0.006), 3 (P < 0.001), and 4 (P < 0.000), and group 4 also had statistical significances from rest of the groups (P < 0.000). CONCLUSIONS: For 2.5 mm titanium elastic nail, it is necessary to make fixation with a titanium elastic nail that is longer than 3 diameter lengths, and length that is longer than and equal to 3 diameter length titanium elastic nail was required for 3.5 mm titanium elastic nail to provide appropriate stiffness for firm fixation. Also, variances in both thickness and length have shown a similar effect. STUDY DESIGN: Cadaveric study.