LAUSR

Supplemental Digital Content is available in the text Abstract Background: Although preventing triceps fragment displacement is essential for treating an olecranon fracture, we frequently encounter situations in which only a few screws can be fixed to the triceps fragment. The aim of this study was to compare the stability of double-plate fixation and posterior plate fixation for olecranon fractures when the triceps fragment was small and only 2 screws could be inserted. Methods: A composite ulna model was used to simulate olecranon fracture. Four groups were formed consisting of double-plate and posterior plates with cortical and locking screws. The cyclic loading test was conducted for 500 cyclic loads of 5 to 50 N on a specimen to measure micromotion and displacement of the gap caused by light exercise. The load-to-failure test was performed by applying a load until fixation loss, defined as when the fracture gap increased by 2 mm or more or catastrophic failure occurred, to measure the maximum load. Results: Eight samples per group were tested through the pilot study. All groups were stable with a micromotion of <0.5 mm. However, the mean micromotion showed significant differences between the 4 groups (P < .001, Table 1Table 1 Mean gapping and displacement in the cyclic loading test. Displacement after the test Group Gapping during the test (range) Anterior cortex (range) Posterior cortex (range) Double-cortical 0.42 ± 0.11 (0.25–0.58)∗ 0.02 ± 0.18 (−0.78–0.31) 0.14 ± 0.14 (−0.13–0.16)† Double-locking 0.17 ± 0.03 (0.12–0.21)∗ 0.05 ± 0.10 (−0.16–0.16) 0.08 ± 0.14 (−0.17–0.11) Posterior-cortical 0.09 ± 0.02 (0.05–0.12)∗ 0.03 ± 0.13 (−0.37–0.22) 0.03 ± 0.19 (−0.14–0.28) Posterior-locking 0.12 ± 0.04 (0.07–0.17)∗ 0.04 ± 0.10 (−0.12–0.22) −0.03 ± 0.22 (−0.44–0.20) The values are presented as the mean ± standard deviation, with ranges in parentheses. All values are in mm.∗ Significant difference between groups (P < .05).† Significant difference in the gap before and after the test (P = .023).). In the mean micromotion during exercise, posterior plating with cortical screws was the most stable (0.09 ± 0.02 mm) while double-plating with cortical screws was the most unstable (0.42 ± 0.11 mm). At the maximum load, posterior plating with locking screws was the strongest (205.3 ± 2.8 N) while double-plating with cortical screws was the weakest (143.3 ± 27.1 N). There was no significant difference in displacement after light exercise between the groups. Conclusions: This study showed that when 2 triceps screws were used, both groups were stable during light exercise, but posterior-plating was stronger than double-plating.