Biomechanical comparison between double-plate fixation and posterior plate fixation for comminuted olecranon fracture using two triceps screws in synthetic bone model

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 1 Table 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) ). 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...

Olecranon Fractures

“…Those studies suggested that risk of failure is higher with osteoporotic bone and when the fracture is proximal to the midpoint of sigmoid notch. The use of 2 proximal triceps screws and augmentation with SR or TBW might be beneficial in more proximal fractures [51][52][53][54][55][56][57][58][59][60][61][62] (Fig. 6).…”