(A) A typical force vs. displacement curve at the initial linear phase of the compression test (0–1 mm). (B) The average compression stiffness of various ARDs secured with 4, 5, and 6 screws determined in the compression test.

<p>The monoaxial ARD demonstrated the highest compressive stiffness, whereas the standard ARD had the lowest. The groups without significant differences are indicated with ‘‘NS”.