Mechanics of the antebrachial interosseous membrane: response to shearing forces.

The interosseous membrane functions to maintain the structural integrity of the forearm; however, the age-related mechanical properties of the intact membrane are incompletely defined. The purpose of this study is to quantify the mechanical properties of the interosseous membrane by applying a quasi-equilibrium shearing force between the radius and ulna. A 5-cm section of the central (main and accessory bundles) fiber from 11 (5 male and 6 female) fresh-frozen cadaver arms (age, 74 +/- 6.9 years) was isolated with the radial and ulnar attachments, measured, and positioned into the testing apparatus. A shear force was applied at 12.7 mm/min to produce a quasi-equilibrium state, and the applied force and elongation were monitored. The average ultimate force, ultimate strength, and elastic modulus were 1101 +/- 191 N, 13.98 +/- 4.85 MPa, and 135.29 +/- 41.57 MPa, respectively. Age-related changes were also noted with an increase in thickness by 0.056 mm per year of age and a decrease in fiber stiffness of 4.78 MPa/yr. The age-related mechanical properties of the intact interosseous membrane are necessary for modeling forearm stability in normal and pathologic conditions. This information is required for analysis of repair or reconstructive procedures.