TENSILE PROPERTIES OF THE INTEROSSEOUS MEMBRANE OF THE HUMAN FOREARM

The interosseous membrane is a structure deep in the forearm that join s the radius and the ulna. It is made up of membranous and ligamentous regions. Two main ligamentous structures have been described; a promi nent central fiber group, the ''central band,'' and a smaller proximal fibrous band, the ''oblique cord.'' many authors believe that the cen tral band plays a biomechanical role in the normal and fractured forea rm and that it may function much like a ligament. The objective of thi s study was to determine the tensile properties of the central band. E ighteen fresh frozen forearms from cadavers (45-70 years of age, both sexes) were used. A fiber bundle of the central band was subjected to a uniaxial tensile test to failure in a materials testing machine, and its tensile properties were calculated. Stiffness, ultimate load, and energy absorbed to failure were expressed as a function of specimen w idth. The central band structure had a stiffness of 13.1+/-3.0 N/mm pe r mm width and an ultimate load of 56.6+/-15.1 N per mm width (mean+/- SD). The tissue of the central band displayed a modulus of 608.1+/-160 .2 MPa, ultimate tensile strength of 45.1+/-10.3 MPa, and strain at fa ilure 9.0+/-2.0%. This study demonstrated that the central band is com prised of strong tissue. The material properties of the central band c ompare with those of patellar tendon: modulus is 120% and ultimate ten sile strength is 84% that of patellar tendon. As a structure, the inte rosseous membrane is stiff and capable of bearing high loads. Although distribution across the central band is unknown, a 1.7 cm wide, evenl y loaded homogenous portion of the central band would possess a stiffn ess comparable with that of the anterior cruciate ligament. The result s of this study provide a basis for future analyses of radioulnar stab ility and load transfer.