A biomechanical study on the interosseous membrane and radial head in cadaveric forearms

Our aim was to evaluate the biomechanical properties of the interosseous membrane (IOM) and radial head and investigate the pathomechanics of the Essex-Lopresti injury.

Twelve adult fresh frozen upper limbs of human cadavers were chosen for test. First, the 12 intact specimens were mounted onto a materials testing machine to carry out biomechanical tests in pronation, supination and neutral positions, respectively. An axial load of 100 N was applied along the longitudinal axis of the forearm for 30 seconds in each position. Then, the twelve specimens were randomly divided into two groups. The radial head was resected in 6 specimens. And the central band of IOM was severed in another 6 specimens. Each group was tested by the same method. Finally, both the radial head and the IOM were excised in all specimens and biomechanical tests were performed.

The rotational position of the forearm or simple severance of the IOM had no effect on longitudinal displacement. The radial longitudinal displacement increased significantly after resection of the radial head. The severance of the IOM had no effect on compressive stiffness of the radius. However, compressive stiffness of the radius decreased significantly after resection of the radial head.

The radial head fracture combined with the IOM injury was the most important cause of the Essex-Lopresti injury, and the radial head fracture was the major factor. The IOM was the major structure to maintain the longitudinal stability of the forearm after resection of the radial head.