Forearm rotation alters interosseous ligament strain distribution

Recent interest in reconstruction of the interosseous ligament (IOL) of the forearm has led to questions concerning optimal placement of the reconstructive graft as well as the ideal rotational position of the forearm during graft tensioning. We therefore studied the strain distribution in the IOL to determine which fibers are strained in different positions of forearm rotation. Five cadaveric human forearms were subjected to compressive axial load (simulating power grip) and the strain values across the entire IOL were measured with the forearm in neutral, supination, and pronation. The strain distribution in the IOL changed with forearm rotation. The highest overall strain was found in neutral. In neutral and pronation, higher strain was observed in the proximal region of the IOL. In supination, however, higher average strain was seen in the distal region of the IOL. These results suggest that a reconstructive graft placed in the proximal region of the IOL and tensioned in neutral rotation would provide balanced constraint in different positions of forearm rotation. A graft placed in the distal region and tensioned in forearm neutral, however, may limit forearm rotation.