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 reconstru ctive graft as well as the ideal rotational position of the forearm during graft tensioning. We therefore studied the strain distribution in the IOL t o determine which fibers are strained in different positions of forearm rot ation. Five cadaveric human forearms were subjected to compressive axial lo ad (simulating power grip) and the strain values across the entire IOL were measured with the forearm in neutral, supination, and pronation. The strai n distribution in the IOL changed with forearm rotation. The highest overal l 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 sugg est that a reconstructive graft placed in the proximal region of the IOL an d tensioned in neutral rotation would provide balanced constraint in differ ent positions of forearm rotation. A graft placed in the distal region and tensioned in forearm neutral, however, may limit forearm rotation. Copyrigh t (C) 2000 by the American Society for Surgery of the Hand.