THE ROTE OF THE INTEROSSEOUS MEMBRANE AND TRIANGULAR FIBROCARTILAGE COMPLEX IN FOREARM STABILITY

This study investigated the relative roles of the interosseous membran e (IOM) and triangular fibrocartilage complex (TFCC) in the transmissi on of force from the hand to the humerus. Our findings suggest a spect rum of forearm destabilizing injuries. The intact radius abutting the capitellum provides the primary restraint to proximal migration of the radius. After radial head excision, up to 7 mm of proximal radial mig ration can occur under axial compression. if the TFCC or the IOM alone is disrupted, little alteration in load or displacement is evident. W hen both the midportion of the IOM and TFCC are incompetent, however, further proximal radial migration occurs, the radial stump abuts the h umerus, and load is shifted back to the radial column. These data sugg est that the central portion of the IOM is the crucial structural subd ivision within the IOM acting as a restraint to proximal radial migrat ion. The TFCC also resists proximal radial migration and participates in load transfer. We propose that clinical migration of the radius und er an axial load greater than 7 mm implies disruption of both the midp ortion of the IOM and TFCC.