In vivo MR studies of dynamic changes in the interosseous membrane of the forearm during rotation

In vivo dynamic changes in the interosseous membrane (IOM) during forearm r otation were studied using magnetic resonance imaging (MRI). The right fore arms of 20 healthy volunteers mere examined in five different rotational po sitions. Axial slices were obtained at the proximal quarter, the middle and the distal quarter of the forearm. The changes in shape of the IOM during rotation were observed in an axial MR plane. For each image, we measured th e interosseous distance and the length of the interosseous membrane. Images of the tendinous and membranous parts of the IOM could be differentiated b y thickness. There were minimal dynamic changes in the tendinous part on th e MRI while the membranous part showed numerous changes during rotation. Th e interosseous distance and the length of the interosseous membrane were ma ximum from a neutral to a slightly supinated position. The tendinous part i s considered to be taut during rotation to provide stability between the ra dius and the ulna, but the membranous part which is soft, thin and elastic, allows smooth rotation.