Length Changes in the Interosseous Membrane During Forearm Rotation: A 3-Dimensional Study In Vivo

Purpose: The length change of the interosseous membrane (IOM) during forearm rotation has not been fully studied. To explore the meaning of length change in the distal oblique band (DOB), the distal accessory band (DAB), and the proximal, middle, and distal parts of the central band (CBP, CBM, and CBD, respectively), we investigated the length change in these ligaments at maximum pronation, 45 degrees of pronation, neutral position, 45 degrees of supination, and maximum supination in vivo. Methods: The images of the right forearms from 6 healthy volunteers were obtained by computed tomography scanning at the 5 above-mentioned rotation positions. We created 3-dimensional models of the radius and ulna, DOB, DAB, and central band based on the points of origin and insertion. Finally, the length of each ligament was estimated from the points of insertions and origins registered on the 3-dimensional models. Results: The DAB and CBD lengths increased significantly from maximum pronation to 45 degrees of pronation. The DOB length increased significantly from 45 degrees of pronation to neutral position and decreased significantly from 45 degrees of supination to maximum supination. The DAB and CBM lengths increased significantly from neutral position to 45 degrees of supination. The DAB length decreased significantly from 45 degrees of supination to maximum supination. For the CBP, no difference in length was observed during forearm rotation. Conclusions: The DOB becomes taut at neutral position, and the central band, especially the CBP, is nearly isometric. The findings indicate that the DOB may provide the primary stabilization of the distal radioulnar joint and that the central band is the key stabilizer during forearm rotation.