gms | German Medical Science

Objectives/Interrogation: Interosseous membrane of the forearm plays very important role in forearm stability. The early studies described five ligamentous components in the interosseous membrane of the forearm (central band, accessory band, distal oblique bundle, proximal oblique cord, and dorsal oblique accessory cord) and classified them into 3 portions (distal, middle and proximal) according to their location. In the present study, we investigated in vivo length changes of ligaments from distal and middle portions (central band, distal accessory band and distal oblique bundle) during forearm rotation to understand the function of the ligaments.

Methods: Computed tomography of six adult forearms from six healthy volunteers was obtained at 5 forearm positions: maximum pronation, 45 degrees pronation, neutral position, 45 degrees supination and maximum supination. According to previous anatomic study we marked out the attachments of each ligaments on 3-dimensional models of the radius and ulna. The 3-dimensional ligament lengths' path between attachments during forearm rotation were measured and calculated based on computer modeling and simulation.

Results and Conclusions: The three portions of central band presented same fashion during the forearm rotation: the length increased significantly from maximum pronation to neutral position, but it stayed almost static from neutral position to supination. However, the distal accessory band and distal oblique bundle showed the same fashion, which was different from that of central band: the length increased significantly from maximum pronation to neutral position, but it decreased significantly from neutral position to supination. The distal accessory band has the length changes similar to those of the distal oblique bundle, which is very different from those of the central band. The findings suggest that distal accessory band functions in conjunction with the distal membranous portion of the interosseous membrane of the forearm.