An experimental study of instability during supination and pronation of the fractured scaphoid.

Rotatory instability of scaphoid fractures was studied by a method not used previously. On two fresh specimens the scaphoid bone was fractured by osteotomy, and the fracture was fixed by a Hoffmann apparatus extending from the distal radius to the 1st, 2nd and 3rd metacarpals. This permits free rotation in the forearm. The scaphoid fragments were marked by Kirschner wires. No movement occurred between the fragments when supination/pronation was kept within the normal range of movement.