24. The consolidation being completed generally in twenty-four or twenty-five days, leaves, at this time, a little stiffness in the joints, in consequence of their having remained so long without motion: the movements of pronation and supination are performed but imperfectly. Their return is facilitated and hastened by frequent exercise of the limb, as well at its junction with the os humeri, as in its own proper joints; and, in general, by the fifteenth or twentieth day from the removal of the apparatus, things are in the same state in which they stood before the fracture. FRACTURE OF THE RADIUS. § VII. OF THE CAUSES AND THE DISPLACEMENT. 25. The radius, which is the moveable and almost the only support or abutment of the hand, receives, in falls on that part, a much greater share of the shock than the ulna, which is joined to the hand by only a small surface. Hence, without doubt, arises the greater frequency of the fractures of the radius; fractures which, when produced by falls on the hand, are evidently the result of a counter-stroke. Oftentimes also this bone is broken by the immediate action of external bodies, because it is defended below with but a thin covering of muscles. In whatever way the fracture may be produced, it occurs in the middle or at the extremities of the bone; very rare near its articulation with the os humeri, it is more common in its middle; but more frequent still at its lower end. The difference arises probably from this circumstance, that, in falls on the wrist or hand, the shock is weakened and lost in proportion as it is propagated upwards. 26. In such fractures, displacement is almost constantly observable in the thickness or cross direction of the bone and fore-arm, and is produced by the action of the pronator muscles, which, by forcing the fragments of the radius towards the ulna, tend to diminish the interval between the bones. The ulna remaining unbroken, always prevents any displacement in a longitudinal direction. The first kind of displacement is the more perceptible, in proportion as the fracture is nearer to the middle part of the radius, where the bones are at the greatest distance from each other. This displacement is seldom outwards, because the interosseous ligament prevents that: yet experience furnishes some exceptions to this rule.