Thus far then we have treated of fractures. Now the bones are dislocated in two ways. For sometimes those that are joined together, separate from each other, as when the broad bone of the scapula recedes from the humerus(22), and in the fore-arm the radius from the cubitus, and in the leg, the tibia from the fibula, and sometimes in leaping the heel-bone from the ancle; which last, however, seldom happens. Sometimes the articulations are displaced. I shall speak first of the former.

When such an accident happens, the part is immediately hollow, and by pressing upon it with the finger one feels a cavity. After that, a violent inflammation comes on; and particularly in the ancle; for generally it occasions fevers and gangrenes, and either convulsions, or contractions, which draw the head down upon the shoulders. To avoid which, the same method must be followed here, as in injuries of the moveable bones. And whenever it happens, the medicines prescribed before must be laid on these parts to remove the pain and tumour: for bones once separated in this manner never come together again; and though some degree of comeliness be attainable in the part, yet it is of no use(23).

But the lower jaw and the vertebræ, and all the joints, though they be secured by strong ligaments, are luxated by the force of a blow, or when the ligaments are either ruptured, or some way weakened; and more easily in children or lads, than in those that are more robust. And they slip out forward and backward, and inward and outward; some of them in all these ways, others in particular ways. And there are some general signs belonging to all, others peculiar to each one: for there is always a tumour in that part, to which the bone is propelled, and a cavity in that from whence it recedes. Now these marks are common to them all; the others peculiar to the several bones will be mentioned, when I speak of each case distinctly.

But though all the articulations may be dislocated, they cannot be all replaced; for the head is never reduced, nor a vertebra in the spine, nor a jaw-bone, which being out on both sides, has raised an inflammation before it could be returned. Again, those that slip out from the fault of the ligaments, when they are forced into their places, give way again. And those that have been dislocated in childhood, and have not been reduced, grow less than the rest: and the flesh of all these that are not in their place, is decayed, and more so in the member nearest to it, than in one beyond it. For instance, if the humerus is not in its place, the arm wastes more than the fore-arm, and that more than the hand. Then according to the situations, and the nature of the accidents, there is left either more or less use of the limb; and the more use remains of it, the less it is wasted.

Now whatever is dislocated should be reduced before an inflammation begin. If that has already seized it, till it cease, it must not be meddled with; after its removal, trial must be made in such limbs as are reducible. A great deal depends upon the habit both of the body and the ligaments: for if the body be slender, or humid, or if the ligaments be weak, the bone is more quickly reduced; but it is both more liable to dislocation, and is less firmly held after it is reduced(24). Bodies of the contrary qualities hold it faster in its place; but when once forced out, admit of its return with difficulty. It is proper to alleviate the inflammation by applying sordid wool squeezed out of vinegar; and if the misfortune be in a strong articulation, to abstain from food for three, and sometimes even five days; to drink warm water till the thirst be gone; to observe these rules more strictly in luxations of those bones, that are held by strong large muscles; and much more so if a fever has ensued; on the fifth day to foment with hot water; and taking away the wool, to apply cerate made of Cyprine oil, with the addition of nitre, till the inflammation be entirely removed. Then it is proper to use friction to the limb; to take food of good juices, wine in moderate quantity; and by this time, to make some use of the limb: because motion, as it is extremely hurtful in pain, so it is very salutary when the pain is removed. These observations are general; I shall now treat of the particular cases.