Having treated of the humerus(28), what I said there may seem to suffice for the lower extremities; for there is some similitude in this case between the femur, and humerus, the tibia, and cubitus, the foot and hand. However something must be said in particular about these.

The femur is protruded in all the four ways; most frequently to the internal part, next externally, very rarely forward, or backward. If it be luxated internally, the leg is longer and turned round externally more than the other; for the toes point outward. If to the external part, it is shorter and bowed inward, and the foot turns the same way; the heel in walking does not touch the ground, but the person rests upon the extremity of the sole of the foot; and in this case, the leg sustains the superior part of the body better than in the former, and less needs the help of a staff. If forward, the leg cannot be bent, and being extended is as long at the heel as the other: but the toes are turned less inward; also the pain is most violent in this case; and the urine very liable to be suppressed: when the inflammation together with the pain have ceased, such patients walk pretty well, and their foot is straight. If the luxation be backward, the leg cannot be extended; and is shorter; also in standing, the heel does not reach the ground.

But there is a great danger attending the femur, that it be either difficult to reduce, or slip out again after it is replaced: some affirm it always comes out again; but Hippocrates, and Diocles, and Philotimus, and Nileus, and Heraclides the Tarentine, very celebrated authors, have affirmed, that they have made a perfect cure. Neither would Hippocrates, Andreas, Nileus, Nymphodorus, Protarchus, Heraclides, and a certain artificer too, have contrived so great a variety of machines for extending the femur in this case, if it were to no purpose. But as this is a false opinion, so on the other hand it is true, that the ligaments and muscles there being very strong, if they retain their natural firmness, they will hardly admit of a reduction; if they do not, they do not hold it fast, when reduced.

Therefore trial must be made, and if the limb be but tender, it is sufficient to make an extension by one strap at the groin, and another at the knee; if it be muscular, the extension will be better made by tying these straps to strong sticks; and then putting the lower ends of the sticks against a fulcrum, and pulling the upper ends with both hands. The extension of the limb is still more strong upon a bench, that has axes at both ends, to which these straps are tied; which being turned as in a wine-press, by persevering, they will not only extend, but even break the ligaments and muscles. Now the patient must be laid upon this bench, either prone or supine, or on one side, so that the part, into which the bone has slipped, be always uppermost, and that, from which it has receded, lowermost. When the ligaments are extended, if the bone is luxated forward, some round body must be put upon the groin; and the knee must suddenly be drawn towards the body, in the same manner, and for the same reason, as is done in the arm; and if the femur gives way to the flexion, it is reduced.

But in the other cases, where the bones have receded a little from each other, the physician ought to force back the prominent part; and an assistant to push the hip in a contrary direction. When the bone is reduced, there is nothing different required in the treatment, except confining the patient longer to his bed; lest if the femur be moved, while the ligaments are too lax, it may slip out again. However it may be secured by keeping the middle or upper part of the joint in some canaliculus(29).