The Posterior Luxation is thus reduc'd; The Patient being laid upon his Belly, the double Extension is to be made, and his Knee drawn outward, to set the Bone in its place. After the Operation hath been perform'd, a Bolster is to be apply'd, steept in Spirituous Medicaments; and the Bandage call'd _Spica_, of which we have given an Account in treating of the Luxation of the Shoulder. * * * * * CHAP. XIV. _Of the Luxation of the Knee._ When the _Tibia_ is luxated behind, its Prominences are in the Cavity of the Ham, and the Leg flies off, or is bended. If the same _Tibia_ be dislocated on the side, a kind of Tumour appears in the luxated side, and a Sinking in the opposite. But if the _Condylus_ of the _Tibia_ remains in the inside, the Leg turns outward; and if it be in the outside, it turns inward. The Posterior Luxation is reduc'd by obliging the Patient to lie upon his Belly, whilst the Surgeon during the Extensions bends the Leg, in drawing the Heel toward the top of the Thigh. If the _Tibia_ be luxated on the side, the usual Extensions are to be made, and the Bone is to be push'd with the Knee. {313} If the Luxation were in the fore-part, it wou'd be requisite to lay the Patient upon his Back, to make the Extensions, by drawing the Thigh and Leg; and to press the protuberant Parts. _The Bandage_ Is prepar'd with a Band three Ells long, and two Fingers broad, roll'd with two Balls: A Circumvolution being at first made above the Knee, the Figure KY is form'd underneath, and a Circumvolution above it; then the Band is carry'd up again over the Knee, in making Rollers and KY's underneath, till the Knee be entirely cover'd. * * * * * CHAP. XV. _Of the Luxation of the _Patella_ or Knee-Pan._ The Knee-Pan is luxated by starting upward; and to reduce it, the Patient's Leg is to be held streight, whilst it is thrust back into its place with the Hands. Then he must be oblig'd to keep his Bed; and the same Bandage is to be apply'd with that which hath been describ'd for the Luxation of the Knee. If the _Perone_ or _Fibula_ be remov'd from the _Tibia_, the sides of the Foot are to be press'd, to draw it back again; and it may be kept close {314} with the Bandage which is appropriated to the Fractures of the _Tarsus_. The _Astragalus_ may be also luxated in the fore-part; so that the Operator ought to thrust it back into its place, and to make use of the Bandage which we have prepar'd for the Fracture of the Foot. The _Calcaneum_ sometimes flies off from the _Astragalus_ both in the inside and without; and the Bones of the _Tarsus_, _Metatarsus_, and Toes are likewise apt to be luxated. But a little Circumspection is only requisite to reduce all these Dislocations. * * * * * {315} A TREATISE OF _Medicinal Compositions_ Necessary for a SURGEON. * * * * * CHAP. I. _Of Balsams._