Removal of a marginal metatarsal bone (either alone or with its neighbour), tends to make the foot tilt into varus or valgus; so that the boot needs to be stiffened and the sole thickened to avoid this. _CHAPTER VII_ ARTIFICIAL LIMBS FOR AMPUTATION THROUGH THE FOREARM The constituent parts of an artificial arm are the same in principle as for those of an artificial leg, they are-- 1. A means of attachment preventing the appliance from dropping as the result of its weight. 2. A socket, fitted to the stump and articulated with the last named at the elbow. 3. The terminal appliance, intended to replace as far as possible the amputated hand and, if possible, resembling it in appearance. In the case of the upper limb the advantages that wood possesses in giving strength and accuracy of fit do not apply, and the arm and the forearm pieces are made of leather, with lateral steels articulated at the elbow: this joint is active in the case of amputations of the forearm but purely passive in amputations of the arm. We will commence by describing the appliance for amputation through the forearm, taking as our type amputation in the lower half. This will furnish an example which illustrates all the principles that should guide us, the ends we should have in view, and the means by which we can attain them. When once we have studied the apparatus by means of which the functions of the hand can as far as possible be replaced, a short description will suffice to explain what can be done when the loss of movement of the elbow and then a shorter and shorter stump in the upper arm oblige us to diminish the utility of the appliance. We must study in turn: (1) The attachment of the upper arm socket; (2) the joint between this and the forearm socket; and (3) the appliances attached to the extremity of the forearm whether these take the shape of a hand or not. 1. POINTS OF ATTACHMENT 1. SUSPENSION.--In the exceptional amputation very low down, in which the roots of the thenar and hyperthenar eminences remain, the enlargement thus formed at the extremity of the forearm may be used for the attachment of a wristlet which may suffice to support the artificial appliance, provided that the latter is not intended for heavy work. In the latter case an attachment from the elbow at least must be added. This method would evidently be out of the question in the usual class of case, viz. ordinary amputations through the forearm. In these the attachment may be made in two ways:-- (1) To the humerus above the condylar enlargements, the epicondyle and the epitrochlea, the latter being much the more prominent. (2) To the top of the shoulder, _i.e._ to the surface over the acromion and clavicle.