The preceding methods are chosen according to the particular conditions presented by the wounds it is desired to close. These wounds may be divided into different categories according to age and the presence or absence of previous suppuration.
1st. Closure of Fresh Wounds which have become Sterile before the Twelfth Day. - Wounds of the soft parts may be closed in the majority of cases - that is to say, in nearly ninety per cent. of the cases - before the twelfth day. As, at this period, the skin is movable on the deeper structures, bringing together of the margins of the wound by strapping is habitually practised. Even when the wound is deep and irregular and a fracture is present, the operation is not painful and needs no anaesthetic. Multiple wounds on the same patient may be closed one after another as they become sterile. If the skin has been irritated by tincture of iodine, or the wounds are too close together to allow of the strapping method being applied, we have recourse to suture, and if there is loss of substance, to elastic traction. The method of suture is also employed in fresh wounds, when one has to unite tendons, muscles, or nerves. As anaesthesia is necessary for suture of nerves, tendons, or muscles, the operation is terminated by cutaneous suture. With the exception of these cases, we always use the strapping method, which has the merit of bringing together the deep parts of wounds as well as the superficial portions.
2nd. Closure of Fresh Wounds which have become Sterile after the Twelfth Day. - When the sterilisation of the wound has only been achieved after the twelfth day, it is no longer possible to use the strapping method. Suture is then practised. As the wound has been subjected from the outset to antiseptic treatment, and it is probable that the cicatricial tissue contains no microbes, catgut stitches may be put in without danger of reinfection. In wounds which have remained open longer, careful bringing together of the deeper parts is carried out. It is not sufficient merely to approximate the skin. 3rd. Closure of Wounds which have become Sterile after a Period of Suppuration. - When it has not been possible to apply the treatment from the beginning, and the wound has suppurated for a longer or shorter period, the process of closure must be a little different. In these cases, in fact, numerous microbes have been shut up within the cicatricial tissue. Smears show that the surface of the wound is sterile, but they yield no indication as to the state of the deep parts which are already cicatrised. It is therefore important to bring the tissues together without injuring them, that is to say, without making a deep dissection, and without interstitial sutures. The scalpel or the needle, when traversing a cicatrix which contains microbes, may start reinfection. We must, therefore, be content with bringing together the deep parts by external means, and only suture skin. Also, one may operate in two stages. In the first stage, dissect up the tissues, prepare the wound for closure, loosely insert sutures; then for a few days continue the sterilisation of the wound. In the second stage, close the wound. By taking these precautions, a result may be obtained as favourable as in the union of wounds which have never suppurated.