When the Complication of Necrosed Tendon or Ligament exists. - We may take it as an axiom that wherever this exists, whether it is in the extensor pedis, in the lateral ligaments of the joint, or in portions of the flexors, all diseased structures should, where possible, be removed. This is done either with a scalpel or with a curette.
When septic matter has gained the sheath of the perforans, and the formation of pus therein is indicated by inflammatory swellings in the hollow of the heel, it is sometimes advisable to lay the sheath open for 1 to 2 inches along the course of the tendons. This, if a fistula is present, may be best done with a blunt-pointed bistoury, or with a cannulated director and a scalpel. With the pus thus given exit, and an antiseptic dressing regularly applied, the case sometimes ends in rapid resolution. More often than not, however, it is found that the pus has been liberated too late, and that it has gravitated in the sheath to the extent of affecting the plantar aponeurosis. Or it may be, of course, that it was in the plantar aponeurosis the disease commenced. Whichever may have been the case, we have in the hollow of the heel one or more fistulous openings, or an opening we have made ourselves, leading down to a necrosed portion of the terminal expansion of the perforans.
In such cases we ourselves have derived benefit from a regular flushing of the sinuses with a 1 in 2,000 solution of perchloride of mercury, introduced by means of a glass syringe, followed later by flushing in the same manner with a 1 in 40 solution of carbolic acid, the hollow of the heel meanwhile being kept clean with an antiseptic pad and bandage, or by liberal applications of an antiseptic powder.
The septic materials are in this way destroyed, and the wound heals without further complication. We must admit, however, that the cure of the lesion is generally at the expense of slight lameness, due, in all probability, to inflammatory tissue adhesions between the flexor perforans and the perforatus, and to a partial destruction of the synovial membrane of the sheath.
If, in spite of the antiseptic irrigations, the fistula persists, then nothing remains but to resort to excision of the aponeurosis, as described on p. 222.
When Necrosis of the Lateral Cartilage is present. - In this case we may at first try the ordinary treatments of poulticing; and blistering, of antiseptic caustic injections, and of plugging. In some cases a cure is effected. Should these fail, however, and we intend to see the finish of our case, then operative measures must be determined on. This means cutting down upon the diseased cartilage, and either removing the necrosed portion, or excising the cartilage in its entirety.
The latter method is seldom practised in this country. As it is the most radical of the two, however, we shall describe it here first.
Extirpation of the Lateral Cartilage. - The operation of extirpating the lateral cartilage is by no means a new one, being introduced, according to Zundel, by the senior Lafosse in 1754. It consisted in removing a portion of the wall by grooving and stripping it, and of excising the exposed cartilage by means of a sage-knife.
As to what portion of, and how much of the horn of, the quarter should first be removed, and as to what particular direction each groove should take, opinion among the older writers varied considerably. This we know now is not an important matter, and it is sufficient to say that the first preliminary is a thinning down of the horn of the quarter with the rasp over the position occupied by the cartilage. At the present time there are two or three modifications of the operation as originally introduced. In all, however, the preliminary steps are the same. We shall therefore describe them collectively, as applying correctly to either of the three methods of operating we are about to show.
Preparation of the Subject and Preliminary Steps in the Operation. - On the day previous to the operation the horn of the wall immediately over the cartilage must be so thinned with a rasp as to yield readily to pressure of the thumb in any position. It should be so thin as to only just avoid wounding the sensitive structures below.
The whole of the foot must then be thoroughly cleansed, and rendered as nearly aseptic as possible. The use of warm water, soap, and a stiff brush is the readiest means of removing the surface dirt. Afterwards the foot should be soaked for some time in a reliable antiseptic solution, a 1 in 1,000 solution of perchloride of mercury being the most suitable. When removed from the solution the foot must be packed round with wool or tow impregnated with corrosive sublimate, and then bandaged, the whole afterwards wrapped in a thick cloth, or protected with a boot.
On the following day the animal is brought out and cast, and the foot desired to be operated on firmly secured, after the manner described on p. 81. The bandages and sublimate pads are then removed, and the skin of the coronet over the seat of operation shaved of hair. An Esmarch rubber bandage is next run up the limb, and the tourniquet applied, thus rendering the operation a nearly bloodless one.
This done, the animal is chloroformed, and an antiseptic douche played over the foot.
So far, the steps in the operation are common to all methods. There are now, however, three slightly differing modes of extirpating the cartilage, which modes vary simply according to the structures severed by the knife.
First Method. - This is the oldest method of the three, and consists in making (1) a horizontal incision through the sensitive laminae along the lower border of the cartilage, and (2) a vertical incision through the skin of the coronet, the coronary cushion, and a portion of the sensitive laminae (see Fig. 139).
The flaps (Fig. 139, a, a) are now held back by tenaculae, and the whole of the cartilage, or only the necrosed portion, carefully excised by means of right- and left-handed sage-knives. Fistulous openings in either of the flaps a, a must now be carefully curetted and dressed, and the flaps allowed to fall into position. They are then sutured with carbolized gut, and the wound finally dressed as to be described later (p. 357).
Fig. 139. - Excision Of The Lateral Cartilage (Old Method). The Wall Covering The Lateral Cartilage First Thinned And Stripped Off; The Two Flaps (A, A) Of Skin And The Coronary Cushion Made By The Vertical Incision Turned Back. A, The Operation Flaps; B, The Exposed Cartilage; C, The Sensitive Laminae; D, The Coronary Cushion.