THE MANNER OF OPENING THE DIRT SAC, IN CASE ONE SHOULD BE PRESENT WITH OPEN JOINT.
The suspected sac having been discovered, a large spatula is placed below the knee. A knife with a keen point, but with the edge only sharpened for one-third of its length, is to be used. Upon the cutting point of the knife a piece of beeswax is firmly moulded. The wax answers the purpose of a temporary probe; the blade, thus guarded, is cautiously inserted beneath the loose flap of skin. When the bottom of the pouch is reached, a certain amount of resistance will be encountered; through this the knife is driven. The force cuts in twain the wax, and pushes through the integument the blade, which the spatula guides from the leg. This operation should be performed quickly; the hand should simply be carried downward, and then brought upward when all is concluded; care, however, being taken that the withdrawal of the knife does not injure any part save those it was designed to cut.
Should the horse be nervous, it is desirable to blindfold the animal and order the groom to hold up the sound leg; the creature can then only rear. When thus disabled, that movement is rendered difficult, and it is proportionably slow. The operation, if properly performed, should be over before action can be prepared for; and by the knife a considerable incision is made in the bottom of the sac, through which all grit or dirt can, with the pus, readily pass.
The examination concludes with a second resort to the probe. The instrument is in surgery of great use; but as it is commonly employed, reason may doubt whether injured life has been much benefited by its invention. It generally is raked and poked about as though the person holding it was determined, at all hazards, to ascertain the length, breadth, and every irregularity of the wound he is asked to cure; much harm is thereby done. Delicate attachments which, if not interfered with, might induce speedy reunion, are thus broken down, and the injury aggravated; while the operator thinks he ought to know all about the lesion he is to treat, and supposes that he can possibly do no harm with an instrument which the best schools order to be employed.
A good surgeon has no curiosity to gratify; all he desires to know is so much as will enable him to benefit the patient placed under his care. Therefore never abuse the probe in cases of open synovial cavities. Imagine the distance the bones are from the surface; and, if the probe can enter a very little beyond that distance, such a fact demonstrates the cavity to be exposed. When a horse is before you with synovia running from a wound upon the knee, have the leg slightly flexed; look for the most free space, and into that insert the probe. The bones of the knee-joint are directly under the skin; and, when no opposition is encountered for three-quarters of an inch, be sure the joint is exposed.
PROBING AN OPEN JOINT.
Most of the cases narrated as opened joints were simply punctures into synovial sheaths; as such, they were sufficiently serious, but not of so important a character as is assumed for them. Synovia is placed between the ends of bones, its use being to prevent the friction which otherwise would be occasioned by the movement of one hard body upon another. Being confined in a circumscribed sac and incapable of much compression, the liquid performs all the uses which could appertain to the most solid substance. When the fluid—which, from its thick appearance and unctuous feel, was formerly termed "joint oil"—has escaped, the bones grate against each other, inflammation ensues, all neighboring parts sympathize, and the constitution suffers from intense irritation.
