ceeding by which it can be accomplished, and which, in certain cases of gunshot wounds of the articulation, might be usefully employed on the living.

The operator standing on the inner side of the leg*, should commence an incision on the posterior border of the fibula, two inches above the extremity of the outer malleolus ; this cut must be carried down the bone to its extremity, and, crossing the front of the ankle-joint, should pass behind the inner malleolus to the same extent up the posterior border of the tibia; the flap thus traced out must be reflected, taking care that the subjacent tendons are not injured. The peronei muscles should now be turned out of their groove; and the extremity of the fibula being cleared, the director should be passed behind it and the bone sawn through. The lower end should now be grasped with the lion forceps, while with the scalpel its ligamentous connections are divided, when it may be removed. The operator should now attack the lower end of the tibia in the same manner; and having divided its ligaments, the foot may be dislocated outwards, and the articular extremity of the bone sawn off. This proceeding saves the neighbouring tendons and vessels, but is extremely difficult of execution, even on the dead body.

Resection of the knee-joint.—The operator, standing on the right-hand side of the limb-i e. outside the right knee and inside the left--should trace out with a scalpel a semilunar flap, commencing opposite the posterior part of the condyle most distant from himself, crossing the front of the joint below the patella, and terminating over the upper part of the other condyle of the femur. This flap, consisting of integuments alone, should be dissected up from the front of the joint, which latter must now be fully opened; the assistant at the same time strongly flexing the *This description applies to the left leg.

limb. As he does so, the operator should sever all remaining ligamentous connections between the bones, being especially careful during the division of the posterior ligament. He should now pass the knife around the lower end of the femur, just at that part where he wishes to apply the saw; with this he may remove a portion of the bone, cutting from its anterior towards its posterior surface, and taking care that the section be at right angles to the long axis of the shaft. Any connection that this portion of bone may still retain after the application of the saw should be divided carefully with the scalpel. A thin shell of bone being removed in the same manner and with the same precautions from the extremity of the tibia, the operation will be complete. The patella is generally removed with the portion of the femur that is taken away. No blood-vessels of any consequence should be divided.

Resection of the hip-joint. — The operation which passes by this name consists in the removal of the head of the femur: it may be well to practise it on the dead body, though on the living, the head of the bone is in most cases dislocated by disease previous to being subject to operation; the ordinary instruments for resection are sufficient for this proceeding.

The body being turned over towards the opposite side, and the thigh slightly flexed, the operator should place himself by the side of the joint he is about to excise, and make a curved incision on the outer side of the joint, embracing in its concavity and passing close behind, the most prominent part of the great trochanter. This incision should be from four to five inches in length, and should commence between the anterior superior spine of the ilium and the top of the trochanter major. The glutei muscles being divided, and the external rotator muscles, the capsule may be opened from behind, while the limb is forcibly flexed and adducted by an assistant; this will

being the ligamentum teres within reach, which when cut, will allow of the dislocation of the head of the bone. The director being passed around its neck, the head may be removed with the saw, and the operation will be complete. There are various methods of dividing the soft parts over this joint; but whatever plan be pursued, it must be put in practice over the posterior and outer part of the articulation, and the incision, of whatever form, should fall between the trochanter and the great sciatic nerve.

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CHAP. IX.

ON THE USE OF CERTAIN INSTRUMENTS.

Application of the Trephine to the Skull.-To long Bones.-Operation for the Removal of a Sequestrum.-The Stomach-pump.

THE trephine, be sides its more obvious purpose for removing portions of the bones of the vault of the skull, is used for exploring the cancellous extremities of long bones, and for exposing the medullary cavity of their shafts.

For trephining the skull a small scalpel, a probe, and an elevator are required in addition to the trephine itself. In applying this instrument to the cranium on the dead body, a precaution should be adopted which cannot always be followed on the living-namely, that of selecting a spot for its application out of the course of the trunk of the middle meningeal artery, and clear of the longitudinal or lateral sinuses; as a general rule, the immediate neighbourhood of the sutures should be avoided. A spot having been selected, the scalp should be cleanly reflected from the bone over the parts, either by a semilunar, crucial, or ▲ -shaped incision; the operator, standing well above the part, should project and fix the central pin of the trephine about a lint beyond its serrated edge, and apply the instrument to the bone with an alternating semirotatory movement, until it has cut for itself a groove of sufficient depth to obviate the chance of slipping aside: the pin may be now removed and the rotatory movement of the instrument continued until the diploe is reached; this may be ascertained by the

more casy movement of the trephine, and the grating sensation communicated to the hand. The elevator may now be used to raise and remove the outer table of the bone: to the deeper part the trephine should be employed more carefully until the inner table is nearly cut through; when, from time to time, the flat end of a probe or a pointed piece of quill may be introduced into the groove, to ascertain if the dura mater be exposed at any spot. Owing to the spheroidal form of the skull, this is almost sure to take place at one part of the circumference of the groove before another, as it is impossible to make the instrument cut to an equal depth in its whole circumference; if the bone is ascertained to be perforated at one spot, the trephine should be inclined towards the opposite side, until the included portion be almost wholly separated, when its complete removal can be effected by using the elevator.

Cancellous extremities of bones. In exploring these with the trephine, the soft parts over the bone having been reflected, the instrument may be applied in the same manner as described above, though less caution is required; and the trephine must occasionally be removed to clear it from the portions of bone which it separates and which clog its serrated edge.

The cancellous ends of bones may also be advantageously explored by means of the gouge; and this is particularly useful when it is advisable that the perforation in the bone should be of small size, though extending deeply into its substance. The gouge should be used in the same manner as an ordinary gimlet, being screwed round and round, while pressure is made against its handle with the palm of the hand.

One of the readiest methods of removing a portion of the shaft of a bone, such as the tibia, so as to expose its

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