axiom that no operation for internal derangement of the knee-joint should be considered complete, in cases in which the joint is locked or extension is defective, unless extension to the normal limit is immediately possible; the movements of the joint, in fact, at the end of the operation should be as perfect as those of the opposite limb. In cases of recent displacement of a semilunar cartilage this is undoubtedly sound teaching, but it is certainly not so in old-standing displacement with restriction of movements-not a very rare class of case-when the mere removal of the mechanical obstacle in the joint itself does not always allow of immediate normal extension, which is, however, recovered gradually by the aid of massage and exercises.

The importance of an appreciation of this point. lies in the fact that, no matter what operation is performed or how freely the joint is opened, there are a certain number of cases in which a resumption of normal movement does not immediately follow the removal of the objective abnormality in the joint, although complete recovery of all natural movement gradually follows, a matter which has a practical bearing upon the transpatellar exploration, as the following case, which came under my notice after ankylosis had taken place, will show. A man with a long-standing displacement of a semilunar cartilage, the knee being fixed in a slightly bent position, was

operated upon by a surgeon of repute, the lateral incision being employed and the displaced structure removed. Complete extension being still impossible, the joint was explored by the transpatellar method with a view to finding the obstacle to free movement. Nothing further was found and the defective movement remained as before; suppuration unfortunately followed, and a stiff joint in the same slightly bent position resulted. The transpatellar exploration was obviously superfluous here, and had the operator been content with the slighter operation complete movement would have been almost certainly obtained by the usual means—at least such is the conclusion to which

my experience in these cases leads me. I very much doubt whether any obstacle to movement in conditions of this sort could exist which the finger introduced in the manner I have mentioned would fail to detect, assuming, of course, that it is endowed with sensation of average acuteness.

An additional point of interest connected with the method of operation was very plainly demonstrated by the condition of the parts in every one of the cases operated upon in which the cartilage was displaced-viz., that it would have been not only useless but impossible to fix effectually in its normal place any one of the displaced cartilages with the least prospect of its remaining in the restored position a fact which, considering the number of cases

dealt with, ought, I think, to be sufficient to dispose of the idea which I understand still exists, with some people, that a truly displaced cartilage can be effectually stitched in position.1

The result in all the cases but two was perfect, the mechanics of the joint being entirely normal. In one of the two exceptions the movements were slightly restricted, as the patient declined to submit to the necessary manipulation; the defect, however, was not sufficient to interfere with ordinary occupations, and no lameness was apparent. The other defective example occurred in a boy in whom the power of complete extension has not been quite regained, but as the operation in his case is comparatively recent (about eight months) a perfect result may yet ensue.

One disaster only has followed the exploration of a knee-joint in my practice. This happened some years ago in a hospital case, not coming under the category of those now being considered, in which

1 Although the observation may perhaps be thought unnecessarily elementary, I venture to point out that in the normal condition the semilunar cartilages are not 'fixed' in the ordinary meaning of the term. It is, in fact, quite possible for an inexperienced operator, upon passing a hook under the free edge of a normal cartilage, to find it so comparatively movable as to lead to the impression that it is pathologically loose, with the result of its being dealt with accordingly; in such circumstances careful stitching of the cartilage to the head of the tibia would naturally end in an ideal result so far as the cartilege itself is concerned.

some sponges that had previously been used by another operator in a case of gangrenous appendicitis were included, by a regrettable oversight, amongst those used at my operation. Acute septic infection followed in this and two other cases operated upon on the same day.

With regard to the mechanical treatment of displacement of the semilunar cartilages, it seems even now, judging from the numerous patients whom I have seen who have already been provided with some sort of apparatus or support, that the object to be aimed at by the use of an instrument is not understood by the majority of people. The objects. to be attained by an instrument in these cases are (1) the prevention of rotation of the tibia upon the femur, the movement which is invariably the cause of semilunar displacement, and (2) the prevention of the lateral movement or wobbling of the knee-joint which is present in a greater or less degree in all these cases. Instruments devised for the purpose of keeping the faulty cartilage in position by exercising pressure over the apparently affected part must be useless in a general way, because the displacement is into the joint and not out of it, saving exceptional cases like that shown in fig. 7, but even in such a case pressure would not retain the displaced structure in position during the free movement of the limb. After extensive experience of all the instru

mental supports available, I have come to see that the only one which meets the requirements of these cases under all the circumstances in which an instrument can possibly be of use is that shown in fig. 2, which is made by Mr. Ernst.

CONDITIONS OF THE DAMAGED CARTILAGES.

The injuries to the cartilages arranged themselves into seven groups, which will be perhaps most readily understood from the following diagrams. Each diagram shows the condition found in an operation and forms the basis of a group in which are included all the cases presenting injuries either identical with, or of the same type as, that depicted.

It is interesting to note, that in detachment of the external cartilage the structure itself is generally much more damaged (i.e. split, crushed, or torn) than is the internal cartilage when it is the seat of lesion. This is precisely what would be anticipated, seeing that in a large proportion of the instances in which

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