Internal derangement of the knee-joint.

[Read before the Liverpool Medical anad Pathological Society, February 8th, 1855.] IN-TERNAL derangement of the knee-joint is the appellation given to an injury, the precise nature of which, as may be inferred from its vague title, is not very clearly understood. The accident, howvever, is not very uncommon, nor is it unimportant in its consequences; for, if overlooked, it may prove very embarrassing to the surgeon, and may lay the foundation of more serious disease. The elder William Hey 1ha the credit of having first called attention to this injury. It is noticed by Sir A. Cooper, in his work upon the joints, and by other surgical writers; but the subject appears scarcely to have received the attention which its importance deserves. I have no recollection of seeing a case or hearing one mentioned during my attendance on hospital practice in London and elsewhere, and it was only recently that my attention was particularly drawn to it by a clinical lecture of Mr. Smith of Leeds, which appeared in the Lancet of the 20th September 1851. A short time after perusing that lecture, I met with a case, which I at once recognised from his description. I was also then able to explain satisfactorily to my own mind cases which had come under my notice previously, and which had puzzled me a great deal. The accident is generally produced by some slight fall, slip, or sprain. Sir A. Cooper observed that it occurred most frequently when a person in walking strikes his toe, the foot being at the same time everted, against any projecting body, as the fold of a carpet; he also relates cases in which the accident happened from a person having suddenly turned in his bed, when the clothes not suffering the foot to turn with the body, the thigh-bone has slipped from its semilunar cartilage. The symptoms, when the accident is recent, are very characteristic and readily recognised, when attention has once been drawn to these cases; but yet so slight, as very likely to be overlooked or misunderstood by those who are not aware of their occurrence. There is little or no alteration in the appearance of the joint; no swelling or effusion; and no pain when the limb is at rest. The patient walks with a limp, with or without pain, and cannot bring the heel to the ground, from inability to accomplish full extension of the limb; the motions of the joint are unimpaired, except that extension either by the patient's efforts or those of the surgeon can only be partially effected, so that the limb remains constantly a little bent. In some instances, the cure takes place suddenly -and accidentally; in others it will continue for days, weeks, or months. Some patients are Liable to a recurrence of the accidebt, as is recorded by Sir A. Cooper, and which I have observed in one instance in my own practice. When accompanied by other severe injury or disease of the knee-joint,