During the year 1942, there were admitted to the Station Hospital of Fort Jackson, for all causes, 22,186 patients. The seventy-five soldiers and officers with internal derangement of the knee joint which required operative intervention represent an incidence of one in each 295 patients admitted. Only a little under 15 per cent. of the total patients admitted with knee injuries were operated upon. Sprains and contusions of the knee are very frequently encountered. Of the patients at this post admitted to the Hospital with injured knees, approximately one out of seven has been operated upon for internal derangement of the joint.

A large number of patients with internal derangement of the knee joint, existing prior to induction, have been either returned to duty for a further trial or to Limited Service. The authors have always tried to avoid operative work on soldiers or officers who have obviously inadequate personalities; who will, in all probability, never do full combat duty; and who may use the operation as a means of avoiding military service. It frequently taxes the surgeon's ingenuity to determine whether a soldier or officer is a good candidate for elective surgery. There are many reasons for this in time of War, and the surgeon must consider the psychic as well as the somatic manifestations in each instance.

A diagnostic accuracy in 89.5 per cent. of internal derangements of the knee joint is, we believe, creditable. In no instance, has a diagnosis of "loose meniscus" been made. There may be such an entity, but the authors are not satisfied unless there is an actual tear.

The patients are seen regularly at ward rounds, and, if there is a doubt of the diagnosis, they may be presented at the daily staff conference. If the injury is the initial one and responds to conservative treatment, the patient is returned to duty, and only if the symptoms recur, and again necessitate hospitalization, is operation recommended. The authors have insisted upon some physical signs, regardless of how typical the story sounds.

These physical signs, one or more of which may be present, are, in order of frequency:

1. Atrophy of the quadriceps muscle.

2. Tenderness at the joint margin over the involved meniscus.

3. Increased intra-articular fluid.

4. A palpable slipping of the joint.

5. Blocking of motion in the joint. This usually occurs at 150 to 160 degrees of extension. It is called locking, but the knee is not actually locked, as there may be 50 to 75 degrees of motion present in the knee.

There was only one serious complication, a low-grade infection which progressed to ankylosis of the joint,—an incidence of 1.33 per cent. There were no deaths.

There is but one point in technique which should be stressed. The operative removal of the meniscus should mean that the entire meniscus is removed. This is made possible by a second, posterior incision in the capsule as described by D. M. Bosworth.