1. In order to prognosticate which patients with internal derangement of the knee will return to full duty after operation, careful preoperative evaluation of the patient as a whole is essential. This involves the sizing up of the individual from the psychological standpoint; the taking of a detailed history as to the mechanism of injury; a systematic and thorough physical examination including: inspection, palpation, motions, stability, stance, and examination of the joints above and below the knee. The opposite or normal knee should always be examined for comparison.

2. Usually the patients can be classified into two groups: (1) those having uncomplicated injuries to the meniscus, and (2) those with damage to the articular surfaces or ligaments, which may or may not be associated with injury to the meniscus.

3. The vast majority of patients with an uncomplicated meniscus injury can be returned to, and will remain at, full military duty, if a careful operation is carried out, and if the patient is reconditioned prior to his discharge from the hospital.

4. Patients whose knee disability is due to, or complicated by, articular damage or instability of the joint should not be operated upon in an overseas theater, unless symptoms are sufficient to cause severe pain or locking of the joint.

5. Exceptions to the previous statement may be made in so-called "key personnel" who, after operation, can return to limited service, not requiring excessive use of the knee.