The arthroscopic surgery that Joe Washington will undergo today has revolutionized the diagnosing, repairing and recovery time of knee injuries.

The arthroscope resembles a long, very narrow metal tube with a magnifying lens at one end. The surgeon inserts the scope into the knee through an incision about an inch wide. By looking into the scope, he can examine much of the knee area and, by inserting one or two other small instruments in other tiny holes, he can operate. More sophisticated models, costing $8,000 or more, magnify what is seen through the scope onto a television screen.

In many cases, a local anesthetic is used. The incision normally is covered with a compression bandage, not closed with stitches. Conventional knee operations necessitate a week or two in the hospital and the patient isn't allowed to walk for days. Washington possibly could be walking by tonight and out of the hospital within 24 hours, mainly because the arthroscope doesn't cause as much trauma in the knee or as much pain.

Cartilage helpes stabilize the knee, and it prevents the knee from locking. Ligament damage is considered far more serious, and normally sidelines an athlete for much longer periods than cartilage problems.