Falling linemen rolled up the left knee of the Washington Redskins' Joe Jacoby during a field-goal attempt in Philadelphia last year, dislocating his kneecap and ending his season. The game before, teammate Mark May blew out his right knee during a home game against the Cowboys.
In the third game this season, tumbling players bent Redskins quarterback Mark Rypien's left knee backward, knocking him out of that and subsequent games. Three games later, Eagles defensive end Reggie White took down backup Redskins quarterback Stan Humphries, spraining his right knee in the process.
Some of the carnage even comes in the offseason. A. J. Johnson, who had a successful season last year as a rookie defensive back, locked up his right knee just getting up off the floor at home, ultimately leading to surgery.
"Knee injuries are the biggest injury that we have," said Redskins Coach Joe Gibbs. "It is a major problem for us all the time."
Small wonder. Unlike hips and shoulders, where ball-shaped ends on the bones fit into sockets to form a solid joint, the knees are like two abutting broomsticks, with rubber pads between the ends, held together by four ropes. When a player runs, the forces flowing through the knees exceed five times body weight; when a blow or a sudden direction change stretches one of the four cable-like ligaments by more than 10 or 15 percent, that ligament can tear, causing extreme pain and joint instability.
Damaged knees make up between 20 and 25 percent of the injuries that cause football players to miss games, said Redskins trainer Bubba Tyer. "And that's compared to everything else: fingers, hands, wrists, shoulders, necks, backs, hamstrings, (quadriceps) and ankles."
But players are coming back from major knee injuries faster and more frequently than ever. All five key Redskins recently felled by serious knee problems are either back on the field or physically ready to resume playing.
"These players are neuromuscular geniuses," Tyer said. "They are highly motivated. Strong. Tough. They have all the qualities you want in a patient. That is one reason we get them back."
Technical advances also have made a difference, including a new approach to reconstructive knee surgery, the widespread use of the arthroscope, a viewing device that allows doctors to see inside the knee without cutting it open, and more aggressive rehabilitation programs to restore strength and flexibility.
The arthroscope has made the biggest impact, said Redskins orthopedic surgeon Charles Jackson. The device has a hollow steel barrel, not much thicker than a pen, that can be poked through the skin. Inside the barrel are glass fibers for viewing the knee's internal anatomy, hollow tubes for squirting in fluids and flushing out bone chips and other debris, and tiny cutters for trimming rough cartilage.
"We used to feel that we had only one crack at a knee," Jackson said. "The arthroscope makes it possible to look at the knee repeatedly, do what you have to do, and get out. Before that, washing out a knee or trimming cartilage would have been a major procedure."
Because the knee is not cut wide during an arthroscopic exam, healing takes less time. Rypien is a classic example.
"I had a partial tear of the posterior cruciate ligament and the capsule of the joint," Rypien said.
The posterior cruciate is the strongest ligament in the knee and rarely torn. Rupturing the sac that encases the knee joint caused blood to leak down into Rypien's calf, painfully swelling the muscle.
In the past, this would have looked serious enough to open the knee. Instead Jackson used the arthroscope the next day and found it wasn't all that bad.
"It was just a basic tear," Rypien said. "There wasn't any cartilage tearing. They did not have to clean any of that out."
Jackson decided that the tear could heal on its own without reconstructive surgery, but that would take a month or so. Two days after the exam, Rypien was back at Redskin Park, icing the joint and starting rehabilitation.
The injury to Humphries was so minor, Tyer said, that "we didn't scope Stan." He sprained a ligament on the inner portion of the knee that recovered on its own. "Stan has been well for a good while," Tyer said.
Too often, however, the injuries are not so minor.
Late in his rookie season last year, A. J. Johnson sprained his knee, primarily stretching the anterior cruciate ligament (ACL). The anterior cruciate and the posterior cruciate, which Rypien injured, crisscross inside the knee joint, giving it rotation, as well as backward and forward stability. If knee injuries are the most common killer of football careers, destruction of the anterior cruciate ligament is the most common kind of serious knee injury.