Carson Wentz's ACL tear recovery won't look like the average person's

In light of Carson Wentz's season-ending ACL injury, we talked with three doctors about ACL tears and what they mean.  Here's what we learned from Brett Toresdahl, a primary care sports medicine physician at Hospital for Special Surgery in New York; Brian Sennett, an orthopedic surgeon and chief of sports medicine at Penn Medicine; and Donald W. Mazur, sports medicine surgeon at the Rothman Institute. None has treated Wentz.

The anterior cruciate ligament is one of the major ligaments in your knee. Ligaments are the bands of fibrous tissue that connect bones, cartilage or joints. The ACL is one of two ligaments that cross in the middle of the knee and help stabilize the knee joint. It connects the thigh to the lower leg. It is most commonly injured during sudden stops or changes in direction. The ligament, Mazur said, is crucial for starting, stopping, changing direction and landing.

When the injury occurs, people often hear a "pop" and feel their knee give out. The severity of an injury to the ACL varies from small to complete tears in the ligament to a separation of the ligament from the bone. The most common injury is a complete tear in the middle. Most often, Toresdahl said, it's an "all or nothing" injury.

"It's just like a rope breaking in half," Sennett said. While ligaments in other parts of the body can heal, this one can't because fluid in the knee impedes healing.

Mazur said there are more than 100,000 ACL tears a year in the United States. Female athletes are about five times more likely to get them than men.

For many people, a surgeon likely would replace the torn ligament with a piece of the patient's hamstring or ligament from a cadaver, but elite athletes are on a different protocol. In their case, Sennett said, surgeons remove a two-inch-long piece of a tendon that runs under the kneecap along with bone on either end and screw it into place. The tendon is a little wider than an inch. The surgeon makes a strip for the new ligament out of the middle third. Over the next few months, the tendon regenerates itself and the cellular structure of the reconstructed strip changes from tendon to ligament.

Sorry sports fans. Six to 12 months.

"My expectation is that [Wentz] will be back in training camp in August," Sennett said.

Toresdahl said non-athletes can often go back to work a week after the injury, and many will never need surgery.

If surgery is needed, Sennett said an office worker could be back on the job in 10 days. Someone who does a lot of standing might need six to eight weeks. A construction worker who works on tall building could be out three months. People who might have to run or pivot on the job like firefighters, police officers or military personnel need five to six months.

It takes time to rebuild strength in leg muscles and for the tendon and new ligament to heal and generate a new blood supply.

"You have to restore your strength and you have to restore you muscle coordination and what's called proprioception and that is kind of knowing where your joint is in space," Mazur said.

Wentz will have more time than most people to devote to rehab. "The average person usually has to work for eight hours," Mazur said.

Most prevention programs focus on strengthening and stretching. About 70 percent of ACL tears are non-contact injuries, Sennett said. People who bang into giant men for a living can't prevent the contact kind.

There's a good chance he'll be just as good as he was before the injury, especially if the ACL tear is the only damage. "The norm," Sennett said, "is to recover and to return to a similar level of productivity."

Mazur agreed. The surgical procedure, he said, is common and minimally invasive. "If anybody has a shot at that," he said. "I think it's this kid."