The goal of ACL surgery is to stabilize the knee joint, return it to normal mechanical function, and permit the athlete to resume sports without a deficit. Here are the most common reasons I see failures and what can be done about it.

The ACL Study Group meets every two years to update the latest knowledge on ACL injuries and treatments. This year’s meeting was at the base of the Hahnenkamm ski race in Kitzbuhel Austria—the most famous downhill ski race on the World Cup circuit. One hundred and fifty of the world’s top ACL surgeons watched 30 of the world’s bravest ski racers hurtle down the ice-crusted hill at 140 km/h (84 mph). The outcome of the race was predictable: The Austrians dominated. The outcome of the scientific meeting, however, was less conclusive; the ACL is still a tough problem to solve.

For decades there have been unsuccessful efforts to repair the anterior cruciate ligament (ACL) after rupture. Why? Because the forces required to tear the complex weave of the ACL’s collagen fibers involve both tearing and pulling apart. Think of a climbing rope: When overstretched the rope fails within its sheath, not just at a single clean edge. Here is why the ruptured anterior cruciate ligament is most often replaced (reconstructed) rather than repaired.

“Doc, my knee popped, it now catches and gives way.” Whether it is the knee, the ankle, the hip, or the shoulder, catching and giving way—especially after hearing a pop—is bad news.

The ACL is the key stabilizer of the knee and is torn 300,000 times a year in the U.S. alone. The treatment of these torn ligaments has evolved in some ways, but not so much in others. Here is what we know today.

Almost all orthopaedic injuries are best repaired immediately. The old “wait and see” for most joint injuries has been proven to lead to scar tissue, loss of motion, and arthritis. With today’s accurate imaging, using repair and reconstructing techniques to restore normal anatomy beats living with deformities.

To cut, or not to cut? To repair, or to let heal? To rehab without fixing? To live with imperfect parts? Each of these questions is faced every day by surgeons and their patients. Here are a few decisions about incisions.

Arthritis is preventable. Yet until recently most people thought it was inevitable. Here are some examples of how to best treat your injured knee.

Hard to reach, the Posterior Cruciate Ligament was often ignored or left ruptured after injury. New techniques now permit effective reconstruction.

Standardized care is not always the best care. What we really need is an agile medical system that values innovation.

Excellent coverage on ABC News of Dr, Kevin Stone's pioneering Z-lig ACL replacement device which uses animal tissue to repair human joints.

What used to be a career ending injury for many athletes is now usually reduced to a season ending injury. Even this may change with ever improving techniques to reconstruct ruptured ACLs.

When skiing superstar Lindsey Vonn recently announced her withdrawal from the Winter Olympics, she demonstrated that reconstructing the torn anterior cruciate ligament of a world-class athlete has its unique problems.

When it comes to knee injuries through playing sports, statistics tell us that women are more likely to be injured than men.

We like to do everything possible to rebuild the knee joint with biologic tissues rather than artificial materials to help delay the time in which an artificial joint replacement is necessary.