Why A.C.L. Injuries Sideline So Many Athletes


By Nytimes

For athletes, few sounds are more ominous than the percussive pop that can signal a ruptured knee ligament.

Tears to the anterior cruciate ligament sideline more athletes for longer periods of time than almost any other acute injury. Seasons, even careers, end when the A.C.L. tears.

Until recently, however, researchers couldn’t explain why torn A.C.L.’s were so difficult to treat. But studies recently completed at Boston Children’s Hospital and Rhode Island Hospital in Providence help to elucidate why the A.C.L., almost alone among ligaments, doesn’t heal itself. The findings also shed light on how that situation could potentially be changed, and blown knees more easily repaired.

The particular problem with the A.C.L. — which runs diagonally through the knee, helping to maintain joint stability — is that it is a tiny tissue asked to handle intolerable loads when an athlete’s knee violently twists and torques during contact sports or tumbling falls. The American ski racer Lindsey Vonn tore her A.C.L. during a competition last winter and is still rehabilitating her knee, in preparation for the 2014 Winter Olympics.

The more puzzling aspect of the A.C.L., though, is that it doesn’t get better. Other ligaments in the knee, including the medial collateral ligament, which is often torn along with the A.C.L., reknit after an injury. But the A.C.L. does not, and so past attempts at what doctors call “primary repair,” or fixing the torn ligament by stitching it back together, have generally failed.

In the past few decades, surgeons have instead replaced torn A.C.L.’s with new, rejiggered tendons formed from other portions of the person’s own leg, or from cadaver tissue. Known as A.C.L. reconstruction, this surgery provides patients with a well-functioning knee, but not the knee they once had. (It is also possible to skip surgery and live without an A.C.L., although most athletes opt for reconstruction.)….

Click here to read more