Many athletes expect to return to sports like basketball and soccer after tearing a knee ligament, but it might not be in their best interest, some researchers say.

Ruptures of the anterior cruciate ligament, or ACL, are among the most serious and common knee injuries among athletes. The ligament, a strong band of tissue that connects the thigh and shin bones, is a major stabilizer of the knee joint. It is most often torn through a sudden, twisting action, as in sports that are filled with pivoting and quick direction changes - including basketball, soccer and handball.

When high-level athletes sustain an ACL tear, they often have surgical reconstruction - which, typically, replaces the ACL with a strip of tendon from the kneecap or back of the thigh - then get back into the game in a matter of months.

But whether that’s a good idea is debatable, according to a report in the March issue of the British Journal of Sports Medicine.

In a review of studies that followed ACL-injured athletes for four to 14 years, researchers at the Norwegian University of Sport and Physical Education found that players who returned to their sport had fairly high rates of re-injury - whether they had ACL reconstruction or opted for physical therapy instead.

In addition, their risk of developing Osteoarthritis of the knee was substantial, though it’s not clear that retiring from sports would have lowered the risk, according to the researchers, led by Grethe Myklebust.

Across the studies they reviewed, the rate of ACL re-rupture among returning athletes ranged from about two percent to 13 percent. In one study, which followed surgically treated athletes for eight years, 12 percent re-injured the ligament, in all cases during a “pivoting” sport.

Athletes who did not have surgery also faced a high risk of further knee problems, including damage to the cartilage lining the joint. In a study led by Myklebust, 22 percent of team handball players who returned to their sport after non-surgical treatment of an ACL tear ended up needing surgery for injury to the meniscus, a cartilage disk that cushions the knee joint.

“It seems reasonable,” the researchers write, “to question whether return to high level pivoting sports really is in the athlete’s best interests - if long term knee health is the primary concern.”

Besides the chance of further trauma to the knee, the risk of developing arthritis in the ACL-injured joint appears substantial, according to Myklebust’s team. Overall, the evidence suggests that within 10 years of the injury, half of patients will show X-ray evidence of knee arthritis - a wearing down of the joint’s cartilage that can lead to chronic pain, stiffness and limited mobility.

This figure, according to the researchers, suggests that nearly all patients will have signs of arthritis within 20 years of an ACL tear - regardless of whether they have surgery or more conservative treatment.

It’s unknown, the authors add, whether avoiding high-level sports can delay the onset of arthritis, and there is an “urgent need” for studies into the question.

For now, they say, athletes who want to return to high-risk sports should be aware that while ACL reconstruction does improve knee stability, it “does little or nothing to secure a future healthy knee.”

Though athletes usually want to know when they can return to play, Myklebust’s team notes, the more difficult question that needs to be asked is whether they should return.

SOURCE: British Journal of Sports Medicine, March 2005.