Two ACL studies, two outcomes—which one wins?

Tearing the anterior cruciate ligament — better known as the ACL — sometimes results in early surgery, sometimes in later surgery and sometimes in no surgery. But which scenario has the best outcome? Two studies released this week seem to contradict each other. One study found that for children younger than 14 who needed ACL reconstruction, early surgery was better than delayed surgery. But for 18- to 35-year-olds, early surgery with rehabilitation was no better than rehab plus later surgery if it was needed.

Confused yet? Let’s review.

The first study, presented at the American Orthopaedic Society for Sports Medicine recent annual meeting in Rhode Island, looked at cases of ACL reconstruction surgery in children 14 and younger from 1991 to 2005. The ACL is one of four knee ligaments and is involved with keeping the knee stable. It’s often injured in sports that require pivoting and jumping.

Outcomes from surgeries done 12 weeks or less after the injury were compared with results from surgeries done after 12 weeks. ACL surgery in children this young is somewhat controversial, since it may damage the growth plates (areas of the bone near the knee joint), causing them to grow abnormally.

But in this study, early surgery was generally associated with better outcomes and did not significantly disturb growth plates. For girls, it was linked with fewer medial and lateral meniscal tears, along with fewer cartilage injuries. In boys, early surgery was linked with fewer medial tears but more lateral tears, as well as substantially lower cartilage injuries.

In a study in the New England Journal of Medicine, researchers studied surgery results in 121 active men and women ages 18 to 35 with ACL injuries. About half were assigned to rehabilitation and early surgery, while the others also did rehabilitation and could opt for surgery later.

Neither track proved to be superior. Both groups improved over two years, and there were no major differences in scores for knee-injury and osteoarthritis outcome scores, which measure pain, symptoms, ability to function in sports and recreation, and knee-related quality of life. But those who had rehab plus early surgery had greater knee stability after two years.

Though the two studies may seem to cancel each other out, they really don’t, says Dr. David McAllister, professor of orthopedic surgery at the David Geffen School of Medicine at UCLA.

“I don’t think they can be compared at all,” McAllister said. “They both shed light on the problem, but they’re looking at two different patient populations.” Children with immature skeletons, he noted, have different concerns than adults whose bones have stopped growing.

Each ruptured ACL case needs to be evaluated individually, he says, although the conventional wisdom on adults is that earlier surgery results in better outcomes, while for children the jury is still out.

“There are several factors that need to be taken into consideration before deciding on surgery,” he added. “Age is a factor, as is the type of sport the patient plays, how active they are, and what other injuries are associated with the ACL tear, such as meniscus or cartilage damage or other ligament injuries.”