Miriam E. Tucker

November 04, 2015

WASHINGTON, DC — Anterior cruciate ligament (ACL) tears have been on the rise in children and adolescents over the past couple of decades, and the greatest risk is seen in female high-school soccer and basketball players, two new studies suggest.

Both were presented here at the American Academy of Pediatrics (AAP) 2015 National Conference.

Everyone thought the incidence of ACL tears had increased, but there were no longitudinal data, said John Todd Lawrence, MD, PhD, from the Children's Hospital of Philadelphia, who presented one of the studies.

Previous studies have assessed the surgical treatment of patients with ACL tears, but not the overall incidence over time.

"We believe these to be the first longitudinal data looking at ACL tear incidence in the pediatric population," Dr Lawrence reported. "We feel fairly confident now that we can say that the incidence of ACL tears has increased over the past 20 years, and that the burden has been borne more by females than males."

Dr Lawrence and his colleagues reviewed insurance data for all 4- to 18-year-olds with procedure codes for ACL tears or reconstruction from January 1994 to December 2013.

The overall incidence during the study period was 0.12%, and the annual increase was 2.3% (P < .001).

The incidence was higher in females than males (2.5% vs 2.2%; P < .001), and the peak incidence of injury was at a younger age in girls than in boys (16 vs 17 years).

There was an annual 3% increase in the proportion of ACL tears treated surgically during the study period — from 55% in 1994 to 75% in 2013 (P < .001).

ACL Tears by Sex and Sport

"More than half of all high-school students participate in organized athletics," said Alex Gornitzky, BS, also from the Children's Hospital of Philadelphia, who presented the second study.

"Adolescents have a number of unique risk factors that differentially affect their ACL injury risk profile, including player variation in size and skill, differences in physical and emotional maturity, and potentially underdeveloped sensorimotor and neuromuscular control," he explained. "To date, no studies have described sport-specific risk by gender and sport."

Gornitzky, a medical student, and his colleagues identified 10 studies that provided data on sex and specific sport after a search of PubMed, EMBASE, and the Cochrane Controlled Trial Register for all articles pertaining to confirmed ACL tears per athletic exposure in high-school-aged athletes.

Of the 11,239,029 athletic exposures, there were 699 ACL tears, for an overall injury rate of 0.062 per 1000 exposures. There were more injuries in males than females (374 vs 326), but the incidence was higher in females because their exposure was lower (relative risk, 1.6).

Table. Sports With the Highest Risk for ACL Tears per Season

Sport Rate per 1000 Exposures
   Soccer 1.1
   Basketball 0.9
   Lacrosse 0.5
   Football 0.8
   Lacrosse 0.4
   Soccer 0.3


For athletes who play multiple sports, the risk is cumulative, Gornitzky explained. For example, an adolescent girl who plays basketball, soccer, and lacrosse has a cumulative risk for an ACL tear of 2.5% per season, or 10.0% over a 4-year high-school career. For a boy who plays basketball, football, and baseball, the risk would be about 1.0% per season, or 4.0% over a 4-year high-school career.

Information on sport-specific incidence and seasonal risk for high-school athletes "is essential for future injury-reduction programs, shared parent–athlete decision-making, and accurate physician counseling," he concluded.

More Cases or Better Diagnosis?

At least part of the increased incidence has to do with better diagnosis of the condition, said session moderator Kevin Latz, MD, chief of sports medicine at Children's Mercy Hospital in Kansas City, Missouri.

"The data suggest that it's actually increasing in real numbers, but I still think it's a higher recognition that they occur," he told Medscape Medical News. "We're just now appreciating that tears occur, and we are doing a better job of diagnosing them."

But, he said, he believes that the increased risk in females is indisputable.

"Clearly, we know that women are more vulnerable," said Dr Latz. "It has to do with the way a woman's knee responds to stress, which is different than a man's, and probably with the firing patterns of the hamstrings and quadriceps."

Preventing ACL Tears

In recognition of the increasing incidence of ACL tears, the AAP issued clinical guidelines on the diagnosis, treatment, and prevention of ACL tears in adolescents last year, as reported by Medscape Medical News.

There are measures to help prevent ACL tears, Dr Latz pointed out.

One is having girls observe themselves in a mirror while jumping, so they can see where their knees are vulnerable and can then consciously correct improper landings, he told Medscape Medical News. However, this isn't as effective at preventing ACL tears in boys, for whom player contact is more often the source of injury.

Another preventive measure is to avoid overdoing it.

"An athlete performing fatigued is at higher risk of injury. Once your muscles become fatigued, it puts even more stress on your ligaments," Dr Latz explained. "I counsel patients to not play two competitive sports simultaneously, because we know that the more they're out there doing drills and exposing the knees to stress, the more likely they are to be injured."

He recommends that patients consult the Stop Sports Injuries website, which is sponsored by the AAP and a number of professional societies, for clinical information.

"It's geared toward the public, but it's got depth," he said.

Dr Lawrence, Mr Gornitzky, and Dr Latz have disclosed no relevant financial relationships.

American Academy of Pediatrics (AAP) 2015 National Conference. Presented October 24, 2015.


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