LAS VEGAS — American football players would benefit from a knee-injury prevention program, similar to the programs developed for soccer, according to a new study.
Players in the National Football League (NFL) are tearing their anterior cruciate ligaments (ACLs) with movements that were identified as risk factors in female soccer and basketball players in the 1990s, said Bert Mandelbaum, MD, an orthopedic sports doctor from Santa Monica, California, who helped design an injury-prevention program for the Fédération Internationale de Football Association (FIFA).
"The theory is that it's the same dynamic valgus mechanism we see in 14-year-old girls," Dr Mandelbaum told Medscape Medical News here at the American Academy of Orthopaedic Surgeons 2015 Annual Meeting.
Dr Mandelbaum and other orthopedic surgeons began studying risk factors for ACL tears in the 1990s, when they noticed an uptick in the number of female athletes coming to them with these injuries.
They found that ACL tears were twice as common in females as in males participating in the same sports.
After considering physiologic differences and analyzing videos, the researchers found that many of the injuries occurred when the knees of the athletes were in a valgus position.
The position is more common in females than males, but the researchers found they could train both male and female athletes to avoid it.
Dr Mandelbaum and others developed exercise routines for athletes to improve balance, strengthen muscle groups that stabilize the knees, and teach safer running and jumping forms.
In clinical trials, Dr Mandelbaum and others have shown that the FIFA 11+ program, for example, can halve the rate of lower-extremity injuries, including ACL tears in soccer and basketball players.
American football players frequently tear their ACLs, but team physicians have assumed that the injuries resulted from the trauma of direct contact with other players.
In their trial, Dr Mandelbaum and his colleagues analyzed 27 ACL injuries that occurred during the 2013/14 NFL season, and found that two-thirds happened without contact between players.
The players were mostly near the line of scrimmage and were injured while planting or cutting to change direction.
Videos of some of these injuries showed players suddenly collapsing after catching the ball or changing directions, without being touched by another player.
The NFL tries to make it clear that it will not tell physicians how to practice medicine.
Other injuries occurred after light contact that did not apply force to the knee but appeared to throw the injured player off balance, a pattern Dr Mandelbaum called "perturbations."
The noncontact injuries occurred most often when the hip of the affected limb was flexed and abducted, the knees were in the valgus position and flexed less than 45 degrees, and the foot was externally rotated.
The occurrence of the injuries was evenly distributed among players' positions and timing during the game and season.
One reason for the injuries could be a change in the way American football is played, Dr Mandelbaum explained. Players are ranging farther over the field, and "are playing like soccer players," he said.
This study is so important that Matthew Matava, MD, team physician for the St. Louis Rams football team and immediate past president of the NFL Physicians Society, has signed on to help analyze more videos as the study continues.
However, the data so far are insufficient to recommend training changes, Dr Matava told Medscape Medical News.
"I think the results of the study are sort of counter to what the data from the NFL show," he said. Statistics reported by athletic trainers for the league show that about 60% to 75% of ACL injuries result from contact, he explained.
One explanation could be that the trainers use a different definition of contact than the physicians who analyzed the videos. Even if the data are borne out by future research, the NFL is unlikely to create a program similar to FIFA 11+, said Dr Matava.
"I would say pretty strongly that it will not be an official NFL program," he said. "The NFL tries to make it clear that it will not tell physicians how to practice medicine."
However, teams might adopt elements of the injury-prevention program that they think will reduce ACL injuries, which are common and typically sideline a player for a season or more.
It is likely that trainers and players would readily adopt exercises like those in the FIFA 11+ program, said Laith Jazrawi, MD, from NYU Langone Medical School in New York City.
"I absolutely think they will," said Dr Jazrawi. "Football is all about getting faster and stronger. This is going to fit right into that."
Dr Mandelbaum, Dr Matava, and Dr Jazrawi have disclosed no relevant financial relationships.
American Academy of Orthopaedic Surgeons (AAOS) 2015 Annual Meeting: Poster P474. Presented March 24, 2015.