As athletes have become stronger and the number of games they’re playing has increased, the incidence of anterior cruciate ligament (ACL) tears also has increased. “We’re making people bigger and stronger than they were 20 years ago and the amount of force generated is much higher. But their ligaments are still the same size,” says K. Donald Shelbourne, MD, orthopedic surgeon at Shelbourne Knee Center.
About two-thirds of ACL tears occur in games, where athletes are more likely to take chances, says Dr. Shelbourne. Risk factors for ACL tears, based on research conducted at Shelbourne Knee Center, include gender, race and sport.
ACL Tears More Common in Women
Because more men play sports than women, the number of ACL reconstructions is higher in men. Of 6,700 ACL reconstruction patients treated at Shelbourne Knee Center over 36 years,1 62% were male and 38% were female.
In general, female athletes are about twice as likely to tear their ACL as men.2 “There’s been a huge amount of speculative research on why women have more ACL tears. Our data show that the reason is that women have smaller intercondylar notches and ligaments,” says Dr. Shelbourne.
Shelbourne Research Center data show a statistically significant correlation between the mean intercondylar notch width and ACL tears:
- Normal ACL: 16.9 mm
- ACL tear:15.9 mm
- Normal: 15.4 mm
- ACL tear: 13.9 mm.3
The lower incidence of ACL tears in African Americans compared to Caucasians is also likely due to the size of the intercondylar notch, says Dr. Shelbourne. The intercondylar notches of African Americans are of a statistically significant greater width than the intercondylar notches of Caucasians:
- African American: 18.0 mm
- Caucasian:16.9 mm
- African American: 15.5 mm
- Caucasian: 14.1 mm.4
The Riskiest Sports
Nationally, athletes are most likely to injure their ACL playing soccer than any other sport. “Soccer players cannot predictably plant their foot because they’re getting jostled by an opponent while turning for the ball. A mis-planted foot can lead to an ACL tear,” says Dr. Shelbourne.
By percentage of ACL reconstructions performed at Shelbourne Knee Center, basketball is the riskiest sport for both men (32%) and women (34%). Other high-risk sports are:
- Football: 23%
- Soccer: 10%
- Soccer: 16%
- Volleyball: 11%.1
Most of these patients live in the Midwest. In other areas of the country, especially ski country, snow skiing has the highest risk of an ACL tear.
The top 3 sports by number of ACL reconstructions at Shelbourne Knee Center are:
- Males: 38.8%
- Females: 61.2%
- Males: 97.6%
- Females: 2.4%
- Males: 49.3%
- Females: 50.7%
While little can be done to prevent ACL tears, knowing the statistics helps Dr. Shelbourne and orthopedic surgeon Rodney Benner, MD, advise patients and their parents about risk.
Research-Backed, High-Volume Treatment
Lack of effective ways to prevent ACL tears is a key reason that Shelbourne Knee Center has developed a research-backed, three-phase protocol for treating ACL tears:
Pre-op physical therapy (rehab) to prepare patients for surgery and help them recover faster afterwards
ACL reconstruction using a patellar tendon graft, the strongest graft available
Post-op physical therapy (rehab) that prevents swelling and helps patients recover quickly.
Dr. Shelbourne and Dr. Benner also perform a high volume of ACL reconstructions: an average of about 140 procedures per year. The average orthopedic surgeon performs 10 or fewer ACL reconstructions per year, says Dr. Shelbourne.
For more information about our research and treatment of ACL tears, call 888-FIX-KNEE.
Shelbourne Knee Center, Internal research report, 2018.
Interview with K. Donald Shelbourne, April 2019.
Shelbourne KD, Davis TJ, Klootwyk TE. The relationship between intercondylar notch width of the femur and the incidence of anterior cruciate ligament tears. A prospective study. Am J Sports Med. 1998;26:402-408.
Shelbourne KD, Benner RW, Gray T. Intercondylar notch width measurement differences between African-American and Caucasian men and women with intact-ACL knees. Am J Sports Med. 2007;35:1304-1307.