Anterior Cruciate Ligament Injuries in Athletes

ACL Injury in Pediatric Athletes -
Differences between males and females

Authors:

1. Kevin G. Shea MD, Intermountain Orthopaedics, Boise, ID
2. Ronald P Pfeiffer EdD, ATC, Boise State University, Boise, ID
3. Johan Wang ATC, MS, Boise State University, Boise, ID
4. Mike Curtin MD, Intermountain Orthopaedics, Boise, ID, United States of America

Objective:  Adult female athletes sustain ACL injuries at two to eight times the rate of men. Recent studies on female athletes suggest that the risk of ACL injury can be reduced with exercise intervention programs. There is limited research about the incidence of ACL tears in pediatric and adolescent athletes. The purpose of this study was twofold: (1) to analyze the incidence and age of onset of ACL and other knee injury in pediatric and adolesecent athletes, and (2) provide recommendations for the age of implementation of ACL injury prevention programs for female athletes.

Methods:  This study was a retrospective review of insurance data. Bene-marc, Inc.® provides injury insurance to youth soccer leagues throughout North America. Injury claims filed by youth soccer participants for the 5-year period from 1995 to 1999 were examined, which represented approximately 6 million athletes. A total of 8215 claims (3340 females, 4875 males) were submitted for reimbursement during the study period. The data were divided into 2 categories: 1) knee injury claims, and 2) ACL injury claims. The data were analyzed to determine the age of onset of knee and ACL injury, and to evaluate the differences between males and females

Results:  Claims for knee injuries accounted for 22% overall of total injury claims filed (30% for females, 16% for males). The youngest subject filing a claim for ACL injury was age 5 (male) and age 11 (female). ACL injury claims represented 31% of total knee injury claims (37% in females and 24% in males). Ratios of ACL injury/knee injury increased with age for both sexes. Females demonstrated higher ratios of ACL injury/total knee injury claims when compared to males, for all age groups. A notable increase in ACL injury occurred at ages 11-12 for females, and at age 15-16 for males.

Conclusions:  The incidence of ACL injury and knee injuries increases at age 11-12 for females, and age 15-16 for males. Pediatric and adolescent female athletes appear to have a higher risk of ACL injury and knee injury compared with males. Continued research related to etiology and prevention of ACL injury will need to focus upon pediatric and adolescent patients. If proven effective, intervention programs designed to reduce the incidence of ACL injury in female athletes should be implemented prior to age 11-12 in females.

A DROP LANDING STUDY COMPARING MUSCLE RECRUITMENT STRATEGIES AND LANDING MECHANICS OF PREADOLESCENT MALE AND FEMALE SOCCER PLAYERS

PI—Ms. Jeanie Sutter (Master’s Thesis study)

Co-PIs--Thesis Committee—R. Pfeiffer, (Chair), M. Sabick & C. Harris (Committee Members)

Medical Consultant—K.G. Shea, MD

BACKGROUND:  Anterior cruciate ligament (ACL) injuries in female athletes have become a focus of medical professionals and researchers in the last decade.  The incidence of ACL injuries in female athletes is estimated two to eight times greater as compared to male athletes participating in the same sport (Ardent and Dick, 1995).  In a study exploring muscle recruitment strategies and landing techniques, Cowling and Steele (2001) found that landing strategies employed by female athletes with respect to timing and recruitment of muscles around the knee differ from male athletes potentially putting females at greater risk for ACL injuries. 

PURPOSE:  The purpose of this study is to examine and compare muscle recruitment strategies in nine and ten year old male and female soccer players during a dynamic hand-drop maneuver.

HYPOTHESES:  1) There will be no difference in muscle activation patterns of the knee relative to time of peak knee shear forces in male and female youth soccer players when performing a one-footed landing from a height of 15 inches.  2)  There will be no difference in landing mechanics of the knee in male and female youth soccer players when performing a one-footed landing from a height of 15 inches.  3) There will be no difference in landing impact forces in male and female youth soccer players when performing a one-footed landing from a height of 15 inches.

METHODS:  Surface electrodes will be placed over the following muscles: rectus femoris, vastus lateralis, vastus medialis, lateral hamstring, and the medial head of the gastrocnemius.  Subjects will hang from a horizontal bar approximately 15 inches above the ground and, on command, drop onto a floor mounted force plate with a one-footed landing.  Kinematic data, force data (peak vertical & peak anterior shear), and sEMG will be used to assess muscle activation patterns, timing of peak vertical and shear forces relative to muscle onset times, and landing mechanics (hip, knee, ankle angles at impact).

ANALYSIS:   Independent t-tests will be used to show relationships between males and females with regard to kinematic, force, and sEMG data. 

Contact: Ron Pfeiffer, EdD rpfeiff@boisestate.edu

Last Updated 03/24/2005