Physician Assistant M.S.

Year Approved


First Advisor

Ingraham, Stacy


Introduction: Young, active populations who play sports that include sudden cutting motions, are at heightened risk of injury to the anterior cruciate ligament (ACL). Female athletes with increased joint laxity and subsequent hyperextension of the knee, are at greatest risk of ACL injury when compared to males. Purpose: The purpose of this retrospective study was to explore the incidence of dynamic knee hyperextension in high school soccer athletes by sex and team level, as observed through high-speed photography. This could lead to a potentially practicable screening tool for identifying high school soccer athletes at increased risk of ACL injury. Methods: Dynamic knee extension of 87 male (n=41) and female (n=46) high school soccer athletes was captured using high-speed photography while punting a soccer ball. One photo demonstrating each athlete’s maximal knee extension was assessed for degree of extension, both visually and using Kinovea, a motion analysis software program. Results: Multinomial logistic regression regarding certainty of hyperextension with a 5-point scale by two judges showed no significant differences by sex of the player (p=.456) or team level (p=.064). Results of binary logistic regression on the presence or absence of observed hyperextension showed no significant differences by sex of the players (p=.702) or by team level (p=.191). Results of categorical data analysis showed no significant differences among six player groups consisting of freshman, junior varsity, and varsity levels for both boys and girls (chi-square=3.928, p=.560). Interestingly, there was an increased incidence of hyperextension in younger athletes. The incidence of hyperextension among all participants of this study is not congruent with published ACL injury surveillance, confirming the multifactorial nature of ACL injuries. Conclusion: The results indicate that with a larger sample size, a difference between team levels may emerge. Based on the agreement between visual analyzers and Kinovea measurement, visual observation of active hyperextension could potentially serve as a screening tool for ACL injury potential. More research is needed to identify the relationship between observed dynamic knee hyperextension and ACL injury.

Degree Name

Masters of Science in Physician Assistant

Document Type

Masterʼs thesis

Included in

Primary Care Commons