Feb. 7, 2006

Terri Jo Rucinski, PT, ATC
University of North Carolina Sports Medicine

Anterior cruciate ligament injuries are prevalent in sports that involve jumping, cutting, and deceleration. The ACL injury rate is up to five times greater for females than males participating in soccer and basketball. There are several factors that have been found to place females at higher risk for ACL injury compared to their male counterparts. These risks include hormonal influences, intercondylar notch width, ligament size, joint laxity, limb alignment (Q angle), muscle strength, neuromuscular activation, sports activity and training/conditioning level. Although these risk factors have been identified; only a few are modifiable.

Since females are at greater risk for sustaining an injury to their anterior cruciate ligament, an intervention program aimed at reducing this risk would be beneficial. Several ACL prevention programs have been designed to correct the modifiable risk factors. These programs focus on teaching proper landing techniques, strength training of the lower extremities, proprioceptive-balance training and plyometric-agility training. Teaching athlete's to land properly includes having them land as softly as possible, landing with their knees bent, toes straight ahead with their knees over their toes, not letting the knee collapse inwards. Strength training should involve squats emphasizing proper form and alignment, lunges (forwards, sideways and with rotation), tube walking sideways, single leg squat touchdowns, prone strider hamstring curls, supine stability ball walkouts, medicine ball rotations side to side, medicine ball diagonal lifts as well as single leg squat touchdowns.

Proprioceptive-balance training focuses on single leg balance activities and works on improving an athlete's coordination as well as balance. Common exercises include single leg balance on an unstable surface (i.e., wobble board, balance disc, foam), and also incorporates upper extremity movements/exercises while standing on one leg. Plyometric-agility training involves having the athlete perform various jumping, landing and cutting activities in different planes of motion with varying levels of intensity. Common exercises include single leg hops with stabilization, squat jumps with stabilization and cone hopping forward/sideways with stabilization.

Due to the wide variety of intervention programs preventing ACL injuries in the female athlete, more studies focusing on the modifiable risk factors including muscle strength and human movement are needed. One such study is the Jump-ACL Study currently being conducted by the University of North Carolina in conjunction with the United States Air Force Academy, the United States Naval Academy and the United States Military Academy. The Jump-ACL Study involves screening the incoming cadets for possible ACL risk factors. The cadets have their postural alignment evaluated including Q angle, and navicular drop. The cadets also have a biomechanical analysis of their jump landings performed as well as evaluating their lower extremity strength. The cadets are then tracked for ACL injuries throughout their tenure at the academies. The Jump-ACL study aims to determine the association between neuromuscular risk factors, including poor jump-landing techniques and the rate of ACL injuries, it also aims to determine the association between selected non-neuromuscular risk factors (gender, anatomical factors, hormonal factors) and the rate of ACL injuries, and thirdly it aims to quantify the differences in neuromuscular risk factors between men and women. Outcomes of studies such as the Jump-ACL Study will help to develop more strategies in the prevention of ACL injuries in the female athlete.