LE3 .A278 2019

2019

Landry, Scott

Acadia University

Bachelor of Kinesiology

Honours

Kinesiology

Kinesiology

The anterior cruciate ligament (ACL) is an important stabilizer of the knee. Rupturing this ligament is considered to be one of the most devastating knee injuries that can occur in sport and has many short-and long-term consequences, including the costly surgery and rehabilitation and being more likely to develop knee osteoarthritis in the future. Non-contact ACL injuries are the most common ACL injuries, with common mechanisms for non-contact ACL injuries including landings from jumps, cutting and sudden decelerations. Before puberty, there is no sex difference for risk of sustaining an ACL injury. However, after puberty, females are 4 to 6 times more likely to sustain an ACL injury compared to their male counterparts. A proposed theory linked to increased injury risk and the sex bias of this injury is the leg dominance theory, which is described as significant asymmetries in muscular strength, joint loading or muscle recruitment patterns, especially in females. Mature females are thought to be more leg dominant compared to males, thus placing their lower extremity at greater risks of sustaining an ACL injury. The purpose of this study was to investigate the effect of task, sex and age on lower extremity sagittal plane asymmetry. The hypotheses for the current study are: a) post-pubescent females will have the greatest asymmetries compared to the other participant groups; b) pre-pubescent males and females will have similar asymmetries; c) single leg drop jumps (SLJ) will have greater asymmetries compared to double leg drop jumps (DLJ). A total of 125 athletes involved in cutting and jumping sports who were between the ages of 8-28 years participated in the current study. Participants were divided into four groups, pre-pubescent males (n=20, age=10.14± 1.61 years, playing experience = 4.55±2.31 years), pre-pubescent females (n=23, age=10.58±1.25 years, playing experience=5.96±1.77 years), post-pubescent males (n=37, age=20.73±2.53 years, playing experience=12.22±4.19 years) and post-pubescent females (n=45, age=19.73±1.85 years, playing experience=11.2±3.95 years). A 12-camera motion capture system and three force plates were used to capture sagittal plane joint angles and moments at the hip, knee and ankle during a double leg and single leg drop jump protocol. A three-way ANOVA (p £0.05) was used on asymmetry indexes of maximum sagittal plane moments and angles during stance and angles at initial contact to test for a task (DLJ vs. SLJ), sex (male vs. female), age (pre-pubescent vs. post-pubescent) and interaction effect. Bonferroni pairwise comparisons were performed when an interaction effect was identified. Results showed main (task and age) and interaction effects. It was found that pre-pubescent males had greater asymmetries (peak knee flexion angle, peak hip extension moment) compared to pre-pubescent females. This suggests that asymmetries should also be a focus within pre-pubescent athletes in addition to post-pubescent athletes. Furthermore, while not significant, there was a strong trend for post-pubescent females having greater asymmetries compared to pre-pubescent females for maximum hip extension moment. There were mixed results in terms of whether the DLJ or SLJ produced greater asymmetries. The SLJ had greater asymmetries compared to the DLJ for maximum ankle dorsiflexion and hip flexion angle, while the DLJ had greater asymmetries for ankle dorsiflexion angle at contact. More research is needed to determine whether or not the DLJ or SLJ yields greater limb asymmetry.These findings provide some insight into the influence that inter-limb asymmetry may have as a potential risk factor for non-contact ACL injuries in athletes

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https://scholar.acadiau.ca/islandora/object/theses:3234