| Anterior cruciate ligament (ACL) rupture is one of the most common and serious injuries in sports. ACL injuries have devastating influences on patients'activity levels and quality of life. In most cases, ACL injuries are non-contact mechanism of injuries which occur without physical contact between athletes. The ACL injuries occured with non-contact mechanisms can be prevented. The majority of ACL injuries occur in sports in which sudden deceleration, landing, and pivoting maneuvers are repeatedly performed. A better understanding of the mechanisms underlying the non-contact ACL injury will undoubtedly be an important step towards the prevention of such injuries. The purpose of this study developed a stochastic biomechanical model from a sagittal plane inverse dynamic knee model, and estimated the probability of ACL injury in selected sports events using stochastic biomechanical model and Monte Carlo Simulation as an attempt to understand the mechanisms and risk factors of ACL injuries.Kinematic, kinetic and EMG data were collected from subjects in five different sports events, including soccer, basketball, volleyball, Chinese martial arts, gymnastics and college students during side-cutting and stop-jump tasks. Lower extremity movement patterns and the parameters related with ACL loading were determined for each of these subjects. Monte Carlo Simulation was used to obtain the probability of ACL injury and biomechanical characteristics of simulated injury and non-injury jumps in different sports events, tasks and gender. The risk factors of ACL injuries were indentified by comparing the difference of biomechanical characteristics between injury and non-injury jumps. In addition, the study replaced the females'density distributions of independent variables with males'and then compared the difference of probability for ACL injury, which was helpful for better understanding of risk factors for non-contact ACL injury.The knee flexion angle and posterior ground reaction force are two important factors of ACL injury. The ACL is more likely to be injured when landing at a small knee flexion angle accompanied with a large posterior ground reaction force. Landing on the heels or the increase of the anterior-tilted tibial angle could increase the risk of ACL injury. Knee internal-external rotation moment, the hamstring and gastrocnemius forces have little effect on ACL loading. Female are more likely to have the ACL injuries than male. The major cause of gender difference in the risk of ACL injuries could be explained by the gender differences in lower extremity motor control. However, the smaller ACL injury loading for female and the knee anatomy also contribute to the gender difference in the risk of ACL injuries.The subjects are more likely at risk of injury during cutting task compared with stop-jump task. Non-sagittal plane biomechanics increase the contribution to ACL loading during cutting task. The basketball players have the highest risk of ACL injury compared with the other subjects. The volleyball and soccer athletes are also more likely to have ACL injury, while the Chinese martial arts athletes, female gymnasts and college students have a lower possibility. The distribution of the lower extremity biomechanics parameters could affect ACL injury and the mean or standard deviation could influence the ACL loading. The results also indicate that the targeted lower extremity configurations in future training programs for the prevention of ACL injuries should be different for different events, tasks or gender. The increased knee flexion angle and posterior-tilted tibial angle, and landing on toes may be used as specific training objectives of lower extremity configuration in training programs. Decrease the peak posterior ground reaction force can also be used as specific training objectives. |
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