Introduction: Anterior cruciate ligament (ACL) injuries are the most common ligamentous injury in the adolescent knee, resulting in long-term health consequences including early onset knee osteoarthritis and a high predominance of re-injury. The current ACL rehabilitation measures need improvement, in particular for adolescents. Information surrounding energy absorption strategies during demanding tasks may provide important insight into functional capacity and movement quality and could be a variable that is considered in ACL rehabilitation programs. The purpose of this thesis was therefore to evaluate energy absorption strategies in adolescent males and females with and without ACL injuries. Specifically, to first identify sex and injury status differences in lower extremity kinematics and kinetics in adolescent males and females with and without an ACL injury, and then secondly, determine if there is a generalizable relationship between strength and energy absorption strategies within these populations during drop-vertical jumps. Methods: Fifty-two ACL injured (17 males) and 68 control adolescent (34 males) males and females between the ages of 10 and 18 performed five trials of a lunge and drop vertical jump (DVJ) task. Ankle plantarflexion, and knee extension and flexion maximum voluntary isometric contractions (MVIC) were collected, along with 3D kinematics and kinetics including joint angles, joint moments, and energy absorption at the hip, knee, and ankle joint. Two-way analyses of variance (ANOVA), statistical non-parametric mapping (SnPM), and multiple linear regressions were used to determine statistically significant differences and relationships in joint kinematics, kinetics, and MVIC's between the male and female ACL injured and control individuals. Results: Males displayed greater knee extension torque compared to females, while controls displayed greater knee extension and ankle plantarflexion torque compared to ACL injured. There were no energy absorption differences found during the DVJ, however, during the lunge male controls display greater energy absorption compared to females. Furthermore, small effect sizes were found in the hip, knee, and ankle joint energy absorption for knee strength (knee extension or knee flexion), sex, and injury status. However, sex, injury status, and knee strength did not significantly add to the prediction of energy absorption. Conclusion: These findings indicate that isometric strength might be an important variable to be considered in ACL injury rehabilitation and injury prevention programs with injured individuals displaying weaker knee extension and ankle plantarflexion torques. However, energy absorption may not be as important of a variable to consider as there were limited statistically significant differences between injury status and sex at the hip, knee, and ankle joints. Additionally, there does not appear to be a generalizable relationship between hip, knee, and ankle energy absorption and knee flexion and extension isometric strength in male and female control and ACL injured individuals. Injured individuals absorb similar energy levels at each joint compared to controls, with isometric strength showing a weak relationship with energy absorption. Therefore, it is possible that there is not a specific energy absorption or muscular strength strategy that can be used to improve adolescent ACL rehabilitation measures.

Background: Epidemiological studies have demonstrated higher ACL injury rates in female athletes when compared to males involved in the same sport. A recent meta-analysis of ACL injury prevention programs found that technique training was a common component of programs that were successful in reducing ACL injury. Purpose: The primary purpose was to determine the immediate and long-term effects of technique training aimed at minimizing medial knee displacement during jump-landings in female recreational athletes. The secondary purpose was to determine if any transfer of skill occurred as a result of our technique training. Study Design: Controlled laboratory study. Methods: A total of 26 participants who presented with medial knee displacement during a basketball rebound screening task completed the study protocol. Participants were randomly assigned to two groups (experimental and control groups, 13 each). The experimental groups received jump landing instructions aimed at minimizing medial knee displacement. The control group received "sham" training consisting of jump training for maximum height. Baseline motion analyses of participants performing a basketball rebound task were performed prior to participants receiving technique training. Immediate and delayed retentions tests were performed after the initial instructional session and after home-based training. Additionally, motion analyses were also performed on a stop-jump task during the baseline assessment and the delayed retention test to help in determining if any transfer occurred. Results: The initial instructional session resulted in increased knee excursion and reduced peak knee adduction moments in the experimental group. Following home-based training, the experimental group continued to exhibit increased knee excursion along with decreased landing forces. No evidence of transfer was present following the initial training session or after home-based training. Conclusion: Our jump training instructions led to temporary changes, most notably increased knee excursion about the sagittal plane. No transfer of skill occurred as a result of our training. Clinical Relevance: Technique training instructions aimed at reducing medial knee displacement resulted in increased sagittal plane motion, but were unable to minimize medial knee displacement. ACL injury prevention programs may need to include a variety of drills, tasks, and sport-specific movements.

The knee is one of the most complex joints in the body, relying entirely on ligaments and muscles for stabilization. With the rise in people participating in sports, including a significant increase in female athletes, the prevalence of anterior cruciate ligament (ACL) injuries is very evident. With recent research showing that ACL injuries lead to osteoarthritis 10-20 years after the injury, determining the cause of these injuries to be able to prevent them is crucial. To date, both in-vivo and in-vitro techniques have been used to analyze the influences of the ACL injury including neuromuscular, anatomical, and kinematic. In-vivo techniques used to investigate knee kinematics is limited by the inability to take real ACL strain measurements while in-vitro techniques used to investigate anatomical considerations is limited by the inability to apply true muscular and kinematic forces. The purpose of the present thesis is to show the design and validation of a dynamic knee injury simulator. The simulator puts a cadaver knee, original ligaments and patellar tendon still attached, through motions which put the ACL at a high-risk of injury with realistic influence of muscles. The muscular influences are applied with actuators pulling the same force pro les as natural muscles. To get realistic muscle pro files, Anybody Software is used. Anybody Software is a modeling software which puts a skeletal system through prescribed motions and using an optimization algorithm calculates the muscle force pro file. The motion of the knee in the sagittal plane is simulated with actuators. The simulator consists of four actuators which are used in force control mode to add the muscle influence to the knee. Another two belt actuators are used for the joint motions, one each for the hip and ankle. The hip will move along the resultant Z motion and the ankle will move along the resultant Y motion. Simple gait is used for initial validation, the actuators chosen have speed and force capabilities for high-risk motions. The gait was successfully simulated and muscle force versus time profi le tracked the input well. The regression coeffcient study shows very good comparison. The hamstring muscle group is the only one which does not show very good comparison however this is only due to the jumpy nature of the hamstring profi le. The ACL strain fell within a similar range to published gait ACL strain data. The validation was successful, and with greater available force and speeds in the actuators, showing the use of this simulator during high-risk motions is possible.

The knee is one of the most complex joints in the body, relying entirely on ligaments and muscles for stabilization. With the rise in people participating in sports, including a significant increase in female athletes, the prevalence of anterior cruciate ligament (ACL) injuries is very evident. With recent research showing that ACL injuries lead to osteoarthritis 10-20 years after the injury, determining the cause of these injuries to be able to prevent them is crucial. To date, both in-vivo and in-vitro techniques have been used to analyze the influences of the ACL injury including neuromuscular, anatomical, and kinematic. In-vivo techniques used to investigate knee kinematics is limited by the inability to take real ACL strain measurements while in-vitro techniques used to investigate anatomical considerations is limited by the inability to apply true muscular and kinematic forces. The purpose of the present thesis is to show the design and validation of a dynamic knee injury simulator. The simulator puts a cadaver knee, original ligaments and patellar tendon still attached, through motions which put the ACL at a high-risk of injury with realistic influence of muscles. The muscular influences are applied with actuators pulling the same force pro les as natural muscles. To get realistic muscle pro files, Anybody Software is used. Anybody Software is a modeling software which puts a skeletal system through prescribed motions and using an optimization algorithm calculates the muscle force pro file. The motion of the knee in the sagittal plane is simulated with actuators. The simulator consists of four actuators which are used in force control mode to add the muscle influence to the knee. Another two belt actuators are used for the joint motions, one each for the hip and ankle. The hip will move along the resultant Z motion and the ankle will move along the resultant Y motion. Simple gait is used for initial validation, the actuators chosen have speed and force capabilities for high-risk motions. The gait was successfully simulated and muscle force versus time profi le tracked the input well. The regression coeffcient study shows very good comparison. The hamstring muscle group is the only one which does not show very good comparison however this is only due to the jumpy nature of the hamstring profi le. The ACL strain fell within a similar range to published gait ACL strain data. The validation was successful, and with greater available force and speeds in the actuators, showing the use of this simulator during high-risk motions is possible.

No description available.

Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.

It´s important to consider all the risks that the players are exposed to and have a holistic view on the matter. The conclusions from my sponsor and looking through research in the area I came to the conclusion that surface and shoes have minimal consequences and are not an area of interest for me in this project.

Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.

No description available.

Women are four to eight times more likely to injure their anterior cruciate ligament (ACL) compared to men. It is most commonly injured through a non-contact mechanism during game time situations. During landings, women display valgus collapse, where a less active gluteus medius muscle (GMed) may be unable to control the internal rotation of the thigh, causing an increase in knee joint abduction angle, augmenting the risk of ACL injury. This study’s purpose was to determine the difference between 12 male and 12 female athletes in muscle activity, specifically the GMed, and the 3D kinematics and kinetics of the lower-limb during drop jump landings from three heights; maximum vertical jump height, tibial length, and a commonly used height of 40cm. Results showed that females had greater hip adduction and knee abduction angles compared to men. The GMed activity showed no significant differences between sexes at each drop jump height.