Materiały źródłowe

• #1 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  The anterior cruciate ligament (ACL) is one of 2 cruciate ligaments that aids in stabilizing the knee joint. It is a strong band made of connective tissue and collagenous fibers that originate from the anteromedial aspect of the intercondylar region of the tibial plateau and extends posterolaterally to attach to the medial aspect of the lateral femoral condyle, where there are two important landmarks; The lateral intercondylar ridge which defines the anterior boundary of the ACL, and the bifurcate ridge which separates the 2 ACL bundles. The ACL measures 32 mm long and is 7 to 12 mm wide. It has two bundles; an isometric anteromedial and a posterolateral bundle with more versatile length changes.[1] […] The anteromedial bundle is the tightest in flexion and is mainly responsible for anterior tibial translation (85% of the stability), whereas the posterolateral bundle is the tightest in extension, with the main role in providing medial-lateral and rotational stability (secondary restraint).[2][3][4]

• #2 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  The ACL is the most commonly injured ligament in the knee, almost half of all knee injuries. The annual reported incidence in the United States alone is approximately 1 in 3500 people. There are approximately 400,000 ACL reconstructions every year in the united states.[13] However, data may not be accurate as there is no standard surveillance. […] There is no age or gender bias; however, it has been suggested that women are at an increased risk of ACL injury secondary to a multitude of factors.[14] In athletes, the female-to-male ratio has been reported to be 4.5: 1. Female athletes tend to get ACL ruptures at a younger age and more in the supporting leg versus the kicking leg in males. […] Among the factors increasing the female risk, as suggested by some studies that females may have weaker hamstrings (more quadriceps dominant) and preferential recruitment of the quadriceps muscle group while decelerating. Engaging the quadriceps musculature while slowing down places abnormally increased stresses on the ACL, as the quadriceps muscles are less effective at preventing anterior tibial translation versus the hamstring muscles. Additionally, females have weaker core stability than males.

• #3 Anterior Cruciate Ligament Injury: Practice Essentials, Background, Functional Anatomy

  https://emedicine.medscape.com/article/89442-overview

  Anterior cruciate ligament (ACL) injuries are most often a result of low-velocity, noncontact, deceleration injuries and contact injuries with a rotational component. Contact sports also may produce injury to the ACL secondary to twisting, valgus stress, or hyperextension, all directly related to contact or collision. […] The ACL is the primary (85%) restraint to limit anterior translation of the tibia. The greatest restraint is in full extension. […] When the ACL is injured, a combination of anterior translation and rotation occurs. […] Femoral notch stenosis is the ratio of the femoral notch width to the width of the femoral condyles. A notch width index of less than 0.2 is defined as notch stenosis. Individuals with notch stenosis have a higher risk of noncontact ACL injuries. […] The current failure rate for ACL reconstruction is approximately 8%. The 3 major categories of failure in an ACL reconstruction are (1) arthrofibrosis (due to inflammation of the synovium and fat pad), (2) pain that limits motion, and (3) recurrent instability, secondary to significant laxity in the reconstructed ligament.

• #4 The mechanism and cause of anterior cruciate ligament tear in the Korean military environment | Knee Surgery & Related Research | Full Text

  https://kneesurgrelatres.biomedcentral.com/articles/10.1186/s43019-019-0015-1

  Anterior cruciate ligament (ACL) injury is very common but few studies have analyzed the injury mechanism and cause of ACL tear in a specific environment such as a military institution. […] The main mechanism of ACL injury occurring in the military environment was non-contact injury, especially on changing the direction of the lower leg. […] The results showed that the overwhelming majority of ACL injuries occurred through non-contact injury, accounting for 84.5% of the total. […] First of all, the main mechanism of ACL injury that occurred during military service was due to non-contact injury, most commonly by changing the direction of the lower leg at the time of injury, followed by landing with the knee in the valgus position. […] This study showed that ACL injuries occurred more frequently through non-contact injury (84.5%) than through contact injury (15.5%), which is similar to the results of previous studies conducted in the sports setting, which reported non-contact injury as the cause of up to 70% of all ACL injuries.

• #5 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Mechanism of ACL Injury This ligament is most commonly ruptured, often in association with the tears of medial or lateral collateral ligaments. Commonly it occurs as a result of twisting force on a semi-flexed knee. Often the injury to medial collateral ligament, medial meniscus and anterior cruciate ligament occurs together. Types of ACL injuries Three major types of ACL injuries are described: Direct Contact : 30% of the cases Indirect Contact Non-Contact : 70% of the cases : by doing a wrong movement […] The anterior cruciate ligament (ACL) injuries are common in young individuals who participate in sports activities associated with pivoting, decelerating and jumping. Most common are the non-contact injuries are more likely to occur with lower BMI, it caused by forces generated within the athletes body. Approximately 75% of ruptures are sustained with minimal or no contact at the time of injury. A cut-and-plant movement is the typical mechanism that causes the ACL to tear, being a sudden change in direction or speed with the foot firmly planted. Rapid deceleration moments, including those that also involve planting the affected leg to cut and change direction, have also been linked to ACL injuries, as well as landing from a jump, pivoting, twisting, and direct impact to the front of the tibia.

• #6 Epidemiology, Injury Mechanism, and Etiology of ACL Injuries | SpringerLink

  https://link.springer.com/10.1007/978-3-031-29430-3_30

  With an estimated annual incidence of 120,000 in the United States, anterior cruciate ligament (ACL) injuries are commonly encountered in athletes of all skill levels. […] The anterior cruciate ligament is an important stabilizer of the knee, primarily resisting anterior translation and internal rotation of the tibia in relation to the femur. […] When the knee experiences forces that exceed the tensile strength of the ACL, a rupture of the ligament occurs that can be associated with concomitant injuries to the meniscus, cartilage, and other ligaments. […] The majority of ACL tears are noncontact injuries occurring during landing, pivoting, or cutting. […] The typical mechanism is an abrupt axial force applied to a slightly flexed knee causing a dynamic valgus moment with internal tibial rotation.

• #7 Epidemiology, Injury Mechanism, and Etiology of ACL Injuries | SpringerLink

  https://link.springer.com/10.1007/978-3-031-29430-3_30

  With an estimated annual incidence of 120,000 in the United States, anterior cruciate ligament (ACL) injuries are commonly encountered in athletes of all skill levels. […] The anterior cruciate ligament is an important stabilizer of the knee, primarily resisting anterior translation and internal rotation of the tibia in relation to the femur. […] When the knee experiences forces that exceed the tensile strength of the ACL, a rupture of the ligament occurs that can be associated with concomitant injuries to the meniscus, cartilage, and other ligaments. […] The majority of ACL tears are noncontact injuries occurring during landing, pivoting, or cutting. […] The typical mechanism is an abrupt axial force applied to a slightly flexed knee causing a dynamic valgus moment with internal tibial rotation.

• #8 Anterior Cruciate Ligament Injury: Diagnosis, Management, and Prevention | AAFP

  https://www.aafp.org/pubs/afp/issues/2010/1015/p917.html

  There are an estimated 80,000 to 100,000 anterior cruciate ligament (ACL) repairs in the United States each year. Most ACL tears occur from noncontact injuries. […] The ACL is the primary stabilizing structure of the knee. It originates from the posterior aspect of the femur coursing medially, inserting on the anterior aspect of the tibia. The ligament is intracapsular but is located outside the synovial fluid. The ACL is the primary restraint to anterior translation of the tibia, as well as tibial internal rotation. […] ACL injuries caused by contact require a fixed lower leg (i.e., when planted) and torque with enough force to cause a tear. Contact injuries account for only about 30 percent of ACL injuries. The remaining 70 percent of ACL tears are noncontact injuries occurring primarily during deceleration of the lower extremity, with the quadriceps maximally contracted and the knee at or near full extension. In noncontact scenarios, the stress on the ACL resembles that of a collision of the knee. When the knee is at or near full extension, quadriceps contraction increases ACL tensile force. The hamstrings, which stabilize the ACL posteriorly, are often minimally contracted during these injuries, particularly if the hip is extended and the body weight is on the heel, allowing for excessive forward shifting of the femur on the tibia. Examples of this type of noncontact injury include skiers or snowboarders whose ankles are locked when they fall backward onto the snow; soccer players who execute sudden cutting maneuvers; or basketball players who land on an internally rotated knee without full flexion.

• #9 Mechanism of Anterior Cruciate Ligament Injury in Female Soccer Players

  https://brieflands.com/articles/asjsm-13322

  The risk of anterior cruciate ligament (ACL) injury is higher in female soccer players than in male soccer players. The most common reason for non-contact ACL injury has been found to be a cutting or stopping maneuver combined with deceleration and landing from a jump. […] Non-contact ACL injuries have been reported to account for 70% – 84% of ACL injuries in athletes. These injuries mainly result from a cutting or stopping maneuver combined with deceleration and landing from a jump. The alignment associated with a non-contact ACL injury occurs during a deceleration task with the body weight shifted over to the injured leg and the plantar surface of the foot fixed flat on the ground. The knee alignment associated with non-contact ACL injury involves lower flexion, valgus, and internal rotation.

• #10 ACL (Anterior Cruciate Ligament) Injuries Guide: Causes, Symptoms and Treatment Options

  https://www.drugs.com/health-guide/acl-anterior-cruciate-ligament-injuries.html

  An ACL injury is a sprain or tear, in which the ligament is stretched beyond its normal range. When the ACL is torn, it’s almost always due to at least one of the following patterns of injury: […] A sudden stop, twist, pivot or change in direction at the knee joint — These knee movements are a routine part of football, basketball, soccer, rugby, gymnastics and skiing. For this reason, athletes who participate in these sports have an especially high risk of ACL tears. […] Extreme hyperextension of the knee — Sometimes, during athletic jumps and landings, the knee straightens out more than it should and extends beyond its normal range of motion, causing an ACL tear. This type of ACL injury often occurs because of a missed dismount in gymnastics or an awkward landing in basketball. […] Direct contact — The ACL may be injured during contact sports, usually during direct impact to the outside of the knee or lower leg. Examples are a sideways football tackle, a misdirected soccer kick that strikes the knee or a sliding tackle in soccer.

• #11 ACL (Anterior Cruciate Ligament) Injuries Guide: Causes, Symptoms and Treatment Options

  https://www.drugs.com/health-guide/acl-anterior-cruciate-ligament-injuries.html

  An ACL injury is a sprain or tear, in which the ligament is stretched beyond its normal range. When the ACL is torn, it’s almost always due to at least one of the following patterns of injury: […] A sudden stop, twist, pivot or change in direction at the knee joint — These knee movements are a routine part of football, basketball, soccer, rugby, gymnastics and skiing. For this reason, athletes who participate in these sports have an especially high risk of ACL tears. […] Extreme hyperextension of the knee — Sometimes, during athletic jumps and landings, the knee straightens out more than it should and extends beyond its normal range of motion, causing an ACL tear. This type of ACL injury often occurs because of a missed dismount in gymnastics or an awkward landing in basketball. […] Direct contact — The ACL may be injured during contact sports, usually during direct impact to the outside of the knee or lower leg. Examples are a sideways football tackle, a misdirected soccer kick that strikes the knee or a sliding tackle in soccer.

• #12 The Mechanism of Anterior Cruciate Ligament Injuries in the National Football League: A Systematic Video Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9970728/

  Another factor we correlated with ACL injury, consistent with previous literature, was decreased knee flexion. […] The high rate of ACL injury at knee flexion between 0 and 30 (62.3%) observed in our study further supports the previous video analysis and biomechanical studies. […] This is the first study to associate foot positioning preceding ACL injury in NFL athletes, as most studies on sports-related ACL injuries do not assess or highlight initial foot-to-ground contact as a risk factor for injury. […] The compounded forces of heel striking may transmit to the ACL preferentially and increase injury susceptibility. […] In contrast to a recent video analysis study of ACL tears in NFL players, our study found that the majority of ACL injuries occurred via a contact mechanism (58%), including both direct and indirect contact. […] The high injury rates among receivers and defensive backs in our study are likely multifactorial. […] Most ACL injuries in NFL athletes are associated with contact, brisk deceleration, and shallow knee and hip flexion angles. […] Additionally, heel strike is a major kinematic risk factor for injury in this player population.

• #13 The Mechanism of Anterior Cruciate Ligament Injuries in the National Football League: A Systematic Video Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9970728/

  Another factor we correlated with ACL injury, consistent with previous literature, was decreased knee flexion. […] The high rate of ACL injury at knee flexion between 0 and 30 (62.3%) observed in our study further supports the previous video analysis and biomechanical studies. […] This is the first study to associate foot positioning preceding ACL injury in NFL athletes, as most studies on sports-related ACL injuries do not assess or highlight initial foot-to-ground contact as a risk factor for injury. […] The compounded forces of heel striking may transmit to the ACL preferentially and increase injury susceptibility. […] In contrast to a recent video analysis study of ACL tears in NFL players, our study found that the majority of ACL injuries occurred via a contact mechanism (58%), including both direct and indirect contact. […] The high injury rates among receivers and defensive backs in our study are likely multifactorial. […] Most ACL injuries in NFL athletes are associated with contact, brisk deceleration, and shallow knee and hip flexion angles. […] Additionally, heel strike is a major kinematic risk factor for injury in this player population.

• #14 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Mechanism of ACL Injury This ligament is most commonly ruptured, often in association with the tears of medial or lateral collateral ligaments. Commonly it occurs as a result of twisting force on a semi-flexed knee. Often the injury to medial collateral ligament, medial meniscus and anterior cruciate ligament occurs together. Types of ACL injuries Three major types of ACL injuries are described: Direct Contact : 30% of the cases Indirect Contact Non-Contact : 70% of the cases : by doing a wrong movement […] The anterior cruciate ligament (ACL) injuries are common in young individuals who participate in sports activities associated with pivoting, decelerating and jumping. Most common are the non-contact injuries are more likely to occur with lower BMI, it caused by forces generated within the athletes body. Approximately 75% of ruptures are sustained with minimal or no contact at the time of injury. A cut-and-plant movement is the typical mechanism that causes the ACL to tear, being a sudden change in direction or speed with the foot firmly planted. Rapid deceleration moments, including those that also involve planting the affected leg to cut and change direction, have also been linked to ACL injuries, as well as landing from a jump, pivoting, twisting, and direct impact to the front of the tibia.

• #15

  https://www.orthobullets.com/knee-and-sports/3008/acl-tear

  ACL tears are common athletic injuries leading to anterior and lateral rotatory instability of the knee. […] Pathophysiology includes non-contact pivoting injury where the tibia translates anteriorly while the knee is in slight flexion and valgus. […] A blow to the lateral aspect of the knee is also a mechanism of injury. […] The common activities associated with ACL injuries are soccer, basketball, skiing, and football. […] There is a pre-ponderance for females due to landing biomechanics and neuromuscular activation patterns (quadriceps dominant) playing the biggest role.

• #16 Indirect contact is the primary mechanism of anterior cruciate ligament injury in professional male basketball. – Barça Innovation Hub

  https://barcainnovationhub.fcbarcelona.com/blog/indirect-contact-is-the-primary-mechanism-of-anterior-cruciate-ligament-injury-in-professional-male-basketball/

  Injuries that occurred after a jump were often associated with rebounding, blocking, boxing out, or layups, and in the majority of cases, there was indirect contact (88%) and landing on a single leg (88%). […] In terms of biomechanics, injuries generally involved knee flexion (with minimal hip/trunk flexion and reduced plantar flexion) in the sagittal plane and knee valgus loading in most cases (75%). […] Injuries are recurrent when a neurocognitive error or distraction occurs during a change of direction in an attempt to tackle or block. […] Recurrent injuries often stem from neurocognitive errors or distractions when changing direction in attempts to tackle or block. […] This likely stems from the study’s results, showcasing players relying more on rapid lateral movements and increased accelerations and decelerations, common causes of ACL injuries.

• #17 Indirect contact is the primary mechanism of anterior cruciate ligament injury in professional male basketball. – Barça Innovation Hub

  https://barcainnovationhub.fcbarcelona.com/blog/indirect-contact-is-the-primary-mechanism-of-anterior-cruciate-ligament-injury-in-professional-male-basketball/

  Indirect contact is the primary mechanism of anterior cruciate ligament injury in professional male basketball. […] Anterior cruciate ligament (ACL) injuries are among the most serious that basketball players face. […] Although return-to-play rates are high, there is a risk of early development of knee osteoarthritis, which can shorten careers and translate into decreased physical and athletic performance. […] However, despite basketball involving contact, it is considered a non-contact sport, meaning it is a type of discipline where injury prevention can be more effective than in other sports like rugby or soccer. […] According to the study, most occurred during offensive actions (69%). However, only one was due to direct contact (3%) – for example, a collision with an opponent’s knee – while the majority were due to indirect contact (58%) – incorrect landing, sudden change of direction, etc. – and over a third were non-contact (39%) – hyperflexion, fatigue, etc.

• #18 Biomechanics and situational patterns associated with anterior cruciate ligament injuries in the National Basketball Association (NBA) | British Journal of Sports Medicine

  https://bjsm.bmj.com/content/57/21/1395

  No injuries with video available for review involved direct contact with the injured knee. More specifically, no injury since 2011, including a total of 33 injuries, involved direct knee contact. […] Indirect contact accounts for the majority of ACL tears in NBA players, while direct contact to the knee was not observed in the videos that were available to review. Hip abduction and trunk tilt towards the injured leg on IC of the foot with the ground, as well as increases in knee valgus and knee flexion, following IC, may precipitate ACL injury situations in NBA athletes. The most common situational patterns observed include attacking the basket and landing following a jump.

• #19 Video analysis of trunk and knee motion during non-contact anterior cruciate ligament injury in female athletes: lateral trunk and knee abduction motion are combined components of the injury mechanism | British Journal of Sports Medicine

  https://bjsm.bmj.com/content/43/6/417

  The combined positioning of the trunk and knee in the coronal and sagittal planes during non-contact anterior cruciate ligament (ACL) injury has not been previously reported. […] During ACL injury female athletes demonstrate greater lateral trunk and knee abduction angles than ACL-injured male athletes and uninjured female athletes. […] Lateral trunk and knee abduction motion are important components of the ACL injury mechanism in female athletes as observed from video evidence of ACL injury. […] Knee abduction loads and neuromuscular control of the trunk both predict ACL injury risk with high sensitivity and specificity in female athletes. […] The mechanism of non-contact ACL injury may differ in females and males, especially with respect to the dynamic positioning of the knee, as females demonstrate greater valgus collapse of the lower extremity primarily in the coronal plane.

• #20 The Mechanism of Anterior Cruciate Ligament Injuries in the National Football League: A Systematic Video Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9970728/

  Another factor we correlated with ACL injury, consistent with previous literature, was decreased knee flexion. […] The high rate of ACL injury at knee flexion between 0 and 30 (62.3%) observed in our study further supports the previous video analysis and biomechanical studies. […] This is the first study to associate foot positioning preceding ACL injury in NFL athletes, as most studies on sports-related ACL injuries do not assess or highlight initial foot-to-ground contact as a risk factor for injury. […] The compounded forces of heel striking may transmit to the ACL preferentially and increase injury susceptibility. […] In contrast to a recent video analysis study of ACL tears in NFL players, our study found that the majority of ACL injuries occurred via a contact mechanism (58%), including both direct and indirect contact. […] The high injury rates among receivers and defensive backs in our study are likely multifactorial. […] Most ACL injuries in NFL athletes are associated with contact, brisk deceleration, and shallow knee and hip flexion angles. […] Additionally, heel strike is a major kinematic risk factor for injury in this player population.

• #21 Video analysis of trunk and knee motion during non-contact anterior cruciate ligament injury in female athletes: lateral trunk and knee abduction motion are combined components of the injury mechanism | British Journal of Sports Medicine

  https://bjsm.bmj.com/content/43/6/417

  Most ACL injuries in females occur by non-contact mechanisms during landing, deceleration and lateral pivoting. […] The mechanism of non-contact ACL injuries as observed on video has several common components in female athletes: high knee abduction, lateral trunk motion with the body shifted over the injured leg and the plantar surface of the foot fixed flat on the playing surface, displaced away from the centre of mass of the body and low knee flexion. […] Perturbation of the trunk, game or competitive situation and another player within close proximity are other common components of the mechanism. […] If the trunk moves laterally, the ground reaction force (GRF) vector may move laterally and have a greater lever arm relative to the knee joint centre. […] Knee abduction torque places knee ligaments in the high slope (load) segment of their force-length curve and elicits knee pain in female athletes.

• #22 Revisiting the Role of Knee External Rotation in Non-Contact ACL Mechanism of Injury

  https://www.mdpi.com/2076-3417/13/6/3802

  An anterior cruciate ligament (ACL) tear is a severe sports injury that often occurs in young athletes. […] The present work aims to evaluate which knee kinetics result in higher ACL stress and strain. […] The results demonstrated that the peak stress (11.00 MPa) and strain (0.048) occurred at the midportion of the anteromedial bundle with the higher values being obtained under a combined knee valgus, flexion, tibial external rotation and high axial load. […] The tibial external rotation showed a higher contribution to the peak ACL stress and strain as compared to internal rotation. […] These results reinforce the role of axial load and highlight the importance of external rotation on ACL stress and strain, which may be suggestive of the ACL tear mechanism. […] The understanding of how the ACL is torn during a noncontact mechanism is crucial to determine which anatomical structures are ruptured and improve the knowledge on the tear mechanism for diagnostic and treatment purposes.

• #23 Video analysis of trunk and knee motion during non-contact anterior cruciate ligament injury in female athletes: lateral trunk and knee abduction motion are combined components of the injury mechanism | British Journal of Sports Medicine

  https://bjsm.bmj.com/content/43/6/417

  Most ACL injuries in females occur by non-contact mechanisms during landing, deceleration and lateral pivoting. […] The mechanism of non-contact ACL injuries as observed on video has several common components in female athletes: high knee abduction, lateral trunk motion with the body shifted over the injured leg and the plantar surface of the foot fixed flat on the playing surface, displaced away from the centre of mass of the body and low knee flexion. […] Perturbation of the trunk, game or competitive situation and another player within close proximity are other common components of the mechanism. […] If the trunk moves laterally, the ground reaction force (GRF) vector may move laterally and have a greater lever arm relative to the knee joint centre. […] Knee abduction torque places knee ligaments in the high slope (load) segment of their force-length curve and elicits knee pain in female athletes.

• #24 The effect of foot landing position on biomechanical risk factors associated with anterior cruciate ligament injury | Journal of Experimental Orthopaedics | Full Text

  https://jeo-esska.springeropen.com/articles/10.1186/s40634-016-0049-1

  Identification of biomechanical risk factors associated with anterior cruciate ligament (ACL) injury can facilitate injury prevention. […] The authors hypothesize that 1) relative to neutral, the toe-in position increases the biomechanical risk factors for ACL injury, 2) the toe-out position decreases these biomechanical risk factors, and 3) compared to males, females demonstrate greater changes in lower extremity biomechanics with changes in foot landing position. […] Relative to neutral, landing in the toe-in position increased peak hip adduction, knee internal rotation angles and moments, and peak knee abduction angle. […] Toe-in landing position exacerbates biomechanical risk factors associated with ACL injury, while toe-out landing position decreases these factors. […] A combination of increased hip adduction and internal rotation, decreased knee flexion, increased knee abduction and internal or external tibial rotation, termed dynamic knee valgus, may increase the risk of ACL injury.

• #25 The Mechanism of Anterior Cruciate Ligament Injuries in the National Football League: A Systematic Video Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9970728/

  Another factor we correlated with ACL injury, consistent with previous literature, was decreased knee flexion. […] The high rate of ACL injury at knee flexion between 0 and 30 (62.3%) observed in our study further supports the previous video analysis and biomechanical studies. […] This is the first study to associate foot positioning preceding ACL injury in NFL athletes, as most studies on sports-related ACL injuries do not assess or highlight initial foot-to-ground contact as a risk factor for injury. […] The compounded forces of heel striking may transmit to the ACL preferentially and increase injury susceptibility. […] In contrast to a recent video analysis study of ACL tears in NFL players, our study found that the majority of ACL injuries occurred via a contact mechanism (58%), including both direct and indirect contact. […] The high injury rates among receivers and defensive backs in our study are likely multifactorial. […] Most ACL injuries in NFL athletes are associated with contact, brisk deceleration, and shallow knee and hip flexion angles. […] Additionally, heel strike is a major kinematic risk factor for injury in this player population.

• #26 Revisiting the Role of Knee External Rotation in Non-Contact ACL Mechanism of Injury

  https://www.mdpi.com/2076-3417/13/6/3802

  An anterior cruciate ligament (ACL) tear is a severe sports injury that often occurs in young athletes. […] The present work aims to evaluate which knee kinetics result in higher ACL stress and strain. […] The results demonstrated that the peak stress (11.00 MPa) and strain (0.048) occurred at the midportion of the anteromedial bundle with the higher values being obtained under a combined knee valgus, flexion, tibial external rotation and high axial load. […] The tibial external rotation showed a higher contribution to the peak ACL stress and strain as compared to internal rotation. […] These results reinforce the role of axial load and highlight the importance of external rotation on ACL stress and strain, which may be suggestive of the ACL tear mechanism. […] The understanding of how the ACL is torn during a noncontact mechanism is crucial to determine which anatomical structures are ruptured and improve the knowledge on the tear mechanism for diagnostic and treatment purposes.

• #27 Revisiting the Role of Knee External Rotation in Non-Contact ACL Mechanism of Injury

  https://www.mdpi.com/2076-3417/13/6/3802

  An anterior cruciate ligament (ACL) tear is a severe sports injury that often occurs in young athletes. […] The present work aims to evaluate which knee kinetics result in higher ACL stress and strain. […] The results demonstrated that the peak stress (11.00 MPa) and strain (0.048) occurred at the midportion of the anteromedial bundle with the higher values being obtained under a combined knee valgus, flexion, tibial external rotation and high axial load. […] The tibial external rotation showed a higher contribution to the peak ACL stress and strain as compared to internal rotation. […] These results reinforce the role of axial load and highlight the importance of external rotation on ACL stress and strain, which may be suggestive of the ACL tear mechanism. […] The understanding of how the ACL is torn during a noncontact mechanism is crucial to determine which anatomical structures are ruptured and improve the knowledge on the tear mechanism for diagnostic and treatment purposes.

• #28 The effect of foot landing position on biomechanical risk factors associated with anterior cruciate ligament injury | Journal of Experimental Orthopaedics | Full Text

  https://jeo-esska.springeropen.com/articles/10.1186/s40634-016-0049-1

  Identification of biomechanical risk factors associated with anterior cruciate ligament (ACL) injury can facilitate injury prevention. […] The authors hypothesize that 1) relative to neutral, the toe-in position increases the biomechanical risk factors for ACL injury, 2) the toe-out position decreases these biomechanical risk factors, and 3) compared to males, females demonstrate greater changes in lower extremity biomechanics with changes in foot landing position. […] Relative to neutral, landing in the toe-in position increased peak hip adduction, knee internal rotation angles and moments, and peak knee abduction angle. […] Toe-in landing position exacerbates biomechanical risk factors associated with ACL injury, while toe-out landing position decreases these factors. […] A combination of increased hip adduction and internal rotation, decreased knee flexion, increased knee abduction and internal or external tibial rotation, termed dynamic knee valgus, may increase the risk of ACL injury.

• #29 The effect of foot landing position on biomechanical risk factors associated with anterior cruciate ligament injury | Journal of Experimental Orthopaedics | Full Text

  https://jeo-esska.springeropen.com/articles/10.1186/s40634-016-0049-1

  Excessive knee abduction during cutting and landing activities increases ACL injury risk. […] We found that landing in a toe-in position increases knee abduction angle. […] Furthermore, landing in a toe-in position increases hip adduction angle and moment, which are associated with increased risk of ACL injury. […] Landing at toe-in was also found to increase tibial internal rotation angle and moment. […] Biomechanical and MRI studies have shown that greater internal tibial rotation increases ACL load. […] Furthermore, tibial internal rotation combined with knee valgus was found to increase ACL strain more than either individually. […] These findings suggest that an excessive toe-in landing position should be avoided and may be a target for movement pattern modification. […] Toe-out landing position was found to be associated with decreased knee abduction angles and increased tibial external rotation angles.

• #30 Mechanisms of Anterior Cruciate Ligament Tears in Professional National Basketball Association Players: A Video Analysis in: Journal of Applied Biomechanics Volume 39 Issue 3 (2023)

  https://journals.humankinetics.com/view/journals/jab/39/3/article-p143.xml

  Identifying the events leading to ACL injury and the injury mechanisms can help inform new strategies to prevent traumatic knee injuries in the NBA. Therefore, the purpose of this study was to use 2-dimensional video analysis of ACL injury events in professional NBA basketball players to characterize factors leading to ACL injury and to quantify the lower limb kinematics at the time of ACL injury. We expected indirect player-to-player body contact (not to the injured knee) to be present immediately before and during the ACL injury in most ACL injuries. Furthermore, based on previous research, we expected to find a combination of a small angle of knee flexion (an extended knee), knee valgus, hip adduction, and hip internal rotation at the time of ACL injury. […] One-hundred and five ACL injuries were identified among 98 players in the NBA between 1975 and 2022. ACL injuries with no player-to-player contact occurred in 5 out of 27 cases (19%), indirect player-to-player contact (not directly to the knee) occurred prior to the injury in 21 out of the 27 (78%) injuries, indirect player-to-player contact during the injury in 10 out of 27 (37%) instances, and contact both prior to and during injury in 9 out of 27 occasions (33%). Internal tibiofemoral rotation at ground contact at the time of injury was observed in 18/27 (66%) cases.

• #31 Mechanisms of Anterior Cruciate Ligament Tears in Professional National Basketball Association Players: A Video Analysis in: Journal of Applied Biomechanics Volume 39 Issue 3 (2023)

  https://journals.humankinetics.com/view/journals/jab/39/3/article-p143.xml

  Based on the injury sequence, 3 separate categories of injuries were determined based on the sequence of movements leading to injury and the lower limb kinematics at the point of ground contact during the time of injury: (1) single-leg casting, (2) a bilateral pro-hop, and (3) single-leg landing after contact. […] The single-leg casting mechanism represented 48% of the ACL injuries analyzed in this study. This was observed to be a unilateral stance during the injury event at the instance of ground contact during which the foot of the injured limb was anterior to the body center of mass (COM) immediately prior to the injury event and concurrently with a flexed hip joint, an abducted hip joint, or a combination of a flexed and abducted hip. […] The average dorsiflexion angle was 18.9; the average knee flexion angle was 15.6; and the average trunk ipsilateral lateral flexion angle toward the injured limb was 18.2. Player-to-player contact was observed in 69% of the single-leg casting injury occurrences.

• #32 Mechanisms of Anterior Cruciate Ligament Tears in Professional National Basketball Association Players: A Video Analysis in: Journal of Applied Biomechanics Volume 39 Issue 3 (2023)

  https://journals.humankinetics.com/view/journals/jab/39/3/article-p143.xml

  The bilateral pro-hop occurred in 29% of the injuries. This was observed to be a bilateral stance during the injury event occurring during a hopping movement followed by a sudden deceleration of the COM with both feet in parallel or slightly offset. […] The single-leg landing after contact mechanism was defined as player-to-player contact in body regions other than the knee joint occurring while the injured player was airborne followed by a single-leg landing event. The average abduction angle of the swing leg was 105.4, whereas the knee flexion angle upon whole foot ground contact of the injured limb was 34.2. […] The present study consisted of 2-dimensional video analysis to quantify the ACL injury, associated kinematics, and potential injury mechanisms occurring among professional basketball players in the NBA. This study provides new information and a novel perspective on the factors contributing to the etiology of traumatic knee injuries in this population. Our findings include the identification of 3 distinct ACL injury mechanism classifications including single-leg casting, bilateral hop, and single-leg landing after contact.

• #33 Mechanisms of Anterior Cruciate Ligament Tears in Professional National Basketball Association Players: A Video Analysis in: Journal of Applied Biomechanics Volume 39 Issue 3 (2023)

  https://journals.humankinetics.com/view/journals/jab/39/3/article-p143.xml

  The bilateral pro-hop occurred in 29% of the injuries. This was observed to be a bilateral stance during the injury event occurring during a hopping movement followed by a sudden deceleration of the COM with both feet in parallel or slightly offset. […] The single-leg landing after contact mechanism was defined as player-to-player contact in body regions other than the knee joint occurring while the injured player was airborne followed by a single-leg landing event. The average abduction angle of the swing leg was 105.4, whereas the knee flexion angle upon whole foot ground contact of the injured limb was 34.2. […] The present study consisted of 2-dimensional video analysis to quantify the ACL injury, associated kinematics, and potential injury mechanisms occurring among professional basketball players in the NBA. This study provides new information and a novel perspective on the factors contributing to the etiology of traumatic knee injuries in this population. Our findings include the identification of 3 distinct ACL injury mechanism classifications including single-leg casting, bilateral hop, and single-leg landing after contact.

• #34 The 3 Most Common Ways To Tear Your ACL Skiing & How To Stop It: Video Analysis – Newschoolers.com

  https://www.newschoolers.com/news/read/The-3-Common-Ways-Tear-ACL-Skiing-Stop-Video-Analysis

  The most common knee injury, as well as overall injury in skiing, is an ACL injury-representing 15% of all skiing related injuries. […] The first step is being educated on how ACL tears in skiing occur. […] They learned what research experts have concluded, after video analysis of over 20 World Cup ski racers who tore their ACL during competition, are the three most common ACL mechanisms of injury. […] The most common mechanism of injury, representing 50% of ACL injuries, is called the slip catch mechanism. […] The second most common mechanism of injury, representing roughly 25% of ACL injuries, is called landing back weighted. […] The third most common mechanism of injury, representing the last quarter of ACL injuries, is called the dynamic snow plow mechanism. […] Now you know the three most common mechanisms of ACL injuries in the sport of skiing.

• #35 Mechanism of Anterior Cruciate Ligament Injury in Female Soccer Players

  https://brieflands.com/articles/asjsm-13322

  The present study found that ACL injury often occurs as non-contact injury during pressing at the time of defense, regardless of the playing area, in female soccer players. In the present study, the female soccer players had a higher risk of sustaining non-contact ACL injuries than contact injuries, which is consistent with the findings of previous studies. Additionally, non-contact ACL injuries occurred more often during pressing (76%) than during other playing movements (49%), such as dribbling, trapping, and kicking. […] Excessive hip internal rotation and knee internal rotation will be present during this cutting maneuver, and these have been identified as risk factors for non-contact ACL injury. Moreover, the greater knee abduction (valgus) angle in female athletes than in male athletes is associated with a higher risk of non-contact ACL injury in female athletes. […] ACL injury might often occur as non-contact injury during pressing at the time of defense, regardless of the playing area, in female soccer players.

• #36 Mechanism of Anterior Cruciate Ligament Injury in Female Soccer Players

  https://brieflands.com/articles/asjsm-13322

  The present study found that ACL injury often occurs as non-contact injury during pressing at the time of defense, regardless of the playing area, in female soccer players. In the present study, the female soccer players had a higher risk of sustaining non-contact ACL injuries than contact injuries, which is consistent with the findings of previous studies. Additionally, non-contact ACL injuries occurred more often during pressing (76%) than during other playing movements (49%), such as dribbling, trapping, and kicking. […] Excessive hip internal rotation and knee internal rotation will be present during this cutting maneuver, and these have been identified as risk factors for non-contact ACL injury. Moreover, the greater knee abduction (valgus) angle in female athletes than in male athletes is associated with a higher risk of non-contact ACL injury in female athletes. […] ACL injury might often occur as non-contact injury during pressing at the time of defense, regardless of the playing area, in female soccer players.

• #37 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Landing biomechanics in females may increase the risk of ACL injury with increased valgus angulation and extension of the knee.[15][16] One study utilizing video analysis demonstrated that female athletes are more likely to place their knees in increased valgus angulations when changing directions suddenly, which increases the stress on the ACL ligament, in addition to decreased hip and knee flexion and decreased fatigue resistance. […] Other risk factors that might increase the risk of injury include anatomical risk factors such as increased body mass index, smaller femoral notch, impingement on the notch, smaller ACL, hypermobility, joint laxity, and previous ACL injury. […] Certain risk factors related to specific sports participation were reported, such as soccer and basketball, with increased risk in females and males, respectively.

• #38 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Landing biomechanics in females may increase the risk of ACL injury with increased valgus angulation and extension of the knee.[15][16] One study utilizing video analysis demonstrated that female athletes are more likely to place their knees in increased valgus angulations when changing directions suddenly, which increases the stress on the ACL ligament, in addition to decreased hip and knee flexion and decreased fatigue resistance. […] Other risk factors that might increase the risk of injury include anatomical risk factors such as increased body mass index, smaller femoral notch, impingement on the notch, smaller ACL, hypermobility, joint laxity, and previous ACL injury. […] Certain risk factors related to specific sports participation were reported, such as soccer and basketball, with increased risk in females and males, respectively.

• #39 Anterior Cruciate Ligament Injury: Practice Essentials, Background, Functional Anatomy

  https://emedicine.medscape.com/article/89442-overview

  Anterior cruciate ligament (ACL) injuries are most often a result of low-velocity, noncontact, deceleration injuries and contact injuries with a rotational component. Contact sports also may produce injury to the ACL secondary to twisting, valgus stress, or hyperextension, all directly related to contact or collision. […] The ACL is the primary (85%) restraint to limit anterior translation of the tibia. The greatest restraint is in full extension. […] When the ACL is injured, a combination of anterior translation and rotation occurs. […] Femoral notch stenosis is the ratio of the femoral notch width to the width of the femoral condyles. A notch width index of less than 0.2 is defined as notch stenosis. Individuals with notch stenosis have a higher risk of noncontact ACL injuries. […] The current failure rate for ACL reconstruction is approximately 8%. The 3 major categories of failure in an ACL reconstruction are (1) arthrofibrosis (due to inflammation of the synovium and fat pad), (2) pain that limits motion, and (3) recurrent instability, secondary to significant laxity in the reconstructed ligament.

• #40 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Landing biomechanics in females may increase the risk of ACL injury with increased valgus angulation and extension of the knee.[15][16] One study utilizing video analysis demonstrated that female athletes are more likely to place their knees in increased valgus angulations when changing directions suddenly, which increases the stress on the ACL ligament, in addition to decreased hip and knee flexion and decreased fatigue resistance. […] Other risk factors that might increase the risk of injury include anatomical risk factors such as increased body mass index, smaller femoral notch, impingement on the notch, smaller ACL, hypermobility, joint laxity, and previous ACL injury. […] Certain risk factors related to specific sports participation were reported, such as soccer and basketball, with increased risk in females and males, respectively.

• #41 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Landing biomechanics in females may increase the risk of ACL injury with increased valgus angulation and extension of the knee.[15][16] One study utilizing video analysis demonstrated that female athletes are more likely to place their knees in increased valgus angulations when changing directions suddenly, which increases the stress on the ACL ligament, in addition to decreased hip and knee flexion and decreased fatigue resistance. […] Other risk factors that might increase the risk of injury include anatomical risk factors such as increased body mass index, smaller femoral notch, impingement on the notch, smaller ACL, hypermobility, joint laxity, and previous ACL injury. […] Certain risk factors related to specific sports participation were reported, such as soccer and basketball, with increased risk in females and males, respectively.

• #42 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Landing biomechanics in females may increase the risk of ACL injury with increased valgus angulation and extension of the knee.[15][16] One study utilizing video analysis demonstrated that female athletes are more likely to place their knees in increased valgus angulations when changing directions suddenly, which increases the stress on the ACL ligament, in addition to decreased hip and knee flexion and decreased fatigue resistance. […] Other risk factors that might increase the risk of injury include anatomical risk factors such as increased body mass index, smaller femoral notch, impingement on the notch, smaller ACL, hypermobility, joint laxity, and previous ACL injury. […] Certain risk factors related to specific sports participation were reported, such as soccer and basketball, with increased risk in females and males, respectively.

• #43 MRI comparison of injury mechanism and anatomical factors between sexes in non-contact anterior cruciate ligament injuries | PLOS One

  https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0219586

  Non-contact anterior cruciate ligament (ACL) rupture is mostly caused by a pivot shift mechanism including valgus collapse and internal tibial rotation. […] In this study, we hypothesized that 1) in patients with non-contact ACL rupture, the incidence and severity of pivot shift injury, which are determined by injury pattern on MRI, would be significantly higher in females, and 2) anatomical factors associated with pivot shift injury would be significantly associated with female sex. […] Suggested anatomical factors typical in females include a narrow intercondylar notch, large Q-angle, small ACL size including length and cross-sectional area, increased posterior slope especially in lateral tibial plateau, and shallow medial tibial plateau. […] In terms of anatomical factors, the females showed a greater LTS and shallower MTD, however it did not affect the sex difference in injury pattern. […] With regard to anatomical factors, the LTS was significantly larger in females and the depth of the medial tibial plateau was significantly shallower in females.

• #44 MRI comparison of injury mechanism and anatomical factors between sexes in non-contact anterior cruciate ligament injuries | PLOS One

  https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0219586

  Non-contact anterior cruciate ligament (ACL) rupture is mostly caused by a pivot shift mechanism including valgus collapse and internal tibial rotation. […] In this study, we hypothesized that 1) in patients with non-contact ACL rupture, the incidence and severity of pivot shift injury, which are determined by injury pattern on MRI, would be significantly higher in females, and 2) anatomical factors associated with pivot shift injury would be significantly associated with female sex. […] Suggested anatomical factors typical in females include a narrow intercondylar notch, large Q-angle, small ACL size including length and cross-sectional area, increased posterior slope especially in lateral tibial plateau, and shallow medial tibial plateau. […] In terms of anatomical factors, the females showed a greater LTS and shallower MTD, however it did not affect the sex difference in injury pattern. […] With regard to anatomical factors, the LTS was significantly larger in females and the depth of the medial tibial plateau was significantly shallower in females.

• #45 Basic science of anterior cruciate ligament injury and repair | Bone & Joint

  https://boneandjoint.org.uk/Article/10.1302/2046-3758.32.2000241

  Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. […] The ACL has long been thought to have poor healing capacity, with a substantially high rate of failure (40% to 100%), even after surgical repair using suture. […] Recent advancements in functional tissue engineering and regenerative medicine have resulted in a renewed interest in revisiting ACL repair. […] Neuromuscular control deficit during dynamic movements has been hypothesised to be the primary cause for both primary and secondary ACL injury risk (re-injury following ACL reconstruction). […] Non-contact ACL injury mechanisms are multi-planar in nature, involving the tibiofemoral joint articulation in all three anatomical planes. […] The prevention of clot formation is mainly due to the continuous flow of the synovial fluid within the knee joint, dispersing the blood as a haemarthrosis. […] This lack of provisional scaffold leads to a decreased presence of critical ECM proteins and cytokines such as fibrinogen, fibronectin, PDGF-A, TGF-1, FGF-2, and von Willebrands factor (vWF) within the ACL wound site.

• #46 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  The ACL is the most commonly injured ligament in the knee, almost half of all knee injuries. The annual reported incidence in the United States alone is approximately 1 in 3500 people. There are approximately 400,000 ACL reconstructions every year in the united states.[13] However, data may not be accurate as there is no standard surveillance. […] There is no age or gender bias; however, it has been suggested that women are at an increased risk of ACL injury secondary to a multitude of factors.[14] In athletes, the female-to-male ratio has been reported to be 4.5: 1. Female athletes tend to get ACL ruptures at a younger age and more in the supporting leg versus the kicking leg in males. […] Among the factors increasing the female risk, as suggested by some studies that females may have weaker hamstrings (more quadriceps dominant) and preferential recruitment of the quadriceps muscle group while decelerating. Engaging the quadriceps musculature while slowing down places abnormally increased stresses on the ACL, as the quadriceps muscles are less effective at preventing anterior tibial translation versus the hamstring muscles. Additionally, females have weaker core stability than males.

• #47 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  The ACL is the most commonly injured ligament in the knee, almost half of all knee injuries. The annual reported incidence in the United States alone is approximately 1 in 3500 people. There are approximately 400,000 ACL reconstructions every year in the united states.[13] However, data may not be accurate as there is no standard surveillance. […] There is no age or gender bias; however, it has been suggested that women are at an increased risk of ACL injury secondary to a multitude of factors.[14] In athletes, the female-to-male ratio has been reported to be 4.5: 1. Female athletes tend to get ACL ruptures at a younger age and more in the supporting leg versus the kicking leg in males. […] Among the factors increasing the female risk, as suggested by some studies that females may have weaker hamstrings (more quadriceps dominant) and preferential recruitment of the quadriceps muscle group while decelerating. Engaging the quadriceps musculature while slowing down places abnormally increased stresses on the ACL, as the quadriceps muscles are less effective at preventing anterior tibial translation versus the hamstring muscles. Additionally, females have weaker core stability than males.

• #48 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Landing biomechanics in females may increase the risk of ACL injury with increased valgus angulation and extension of the knee.[15][16] One study utilizing video analysis demonstrated that female athletes are more likely to place their knees in increased valgus angulations when changing directions suddenly, which increases the stress on the ACL ligament, in addition to decreased hip and knee flexion and decreased fatigue resistance. […] Other risk factors that might increase the risk of injury include anatomical risk factors such as increased body mass index, smaller femoral notch, impingement on the notch, smaller ACL, hypermobility, joint laxity, and previous ACL injury. […] Certain risk factors related to specific sports participation were reported, such as soccer and basketball, with increased risk in females and males, respectively.

• #49 Anatomical and Neuromuscular Factors Associated to Non-Contact Anterior Cruciate Ligament Injury

  https://www.mdpi.com/2077-0383/11/5/1402

  The majority of anterior cruciate ligament (ACL) injuries occur during non-contact mechanisms. […] Age, BMI, antero-posterior laxity, isokinetic knee strength, passive knee valgus and passive knee extension were associated with non-contact ACL injury. […] According to the multivariate model, a non-contact ACL injury was associated with non-modifiable factors, age (OR: 1.05; p = 0.001), passive knee extension (OR: 1.14; p = 0.001), and with one modifiable factor (Hamstring strength: OR: 0.27; p = 0.01). […] General joint laxity, passive knee extension (recurvatum) and anterior-posterior knee laxity seem to be risk factors for the occurrence of a non-contact ACL injury, especially in women. […] Dynamic knee valgus would be poorly controlled in women during a non-contact ACL rupture, due to an increase in hip varus, knee valgus and Hamstring strength deficit (or an imbalance of Hamstring/Quadriceps ratio).

• #50 Anatomical and Neuromuscular Factors Associated to Non-Contact Anterior Cruciate Ligament Injury

  https://www.mdpi.com/2077-0383/11/5/1402

  The majority of anterior cruciate ligament (ACL) injuries occur during non-contact mechanisms. […] Age, BMI, antero-posterior laxity, isokinetic knee strength, passive knee valgus and passive knee extension were associated with non-contact ACL injury. […] According to the multivariate model, a non-contact ACL injury was associated with non-modifiable factors, age (OR: 1.05; p = 0.001), passive knee extension (OR: 1.14; p = 0.001), and with one modifiable factor (Hamstring strength: OR: 0.27; p = 0.01). […] General joint laxity, passive knee extension (recurvatum) and anterior-posterior knee laxity seem to be risk factors for the occurrence of a non-contact ACL injury, especially in women. […] Dynamic knee valgus would be poorly controlled in women during a non-contact ACL rupture, due to an increase in hip varus, knee valgus and Hamstring strength deficit (or an imbalance of Hamstring/Quadriceps ratio).

• #51 Anatomical and Neuromuscular Factors Associated to Non-Contact Anterior Cruciate Ligament Injury

  https://www.mdpi.com/2077-0383/11/5/1402

  The majority of anterior cruciate ligament (ACL) injuries occur during non-contact mechanisms. […] Age, BMI, antero-posterior laxity, isokinetic knee strength, passive knee valgus and passive knee extension were associated with non-contact ACL injury. […] According to the multivariate model, a non-contact ACL injury was associated with non-modifiable factors, age (OR: 1.05; p = 0.001), passive knee extension (OR: 1.14; p = 0.001), and with one modifiable factor (Hamstring strength: OR: 0.27; p = 0.01). […] General joint laxity, passive knee extension (recurvatum) and anterior-posterior knee laxity seem to be risk factors for the occurrence of a non-contact ACL injury, especially in women. […] Dynamic knee valgus would be poorly controlled in women during a non-contact ACL rupture, due to an increase in hip varus, knee valgus and Hamstring strength deficit (or an imbalance of Hamstring/Quadriceps ratio).

• #52 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  The ACL is the most commonly injured ligament in the knee, almost half of all knee injuries. The annual reported incidence in the United States alone is approximately 1 in 3500 people. There are approximately 400,000 ACL reconstructions every year in the united states.[13] However, data may not be accurate as there is no standard surveillance. […] There is no age or gender bias; however, it has been suggested that women are at an increased risk of ACL injury secondary to a multitude of factors.[14] In athletes, the female-to-male ratio has been reported to be 4.5: 1. Female athletes tend to get ACL ruptures at a younger age and more in the supporting leg versus the kicking leg in males. […] Among the factors increasing the female risk, as suggested by some studies that females may have weaker hamstrings (more quadriceps dominant) and preferential recruitment of the quadriceps muscle group while decelerating. Engaging the quadriceps musculature while slowing down places abnormally increased stresses on the ACL, as the quadriceps muscles are less effective at preventing anterior tibial translation versus the hamstring muscles. Additionally, females have weaker core stability than males.

• #53 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Women are three times more prone to have the ACL injured than men and is thought to be due to the following reasons: 1. Smaller size and different shape of the intercondylar notch: A narrow intercondylar notch and a plateau environment are risk factors of predisposing female non-athletes of aged group 40 to 65years with knee OA to ACL injury 2. Wider pelvis and greater Q angle: A wider pelvis requires the femur to have a greater angle towards the knee, lesser muscle strength provides less knee support, and hormonal variations may alter the laxity of ligaments. Greater ligament laxity: Young athletes with non-modifiable risk factors like ligament laxity are at a particularly increased risk of recurrent injury following ACL reconstruction (ACLR). Shoe surface interface: The chances of injury are approximately 2.5 times higher when higher levels of rotational traction are present at the shoe-surface interface. Neuromuscular factors. The mechanism of ACL injury may differ in females especially with respect to the dynamic positioning of the knee, as females demonstrate greater valgus collapse of the LE primarily in the coronal plane.

• #54 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Women are three times more prone to have the ACL injured than men and is thought to be due to the following reasons: 1. Smaller size and different shape of the intercondylar notch: A narrow intercondylar notch and a plateau environment are risk factors of predisposing female non-athletes of aged group 40 to 65years with knee OA to ACL injury 2. Wider pelvis and greater Q angle: A wider pelvis requires the femur to have a greater angle towards the knee, lesser muscle strength provides less knee support, and hormonal variations may alter the laxity of ligaments. Greater ligament laxity: Young athletes with non-modifiable risk factors like ligament laxity are at a particularly increased risk of recurrent injury following ACL reconstruction (ACLR). Shoe surface interface: The chances of injury are approximately 2.5 times higher when higher levels of rotational traction are present at the shoe-surface interface. Neuromuscular factors. The mechanism of ACL injury may differ in females especially with respect to the dynamic positioning of the knee, as females demonstrate greater valgus collapse of the LE primarily in the coronal plane.

• #55 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Women are three times more prone to have the ACL injured than men and is thought to be due to the following reasons: 1. Smaller size and different shape of the intercondylar notch: A narrow intercondylar notch and a plateau environment are risk factors of predisposing female non-athletes of aged group 40 to 65years with knee OA to ACL injury 2. Wider pelvis and greater Q angle: A wider pelvis requires the femur to have a greater angle towards the knee, lesser muscle strength provides less knee support, and hormonal variations may alter the laxity of ligaments. Greater ligament laxity: Young athletes with non-modifiable risk factors like ligament laxity are at a particularly increased risk of recurrent injury following ACL reconstruction (ACLR). Shoe surface interface: The chances of injury are approximately 2.5 times higher when higher levels of rotational traction are present at the shoe-surface interface. Neuromuscular factors. The mechanism of ACL injury may differ in females especially with respect to the dynamic positioning of the knee, as females demonstrate greater valgus collapse of the LE primarily in the coronal plane.

• #56 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Women are three times more prone to have the ACL injured than men and is thought to be due to the following reasons: 1. Smaller size and different shape of the intercondylar notch: A narrow intercondylar notch and a plateau environment are risk factors of predisposing female non-athletes of aged group 40 to 65years with knee OA to ACL injury 2. Wider pelvis and greater Q angle: A wider pelvis requires the femur to have a greater angle towards the knee, lesser muscle strength provides less knee support, and hormonal variations may alter the laxity of ligaments. Greater ligament laxity: Young athletes with non-modifiable risk factors like ligament laxity are at a particularly increased risk of recurrent injury following ACL reconstruction (ACLR). Shoe surface interface: The chances of injury are approximately 2.5 times higher when higher levels of rotational traction are present at the shoe-surface interface. Neuromuscular factors. The mechanism of ACL injury may differ in females especially with respect to the dynamic positioning of the knee, as females demonstrate greater valgus collapse of the LE primarily in the coronal plane.

• #57 Mechanism of ACL InjURY | PPT

  https://www.slideshare.net/slideshow/mechanism-of-acl-injury/253330988

  Women are three times more prone to have the ACL injured than men and is thought to be due to the following reasons: 1. Smaller size and different shape of the intercondylar notch: A narrow intercondylar notch and a plateau environment are risk factors of predisposing female non-athletes of aged group 40 to 65years with knee OA to ACL injury 2. Wider pelvis and greater Q angle: A wider pelvis requires the femur to have a greater angle towards the knee, lesser muscle strength provides less knee support, and hormonal variations may alter the laxity of ligaments. Greater ligament laxity: Young athletes with non-modifiable risk factors like ligament laxity are at a particularly increased risk of recurrent injury following ACL reconstruction (ACLR). Shoe surface interface: The chances of injury are approximately 2.5 times higher when higher levels of rotational traction are present at the shoe-surface interface. Neuromuscular factors. The mechanism of ACL injury may differ in females especially with respect to the dynamic positioning of the knee, as females demonstrate greater valgus collapse of the LE primarily in the coronal plane.

• #58 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Moreover, hormones were reported to affect coordination, especially the preovulatory phase of the menstrual cycle. Females on OCP were noted to be less affected. Estrogen effects on the strength and flexibility of tissues such as ligaments may play a role and predispose females to injury; however, this remains controversial and has yet to be proven. […] Collagen production (COL5A1 gene) was noted to be associated with lower injury risk in females. […] Although ACL injury can be diagnosed clinically, imaging with magnetic resonance (MRI) is often utilized to confirm the diagnosis. […] MRI is the primary modality to diagnose ACL pathology, with a sensitivity of 86% and a specificity of 95%. Diagnosis may also be made with knee arthroscopy to differentiate complete from partial tears and chronic tears. Arthrography is considered the gold standard as it is 92% to 100% sensitive and 95% to 100% specific; however, it is rarely used as the initial step in diagnosis as it is invasive and requires anesthesia.

• #59 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Most ACL tears occur in athletes by non-contact mechanisms, non-contact pivoting injury where the tibia translates anteriorly while the knee is slightly flexed and in valgus.[6] A direct hit to the lateral knee has also been encountered as an injury mechanism. The most at-risk athletes for non-contact injury include skiers, soccer players, and basketball players.[7] The most at-risk athletes for contact injury are football players.[8] […] Among those are meniscal tears; lateral meniscus injury in over half of acute ACL tears, whereas the medial meniscus is more involved in chronic cases. The PCL, LCL, and PLC could also be injured in association with an ACL injury. Chronic ACL deficiency seems to have deleterious effects on the knee, with the development of chondral injuries and complex unrepairable meniscal tears. Such as bucket handle medial meniscus tears.

• #60 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Most ACL tears occur in athletes by non-contact mechanisms, non-contact pivoting injury where the tibia translates anteriorly while the knee is slightly flexed and in valgus.[6] A direct hit to the lateral knee has also been encountered as an injury mechanism. The most at-risk athletes for non-contact injury include skiers, soccer players, and basketball players.[7] The most at-risk athletes for contact injury are football players.[8] […] Among those are meniscal tears; lateral meniscus injury in over half of acute ACL tears, whereas the medial meniscus is more involved in chronic cases. The PCL, LCL, and PLC could also be injured in association with an ACL injury. Chronic ACL deficiency seems to have deleterious effects on the knee, with the development of chondral injuries and complex unrepairable meniscal tears. Such as bucket handle medial meniscus tears.

• #61 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Most ACL tears occur in athletes by non-contact mechanisms, non-contact pivoting injury where the tibia translates anteriorly while the knee is slightly flexed and in valgus.[6] A direct hit to the lateral knee has also been encountered as an injury mechanism. The most at-risk athletes for non-contact injury include skiers, soccer players, and basketball players.[7] The most at-risk athletes for contact injury are football players.[8] […] Among those are meniscal tears; lateral meniscus injury in over half of acute ACL tears, whereas the medial meniscus is more involved in chronic cases. The PCL, LCL, and PLC could also be injured in association with an ACL injury. Chronic ACL deficiency seems to have deleterious effects on the knee, with the development of chondral injuries and complex unrepairable meniscal tears. Such as bucket handle medial meniscus tears.

• #62 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Magnetic Resonance Imaging (MRI) is 97% sensitive and 100 % specific: it confirms the diagnosis and assesses the presence of associated injuries. Normal ACL fibers are continuous and steeper than the intercondylar roof. ACL tears have primary and secondary signs.[26][27][28] […] Primary Signs […] Secondary signs include bone marrow edema (secondary to bone contusion) in more than half of ACL tears. The characteristic ACL bone bruising involves the middle third of the Lateral femoral condyle and the posterior third of the lateral tibial plateau. Other secondary signs include Segond fracture (as discussed below), associated medial collateral ligament injury, or anterior tibial translation greater than 7 mm of the tibia relative to the femur (best seen on lateral view), and tibial spine avulsion fracture.

• #63 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Magnetic Resonance Imaging (MRI) is 97% sensitive and 100 % specific: it confirms the diagnosis and assesses the presence of associated injuries. Normal ACL fibers are continuous and steeper than the intercondylar roof. ACL tears have primary and secondary signs.[26][27][28] […] Primary Signs […] Secondary signs include bone marrow edema (secondary to bone contusion) in more than half of ACL tears. The characteristic ACL bone bruising involves the middle third of the Lateral femoral condyle and the posterior third of the lateral tibial plateau. Other secondary signs include Segond fracture (as discussed below), associated medial collateral ligament injury, or anterior tibial translation greater than 7 mm of the tibia relative to the femur (best seen on lateral view), and tibial spine avulsion fracture.

• #64 Post-traumatic osteoarthritis following ACL injury | Arthritis Research & Therapy | Full Text

  https://arthritis-research.biomedcentral.com/articles/10.1186/s13075-020-02156-5

  A complete understanding of mechanisms to stratify the patients into different subgroups on the basis of risk factors is critical. […] Structural factors may contribute to the development of clinically significant OA. […] Almost half of patients with ACL injury also suffer from articular cartilage damage of the medial and lateral femoral condyles. […] Higher impact energy during the initial trauma causes more severe damage to the articular cartilage, with over 25MPa initiating chondrocyte necrosis and apoptosis. […] Increased chondrocyte expression of matrix-degrading enzymes and inflammatory cytokines caused by mechanical impact results in chondrocyte apoptosis. […] Following the initial ACL trauma, various biological factors, together with the damage to associated structures, may trigger progressive joint degeneration.

• #65 Mechanisms of non-contact anterior cruciate ligament injury as determined by bone contusion location and severity – Qiu – Quantitative Imaging in Medicine and Surgery

  https://qims.amegroups.org/article/view/67829/html

  The primary relative pattern of the tibiofemoral bone contusion was the PM on the lateral tibial plateau and the CL on the lateral femoral condyle. These results suggest that at the time of non-contact anterior cruciate ligament injury, the direct sites of the impact were the CL of the lateral femoral condyle and the PM of the lateral tibial plateau, which further indicated that an internal rotation of the tibia occurred during anterior cruciate ligament injury.

• #66 Sports Medicine Research Laboratory – Biologic mechanism of ACL injury

  https://research.childrenshospital.org/research-units/sports-medicine-research-laboratory-research/research-focus-areas/biologic-mechanism

  Based upon the observations by many surgeons that removal and replacement (ACL reconstruction) does not preserve the long-term function of the joints, we determined it essential to understand the mechanisms that underlie the inability of an injured ACL to heal so that we can design novel clinically relevant ways to repair it. […] Therefore, we designed a series of experiments aimed at understanding why a torn ACL does not heal. […] These findings led us to hypothesize that the lack of provisional scaffold between the two ends of the torn ACL was the key mechanism behind the failure of this joint tissue to heal. […] Thus, this study supported the hypothesis that there is a lack of provisional scaffold found in the intra-articular wound site of the ACL, and this loss is also associated with a decreased presence of important extracellular matrix proteins and cytokines within the wound site of the ACL.

• #67 Basic science of anterior cruciate ligament injury and repair | Bone & Joint

  https://boneandjoint.org.uk/Article/10.1302/2046-3758.32.2000241

  Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. […] The ACL has long been thought to have poor healing capacity, with a substantially high rate of failure (40% to 100%), even after surgical repair using suture. […] Recent advancements in functional tissue engineering and regenerative medicine have resulted in a renewed interest in revisiting ACL repair. […] Neuromuscular control deficit during dynamic movements has been hypothesised to be the primary cause for both primary and secondary ACL injury risk (re-injury following ACL reconstruction). […] Non-contact ACL injury mechanisms are multi-planar in nature, involving the tibiofemoral joint articulation in all three anatomical planes. […] The prevention of clot formation is mainly due to the continuous flow of the synovial fluid within the knee joint, dispersing the blood as a haemarthrosis. […] This lack of provisional scaffold leads to a decreased presence of critical ECM proteins and cytokines such as fibrinogen, fibronectin, PDGF-A, TGF-1, FGF-2, and von Willebrands factor (vWF) within the ACL wound site.

• #68 Basic science of anterior cruciate ligament injury and repair | Bone & Joint

  https://boneandjoint.org.uk/Article/10.1302/2046-3758.32.2000241

  Injury to the anterior cruciate ligament (ACL) is one of the most devastating and frequent injuries of the knee. […] The ACL has long been thought to have poor healing capacity, with a substantially high rate of failure (40% to 100%), even after surgical repair using suture. […] Recent advancements in functional tissue engineering and regenerative medicine have resulted in a renewed interest in revisiting ACL repair. […] Neuromuscular control deficit during dynamic movements has been hypothesised to be the primary cause for both primary and secondary ACL injury risk (re-injury following ACL reconstruction). […] Non-contact ACL injury mechanisms are multi-planar in nature, involving the tibiofemoral joint articulation in all three anatomical planes. […] The prevention of clot formation is mainly due to the continuous flow of the synovial fluid within the knee joint, dispersing the blood as a haemarthrosis. […] This lack of provisional scaffold leads to a decreased presence of critical ECM proteins and cytokines such as fibrinogen, fibronectin, PDGF-A, TGF-1, FGF-2, and von Willebrands factor (vWF) within the ACL wound site.

• #69 Proposed Mechanism for NonContact Anterior Cruciate Ligament Injury

  https://www.jscimedcentral.com/jounal-article-info/Annals-of-Sports-Medicine-and-Research–/Proposed-Mechanism-for-NonContact-Anterior-Cruciate-Ligament-Injury-4529

  In general, non-contact ACL injuries occur in sports involving jumping, landing, and pivoting where the athlete generates forces upon sudden deceleration that are greater than the ACL can accommodate. […] We propose that when an athlete mis-times a landing or foot-plant by planting the foot a split second after expected, the quadriceps and gastrocnemius muscle contractions, which usually occurs as part of mechanism to absorb the forces, have already occurred but without the usual joint compression forces that are present with ground contact. […] We propose that, because of the downward and shorter slope of the lateral tibial plateau, the impact of the femur on the posterior part of the tibia causes a fulcrum action or crow bar type effect on the tibia, pushing it farther forward as the knee flexes and causing the stretched ACL to rupture.

• #70 Mechanism of Anterior Cruciate Ligament Injuries | SHELBOURNE KNEE CENTER

  http://chnwebapp-auc-prod01.azurewebsites.net/node/307

  When the muscles contract after the injury, they pull the knee back together and the lateral meniscus gets caught in the dent of the lateral femoral condyle. […] It is when the tibia is already in an anterior position on the femur, the blow of the femur on the posterior aspect of the tibia causes the knee to be forced into further flexion therefore causing the ACL to be stretched to the point of tearing; somewhat like a crow bar motion.

• #71 Proposed Mechanism for NonContact Anterior Cruciate Ligament Injury

  https://www.jscimedcentral.com/jounal-article-info/Annals-of-Sports-Medicine-and-Research–/Proposed-Mechanism-for-NonContact-Anterior-Cruciate-Ligament-Injury-4529

  We propose that upon impact, when the tibia was already in an anterior position on the femur, the blow of the femur on the posterior aspect of the tibia caused the knee to be forced into further flexion, which caused the ACL to be stretched enough to be torn. […] If a large unrestricted quadriceps muscle contraction can cause the tibia to be displaced anteriorly as much as 20 mm, then it is possible that the bone bruises typically seen on the lateral femoral condyle and the lateral tibial plateau in conjunction with ACL injuries are caused at the time of impact upon landing and deceleration with foot plant. […] It is likely that there are several different types of mechanisms for non-contact ACL injury. This case illustrates a different type of mechanism for ACL than what has been previous proposed.

• #72 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  ACL management should have an individualized approach. Both operative and non-operative treatments are acceptable.[31][32][31] Multiple factors should be considered when deciding on ACL management, including the patient’s age and demands, activity level, sports participation, and the injury status of other supporting and stabilizing structures.[31] […] Non-operative management was reported to be associated with an increased risk of meniscal and cartilage damage due to repeated „giving way” episodes, especially if there are level I or II activities such as heavy manual labor and side-to-side sports, jumping, or cutting. […] Two main operative management options are repair or reconstruction of the ruptured ACL.[34][35] […] ACL reconstruction: this is indicated in a complete ACL rupture in younger active or older active ( 40 years) high-demand patients. The primary objective is an anatomical ACL reconstruction to reinstitute the anterior and rotational stability, consequently lessening the chances of secondary meniscal or chondral injuries.

• #73 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  Most ACL tears occur in athletes by non-contact mechanisms, non-contact pivoting injury where the tibia translates anteriorly while the knee is slightly flexed and in valgus.[6] A direct hit to the lateral knee has also been encountered as an injury mechanism. The most at-risk athletes for non-contact injury include skiers, soccer players, and basketball players.[7] The most at-risk athletes for contact injury are football players.[8] […] Among those are meniscal tears; lateral meniscus injury in over half of acute ACL tears, whereas the medial meniscus is more involved in chronic cases. The PCL, LCL, and PLC could also be injured in association with an ACL injury. Chronic ACL deficiency seems to have deleterious effects on the knee, with the development of chondral injuries and complex unrepairable meniscal tears. Such as bucket handle medial meniscus tears.

• #74 Post-traumatic osteoarthritis following ACL injury | Arthritis Research & Therapy | Full Text

  https://arthritis-research.biomedcentral.com/articles/10.1186/s13075-020-02156-5

  Post-traumatic osteoarthritis (PTOA) develops after joint injury. Specifically, patients with anterior cruciate ligament (ACL) injury have a high risk of developing PTOA. […] A number of factors are thought to be involved in the underlying mechanism, including structural factors, biological factors, mechanical factors, and neuromuscular factor. […] As reported, 50-90% of ACL injuries progress to PTOA. […] Older age leads to a disturbance of the balance between anabolic and catabolic processes. […] Evidence suggests that it is related to medial compartment joint space narrowing. […] Similarly, BMI is associated with joint space narrowing after ACL injury. […] Obesity is also believed to have a great influence on OA progress in many ways. One is increased joint loading. Another could be the catabolic effect of inflammatory substances released by adipose tissue, including free fatty acids, reactive oxygen species cytokines, and adipokines on joint tissues.

• #75 Post-traumatic osteoarthritis following ACL injury | Arthritis Research & Therapy | Full Text

  https://arthritis-research.biomedcentral.com/articles/10.1186/s13075-020-02156-5

  Post-traumatic osteoarthritis (PTOA) develops after joint injury. Specifically, patients with anterior cruciate ligament (ACL) injury have a high risk of developing PTOA. […] A number of factors are thought to be involved in the underlying mechanism, including structural factors, biological factors, mechanical factors, and neuromuscular factor. […] As reported, 50-90% of ACL injuries progress to PTOA. […] Older age leads to a disturbance of the balance between anabolic and catabolic processes. […] Evidence suggests that it is related to medial compartment joint space narrowing. […] Similarly, BMI is associated with joint space narrowing after ACL injury. […] Obesity is also believed to have a great influence on OA progress in many ways. One is increased joint loading. Another could be the catabolic effect of inflammatory substances released by adipose tissue, including free fatty acids, reactive oxygen species cytokines, and adipokines on joint tissues.

• #76 Anterior Cruciate Ligament Knee Injury – StatPearls – NCBI Bookshelf

  https://www.ncbi.nlm.nih.gov/books/NBK499848/

  A high risk of physeal injury has been reported due to multiple factors which can be modified. […] Overall physeal disruption with no growth disturbance has been reported in 10% of cases. […] ACL-deficient knees are more prone to the progression of arthritis with further injuries to the chondral and meniscal structures. ACL reconstruction restores native knee kinematics, and a high level of return to sports participation has been reported.

• #77 ANTERIOR CRUCIATE LIGAMENT (ACL) INJURIES | Sports Medicine Today

  https://www.sportsmedtoday.com/anterior-cruciate-ligament-acl-injuries-va-11.htm

  An ACL sprain occurs when there is damage to the anterior cruciate ligament (ACL), a major knee ligament that is located inside the knee. The ACL is the main stabilizing ligament of the knee for sudden stopping, starting, cutting and pivoting movements. […] Most ACL injuries are complete or 3rd-degree sprains. ACL injuries are usually caused by a twisting motion of a flexed knee, with the foot firmly planted in the ground. About three quarters of these are non-contact injuries, meaning the athlete did not run into something or someone to cause the injury. […] Another injury mechanism commonly seen in skiers occurs when the patient lands on an outstretched leg and the heel slips forward. […] Surgery is usually successful at preventing instability episodes but does not prevent osteoarthritis. […] If surgery is appropriate, it will usually not be done immediately. Time is needed for the swelling, motion and strength to improve. […] Although commonly used in some sports, bracing has not been found to prevent ACL injuries. […] Mechanisms of Noncontact Anterior Cruciate Ligament Injury.

• #78 The Mechanism of Anterior Cruciate Ligament Injuries in the National Football League: A Systematic Video Review

  https://pmc.ncbi.nlm.nih.gov/articles/PMC9970728/

  Anterior cruciate ligament (ACL) injuries are common among American football athletes, although few studies have performed video analyses of ACL injuries to better understand the injury mechanism. […] We hypothesize that football-specific injury trends will emerge, including high rates of contact injuries and associations with shallow knee and hip flexion angles (0-30). […] Overall, we found that most ACL injuries had preceding contact, deceleration, shallow hip and knee flexion, and heel strike, and subsequent valgus collapse and neutral knee rotation. […] Understanding the risk factors and mechanisms correlated with ACL injuries is important in injury prevention. […] The kinematics most commonly encountered with ACL injuries were deceleration, mild knee flexion (0-30), and initial foot-to-ground contact through heel strike. […] Additionally, most injuries were associated with contact from another athlete, either directly to the knee or indirectly to other parts of the body.

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