ACL Injury Risk Research Articles

Do Functional Tests Predict Knee Dynamics During Play?

Knee dynamics in the sagittal and frontal planes while performing landing and cutting tasks have been associated with non-contact ACL injury risk. Unfortunately, 3-D analysis is not feasible for the vast majority of athletes. Therefore, identifying tests that can be administered widely is desirable to identify those at greatest risk. Isokinetic strength measures and single leg hopping tasks have been utilized as markers of return to play post-injury and have also been suggested as potential predictors of initial injury. It is unclear, however, whether these tasks are valid indicators of knee dynamics during play. PURPOSE: To determine whether functional tests are related to knee dynamics during an unanticipated cutting maneuver. METHODS: Fourteen males and 16 females performed single leg hopping tasks (single (HOP), triple (T-HOP), and triple crossover (T-CROSS) hops for distance), isokinetic knee flexion (HAM) and extension (QUAD) (180deg/s), and cutting maneuvers (4.5-5.0 m/s). Three-dimensional kinematics and kinetics were recorded during the cutting task. Peak knee flexion angle (A-FLEX), peak abduction angle (A-ABD), and peak adduction moment (M-ADD) were extracted. A factor analysis was performed to determine groupings of variables. Three regression analyses were performed with A-FLEX, A-ABD, and M-ADD as dependent variables. RESULTS: Two principal components were extracted from the factor analysis. The hopping tasks and A-FLEX were strongly grouped with the first principle component (variance=57%). A-ABD and M-ADD were strongly associated with the second principle component (variance=19%). QUAD and HAM were moderately related to both components. The regression analyses revealed that A-FLEX was significantly predicted (R-square=.52) by the combination of T-HOP (stand. beta = −1.594) and T-CROSS (stand. beta = 1.041). CONCLUSIONS: Those with a longer T-HOP relative to T-CROSS exhibit greater knee flexion during cutting. These results suggest that performing T-HOP and T-CROSS may provide a reasonable predictor of sagittal plane dynamics and potentially injury risk. Unfortunately, frontal plane mechanics have been more strongly linked to injury, and the functional tests were not predictive of these variables. Supported by the UWM GSRC Award.

Verletzungsproblematik im Frauensport unter besonderer Berücksichtigung des Frauenhandballs

Summary This paper sets a focus on injuries in female handball and other team sports. According to the genetic basis and different effects of sex hormones, male and female athletes differ in some relevant anatomical and physiological aspects with a high impact for injuries. Different studies could demonstrate a higher risk for ACL injuries in female compared to male athletes. In handball, a fivefold higher risk for an ACL rupture could be demonstrated in female compared to male players. This is also true for younger players. Neuromuscular differences are discussed as possible mechanisms for gender-depending risks. Movement patterns while jumping and landing seem to have a high impact for the injury risk in team sports. Data on the injury risk during the menstrual cycle are conflicting. Some dependency, however, seems to exist. A possible mechanism might be a cycle-dependent reduction of the stability of the ACL. Studies on the preventive effects of oral contraceptive pills are also conflicting, not allowing any evidence-based recommendations. From a preventive point of view, some sports-specific movement patterns might be changed, like one- or two-leg landing in handball, width of feet position or ancle of knee flexion while landing, etc. Muscular dysbalances should be reduced, muscular strength in the tigh muscles increased, and proprioception and coordination optimized. A Norwegian group could demonstrate in an interventional study that a proprioceptive training program could reduce the risk for ACL injuries in female handball players dramatically.

Kinematics and Electromyography of Landing Preparation in Vertical Stop-Jump

Background Biomechanical analysis of stop-jump tasks has demonstrated gender differences during landing and a potential increase in risk of noncontact anterior cruciate ligament injury for female athletes. Analysis of landing preparation could advance our understanding of neuromuscular control in movement patterns and be applied to the development of prevention strategies for noncontact anterior cruciate ligament injury. Hypothesis There are differences in the lower extremity joint angles and electromyography of male and female recreational athletes during the landing preparation of a stop-jump task. Study Design Controlled laboratory study. Methods Three-dimensional videographic and electromyographic data were collected for 36 recreational athletes (17 men and 19 women) performing vertical stop-jump tasks. Knee and hip angular motion patterns were determined during the flight phase before landing. Results Knee and hip motion patterns and quadriceps and hamstring activation patterns exhibited significant gender differences. Female subjects generally exhibited decreased knee flexion (P = .001), hip flexion (P = .001), hip abduction (P = .001), and hip external rotation (P = .03); increased knee internal rotation (P = .001); and increased quadriceps activation (P = .001) compared with male subjects. Female subjects also exhibited increased hamstring activation before landing but a trend of decreased hamstring activation after landing compared with male subjects (P = .001). Conclusion Lower extremity motion patterns during landing of the stop-jump task are preprogrammed before landing. Female subjects prepared for landing with decreased hip and knee flexion at landing, increased quadriceps activation, and decreased hamstring activation, which may result in increased anterior cruciate ligament loading during the landing of the stop-jump task and the risk for noncontact ACL injury.

Effects of Age Group and Gender on Landing Mechanics and Strength in Adolescent Basketball Players

Female basketball players are at a greater risk for non contact ACL injury. Frontal and transverse plane motions increase the load on the ACL. The age at which these risk factors occur is largely unknown. PURPOSE: To examine the kinematics and kinetics of a drop landing and to compare hip abduction, knee flexion, and knee extension strength between 3 age groups and gender of basketball players. METHODS: Kinematic and kinetic data were collected from 45 males (6th grade = 15, 9th grade = 15, and 12th grade = 15 and 42 female (6th grade =14,9th grade = 17, and 12th grade =11) athletes. Landings were performed from a 40 cm hang bar. Strength testing for quadriceps and hamstrings included 15 reps at 60 °/s on an isokinetic dynamometer. Isometric hip abductor strength was measured using an anchored dynamometer. All force values and joint moment parameters were scaled to percent body weight (%BW) and N-m/kg of BW, respectively. A two way repeated measures ANO VA was performed (alpha = 0.05). RESULTS: Neither the mean landing phase time nor Vertical GRF was different for gender or age. At initial contact, 6th grade athletes had greater knee abduction angles compared to 12th grade athletes (−7° vs. −2.9°). Females had greater peak hip (42.9°vs. 20.5°) and knee flexion angles (68.3° vs. 56.3°) and knee abduction angles (−9.5° vs. −6.3°) as well as greater hip (15.8° vs. −4.6°) and knee flexion angles (12.7° vs. 8.1°) at initial contact. Overall, females had greater knee extension moments (1.18 N-m/kg of BWvs. 1.0 N-m/kg of BW) than males in landing. Knee extensor and hip extensor male and female strength were similar at 6th grade but strength was significantly greater in males at 9th grade and 12th grade. CONCLUSION: Females demonstrated increased sagittal and frontal plane motion coupled with greater knee extension moments during landing. In particular, sixth grade female athletes increased knee abduction angles at initial contact. Greater knee abduction observed in females in combination with greater reliance on the knee extensors to control knee motion may contribute to non contact ACL tears. 9th and 12th grade females exhibited diminished hip abduction and knee extension strength compared to males which may contribute to the inability to control knee motion during landing.

Methods to Mass Screening and Prevention of ACL Injury Risk in Young Athletes

Methods to Mass Screening and Prevention of ACL Injury Risk in Young Athletes

In Vivo Assessment of Non-Contact ACL Injury Risk

In Vivo Assessment of Non-Contact ACL Injury Risk

The Effects of Plyometric versus Dynamic Stabilization and Balance Training on Lower Extremity Biomechanics

Background Neuromuscular training that includes both plyometric and dynamic stabilization/balance exercises alters movement biomechanics and reduces ACL injury risk in female athletes. The biomechanical effects of plyometric and balance training utilized separately are unknown. Hypothesis A protocol that includes balance training without plyometric training will decrease coronal plane hip, knee, and ankle motions during landing, and plyometric training will not affect coronal plane measures. The corollary hypothesis was that plyometric and balance training effects on knee flexion are dependent on the movement task tested. Study Design Controlled laboratory study. Methods Eighteen high school female athletes participated in 18 training sessions during a 7-week period. The plyometric group (n= 8) performed maximum-effort jumping and cutting exercises, and the balance group (n = 10) used dynamic stabilization/ balance exercises during training. Lower extremity kinematics were measured during the drop vertical jump and the medial drop landing before and after training using 3D motion analysis techniques. Results During the drop vertical jump, both plyometric and balance training reduced initial contact (P= .002), maximum hip adduction angle (P= .015), and maximum ankle eversion angle (P= .020). During the medial drop landing, both groups decreased initial contact (P= .002) and maximum knee abduction angle (P= .038). Plyometric training increased initial contact knee flexion (P= .047) and maximum knee flexion (P= .031) during the drop vertical jump, whereas the balance training increased maximum knee flexion (P= .005) during the medial drop landing. Conclusion Both plyometric and balance training can reduce lower extremity valgus measures. Plyometric training affects sagittal plane kinematics primarily during a drop vertical jump, whereas balance training affects sagittal plane kinematics during single-legged drop landing. Clinical Relevance Both plyometric and dynamic stabilization/balance exercises should be included in injury-prevention protocols.

Effect of Gender and Maturity on Quadriceps-to-Hamstring Strength Ratio and Anterior Cruciate Ligament Laxity

Background Exercise programs have been introduced to reduce the ACL injury risk in female athletes. The most effective age at which to start these programs is not known. Hypothesis Age and gender affect ligament laxity and quadriceps-to-hamstring strength ratio. Study Design Cross-sectional study; Level of evidence, 3. Methods Fifty-three female and 70 male recreational soccer players, 10 to 18 years of age, were studied with physical examination, KT-1000 arthrometry, and manual maximum quadriceps and hamstring strength using a handheld dynamometer. The subjects were separated into 4 groups to examine maturity-related intergender differences: group G1, premenarchal girls (n = 24); group B1, boys 13 years and younger (n = 38); group G2, girls 2 or more years after menarche (n = 29); and group B2, boys 14 years and older (n = 32). Results Both knees of 123 soccer players were evaluated. The mean ages for groups G1, B1, G2, and B2 were 11.50 ± 1.69, 10.63 ± 1.85, 15.5 ± 1.43, and 15.59 ± 1.24 years, respectively, and the mean laxity measurements were 8.84 ± 2.12, 8.51 ± 1.61, 8.85 ± 1.86, and 7.33 ± 1.27 mm, respectively. Laxity was significantly less for the mature boys (P= .0015) than for the immature boys, mature girls, and immature girls. With increasing maturity, significant increases in both quadriceps and hamstring muscle strength were observed for both boys and girls (P< .05). Boys demonstrated a greater percentage increase in hamstring strength with maturity (179%) compared with girls (27%) (P< .05). Mature girls (2.06) had significantly greater quadriceps-tohamstring ratio when compared with immature girls (1.74), immature boys (1.58), and mature boys (1.48) (P< .05). Conclusion Female athletes after menarche increase their quadriceps strength greater than their hamstring strength, putting them at risk for anterior cruciate ligament injury. Anterior cruciate ligament–prevention programs based on improving dynamic control of the knee by emphasizing hamstring strengthening should be instituted for girls after menarche.

288 An investigation of neuromuscular characteristics for two intervention programs in an attempt to reduce ACL injury risk in netball

288 An investigation of neuromuscular characteristics for two intervention programs in an attempt to reduce ACL injury risk in netball

Female Athletes May Have Higher Risk of ACL Injury

Female Athletes May Have Higher Risk of ACL Injury

Effect Of Puberty And Gender On Landing Force And Jump Height

PURPOSE Neuromuscular performance increases rapidly in males throughout pubertal development. A similar neuromuscular spurt is not typically found in females during the same stages of puberty. The hypothesis was that there would be no differences throughout pubertal tanner stages in neuromuscular performance in females while males would show a greater vertical at each stage of development. METHODS 275 middle school and high school athletes volunteered to participate in this study (87 females, 188 males). Subjects were recruited from preseason physical screening. Pubertal development (Tanner Stage) was assessed by trained physicians. Only those athletes who were classified as pubertal through post pubertal (Tanner Stages 2–5) were included. Each subject performed 2 drop vertical jumps (DVJ) from a box height of 31cm (Ford 2003). They were instructed to drop off the box, land and immediately perform a maximal vertical jump. A portable force platform was used to collect the landing from the box and the landing after the vertical jump (AccuPower, AMTI). Maximum vertical ground reaction force (MVGRF) was calculated at three different phases, drop landing (DL), drop take-off (DT), and vertical landing (VL). Maximum vertical jump height (V) was also calculated from each trial. The ratio of the MVGRF (DL/DT) at the eccentric and concentric phases was calculated. A 2 ± 4 ANOVA (Gender*TannerStage) was utilized. RESULTS There was no difference in vertical jump height (V) throughout the developmental stages in females, males increased their vertical jump height by 16.3%, 13.4% and 7.9% at each stage of pubertal development (p = 0.002). The ratio DL/DT was decreased in males throughout pubertal stages while females showed no change (p = 0.047). The ratio of maximum force during the landing after the vertical to the maximum vertical jump (VL/V) decreased in males throughout pubertal stages while females had no change (p = 0.024). CONCLUSIONS These findings confirm the absence of a neuromuscular spurt in females and its presence in males. Lack of the neuromuscular spurt and force attenuation may play a role in the increased risk of ACL injury in female athletes. Injury prevention programs improve neuromuscular control and reduce ACL injuries in young females. The divergence in ACL injury rates between male and female athletes begin around age 12, when the majority of females are pubertal and their impact forces fail to be attenuated.

Effect Of Puberty And Gender On Landing Force And Jump Height

PURPOSE Neuromuscular performance increases rapidly in males throughout pubertal development. A similar neuromuscular spurt is not typically found in females during the same stages of puberty. The hypothesis was that there would be no differences throughout pubertal tanner stages in neuromuscular performance in females while males would show a greater vertical at each stage of development. METHODS 275 middle school and high school athletes volunteered to participate in this study (87 females, 188 males). Subjects were recruited from preseason physical screening. Pubertal development (Tanner Stage) was assessed by trained physicians. Only those athletes who were classified as pubertal through post pubertal (Tanner Stages 2–5) were included. Each subject performed 2 drop vertical jumps (DVJ) from a box height of 31cm (Ford 2003). They were instructed to drop off the box, land and immediately perform a maximal vertical jump. A portable force platform was used to collect the landing from the box and the landing after the vertical jump (AccuPower, AMTI). Maximum vertical ground reaction force (MVGRF) was calculated at three different phases, drop landing (DL), drop take-off (DT), and vertical landing (VL). Maximum vertical jump height (V) was also calculated from each trial. The ratio of the MVGRF (DL/DT) at the eccentric and concentric phases was calculated. A 2 ± 4 ANOVA (Gender*TannerStage) was utilized. RESULTS There was no difference in vertical jump height (V) throughout the developmental stages in females, males increased their vertical jump height by 16.3%, 13.4% and 7.9% at each stage of pubertal development (p = 0.002). The ratio DL/DT was decreased in males throughout pubertal stages while females showed no change (p = 0.047). The ratio of maximum force during the landing after the vertical to the maximum vertical jump (VL/V) decreased in males throughout pubertal stages while females had no change (p = 0.024). CONCLUSIONS These findings confirm the absence of a neuromuscular spurt in females and its presence in males. Lack of the neuromuscular spurt and force attenuation may play a role in the increased risk of ACL injury in female athletes. Injury prevention programs improve neuromuscular control and reduce ACL injuries in young females. The divergence in ACL injury rates between male and female athletes begin around age 12, when the majority of females are pubertal and their impact forces fail to be attenuated.

Reliability Of Single Leg Landing On A Portable Force Platform

Impact forces at landing are related to valgus moments at the knee and potential ACL injury risk. Reliable tests that are portable and applicable to large scale screening are important to identify high risk individuals in order to target them for appropriate interventions. PURPOSE The purpose of this study was to investigate within session reliability of measures of single leg landing in a large group of female athletes. The hypothesis tested was that within session measures of force and center of pressure (COP) would be reliable during single leg landing. METHODS 45 high school and collegiate soccer players volunteered participation. Each performed a 50cm single leg hop and were instructed to balance for 10 seconds after the landing. A portable force platform (AccuPower, AMTI) was used with force and center of pressure (COP) data. Balance during the trial was assessed by calculating the standard deviation of each variable (COPML, COPAP, FML, FAP, FV). The range of COP excursion (ML and AP) was also calculated during the balance portion of each trial. Stability algorithms utilized sequential estimation during the initial 3 seconds after impact (Colby, 1999). The time of stability (medial/lateral (ML), anterior/posterior (AP) and vertical force (V)) derived from sequential estimation has been previously shown to be reliable when collecting 10 trials. Intraclass correlation coefficients (ICC[3, k]) were performed in SPSS for each variable. RESULTS Maximum vertical ground reaction force had high reliability on both the right (r = 0.823) and left side (r = 0.877). The maximum vertical ground reaction force for the three trials on the right side was 2.40BW, 2.41BW and 2.40BW, respectively. The average (right and left side) reliability for the standard deviation was: COPML (r = 0.831), COPAP(r = 0.651), FML(r = 0.824), FAP(r = 0.714) and FV(r = 0.741). Average COP medial/lateral excursion had a reliability of r = 0.736 and anterior/posterior excursion was r = 0.607. The stability time measurement that had an ICC over 0.6 was calculating the vertical force with sequential estimation (right, r = 0.787 and left r = 0.767). CONCLUSIONS Maximum vertical force and the standard deviation and excursion measures had high reliability during three trials in female athletes. Calculation of stability time from medial/lateral and anterior/posterior force was less reliable. Calculation of a stability time from sequential estimation based on the vertical component was improved compared to the use of M/L and A/P.

非接触性ＡＣＬ損傷における性差・左右差

It is assumed that female athletes are prone to non-contact injury, the frequency of which is especially high in the left knee in ACL injuries. (1) ACL injuries were analyzed retrospectively in 467 patients to see whether they were non-contact or not, and which side of the knee was involved. (2) A questionnaire survey was conducted on 106 students belonging to a university athletic club on the laterality of the lower extremity. (1) The result were as follows; contact injury to female left knee was found in 39 cases, contact injury to female right knee in 38 cases, contact injury to male left knee in 48 cases, contact injury to male right knee in 66 cases, non-contact injury female to left knee in 124 cases, non-contact injury to female right knee in 84 cases, non-contact injury to male left knee in 42 cases, and non-contact injury to male right knee in 26 cases. Chi-square test demonstrated that non-contact injury to female left knee was significantly frequent in ACL injuries. (2) The questionnaire survey also revealed the following; left side was significantly involved in non-contact injury to the lower limb from the chi-square test results. We conclude that female left knee is at an increased risk for ACL injuries. Further studies are needed to determine the factors associated with functional characteristics of the female knee.

Anterior Cruciate Ligament Injury in Pediatric and Adolescent Soccer Players: An Analysis of Insurance Data

Injury claims from an insurance company specializing in soccer coverage were reviewed for a 5-year period. A total of 8215 injury claims (3340 females, 4875 males) were divided into three categories: (1) all injury, (2) knee injury, and (3) ACL injury. Knee injuries accounted for 22% of all injuries (30% female, 16% male). ACL injury claims represented 31% of total knee injury claims (37% female, 24% males). The youngest ACL injury was age 5. The ratio of knee injury/all injury increased with age. Compared with males, females demonstrated a higher ratio of knee injury/all injury and a higher ratio of ACL injury/all injury. This study demonstrates that ACL injury occurs in skeletally immature soccer players and that females appear to have an increased risk of ACL injury and knee injury compared with males, even in the skeletally immature. Future research related to ACL injury in females will need to consider skeletally immature patients.

The effects of gender on quadriceps muscle activation strategies during a maneuver that mimics a high ACL injury risk position

While the increased incidence of serious knee injuries in female athletes is well established, the underlying neuromuscular mechanisms related to the elevated ACL injury rate has yet to be delineated. Video analysis of ACL injury during competitive sports play indicates a common body position associated with non-contact ACL injury; the tibia is externally rotated, the knee is close to full extension, the foot is planted and as the limb is decelerated it collapses into valgus. The purpose of the current prospective study was to evaluate gender differences in quadriceps muscle activation strategies when performing a physically challenging, but reproducible maneuver that mimics the high ACL injury risk position (in the absence of high velocity and high loads). Twenty physically active college-aged subjects (10 male and 10 female) performed multiple sets of the prescribed exercise. EMG recordings were employed to measure the ratio of activation between the medial and lateral quadriceps during the 4, 8, 12, 16, and 20th sets of exercise. Females demonstrated decreased RMS medial-to-lateral quadriceps ratios compared to males ( F(1,18) = 5.88, p = 0.026). There was no main effect of set number on RMS quadriceps ratio ( p > 0.05). The results of this study suggest that females utilize neuromuscular activation strategies which may contribute to “dynamic valgus” and ACL rupture when performing high-risk maneuvers.

Neuromuscular Control and Valgus Loading of the Knee Predict ACL Injury Risk in Female Athletes

2001 PURPOSE: Females suffer ACL injury at a 4 to 6-fold greater rate than males. Geometric growth in participation, coupled with the higher injury rate, has lead to a large increase in the number of ACL injuries in female athletes. The hypotheses tested in this study were that pre-screened females that went on to ACL injury would demonstrate decreased neuromuscular control and increased joint loading, which would predict ACL injury risk. METHODS: 205 female athletes in high-risk sports were prospectively measured for neuromuscular control using 3-D kinematics (joint angles) and joint loads using kinetics (joint moments) during jump landing. ANOVA, linear and logistic regression compared groups and identified predictors of risk from ACLinjured athletes. RESULTS: The 9 of 205 athletes that had confirmed ACL rupture demonstrated increased valgus and external knee abduction moment (KABM). Knee abduction angle (KABA) at landing was 8° greater at initial contact (IC) and maximum excursion. Knee flexion angle (KFA) was not different at IC, but 10° lower at peak excursion in ACL-injured than uninjured athletes (p<0.05). ACL-injured had a 2.5- times greater KABM (p<0.001) and 20% higher ground reaction force (GRF, p<0.05), while stance time was 16% shorter (p<0.001). KABM and KABA correlated to GRF (R = 0.74 and R = 0.67, p< 0.05) and hip adduction moment (R = 0.69, p< 0.05) in ACL-injured subjects. KFA did not correlate to GRF (p = 0.36). KABM predicted ACL injury status with 73% specificity and 78% sensitivity and combined valgus measures showed a predictive r2 value of 0.88. CONCLUSIONS: Decreased control (valgus) and high loading (abduction moment) predict ACL injury risk in females. The methods developed in this report may be used to monitor altered neuromuscular control and increased valgus loading of the knee joint in female athletes. These measures of neuromuscular imbalance, neuromuscular control and joint loading may be used to direct potentially high-risk athletes to more effective, targeted interventions.Figure

Neuromuscular Control and Valgus Loading of the Knee Predict ACL Injury Risk in Female Athletes

2001 PURPOSE: Females suffer ACL injury at a 4 to 6-fold greater rate than males. Geometric growth in participation, coupled with the higher injury rate, has lead to a large increase in the number of ACL injuries in female athletes. The hypotheses tested in this study were that pre-screened females that went on to ACL injury would demonstrate decreased neuromuscular control and increased joint loading, which would predict ACL injury risk. METHODS: 205 female athletes in high-risk sports were prospectively measured for neuromuscular control using 3-D kinematics (joint angles) and joint loads using kinetics (joint moments) during jump landing. ANOVA, linear and logistic regression compared groups and identified predictors of risk from ACLinjured athletes. RESULTS: The 9 of 205 athletes that had confirmed ACL rupture demonstrated increased valgus and external knee abduction moment (KABM). Knee abduction angle (KABA) at landing was 8° greater at initial contact (IC) and maximum excursion. Knee flexion angle (KFA) was not different at IC, but 10° lower at peak excursion in ACL-injured than uninjured athletes (p<0.05). ACL-injured had a 2.5- times greater KABM (p<0.001) and 20% higher ground reaction force (GRF, p<0.05), while stance time was 16% shorter (p<0.001). KABM and KABA correlated to GRF (R = 0.74 and R = 0.67, p< 0.05) and hip adduction moment (R = 0.69, p< 0.05) in ACL-injured subjects. KFA did not correlate to GRF (p = 0.36). KABM predicted ACL injury status with 73% specificity and 78% sensitivity and combined valgus measures showed a predictive r2 value of 0.88. CONCLUSIONS: Decreased control (valgus) and high loading (abduction moment) predict ACL injury risk in females. The methods developed in this report may be used to monitor altered neuromuscular control and increased valgus loading of the knee joint in female athletes. These measures of neuromuscular imbalance, neuromuscular control and joint loading may be used to direct potentially high-risk athletes to more effective, targeted interventions.Figure

Valgus knee motion during landing in high school female and male basketball players.

The purpose of this study was to utilize three-dimensional kinematic (motion) analysis to determine whether gender differences existed in knee valgus kinematics in high school basketball athletes when performing a landing maneuver. The hypothesis of this study was that female athletes would demonstrate greater valgus knee motion (ligament dominance) and greater side-to-side (leg dominance) differences in valgus knee angle at landing. These differences in valgus knee motion may be indicative of decreased dynamic knee joint control in female athletes. Eighty-one high school basketball players, 47 female and 34 male, volunteered to participate in this study. Valgus knee motion and varus-valgus angles during a drop vertical jump (DVJ) were calculated for each subject. The DVJ maneuver consisted of dropping off of a box, landing and immediately performing a maximum vertical jump. The first landing phase was used for the analysis. Female athletes landed with greater total valgus knee motion and a greater maximum valgus knee angle than male athletes. Female athletes had significant differences between their dominant and nondominant side in maximum valgus knee angle. The absence of dynamic knee joint stability may be responsible for increased rates of knee injury in females but is not normally measured in athletes before participation. No method for accurate and practical screening and identification of athletes at increased risk of ACL injury is currently available to target those individuals that would benefit from neuromuscular training before sports participation. Prevention of female ACL injury from five times to equal the rate of males would allow tens of thousands of young females to avoid the potentially devastating effects of ACL injury on their athletic careers.

WISSENSCHAFTLICHER BEITRAG: Prävention von Rupturen des vorderen Kreuzbandes im Ballsport: eine Literaturübersicht

A number of epidemiological studies has shown that the rate of ACL ruptures in female athletes is 2.4 to 9.5 times higher than in male athletes. Approximately 70% of these injuires occur without direct contact to another player (noncontact situations). Various studies have shown that the most frequent situations are landing a jump, stopping and plant and cut maneuvers. However, there is evidence that gender specific differences in coordination and neuromuscular control may be an explanation for the high incidence of ACL injuries in female athletes. Female athletes tend to be more upright with a slightly flexed valgus knee when cutting and landing. The muscle mechanics in this position favors the qua-driceps while denying a favourable position for the hamstrings to conteract the quadriceps. Additionally, women also have greater quadriceps activation. Therefore, when cutting, women place their knee in a position that favor a quadriceps-induced anterior drawer maneuver, placing the knee in a position of increased risk for ACL injury. Various studies have shown that specific training programs can reduce the incidence of ACL injuries significantly: 1. The Henning prevention strategies stressed: – changing the plant and cut to an accelerated round turn, – landing with a bent knee rather than a straight knee, – changing a one step stop on a straight knee to a stopping with a multiple-step with a knee bent. 2. The Caraffa Program showed that incorporation of proprioceptive drills such as balance board exercises into pre-season conditioning program is able to reduce the ACL injury rate significantly. 3. The Cincinnati Sportsmetric Program includes a temporal staggered jump training. 4. The Kiel Team Handball Injury Prevention Program includes elements of all three former programs.