Reduce Anterior Cruciate Ligament Injury Research Articles

L'influenza della flessione anteriore del tronco sulla biomeccanica del ginocchio e sull'attività mioelettrica durante l'esecuzione del sidestep cut

BACKGROUND: Trunk motion control may be an important factor affecting the risk of anterior cruciate ligament (ACL) injury by changing knee joint load during dynamic motion, there has been few studies investigating the influence of it on knee joint during sidestep cutting currently, and it has not been studied whether asymmetry between the dominant and non-dominant lower limbs in different trunk motion states during sidestep cutting. The objective of this study was to identify the leg laterality during sidestep cutting in trunk forward inclination state and to explore whether trunk forward inclination could reduce ACL injury risk.METHODS: Twenty healthy male college basketball athletes volunteered for this study. Each individual is required to complete sidestep cutting tasks in four states. They performed sidestep cutting using the dominant and non-dominant side with trunk forward inclination or natural position, respectively. Biomechanical testing equipment were used to synchronously collect knee biomechanics and myoelectricity data. A two-way (trunk motion × support side) ANOVA was used to analyze the influence of trunk motion control on knee biomechanics and myoelectricity and leg laterality.RESULTS: There was no leg laterality during sidestep cutting with trunk forward inclination state. During sidestep cutting with trunk forward inclination state, the knee flexion angle at initial contact (P=0.003 for the dominant side; P=0.011 for the non-dominant side), knee peak flexion angle (P=0.001 for the dominant side; P=0.000 for the non-dominant side) and H/Q ratio (P=0.048 for the dominant side) were significantly greater than trunk natural state.CONCLUSIONS: There was no leg laterality during sidestep cutting in trunk forward inclination state, and the trunk forward state may have a protective effect on the ACL during sidestep cutting, especially for the dominant side.

The Effect of a Knee Brace on Muscle Forces during Single-Leg Landings at Two Heights

Single-leg landing is one of the maneuvers that has been linked to non-contact anterior cruciate ligament (ACL) injuries, and wearing knee braces has been shown to reduce ACL injury incidence. The purpose of this study was to determine whether wearing a knee brace has an effect on muscle force during single-leg landings at two heights through musculoskeletal simulation. Eleven healthy male participants, some braced and some non-braced were recruited to perform single-leg landings at 30 cm and 45 cm. We recorded the trajectories and ground reaction forces (GRF) using an eight-camera motion capture system and a force platform. The captured data were imported into the generic musculoskeletal model (Gait2392) in OpenSim. Static optimization was used to calculate the muscle forces. The gluteus minimus, rectus femoris, vastus medialis, vastus lateralis, vastus medialis medial gastrocnemius, lateral gartrocnemius, and soleus muscle forces were all statistically significant different between the braced and non-braced participants. Simultaneously, increasing the landing height significantly affected the gluteus maximums, vastus medialis, and vastus intermedia muscle forces. Our findings imply that wearing a knee brace may alter muscle forces during single-leg landings, preventing ACL injuries. Additionally, research demonstrates that people should avoid landing from heights due to the increased risk of knee injuries.

Skill-Specific Differences in Equipment-Related Risk Factors for ACL Injury in Male and Female Recreational Skiers.

In recreational alpine skiing, the anterior cruciate ligament (ACL) is affected in approximately 50% of serious knee injuries. There are established sex-based and skill-based differences in ACL injury risk, but the potential impact of equipment used (eg, skis, bindings, and boots) has not been evaluated. To evaluate individual and equipment-related risk factors for an ACL injury depending on sex and skill level. Case-control study; Level of evidence, 3. This was a retrospective questionnaire-based, case-control study of female and male skiers with and without ACL injuries during 6 winter seasons (from 2014-2015 to 2019-2020). Demographic data, skill level, equipment specifications, risk-taking behavior, and ownership of ski equipment were recorded. Ski geometry (ski length; sidecut radius; and widths of the tip, waist, and tail) was taken from each participant's ski. The standing heights of the front and back part of the ski binding were measured using a digital sliding caliper, and the standing height ratio was calculated. Abrasion of the ski boot sole was also measured at the toe and heel. Participants were divided by sex into less and more skilled skiers. A total of 1817 recreational skiers participated in this study, of whom 392 (21.6%) sustained an ACL injury. A greater standing height ratio and more abrasion at the toe of the boot sole were associated with increased ACL injury risk in both sexes, independent of the skill level. Riskier behavior increased the injury risk only in male skiers, independent of the skill level, and longer skis increased the injury risk only in less skilled female skiers. Older age, the use of rented/borrowed skis, and more abrasion at the heel of the boot sole were independent risk factors for ACL injury in the more skilled skiers of both sexes. Individual and equipment-related risk factors for an ACL injury partly differed according to skill level and sex. Consideration of the demonstrated equipment-related factors should be implemented in order to reduce ACL injuries in recreational skiers.

Gym-Based Training Interventions for Anterior Cruciate Ligament Injury Reduction in American Football Players.

Injuries to the anterior cruciate ligament (ACL) of the knee are one of the most prominent injuries affecting players in American football. One primary aim of training to reduce injury risk is to provide exercises for players on attaining the highest athletic performance with the least orthopedic stress. This review article on ACL injury reduction protocols focuses on the protective and performance-enhancing biomechanical patterns during simple exercises used in a gym-based setting, in the following areas: single-leg balance and trunk stability, single-leg jumping/plyometrics, and reflexive strength training. This supplementary training, as part of a sports performance program, might include training to develop maximum strength, explosive power, acceleration, maximum velocity, bioenergetic endurance qualities, mobility/flexibility, agility, and sport skill acquisition.

The counteracting effect of the friction moment against the tibial rotational moment driven by the ground reaction force in an early stance phase of cutting maneuver among healthy male athletes

ABSTRACT The ground reaction force (GRF) is known to produce tibial internal rotation loading associated with the stress in the anterior cruciate ligament (ACL). However, it is unclear whether the friction moment (FM; the moment due to horizontal shoe-floor friction, acting around the vertical axis at the GRF acting point) facilitates or restrains the effect of GRF-driven tibial rotation loading during cutting. The 45° cutting motions with forefoot/rearfoot strikes were captured simultaneously with GRF and FM data from 23 healthy males. The FM- and GRF-driven tibial rotation moments were calculated. Time-series correlation between FM- and GRF-driven tibial rotation moments and the orientation relationship among those moment vectors was investigated. The FM-driven tibial rotation moment negatively correlated with the GRF-driven one within the first 10% of stance phase. The peak regression slope value was −0.34 [SD 0.33] for forefoot and −1.64 [SD 1.76] for rearfoot strikes, showing significant difference from zero (SPM one-sample t-test, p<0.05). The FM-driven tibial “external” rotation moment counteracted the GRF-driven tibial “internal” rotation moment within first 10% of the stance phase in most trials, suggesting that the FM-driven tibial rotation moment potentially diminishes the effect of GRF-driven one and may reduce ACL injury risk during cutting.

GIVING ATHLETES A VOICE TO IMPROVE PRIMARY OA PREVENTION PRACTICE IN SPORT

Purpose: Previous knee joint injury, such as an anterior cruciate ligament (ACL) rupture, is one of the strongest risk factors for the onset of knee osteoarthritis (OA). One in two people who sustain an ACL injury will develop knee OA before the age of 40. ACL injuries are common in high-risk sports that require athletes to jump, land and pivot, with women at 2-8 times greater risk than men. Primary OA prevention strategies, such as exercise-based ACL injury prevention programs, can reduce ACL injury among women by 67%.

Electromyographic Assessment of Anterior Cruciate Ligament Injury Risk in Male Tennis Players: Which Role for Visual Input? A Proof-of-Concept Study.

Anterior cruciate ligament (ACL) injury incidence is often underestimated in tennis players, who are considered as subjects conventionally less prone to knee injuries. However, evaluation of the preactivation of knee stabilizer muscles by surface electromyography (sEMG) showed to be a predictive value in the assessment of the risk of ACL injury. Therefore, this proof-of-concept study aimed at evaluating the role of visual input on the thigh muscle preactivation through sEMG to reduce ACL injury risk in tennis players. We recruited male, adult, semiprofessional tennis players from July to August 2020. They were asked to drop with the dominant lower limb from a step, to evaluate—based on dynamic valgus stress—the preactivation time of the rectus femoris (RF), vastus medialis, biceps femoris, and medial hamstrings (MH), through sEMG. To highlight the influence of visual inputs, the athletes performed the test blindfolded and not blindfolded on both clay and grass surfaces. We included 20 semiprofessional male players, with a mean age 20.3 ± 4.8 years; results showed significant early muscle activation when the subject lacked visual input, but also when faced with a less-safe surface such as clay over grass. Considering the posteromedial–anterolateral relationship (MH/RF ratio), tennis players showed a significant higher MH/RF ratio if blindfolded (22.0 vs. 17.0% not blindfolded; p < 0.01) and percentage of falling on clay (17.0% vs. 14.0% in grass; p < 0.01). This proof-of-principle study suggests that in case of absence of visual input or falling on a surface considered unsafe (clay), neuro-activation would tend to protect the anterior stress of the knee. Thus, the sEMG might play a crucial role in planning adequate athletic preparation for semiprofessional male athletes in terms of reduction of ACL injury risk.

Can Biomechanical Testing After Anterior Cruciate Ligament Reconstruction Identify Athletes at Risk for Subsequent ACL Injury to the Contralateral Uninjured Limb?

Background: Athletes are twice as likely to rupture the anterior cruciate ligament (ACL) on their healthy contralateral knee than the reconstructed graft after ACL reconstruction (ACLR). Although physical testing is commonly used after ACLR to assess injury risk to the operated knee, strength, jump, and change-of-direction performance and biomechanical measures have not been examined in those who go on to experience a contralateral ACL injury, to identify factors that may be associated with injury risk. Purpose: To prospectively examine differences in biomechanical and clinical performance measures in male athletes 9 months after ACLR between those who ruptured their previously uninjured contralateral ACL and those who did not at 2-year follow-up and to examine the ability of these differences to predict contralateral ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: A cohort of male athletes returning to level 1 sports after ACLR (N = 1045) underwent isokinetic strength testing and 3-dimensional biomechanical analysis of jump and change-of-direction tests 9 months after surgery. Participants were followed up at 2 years regarding return to play or at second ACL injury. Between-group differences were analyzed in patient-reported outcomes, performance measures, and 3-dimensional biomechanics for the contralateral limb and asymmetry. Logistic regression was applied to determine the ability of identified differences to predict contralateral ACL injury. Results: Of the cohort, 993 had follow-up at 2 years (95%), with 67 experiencing a contralateral ACL injury and 38 an ipsilateral injury. Male athletes who had a contralateral ACL injury had lower quadriceps strength and biomechanical differences on the contralateral limb during double- and single-leg drop jump tests as compared with those who did not experience an injury. Differences were related primarily to deficits in sagittal plane mechanics and plyometric ability on the contralateral side. These variables could explain group membership with fair to good ability (area under the curve, 0.74-0.80). Patient-reported outcomes, limb symmetry of clinical performance measures, and biomechanical measures in change-of-direction tasks did not differentiate those at risk for contralateral injury. Conclusion: This study highlights the importance of sagittal plane control during drop jump tasks and the limited utility of limb symmetry in performance and biomechanical measures when assessing future contralateral ACL injury risk in male athletes. Targeting the identified differences in quadriceps strength and plyometric ability during late-stage rehabilitation and testing may reduce ACL injury risk in healthy limbs in male athletes playing level 1 sports. Clinical Relevance: This study highlights the importance of assessing the contralateral limb after ACLR and identifies biomechanical differences, particularly in the sagittal plane in drop jump tasks, that may be associated with injury to this limb. These factors could be targeted during assessment and rehabilitation with additional quadriceps strengthening and plyometric exercises after ACLR to potentially reduce the high risk of injury to the previously healthy knee. Registration: NCT02771548 (ClinicalTrials.gov identifier).

Using Behavioral Skills Training With Video Feedback to Prevent Risk of Injury in Youth Female Soccer Athletes.

Female athletes are at a greater risk for anterior cruciate ligament (ACL) injuries than males. Current training programs for ACL injury reduction focus on muscle strengthening, appropriate movement patterns, and balance training. However, there is limited research on effective strategies to teach youth female soccer athletes how to properly perform desired movements associated with a decreased risk of ACL injuries. Behavioral skills training (BST) programs have been shown to be effective in teaching a wide variety of skills, but research on applications to sports is limited. This study evaluated a BST package for teaching a stepwise agility program to 3 youth female soccer athletes that consisted of verbal instructions, modeling, rehearsal, and feedback, which included video replay. Results showed a significant improvement in the number of steps the participants performed correctly relative to baseline, as well as maintenance of skills at follow-up. Implications for coaches and athletes, as well as limitations and directions for future research, are discussed.

Return to Play and Career Length After Anterior Cruciate Ligament Reconstruction Among Canadian Professional Football Players

Background: For many athletes, a tear of the anterior cruciate ligament (ACL) represents a significant injury that requires a prolonged period away from the sport with substantial rehabilitation. Hypothesis: There will be no difference in return to play (RTP) and career length after hamstring tendon (HT) ACL reconstruction in a group of Canadian Football League professional players as compared with what has been already been reported in the literature among professional football players. Study Design: Case-control study; Level of evidence, 3. Methods: Data on athletes who sustained an ACL injury were collected by team physicians and head athletic trainers from 2002 to 2017 from 2 Canadian Football League teams. Patient details included age at the time of injury, initial injury date, position, practice versus game injury, and primary versus rerupture with injury-specific data, such as affected limb, concomitant injuries, graft choice, and procedure performed. RTP rates and career length data were collected through publically available internet sources. Comparisons between the non-RTP and RTP groups were made with independent-sample t tests. Binomial logistic regression was performed to determine variables (ie, games preinjury, graft type, meniscal injury, collateral ligament injury) that contributed to players not being able to RTP. Results: A total of 44 ACL reconstructions were performed over the study period (HT, n = 32 [72.7%]; bone–patellar tendon–bone [BPTB], n = 8 [18.2%]; allograft, n = 4 [9.1%]). Overall, 69.8% (n = 30) were able to RTP in at least 1 game, while 30.2% (n = 13) did not return. Mean time to return was 316.1 days (range, 220-427 days), or 10.4 months. For those players who did RTP, mean career length after ACL reconstruction was 2.8 seasons, or 34.4 games. The majority (56.8%) of injuries occurred early in the season. Breakdown by graft type demonstrated RTP rates among HT, BPTB, and allograft of 64.5% (n = 20), 87.5% (n = 7), and 75% (n = 3), respectively. Career length among HT, BPTB, and allograft was 2.9, 2.4, and 3 seasons. Logistic regression analysis found only concomitant medial collateral ligament (MCL) injuries to be a negative predictor for RTP. Meniscal injuries were associated with a decreased RTP rate and career length, but this was not statistically significant. Conclusion: The RTP rates after ACL reconstruction in this study are similar to those reported in National Football League players. A concomitant injury to the MCL injury was a negative predictor of RTP. Meniscal injuries demonstrated a trend for decreased RTP rate and career length, but this was not a significant predictor. A large portion of injuries occur early in the season, and further study should be done to examine potential preventative strategies to reduce ACL injuries.

PROSPECTIVE MEASURES OF INTRA-REGION BRAIN REGULARITY DIFFERENTIATES ACL INJURED AND UNINJURED ATHLETES

Background:Anterior cruciate ligament (ACL) injuries are debilitating for athletes. While numerous motor and biomechanical deficits contribute to the inciting ACL injury mechanism, the limited knowledge about the underlying neural drivers of these deficits has impeded intervention development to reduce ACL injury rates. A prospective investigation using functional magnetic resonance imaging (fMRI) in female soccer players revealed decreased connectivity between the primary somatosensory cortex and cerebellum for athletes that went on to ACL injury athletes compared to their healthy teammates. Although information about inter-region connectivity patterns is informative, this finding does elucidate the individual, intra-region brain activity that may be further underlie ACL injury mechanisms.Hypothesis/Purpose:The purpose of this study was to prospectively investigate the intra-region regularity of the blood oxygen-level dependent (BOLD) signal activity in 25 knee-related regions of interests (ROI) between athletes who sustained an ACL injury and matched controls.Methods:Adolescent female soccer athletes were evaluated using fMRI to capture resting-state brain connectivity prior to their competitive season. Two of these athletes (16.0±0yrs, 169.0±2.8cm, 60.1±8.3kg) later experienced an ACL injury and were matched to eight uninjured teammates (15.9±0.8yrs, 164.0±4.9cm, 58.3±7.6kg). Standard fMRI data processing was used to determine resting-state BOLD signal activity in 25 knee-related ROIs. Sample entropy (SampEn) was then used to quantify the regularity of each individual ROI. A lower SampEn value indicates a ROI’s BOLD signal activity was more regular (predictable) and a higher value indicates a signal’s activity was more irregular (unpredictable). T-tests—with a Bonferroni correction for the familywise error rate (p < .002)—were used to compare SampEn values between both groups for all 25 ROIs.Results:ACL injured athletes (M = 0.35±0.01) exhibited higher SampEn values in the left primary motor cortex than matched, uninjured athletes (M = 0.29±0.02; t(8)=4.62, p=.0017, d=3.65).Conclusion:Athletes who sustained an ACL injury exhibited less regularity in BOLD signal activity of the left primary motor cortex. As the primary motor cortex serves as the final destination in the brain before efferent information is sent to the spinal cord to initiate movement, decreased BOLD signal regularity in this region may alter such cortical-spinal transmission. Considering ACL injuries often occur during unpredictable environments, irregular activity of motor cortex activity may dampen an athlete’s ability to sustain a safe knee position. These findings may help to guide development of brain-driven biofeedback training to promote adaptive neuroplasticity that ‘pushes’ the motor cortex towards more regular activity.Figure 1.Shown above is the location of the left primary motor cortex (indicated by the black circle to the left). In Panel A, a BOLD signal from an athlete who went on to injure her ACL is presented. In Panel B, a BOLD signal from an athlete who did not injure her ACL is shown.

Generalized joint hypermobility in siblings with anterior cruciate ligament injuries and matched unrelated healthy siblings.

Anterior cruciate ligament (ACL) ruptures are common knee injuries, and siblings of individuals with an ACL injury may be at higher risk of ACL injury. Generalized hypermobility may be a familial factor predisposing siblings to ACL injury and may also relate to faulty lower limb alignment. There is a need to determine whether the interaction between hypermobility, family history, and faulty alignment makes siblings with hypermobility at higher risk for ACL injury so that appropriate preventative measures can be taken. This study therefore aimed to (a) compare the prevalence of generalized hypermobility and faulty limb alignment in siblings with and without injury and (b) assess the relationship between generalized hypermobility and lower limb alignment. In this case-controlled study, 24 siblings with ACL injuries from 10 families were matched with 24 healthy uninjured siblings from 10 unrelated families. Generalized hypermobility was assessed using Beighton's criteria. Chi-square analyses compared generalized hypermobility and lower limb alignment between siblings and sibling pairs with and without injuries. Spearman's rho was used to assess correlations between generalized hypermobility and lower limb alignment. There were significant differences between the number of injured and uninjured siblings demonstrating generalized hypermobility when tallied individually (p = .003) and in same-family sibling pairs (p = .019). Significant (or close) differences were found between siblings for knee hyperextension (p < .001), knee valgus (p = .01), and foot pronation (p = .002) and for sibling pairs sharing knee hyperextension (p < .001), knee valgus (p = .06), and foot pronation (p = .06). Generalized hypermobility correlated with knee hyperextension (rs = .722; p < .001), knee valgus (rs = .385; p = .007), and foot pronation (rs = .328; p = .023). Generalized hypermobility and faulty limb alignment occur significantly more frequently in injured than uninjured families. Screening for both features would assist in identifying at-risk siblings. Prevention programmes reduce ACL injuries by 50-70% and should target hypermobile siblings of the ACL injured.

Evidence-Based Best-Practice Guidelines for Preventing Anterior Cruciate Ligament Injuries in Young Female Athletes: A Systematic Review and Meta-analysis

Background: Injury prevention neuromuscular training (NMT) programs reduce the risk for anterior cruciate ligament (ACL) injury. However, variation in program characteristics limits the potential to delineate the most effective practices to optimize injury risk reduction. Purpose: To evaluate the common and effective components included in ACL NMT programs and develop an efficient, user-friendly tool to assess the quality of ACL NMT programs. Study Design: Systematic review and meta-analysis. Methods: Study inclusion required (1) a prospective controlled trial study design, (2) an NMT intervention aimed to reduce incidence of ACL injury, (3) a comparison group, (4) ACL injury incidence, and (5) female participants. The following data were extracted: year of publication, study design, sample size and characteristics, and NMT characteristics including exercise type and number per session, volume, duration, training time, and implementer training. Analysis entailed both univariate subgroup and meta-regression techniques using random-effects models. Results: Eighteen studies were included in the meta-analyses, with a total of 27,231 participants, 347 sustaining an ACL injury. NMT reduced the risk for ACL injury from 1 in 54 to 1 in 111 (odds ratio [OR], 0.51; 95% CI, 0.37-0.69]). The overall mean training volume was 18.17 hours for the entire NMT (24.1 minutes per session, 2.51 times per week). Interventions targeting middle school or high school–aged athletes reduced injury risk (OR, 0.38; 95% CI, 0.24-0.60) to a greater degree than did interventions for college- or professional-aged athletes (OR, 0.65; 95% CI, 0.48-0.89). All interventions included some form of implementer training. Increased landing stabilization and lower body strength exercises during each session improved prophylactic benefits. A meta-regression model and simple checklist based on the aforementioned effective components (slope = −0.15, P = .0008; intercept = 0.04, P = .51) were developed to allow practitioners to evaluate the potential efficacy of their ACL NMT and optimize injury prevention effects. Conclusion: Considering the aggregated evidence, we recommend that ACL NMT programs target younger athletes and use trained implementers who incorporate lower body strength exercises (ie, Nordic hamstrings, lunges, and heel-calf raises) with a specific focus on landing stabilization (jump/hop and hold) throughout their sport seasons. Clinical Relevance: Clinicians, coaches, athletes, parents, and practitioners can use the developed checklist to gain insight into the quality of their current ACL NMT practices and can use the tool to optimize programming for future ACL NMT to reduce ACL injury risk.

Meta-analysis of meta-analyses of anterior cruciate ligament injury reduction training programs.

Several meta-analyses have been published on the effectiveness of anterior cruciate ligament (ACL) injury prevention training programs to reduce ACL injury risk, with various degrees of risk reduction reported. The purpose of this research was to perform a systematic review and meta-analysis of overlapping meta-analyses evaluating the effectiveness of ACL injury prevention training programs so as to summarize the amount of reduction in risk for all ACL and non-contact ACL injuries into a single source, and determine if there were sex differences in the relative efficacy of ACL injury prevention training programs. Five databases (Medline, PubMed, Embase, CINAHL, and Cochrane) were searched to identify meta-analyses that evaluated the effectiveness of ACL injury prevention training programs on ACL injury risk. ACL injury data were extracted and the results from each meta-analysis were combined using a summary meta-analysis based on odds ratios (OR). Eight meta-analyses met eligibility criteria. Six of the eight only included data for female athletes. Summary meta-analysis showed an overall 50% reduction (OR = 0.5 [0.41-0.59]; I2 = 15%) in the risk of all ACL injuries in all athletes and a 67% reduction (OR = 0.33 [0.27-0.41]; I2 = 15%) for non-contact ACL injuries in females. This paper combines all previous meta-analyses into a single source and shows conclusive evidence that ACL injury prevention programs reduce the risk of all ACL injuries by half in all athletes and non-contact ACL injuries by two-thirds in female athletes. There is insufficient data to make conclusions as to the effectiveness of ACL injury prevention programs in male athletes. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2696-2708, 2018.

Change-of-Direction Biomechanics: Is What's Best for Anterior Cruciate Ligament Injury Prevention Also Best for Performance?

Change-of-direction maneuvers (e.g., side-step cutting) are an important aspect of performance in multi-directional sports, but these maneuvers are also associated with anterior cruciate ligament (ACL) injury. Despite this, the impact of biomechanics on ACL injury risk and performance is often examined in isolation. The purpose of this review was to examine the alignment between biomechanical recommendations for ACL injury prevention and performance with regard to change-of-direction maneuvers. Several studies linking change-of-direction biomechanics to both ACL injury risk and performance were examined. A degree of overlap was identified between biomechanical strategies that could both reduce ACL injury risk and enhance performance during change-of-direction maneuvers. A fore-foot footfall pattern along with trunk rotation and lateral flexion in the intended cutting direction were identified as biomechanical strategies that could both reduce potentially hazardous knee joint moments and enhance change-of-direction speed. Minimizing knee valgus during change-of-direction maneuvers may also reduce ACL injury risk, with this biomechanical strategy found to have no impact on performance. Certain biomechanical strategies proposed to reduce ACL injury risk were linked to reduced change-of-direction performance. A narrow foot placement and "soft" landings with greater knee flexion were identified as ACL injury prevention strategies that could have a negative impact on performance. The findings of this review emphasize the need to consider both ACL injury risk and performance when examining the biomechanics of change-of-direction maneuvers.

Effects of Increased Gluteus Muscle Activation on Hip and Trunk Kinematics during Single-leg Landing

The gluteus maximus (GM) has a triplanar function at the hip joint. It was hypothesized that increased GM activation before and after foot contact (FC) on landing would affect triplanar hip and trunk kinematics and anterior cruciate ligament (ACL) injury risk. PURPOSE: To examine how increased GM activation before and after FC affect hip angles and trunk inclination during single-leg landing. METHODS: A double-leg drop jump from a 30-cm box, followed by single-leg landing onto a force plate, was performed by 13 males and 15 females in both control (CC) and experimental conditions (EC). In EC, transcutaneous electrical stimulation was applied to increase GM activation immediately before FC and during single-leg landing. Kinetic and kinematic data were collected using a force plate and 3-dimensional electromagnetic motion tracking system, respectively. Hip joint angles and sacrum and thorax inclination angles in space on FC, peak ground reaction force (GRFpk), and peak knee extensor moment (KEMpk) during single-leg landing were calculated. Comparisons were performed using two-way (sex×conditions) repeated measures analysis of variance with a significance level < .05. RESULTS: The hip joint exhibited more abduction (EC vs. CC at FC, GRFpk, and KEMpk, respectively: -13.2 ± 7.8° vs. -9.5 ± 6.3°, -8.9 ± 7.7° vs. -4.9 ± 6.8°, -3.3 ± 8.9° vs. -.2 ± 6.5°) and external rotation (-14.8 ± 8.5° vs. -9.8 ± 9.9°, -8.0 ± 3.6° vs. -3.6 ± 9.7°, -6.1 ± 9.7° vs. -1.6 ± 11.2°) at all time points in EC than in CC. The sacrum showed more lateral inclination toward the supporting leg at all time points (14.3 ± 6.4° vs. 11.1 ± 6.4°, 12.1 ± 6.4° vs. 9.0 ± 6.1°, 8.9 ± 7.1° vs. 6.7 ± 6.2°) and more erect position at KEMpk in EC (-1.0 ± 10.6°) than at CC (-4.6 ± 10.5°). No significant differences were observed in thoracic inclination angles. No significant interactions were observed among all variables. CONCLUSIONS: Increased GM before and after FC on single- leg landing may have positive effects on frontal and transverse plane hip motion to reduce ACL injury risk. However, excessive GM activation may result in excessive trunk lean toward the supporting leg and more erect position, which increase risk for ACL loading. Thus, appropriate GM activation is necessary to protect the ACL during single-leg landing.

Effect of Hip-Focused Injury Prevention Training for Anterior Cruciate Ligament Injury Reduction in Female Basketball Players: A 12-Year Prospective Intervention Study

Background: Programs to prevent anterior cruciate ligament (ACL) injuries in female basketball players are scarce. Also, ACL injury prevention training that focuses on hip joint function has not been reported. Purpose: To determine the effectiveness of a hip-focused ACL injury prevention program in female basketball players. Study Design: Cohort study; Level of evidence, 2. Methods: A prospective intervention study was conducted for 12 years. Incidence rates of ACL injuries were collected in the first 4 years (observation period) from college female basketball players. After the observation period, a hip-focused ACL injury prevention program was implemented for 8 years (intervention period). A total of 309 players (mean ± SD age, 19.6 ± 1.2 years; height, 163.7 ± 5.6 cm; weight, 59.1 ± 5.1 kg; body mass index, 22.0 ± 1.4) were tracked in the observation period and compared with 448 players (age, 19.6 ± 1.1 years; height, 162.6 ± 5.8 cm; weight, 58.0 ± 5.7 kg; body mass index, 21.9 ± 1.5) who participated in the intervention period. Athlete-exposures (AEs), ACL numbers and mechanisms of injury (MOIs), relative risk (RR), absolute risk reduction (ARR), numbers needed to treat (NNT), and compliance were analyzed. Results: There were 16 ACL injuries (13 noncontact MOIs) in the 4-year observation period, whereas 9 ACL injuries (8 noncontact MOIs) were recorded in the 8-year intervention period. The overall ACL injury incidence was 0.25/1000 AEs in the 4-year observation period compared with 0.10/1000 AEs in the 8-year intervention period, respectively. Compared with the 4-year observation period, significant RR reduction was observed (0.38; 95% CI, 0.17-0.87; P = .017) with ARR and NNT of 0.032 (95% CI, 0.027-0.037) and 31.6 (95% CI, 27.1-37.7), respectively, in the 8-year intervention period. The noncontact ACL injury incidence was 0.21 per 1000 AEs during the 4-year observation period compared with 0.08/1000 AEs in the 8-year intervention period, which also showed significant RR reduction (0.37; 95% CI, 0.15-0.92; P = .026), with ARR and NNT of 0.024 (95% CI, 0.020-0.029) and 41.3 (95% CI, 34.6-51.3), respectively. The mean compliance rate during the intervention periods (8 years) was 89%. Conclusion: A hip-focused injury prevention program demonstrated significant reduction in the incidence of ACL injury in female collegiate basketball players.

Limited Evidence Suggests a Protective Association Between Oral Contraceptive Pill Use and Anterior Cruciate Ligament Injuries in Females: A Systematic Review.

Context:Female athletes aged 14 to 18 years are at particular risk for anterior cruciate ligament (ACL) injuries. Hormonal factors are thought to predispose them to this injury. Oral contraceptive pills (OCPs) might reduce ACL injury risk, although the literature appears controversial.Objective:To evaluate the association between OCP use and ACL injuries in women. The secondary objective was to determine the rates of ACL injuries in the pre- and postovulatory phases of the menstrual cycle in OCP and non-OCP (NOCP) users.Data Sources:Searches were performed across 4 reference databases (PubMed, CINAHL, Embase, Cochrane), abstracts from 6 specialty societies, ClinicalTrials.gov, and reference lists of relevant papers.Study Selection:We included studies investigating the association between OCP use and ACL injuries in females of any age or the distribution of ACL injuries across the menstrual cycle in OCP and NOCP users.Study Design:Systematic review.Level of Evidence:Level 3.Data Extraction:Data regarding study design, population characteristics, OCP details, outcome definitions, analytic methods, and results were extracted from the included studies. The methodological quality of each study was assessed using the Newcastle-Ottawa scale.Results:The search yielded 1305 citations, of which 7 retrospective observational studies met the inclusion criteria. Two large case-control studies with higher methodological quality suggested that OCP use may reduce the risk of sustaining an ACL injury. Five comparative studies examining injury distribution across the menstrual cycle in OCP and NOCP users had conflicting findings, were heterogeneous, and were limited by low methodological quality.Conclusion:The evidence suggests OCP use may reduce the risk of ACL injury; however, no conclusions can be drawn regarding differences in risk of ACL injuries between OCP and NOCP users across the menstrual cycle. Studies were limited by small sample sizes, heterogeneity, and methodological concerns.

EFFECTS OF A PREVENTION PROGRAM FOCUSED ON HIP JOINT FUNCTION ON THE INCIDENCE OF ANTERIOR CRUCIATE LIGAMENT INJURIES IN FEMALE BASKETBALL PLAYERS

BackgroundPrevious meta-analyses have revealed that effective programs to prevent anterior cruciate ligament (ACL) injuries in female basketball players have not been established.ObjectiveTo investigate the effects of an ACL injury prevention...

Mechanisms, prediction, and prevention of ACL injuries: Cut risk with three sharpened and validated tools

Economic and societal pressures influence modern medical practice to develop and implement prevention strategies. Anterior cruciate ligament (ACL) injury devastates the knee joint leading to short term disability and long term sequelae. Due to the high risk of long term osteoarthritis in all treatment populations following ACL injury, prevention is the only effective intervention for this life-altering disruption in knee health. The "Sequence of Prevention" Model provides a framework to monitor progress towards the ultimate goal of preventing ACL injuries. Utilizing this model, our multidisciplinary collaborative research team has spent the last decade working to delineate injury mechanisms, identify injury risk factors, predict which athletes are at-risk for injury, and develop ACL injury prevention programs. Within this model of injury prevention, modifiable factors (biomechanical and neuromuscular) related to injury mechanisms likely provide the best opportunity for intervention strategies aimed to decrease the risk of ACL injury, particularly in female athletes. Knowledge advancements have led to the development of potential solutions that allow athletes to compete with lowered risk of ACL injury. Design and integration of personalized clinical assessment tools and targeted prevention strategies for athletes at high risk for ACL injury may transform current prevention practices and ultimately significantly reduce ACL injury incidence. This 2016 OREF Clinical Research Award focuses on the authors' work and contributions to the field. The author's acknowledge the many research groups who have contributed to the current state of knowledge in the fields of ACL injury mechanisms, injury risk screening and injury prevention strategies. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1843-1855, 2016.