Anterior Cruciate Ligament Injury Risk Research Articles

Pain-related fear induces aberrant drop jump landing biomechanics in healthy and anterior cruciate ligament reconstructed females.

Rupture of the anterior cruciate ligament (ACL) is a prevalent and debilitating injury typically arising from aberrant biomechanics during landing or deceleration tasks. Pain-related fear, a component of kinesiophobia, has been associated with poor functional outcomes and altered movement patterns in individuals with ACL reconstruction (ACLr), however, the influence of pain-related fear on landing mechanics remains unclear. The purpose of this investigation was to examine the effects of pain-related fear on landing movement patterns in a population of ACLr and healthy females. Thirty-two females (15 recreationally active with a history of ACLr and 17 recreationally active with no history of ACLr) took part. Participants performed five trials of a drop jump (DJ) task (Baseline), underwent a pain stimulus (PS) familiarization task utilizing an electrical stimulus to induce pain-related fear, and performed a subsequent round of DJs while under threat of PS (PS-threat). Lower extremity and trunk kinematics, ground reaction force (GRF) data and muscle activation were analyzed. At baseline, ACLr participants scored higher (21 ± 5.5) on the TSK-11 compared to healthy participants (17 ± 3.4) (p = 0.007). For both groups, the PS intervention significantly increased pain-related fear (ACLr p < 0.001; Healthy p < 0.001). When comparing baseline to PS-threat trials, ACLr participants experienced a significant increase in peak GRF (p = 0.005), decreases in hip (p = 0.003) and knee (p = 0.005) flexion, decreased contact time (p = 0.006) and decreased muscle preactivation for all muscles tested (p < 0.05). Healthy participants experienced significant increases in peak GRF (p = 0.014) and decreased hip (p = 0.005) and trunk peak (p = 0.004) flexion. Pain-related fear alters landing biomechanics in healthy and ACLr females. This may implicate pain-related fear as a contributor to movement alterations commonly associated with ACL injury risk. Level III.

Tired of ACL Injures: A Review of Methods and Outcomes of Neuromuscular Fatigue as a Risk Factor for ACL Injuries

Background/Objectives: One potential risk factor that remains especially contentious in the anterior cruciate ligament (ACL) injury literature is the role of neuromuscular fatigue in ACL injury risk. Therefore, the purposes of this review are (i) to present the research and practical concepts of lower extremity neuromuscular fatigue; and (ii) to review the literature relating to neuromuscular fatigue as an ACL injury risk factor and mechanism. Methods: A structured review was performed in the Medline database using a search strategy that included terms such as “anterior cruciate ligament injury” and “knee injuries” combined with terms such as “injury” and “fatigue”. Articles were included if they included young healthy participants (18–35) and made a comparison between non-fatigued and fatigued states that were assessed with at least one lower extremity biomechanical variable associated with ACL injury risk. Results: Overall, there were 67 studies included, accounting for 1440 participants (627 male and 813 female) across a variety of sports and activities. Of these, 53 (79%) reported a post-fatigue change in the kinematics, kinetics, neuromuscular, and/or other (e.g., proprioceptive) outcomes that indicate that the participants would be at an increased risk of an ACL injury. The most common argument against fatigue as a risk factor is that ACL injuries do not tend to occur later in a game or season, when it is assumed that athletes would be most fatigued. Conclusions: The evidence presented in this review suggests that localized neuromuscular fatigue is a risk factor, among multiple factors, for ACL injuries, providing another modifiable risk factor that should be considered when developing ACL injury risk reduction interventions.

Sex-specific analysis of individual and ski geometry-related risk factors for ACL injuries in recreational alpine skiing: A case-control study

Introduction In recreational alpine skiing, female skiers experience knee injuries at twice the rate of male skiers, with the risk of anterior cruciate ligament (ACL) injuries being three times higher in women (Posch et al. 2021). In addition to individual factors such as, e.g., age or skill level, ski geometry parameters may also influence the risk of ACL injuries (Ruedl et al., 2022). Therefore, the aim of this study was to assess sex-specific effects of individual factors and ski geometry parameters on ACL injury risk in recreational skiers. Methods A retrospective questionnaire-based case-control study was conducted during 6 consecutive winter seasons from 2014/15 to 2019/20. According to Ruedl et al. (2022) individual factors as age, body height, skill level and risk-taking behavior were self-reported, while ski geometry data (ski length, side-cut radius, and widths of the tip, waist, and tail) were recorded from each participant’s skis. Additionally, ski length was relativized to body height. Results A total of 1,817 recreational skiers (49.1% female) participated in this study, of whom 21.6% (n=392, 57.9% female) sustained an ACL injury. The risk of ACL injury was 1.6 times higher in females (95% CI: 1.2-2.0). In both sexes, ACL-injured skiers were significantly older, by approximately five years, compared to uninjured controls (females: 42 vs. 37 years; males: 44 vs. 39 years). In females, a more risky behavior was associated with a reduced ACL injury risk (OR 0.7, 95% CI: 0.4-0.9), while in males, more risky behavior increased the risk (OR 3.5, 95% CI: 2.4-5.0). A lower skill level increased ACL injury risk in both females (OR 3.2, 95% CI: 2.4-4.6) and males (OR 2.2, 95% CI: 1.5-3.2). Ski geometry parameters did not differ significantly in females; however, ACL-injured males used skis with significantly narrower mean values of tip, waist, and tail width compared to uninjured controls. Discussion/Conclusion According to the existing literature, our findings indicate a significantly higher risk of ACL injury in females. Increasing age and lower skill levels were associated with a heightened ACL injury risk in both sexes, while a risky behavior might increase ACL injury risk in males only. Ski geometry parameters appear to have no significant impact on ACL injury risk in females, whereas males with ACL injuries tended to use skis with narrower widths. In addition to enhancing skill levels through ski lessons and modifying individual behavior on the slopes to reduce ACL injuries among recreational skiers of both sexes, equipment-related factors could be easily addressed by male skiers when purchasing or borrowing ski equipment. References Posch, M., Schranz, L., Lener, M., Tecklenburg, K., Burtscher, M., &amp; Ruedl, G. (2021). In recreational alpine skiing, the ACL is predominantly injured in all knee injuries needing hospitalisation. Knee Surgery, Sports Traumatology, Arthroscopy, 29(6), 1790–1796. https://doi.org/10.1007/s00167-020-06221-z Ruedl, G., Posch, M., Tecklenburg, K., Schranz, L., Greier, K., Faulhaber, M., Scher, I., &amp; Burtscher, M. (2022). Impact of ski geometry data and standing height ratio on the ACL injury risk and its use for prevention in recreational skiers. British Journal of Sports Medicine, 56, 1104-1109. https://doi.org/10.1136/bjsports-2021-105221

The Effect of Strength Training Targeting Medial Thigh Muscles on Neuromuscular and Biomechanical Risk Factors for Anterior Cruciate Ligament Injury: A Randomized Controlled Trial

BackgroundKnee valgus loading is thought to be an important contributor to noncontact anterior cruciate ligament (ACL) injuries, but the effects of training programs focusing on decreasing knee valgus loading on lower extremity biomechanics with respect to ACL injury risk remain unclear. Thus, this study aimed to examine the effect of strength training designed to strengthen the medial thigh muscles on lower extremity joint kinematics, kinetics and muscle activity during single-leg landing.MethodsA total of 35 healthy participants randomly conducted either exercises targeting medial thigh muscles (intervention group) or exercises that did not target specific lower extremity muscles (control group). Three-dimensional hip, knee, and ankle kinematic/kinetic data and muscle activity for lower extremity muscles were obtained during single-leg landing. Two-way analyses of variance were conducted for each dependent variable to determine the effect of 8-week of strength training targeting medial thigh muscles.ResultsThe intervention group showed decreased knee varus-valgus excursion (P = 0.009), peak valgus moment (P = 0.032), and peak hip internal rotation moment (P = 0.009) but increased gluteus medius activity in the precontact phase (P = 0.012) and vastus medialis-to-vastus lateralis (VM: VL) coactivation ratio in the postcontact phase (P = 0.043). The change in coronal plane knee excursion was negatively correlated with both the change in gluteus medius activity (R2 = 0.321, P = 0.014) and the change in VM: VL coactivation ratio (R2 = 0.276, P = 0.025).ConclusionsStrength training targeting medial thigh muscles can modify the biomechanics associated with ACL injuries; thus, this intervention might be considered when designing ACL injury prevention programs to reduce dynamic knee valgus during sports-related tasks.

The Protective Role of the FIFA 11+ Training Program on the Valgus Loading of the Knee in Academy Soccer Players Across a Season.

Background: Improper neuromuscular control with excessive dynamic valgus loading of the knee has been identified as one of the main anterior cruciate ligament injury risk factors. This study aimed to analyze the impact of the FIFA 11+ training program on the valgus loading of the knee in academy soccer players over a competitive season. Methods: A prospective study was conducted on 85 players. The drop vertical jump test was carried out before the match and at the end of the same match at the beginning and at the end of the season over a period of 11 months. Results: An increase of the varus angle on the right limb was noted between the start and the end of the season at the beginning of the match (-4.7 ± 8.9 versus -6.9 ± 6, p = 0.003) and between the start and the end of the match in values measured at the beginning of the season (-4.7 ± 8.9 versus -7.7 ± 9, p < 0.001). An increase of the flexion angle of both limbs was noted between the start and the end of the season in values measured at the start of the match (left limb 76.8 ± 32.8 versus 98.6 ± 17.2, p < 0.001; right limb 76.4 ± 32.8 versus 96.1 ± 16.1, p < 0.001) and between the start and the end of the season in values measured at the end of the match (left limb 92.8 ± 19.1 versus 98.5 ± 16.3, p = 0.002; right limb 92.6 ± 19.2 versus 96.7 ± 14.5, p = 0.013). Conclusions: A decrease in dynamic valgus angle and an increase in knee flexion angle measured with the DVJ test were noted between the start and the end of the season, suggesting a protective role of the FIFA 11+ training program.

The Impact of Tibial Slope on Anterior Cruciate Ligament Reconstruction Outcomes – University Hospital Study

Anterior cruciate ligament (ACL) injuries are common knee injuries that often require surgical reconstruction to restore knee function and stability. Despite advances in surgical techniques, the failure rate for ACL reconstruction remains approximately 15%, emphasizing the need to understand factors contributing to suboptimal outcomes. One factor that has garnered attention is the tibial slope, particularly the posterior tibial slope (PTS), which may influence ACL injury and graft failure. Biomechanical studies suggest that an increased PTS can elevate anterior tibial translation, potentially increasing stress on the ACL and raising the risk of both primary ACL injury and graft failure. However, the clinical significance of tibial slope in ACL reconstruction outcomes remains debated. This retrospective study investigates whether an increased PTS is associated with a higher likelihood of revision surgery or poor surgical outcomes. A total of 152 patients who underwent primary ACL reconstruction or revision surgery between 2018 and 2022 with at least two years of follow-up were included. Tibial slope measurements were obtained from lateral tibial radiographs, and patients were categorized into three groups based on post-surgical outcomes: Group A (successful return to prior sport levels), Group B (stable knee without return to sport), and Group C (requiring revision surgery). The Mann-Whitney U test was used to compare tibial slope measurements across groups. No significant differences were found in tibial slope between the groups (p &gt; 0.05). Group A had a median tibial slope of 6.08°, Group B had 6.68°, and Group C had 5.85°. These findings suggest that tibial slope may not be a major factor influencing ACL reconstruction success or failure. Other factors, including surgical technique, rehabilitation, and patient-specific characteristics, may play more significant roles. Further research is needed to explore the relationship between tibial slope and ACL ...

Acute Effects of Unplanned and Planned Hop-Landing Training on Neurocognitive Function and Knee Biomechanics.

Athletes with decreased baseline neurocognitive function may experience noncontact anterior cruciate ligament (ACL) injury in unanticipated athletic situations. Many ACL injury prevention programs (IPPs) focus on improving closed-skill movements (eg, planned landing). However, the more open-skill movements (eg, unplanned reactive movements) required in unpredictable sports scenarios are commonly absent from ACL IPPs, and the acute effects of open-skill training on neurocognitive function remain unclear. To investigate the acute effects of unplanned versus planned training on neurocognitive function and knee biomechanics associated with ACL injury risk during the side-step cutting motion. Controlled laboratory study. A total of 32 adult recreational athletes (16 female, 16 male) were randomly assigned to either an unplanned training (UT) group or a control (CON) group. The UT group performed unplanned hop-landing training while the CON group performed planned hop-landing training. Both before and after the training, neurocognitive function was evaluated using the Trail Making Test-part B and Stroop Color and Word Test. Additionally, unanticipated and anticipated side-step cutting tasks were performed while 3-dimensional kinematic and kinetic data for the dominant leg were collected. Neurocognitive test scores and biomechanical variables relevant to ACL injury were analyzed using 2-way repeated-measures analysis of variance to determine the main effects of training, group, and training × group interaction. Trail Making Test-part B and Stroop Color and Word Test scores significantly improved from pre- to posttraining in both groups (P < .001 for both). There was a significant training × group interaction for peak knee abduction angle during the unanticipated side-step cutting task (pre- vs posttraining: -8.81°± 7.23° vs -7.40°± 7.24° [UT group]; -8.23°± 9.40° vs -9.99°± 9.83° [CON group]; P = .02) and for peak vertical ground-reaction force during the anticipated side-step cutting task (pre- vs posttraining: 3.86 ± 0.59 vs 4.08 ± 0.74 percentage body weight [%BW] [UT group]; 3.70 ± 0.62 vs 3.34 ± 0.62 %BW [CON group]; P = .04). Study findings showed a significant training × group interaction for knee abduction angle during the unanticipated side-step cutting task with unplanned training and for vertical ground-reaction force during the anticipated side-step cutting task with planned training. Designing ACL IPPs based on the sport type (ie, open skill or closed skill) may contribute to better preparation.

Individual and Combined Effects of Sport-Related Concussion and Anterior Cruciate Ligament Injury on Neurocognitive and Neuromechanical Reaction Time.

Recent epidemiological data have indicated a potential connection between sport-related concussion (SRC) and elevated anterior cruciate ligament (ACL) injury risk. Limited research exists in which authors have quantified cognitive and motor outcome measures between SRC and ACL injury history. To examine the individual and combined effects of a history of SRC and ACL injury and reconstruction (ACLR) on neurocognitive and neuromechanical function. Cross-sectional study. Research laboratory. Forty-seven recreationally active college individuals with either an injury history of SRC (n = 12), ACLR (n = 12), combination of SRC + ACLR (n = 11), or uninjured controls (n = 12). Participants completed a neurological battery using the C3 Logix application and TRAZER system for neuromechanical reaction time (RT). C3 Logix subtests consisted of the Trail Making Test (TMT) A, B, and B - A; simple and choice RT; and processing speed. TRAZER subtests consisted of simple, Flanker-task, and Stroop-task RT. Participants were categorized into 3 group comparisons of either (i) SRC, ACLR, SRC + ACLR, and controls, (ii) any or no SRC overall, or (iii) any or no ACLR overall. No differences were demonstrated between SRC, ACLR, SRC + ACLR, and controls on TMT (P = .07-.14), neurocognitive (P = .14-.93), or neuromechanical (P = .64-.99) performance. Those with any SRC had slower TMT B - A times (P = .03), while those with any ACLR had slower TMT A (P = .02) times than those with no ACLR. No differences were noted for the TRAZER simple, Flanker, or Stroop RT for any or no SRC and ACLR groups. College students with a combined effect of SRC and ACLR did not differ from other groups on neurocognition and neuromechanical RT. Individuals with a history of SRC or ACLR had a worse TMT, leading to inquiry about potential long-term neurological deficits, despite no differences in those with a combined history.

Strategies for preventing anterior cruciate ligament injuries in athletes: Insights from a scoping review.

Anterior cruciate ligament (ACL) injuries significantly impact young athletes, leading to long-term physical, psychological, and socioeconomic consequences. There is an urgent need to develop effective preventive strategies. This scoping review aims to evaluate modifiable and non-modifiable risk factors for ACL injuries and assess existing preventive strategies. A comprehensive literature search was performed on November 20, 2024, across databases including Embase, PubMed, Web of Science, Google Scholar, and Cochrane Library. Articles published between 2000 and 2024 focusing on ACL injury prevention were included, while editorial content, non-clinical studies, and non-English publications were excluded. The search yielded 322 articles, narrowing down to 94 after deduplication. After title screening, 46 studies progressed to full review, ultimately leading to the inclusion of 14 relevant manuscripts. Key findings indicate that ACL injuries result from various factors, with female athletes being 2.2 times more susceptible. Genetic predispositions linked to collagen-related SNPs and biomechanical patterns, such as landing techniques and knee positioning, were identified as significant contributors. Effective preventive programs integrated strength training, neuromuscular training, and advanced technology, including wearable devices and video analysis. The study reinforces the importance of a personalized, multifaceted approach to ACL injury prevention, focusing on risk stratification and optimizing training strategies alongside technological advancements. Implementing these strategies can significantly mitigate the risk of ACL injuries in high-risk populations.

The Association of Salivary Estradiol Levels with Anterior Cruciate Ligament Stiffness and Laxity

BACKGROUND: Females are three to six times more likely to sustain an anterior cruciate ligament (ACL) injury than males. Researchers have previously identified hormonal fluctuations as a possible intrinsic factor related to the higher incidence of ACL injuries among female athletes. Whether hormonal levels, with or without use of oral contraceptives (OC), influence ligamentous mechanical properties resulting in increased ACL injury risk remains unclear. Furthermore, previous studies have mainly focused on anterior tibial translatory (ATT) laxity, with limited research on changes in ATT tissue compliance/stiffness. The purpose of this study is to investigate the influence of estradiol levels, menstrual cycle phases, with and without use of OC on ATT tissue compliance/stiffness and laxity. METHODS: Fifty-two female participants (age 24-30 years), divided into two groups of 26 each (Group OC using oral contraception, and Group NOC not using oral contraceptive). Data collection was performed on two different dates corresponding to two menstrual cycle phases: follicular or inactive phase (days 1-3) and the ovulation or active pill phase (days 12-14). Estradiol levels via saliva sampling, ATT tissue compliance/stiffness and laxity measures via the GNRB knee arthrometer were collected each testing session. Spearman’s rank-order correlation product-moment correlations were run to determine the relationship between follicular and ovulation phase estradiol and GNRB outputs related to translation and compliance. RESULTS: Estradiol levels showed a significant change between follicular and ovulation phases across both groups combined (p = 0.01). There were weak non-significant correlations between measured estradiol levels and GNRB measures of anterior translation and compliance, (p&gt; 0.05). No significant relationships were found across subjects whether they were on oral contraceptive or not using hormone regulated birth control. CONCLUSION: Estradiol level changes in the follicular and ovulation phases and oral contraceptive use did not significantly influence ACL laxity (anterior tibial translation) or compliance/stiffness. Additional studies on hormonal fluctuations as a potential risk factor for higher female ACL injury are indicated.

Same Same but Different: Why Both Sport-Specific Cutting Tasks and Generic Change-of-Direction Tasks Might Need to Be Considered to Prevent ACL Injury

OBJECTIVES: To compare knee abduction moment (KAM) magnitudes between a generic 180° pivot turn (modified 505 change-of-direction test [m505]) and a handball-specific sidestep cut, to assess ranking consistency, and to examine the resultant ground reaction force (GRF) and its frontal plane moment arm to the knee to comprehend their contributions to KAM. STUDY DESIGN: Observational laboratory study. METHODS: High-level female handball players (n = 45) performed the m505 and the handball-specific sidestep cut. The resultant GRF and its frontal plane moment arm to the knee as well as KAM were obtained and subsequently compared between tasks. Rank correlation coefficients were employed to assess if the variables of both tasks were related. RESULTS: Peak KAM was similar for the m505 and the sidestep cut (median [range], 1.79 [0.95-3.53] Nm/kg vs 1.64 [0.34-3.60] Nm/kg; rb = .25; P = .14). The ranking of the players’ peak KAM differed substantially ( rs = .26; P = .084), suggesting that different tasks could classify the same player with different injury risk. The m505 generated lower resultant GRFs (24 ± 4 N/kg, 95% CI [23, 24] vs 33 ± 9 N/kg, 95% CI [31, 35]; d = 1.30; P&lt;.001) but longer frontal plane moment arms (7.8 ± 1.8 cm, 95% CI [7.3, 8.4] vs 5.4 ± 1.5 cm, 95% CI [5.0, 5.8]; d = 1.36; P&lt;.001) compared to those generated by the sidestep cut. CONCLUSION: A difference in individual anterior cruciate ligament injury risk assessment depending on movement type was revealed. While KAM magnitudes were similar across direction-change tasks, player rankings differed. The contributions of resultant GRF and frontal plane moment arms to peak KAM varied between tasks, underscoring the importance of task-specific and individualized injury prevention. JOSPT Open 2025;3(2):1-9. Epub 4 December 2024. doi:10.2519/josptopen.2024.0076

Does Tibial Plateau Slope and Depth Influence ACL Strain In Vivo?

The anterior cruciate ligament (ACL) is loaded under tension when the tibia translates anteriorly relative to the femur. The shape of the articular surfaces of the tibiofemoral joint may influence the amount of anterior tibial translation under compressive loading. Thus, a steep lateral tibial plateau and a shallow medial plateau are thought to be risk factors for ACL injury. The purpose of this study was to evaluate whether tibial plateau slope and depth influence peak ACL strain during a single-leg jump. We hypothesized that there would be a significant correlation between tibial plateau slope and depth with ACL strain. Descriptive laboratory study. A total of 17 healthy participants (8 male, 9 female) were assessed using magnetic resonance imaging (MRI) and high-speed biplanar radiography to obtain peak ACL strain during a single-leg jump. Two orthopaedic surgeons used the sagittal plane MRI scans to measure the medial and lateral tibial plateau slopes and the medial tibial plateau depth. The intraclass correlation coefficient was used to assess measurement reliability, and the Spearman rank correlation was used to evaluate the relationship between measurements of tibial morphology and peak ACL strain during the single-leg jump. The overall range of intraclass correlation coefficients for intra- and interrater reliability of the medial and lateral tibial plateau slopes and medial plateau depth was 0.59 to 0.97. No significant correlations were found between peak ACL strain and any of the slope or depth measurements. In this cohort of healthy participants, correlations between any of the tibial plateau measurements with peak ACL strain during a single-leg jump were not detected. These findings are consistent with prior work, suggesting that tibial plateau slope and depth may not be linked to risk for ACL rupture. However, it is possible that tibial plateau morphology may interact with other factors to increase ACL injury risk or that individuals with extreme slope angles may produce differing results. This study enhances the knowledge of the loading mechanisms for the ACL and thus improves the understanding of risk factors for ACL injury.

Reducing ACL injury risk: A meta-analysis of prevention programme effectiveness.

The aim of this study was to conduct a meta-analysis of the literature regarding anterior cruciate ligament (ACL) injury prevention programmes (IPPs) in order to assess the effectiveness of ACL prevention programmes based on current high-quality studies. The hypothesis was that the implementation of ACL IPPs significantly reduces the incidence of ACL ruptures compared to standard practice. A meta-analysis of the literature was conducted using the databases PubMed, EMBASE, MEDLINE, CINHAL and Cochrane Central Register of Controlled Trials. The search terms utilized were ACL, injury, knee, control and prevention. The collected data and reported clinical outcomes were independently gathered by three different individuals. After evaluating the heterogeneity of the studies, the DerSimonian-Laird random effects models were employed to determine the pooled risk ratios (RRs) and the risk differences (RDs) regarding ACL Injuries. The RD was utilized to ascertain the number needed to treat. The search strategy identified 743 studies, of which 11 met all inclusion and quality criteria for pooled analysis. The total number of study participants was 16,316. The overall RR of sustaining an ACL injury in the intervention group was 0.36 (95% confidence interval [CI]: 0.23 to 0.57) of the control group, showing a significant reduction in the ACL injury risk of the intervention group (p < 0.001). We identified an RD of -1.4% (95% CI: -2.4% to -0.4%) in favour of the intervention group. The number needed to treat in preventing one ACL rupture was 71. In conclusion, the study clearly demonstrates a significant positive preventive effect of training programmes concerning ACL injuries (p < 0.001). The pooled estimates indicate that such programmes result in a significant reduction of ACL injury risks (p < 0.001). Despite the moderate quality of the included literature, the results exhibit robustness. However, based on the literature examined, no definitive superior training programme could be identified. II.

Hamstring-to-Quadriceps Strength Ratios in Women Team Sport Athletes: A Systematic Review

ABSTRACT Women experience a higher rate of anterior cruciate ligament (ACL) injuries than men. Muscle imbalance, in particular hamstring-to-quadriceps (H:Q) strength ratio, is considered a risk factor for ACL injury. The purpose of this systematic review was to identify isokinetic H:Q strength ratios in women team sport athletes and determine whether cutoff values, determined from research with predominantly males, of &gt;0.6 for conventional ratio (Hamstringconcentric:Quadricepsconcentric [CR]) and &gt;1.0 for functional ratio (Hamstringeccentric:Quadricepsconcentric [FR]) were met. The CR (0.6) was not met for team ([mean ± SD: 0.56 ± 0.08]), field (0.57 ± 0.08), and court (0.56 ± 0.08) sports. Handball presented the highest (0.58 ± 0.07), and softball presented the lowest CRs (0.47 ± 0.06). The FR (1.0) was not met for team (0.69 ± 0.14), field (0.85 ± 0.14), and court (0.65 ± 0.14) sports. Soccer presented the highest (0.85 ± 0.14) and handball the lowest (0.66 ± 0.13) FRs. When assessing hamstring and quadriceps strength balance, women team sport athletes did not meet CR or FR values, which may contribute to increased ACL injury risk. H:Q ratios below cutoff values may indicate compromised hamstring strength. It is recommended practitioners implement strength exercises aimed to improve H:Q ratios.

Clinicodemographic Risk Factors for Anterior Cruciate Ligament Injury: A Prospective 3-Cohort Study on Collegiate Varsity Athletes

Background: Anterior cruciate ligament (ACL) injuries are among the most distressing injuries for collegiate varsity athletes. Identifying easily attainable clinicodemographic risk factors in this subgroup can help screen for high-risk athletes who may benefit from proven ACL injury risk reduction programs. Purpose: To identify clinicodemographic risk factors for noncontact ACL injury among female and male collegiate varsity athletes from 10 different sports. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 777 (276 female and 501 male athletes) collegiate varsity athletes from 3 consecutive seasons had an extended panel of clinicodemographic parameters recorded at their respective preseason physical sessions. The athletes were followed for 1 athletic season for noncontact ACL injuries. Results: Fifteen (6 female and 9 male athletes) athletes suffered a noncontact ACL injury during their season. Among all athletes, previous lower limb surgery and cutting sport participation were significantly associated with an increased risk of noncontact ACL injury. Among female athletes, previous ACL injury and previous lower limb surgery were significant risk factors. No significant clinicodemographic risk factors were identified in male athletes. Female sex was not a significant risk factor for noncontact ACL injury. Conclusion: The clinicodemographic risk factors for noncontact ACL injury identified in this study are easily attainable and may guide preseason screening for ACL injury risk in collegiate varsity athletes. The lack of association of these risk factors in male athletes may highlight the need to focus on other factors such as kinematics for these athletes.

Pressing, pressure and re-aggressing as tactical movement of anterior cruciate ligament injuries in women's soccer.

A better understanding of anterior cruciate ligament (ACL) injury mechanisms in female soccer can guide better research on both prevention programs and late-stage rehabilitation for the return-to-sport process. This narrative review investigates the technical and tactical game situations in female soccer linked to ACL injury mechanisms. Through a literature search, we reviewed scientific literature to identify soccer-specific technical movements and tactical patterns that increase the risk of ACL injuries in female players. Articles were retrieved through Web of Science, SPORTDiscus, ScienceDirect, PubMed, and PubMed Central. Inclusion criteria were: 1) studies on ACL injury mechanisms in women's soccer; 2) studies examining soccer techniques/tactics to identify non-contact injury mechanisms. Gray literature was included to supplement limited indexed data, aiming to stay within author guidelines. Female athletes experience a 2-8 times higher risk of ACL injury than males, with 70% of these injuries being non-contact. Common scenarios leading to these injuries involve ball possession/non-possession phases, tactical actions (pressing, pressure, re-aggression), and technical movements (cutting, changing direction). Tactical aspects, particularly pressing and re-aggression, are key contributors to ACL injury risk regardless of ball possession. In female soccer, ACL injuries are related to non-contact injury mechanisms during technical and tactical situations. The knowledge and study of these situational patterns of play, such as pressing, re-aggression, pressure, and cutting maneuvers, are essential to target prevention strategies and return-to-sport processes objectively.

Impact of the COL1A1 (RS1107946) gene polymorphism on anterior cruciate ligament rupture in professional soccer players

Objectives To describe the allelic frequency of rs1107946, belonging to the COL1A1 gene in professional soccer players and compare these findings with data from continental populations described in the 1000 Genomes database, in order to evaluate the frequency of genotypes highly associated with genetic susceptibility to anterior cruciate ligament (ACL) injuries in the literature. Methods The DNA of the 38 professional soccer players was collected from oral mucosa samples. DNA extraction was performed using the PureLinkTMGenomicDNAMini Kit, according to the manufacturer's protocol. For genotyping and allelic discrimination of the selected SNP (rs1107946), real-time PCR was used with TaqMan® SNP GenotypingAssay specific probes (AppliedBiosystems, Foster City, CA, USA) on the QuantStudio 6 Flex Realtime PCR system. The MMA was consistently identified in all specimens. In 26 of 33 (82%) specimens, the MMA branched directly from the popliteal artery, while in 6, the MMA shared a common trunk with the inferior medial genicular artery (IMGA). The MMA was easily distinguishable from the superior MGA, inferior MGA, and MGA, given its direct course to the medial joint line with terminal branches to the posterior horn of the medial meniscus and deep to the semimembranosus tendon. The MMA exhibited a smaller vessel diameter relative to the genicular arteries. Results Our findings demonstrated that the frequency of the wild-type allele C was 65%, while the frequency of the mutant allele A was 45%, highlighting that despite the wild-type allele, which confers protection against the risk of ACL injury, is predominantly distributed in the sample, the mutant allele is significantly present in the individuals investigated. When comparing our findings with data from continental populations described in 1000 Genomes, we found statistically significant allelic and genotypic distributions (Student's T Test p = 0.021), demonstrating that the athletes investigated have a different genetic profile. In our findings, the individuals studied presented a statistically significant allelic frequency of the mutation when compared to the European population, inferring that the frequency of this mutation is higher in European individuals than in mixed-race individuals from Brazil. Conclusion The prevalence of the rs1107946 polymorphism of the COL1A1 gene in athletes may have an important role in the development of ACL injuries.

The Relationship Between Exogenous Testosterone Use and Risk for Primary Anterior Cruciate Ligament Rupture.

In the United States, testosterone therapy has markedly increased in recent years. Currently, there is a paucity of evidence evaluating the risk of ligamentous injuries in patients taking testosterone replacement therapy (TRT). The purpose of this study was to quantify the association between TRT and the incidence of anterior cruciate ligament (ACL) injuries and the subsequent risk of ACL reconstruction (ACLR) failure. It was hypothesized that individuals receiving TRT would demonstrate an increased risk for index ACL injury and ACL rerupture. Cohort study; Level of evidence, 3. This is a retrospective cohort study utilizing the PearlDiver database. Records were queried between 2011 and 2020 for patients aged 18 to 59 years who filled a testosterone prescription. A matched control group based on age, sex, Charlson Comorbidity Index, tobacco use, diabetes, and hypothyroidism consisted of patients aged 18 to 59 years who had never filled a prescription for exogenous testosterone. International Classification of Diseases, 9th and 10th Revisions and Current Procedural Terminology (CPT) codes were utilized to identify patients with ACL injuries and those undergoing reconstruction. Multivariable logistic regression was used to compare rates of ACL injury at 6 months, 1 year, and 2 years after initiating TRT. ACLR failure was also examined at 1-year intervals for 5 years for individuals filling a TRT prescription. A total of 851,816 patients were enrolled, with 425,908 patients in the TRT and control groups, respectively. The TRT cohort was significantly more likely to experience an ACL tear during 6-month (OR, 2.66; 95% CI, 2.17-3.26), 1-year (OR, 2.46; 95% CI, 2.11-2.86), and 2-year (OR, 2.22; 95% CI, 1.98-2.48) periods. The rate of reconstruction failure did not differ between the 2 cohorts at up to 5 years of follow-up (P > .05). Patients receiving TRT were significantly more likely to sustain a primary ACL rupture but were not at a statistically significant increased risk of reconstruction failure.

Relationship between Cognitive Demands and Biomechanical Indicators Associated with Anterior Cruciate Ligament Injury: A Systematic Review.

Anterior cruciate ligament (ACL) injury during contact sports has a high incidence that has not been reduced despite the immense resources devoted to understanding its aetiology. A neurocognitive approach could increase knowledge of the mechanisms contributing to ACL injury enabling practitioners to address and minimise future risk. To systematically review the influence of manipulating cognitive demands during motor tasks (i.e. degree of uncertainty) on biomechanical variables associated with ACL injury risk. A systematic review was performed according to the Cochrane Handbook for Systematic Reviews of Interventions by searching the major sporting electronic databases. The search strategy included four groups of terms and was conducted by two authors independently. All studies were screened using unique inclusion criteria, with the included studies assessed for risk of bias. Twenty-five studies were identified from 2031 records and included into the review process. During the experimental conditions where cognitive demands were higher, most biomechanical indicators associated with a greater risk of ACL injury during landing and cutting tasks were significantly enhanced compared with conditions with low or no cognitive demands. An increase in task complexity through cognitive load significantly leads to changes in mechanisms associated with ACL injury during single-leg landings and cutting movements. Consequently, coaches and exercise professionals should consider inclusion of dual-task paradigms or uncertainty during injury risk assessment scenarios and injury prevention programs to help identify athletes at risk of ACL injury and reduce ACL injury frequency. This protocol was registered in the PROSPERO database ( https://www.crd.york.ac.uk/PROSPERO ) in May 2022, with the registration number CRD42022315795.

Posterior tibial slope angle in contact versus non-contact anterior cruciate ligament injuries.

Increased Posterior Tibial Slope (PTS) angle has been reported to be a risk factor for primary anterior cruciate ligament (ACL) tears. However, it is unknown whether increased PTS has an associated increased risk for non-contact versus contact ACL injury. The purpose of this study is to determine whether patients with non-contact ACL injury have a higher PTS angle than those with contact ACL injury. A total of 1700 patients who underwent primary ACL reconstruction between January 2011 and June 2023 at a single academic institution were initially included. Electronic medical records were reviewed for demographic information as well as evidence that the patient sustained a contact or non-contact ACL injury. Patients in the contact cohort were propensity score matched to patients in the non-contact cohort by age, sex and BMI. Additionally, patients in the contact cohort were then propensity score matched to a control group of patients with intact ACLs also by age, sex and BMI. One hundred and two patients with contact injury were initially identified and 1598 patients with non-contact injuries were identified. Of the 102, 67 had knee X-rays that were suitable for measurement. These 67 contact injury patients were propensity score matched to 67 noncontact patient and 67 patients with intact ACLs based on age, sex and BMI. There were no significant differences between contact and non-contact cohorts in age (28.7±6.3 vs. 27.1±6.5, p = 0.147), sex (Female: 36.0% vs. 34.3%, p = 0.858), or BMI (26.7±5.6 vs 26.1±3.4, p= 0.475). There was no significant difference in PTS angle between contact versus non-contact ACL injury patients (11.6±3.0 vs.11.6±2.8, p= 0.894). There was a significant difference in PTS between the contact ACL injury and the intact cohort (11.6±3.0 vs. 10.0±3.9, p= 0.010) and the non-contact ACL injury and the intact cohort (11.6±2.8 vs. 10.0±3.9, p = 0.010). There was no significant difference in the degree of PTS between patients who sustained contact versus non-contact ACL injuries. Additionally, there was a significantly increased PTS in both the contact and non-contact ACL injury cohorts compared to patients with intact ACLs.