Anterior Cruciate Ligament Injuries in Female Athletes: Part 2, A Metaanalysis of Neuromuscular Interventions Aimed at Injury Prevention. Am J Sports Med

Cincinnati Children's Hospital, 3333 Burnet Avenue, MLC 10001, Cincinnati, OH 45229, USA.
The American Journal of Sports Medicine (Impact Factor: 4.36). 03/2006; 34(3):490-8. DOI: 10.1177/0363546505282619
Source: PubMed


Female athletes have a 4 to 6 times higher incidence of anterior cruciate ligament injury than do male athletes participating in the same landing and pivoting sports. This greater risk of anterior cruciate ligament injury, coupled with a geometric increase in participation (doubling each decade), has led to a significant rise in anterior cruciate ligament injuries in female athletes. The gender gap in anterior cruciate ligament injury, combined with evidence that the underpinnings of this serious health problem are neuromuscular in nature, leads to the development of neuromuscular interventions designed to prevent injury. A systematic review of the published literature yielded 6 published interventions targeted toward anterior cruciate ligament injury prevention in female athletes. Four of 6 significantly reduced knee injury incidence, and 3 of 6 significantly reduced anterior cruciate ligament injury incidence in female athletes. A meta-analysis of these 6 studies demonstrates a significant effect of neuromuscular training programs on anterior cruciate ligament injury incidence in female athletes (test for overall effect, Z = 4.31, P < .0001). Examination of the similarities and differences between the training regimens gives insight into the development of more effective and efficient interventions. The purpose of this "Current Concepts" review is to highlight the relative effectiveness of these interventions in reducing anterior cruciate ligament injury rates and to evaluate the common training components between the training studies. In addition, the level of rigor of these interventions, the costs and the difficulty of implementation, the compliance with these interventions, and the performance benefits are discussed. This review summarizes conclusions based on evidence from the common components of the various interventions to discuss their potential to reduce anterior cruciate ligament injury risk and assess their potential for combined use in more effective and efficient intervention protocols.

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    • "Importantly, anthropometry or strength does not appear to explain the sex differences in agility (Brughelli et al., 2008), at-risk movement behavior (Beutler et al., 2009; Herman et al., 2008; Mizner et al., 2008) or LED-test performance (Lyle et al., 2013). In addition, exercise interventions that only include muscle strengthening have not been shown to reduce ACL injury rates (Hewett et al., 2006). Instead, intervention programs shown to reduce injury rates in females incorporate multiplanar jumping and landing and agility tasks (Gilchrist et al., 2008; Kiani et al., 2010; Mandelbaum et al., 2005; Olsen et al., 2005). "
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    ABSTRACT: Controlling dynamic interactions between the lower limb and ground is important for skilled locomotion and may influence injury risk in athletes. It is well known that female athletes sustain anterior cruciate ligament (ACL) tears at higher rates than male athletes, and exhibit lower extremity biomechanics thought to increase injury risk during sport maneuvers. The purpose of this study was to examine whether lower extremity dexterity (LED) - the ability to dynamically control endpoint force magnitude and direction as quantified by compressing an unstable spring with the lower limb at submaximal forces - is a potential contributing factor to the "at-risk" movement behavior exhibited by female athletes. We tested this hypothesis by comparing LED-test performance and single-limb drop jump biomechanics between 14 female and 14 male high school soccer players. We found that female athletes exhibited reduced LED-test performance (p=0.001) and higher limb stiffness during landing (p=0.008) calculated on average within 51ms of foot contact. Females also exhibited higher coactivation at the ankle (p=0.001) and knee (p=0.02) before landing. No sex differences in sagittal plane joint angles and center of mass velocity at foot contact were observed. Collectively, our results raise the possibility that the higher leg stiffness observed in females during landing is an anticipatory behavior due in part to reduced lower extremity dexterity. The reduced lower extremity dexterity and compensatory stiffening strategy may contribute to the heightened risk of ACL injury in this population.
    Journal of Biomechanics 11/2013; 47(2). DOI:10.1016/j.jbiomech.2013.10.038 · 2.75 Impact Factor
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    • "Despite the modest success of anterior cruciate ligament(ACL) injury prevention efforts (Hewett et al., 2006; Yoo et al., 2010), the precise injury mechanism(s) and most appropriate factors to be targeted via these efforts remain unclear (Griffin et al., 2006), and injury surveillance over nearly two decades indicates that ACL injury rates have not changed (Agel et al., 2005; Arendt and Dick, 1995; Hootman et al., 2007). However, numerous investigations have established that anterior tibial translation and shear force, and knee valgus motion and moment result in ACL loading (DeMorat et al., 2004; Li et al., 1999; Markolf et al., 1995; Withrow et al., 2006), thus minimizing these ACL loading mechanisms would seemingly limit ACL injury risk. "
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    ABSTRACT: Greater hamstring musculotendinous stiffness is associated with lesser anterior cruciate ligament loading mechanisms during both controlled joint perturbations and dynamic tasks, suggesting a potential protective mechanism. Additionally, lesser hamstring stiffness has been reported in females, potentially contributing to their greater risk of anterior cruciate ligament injury. However, the factors which contribute to high vs. low stiffness are unclear. Muscle geometry and architecture influence force production and may, therefore, influence stiffness. The purpose of this investigation was to evaluate the contributions of geometric and architectural muscle characteristics to hamstring stiffness. Thirty healthy individuals (15 males, 15 females) volunteered for participation. Biceps femoris long head cross-sectional area, pennation angle, fiber length, tendon stiffness, and posterior thigh fat thickness were assessed via ultrasound imaging, and strength was measured via isometric contraction. Stiffness was assessed via the damped oscillatory technique. Following normalization to anthropometric factors, only strength (r=0.535) and posterior thigh fat thickness (Spearman ρ=-0.305) were correlated with stiffness. Normalized tendon stiffness (0.06 vs. 0.10N/m·kg(-1)) and strength (7.1 vs. 10.0N·kg(-1)) were greater in males, while posterior thigh fat thickness (10.4 vs. 5.0mm) was greater in females. Greater posterior thigh fat thickness may influence stiffness by contributing to greater intramuscular fat and shank segment mass, and lesser muscle per unit mass in the thigh segment. These findings suggest that training designed to increase hamstring strength and decrease fat mass may be beneficial for anterior cruciate ligament injury prevention.
    Clinical biomechanics (Bristol, Avon) 10/2013; 29(1). DOI:10.1016/j.clinbiomech.2013.10.011 · 1.97 Impact Factor
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    • "season . It would be interesting to assess the effects of plyometrics in a longer duration training program . Similarly the study of Hewett et al . ( 1999 ) was also performed for only 6 weeks . It is interesting that for the volleyball players , no ACL injuries were noted either in the control or the intervention groups in both relevant studies ( Hewett et al . , 1999 ; Pfeiffer et al . , 2006 ) . This finding may be attributed to the biomechanics of volleyball not exposing athletes to injury , as there is a low incidence rate of ACL injury in volleyball from epidemiologic studies ( Hootman et al . , 2007 ) ."
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    ABSTRACT: Background Anterior Cruciate Ligament (ACL) injury is frequently encountered in sports. Purpose To analyze the effects of ACL injury prevention programs, on injury rates in female athletes between different sports. Methods A comprehensive literature search was performed in September 2012 using Pubmed Central, Science Direct, CINAHL, PEDro, Cochrane Library, SCOPUS, SPORTDiscus. The key words used were: ‘anterior cruciate ligament’, ‘ACL’, ‘knee joint’, ‘knee injuries’, ‘female’, ‘athletes’, ‘neuromuscular’, ‘training’, ‘prevention’. The inclusion criteria applied were: (1) ACL injury prevention training programs for female athletes; (2) Athlete–exposure data reporting; (3) Effect of training on ACL incidence rates for female athletes. Results 13 studies met the inclusion criteria. Three training programs in soccer and one in handball led to reduced ACL injury incidence. In basketball no effective training intervention was found. In season training was more effective than preseason in ACL injury prevention. A combination of strength training, plyometrics, balance training, technique monitoring with feedback, produced the most favorable results. Conclusion Comparing the main components of ACL injury prevention programs for female athletes, some sports-dependent training specificity issues may need addressing in future studies, related primarily to the individual biomechanics of each sport but also their most effective method of delivery.
    Physical Therapy in Sport 01/2013; 15(3). DOI:10.1016/j.ptsp.2013.12.002 · 1.37 Impact Factor
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